Module 2 Unit 16 Skin Products

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PART 1

Module 2 Unit 16 Skin Products

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Society of Cosmetic Scientists Distance Learning

Unit 16

Prepared by Grace Abamba Amended by Paul Hebditch and John Woodruff

This material is the property of the SCS and is for the personal use of Jane Barber (Copyright 2013). Prepared at 24/12/2013 17:16:14 Society of Cosmetic Scientists

DIPLOMA/CERTIFICATE IN COSMETIC SCIENCE MODULE 2 UNIT 16

Overview The skin is a common substrate for the major disciplines within cosmetic science. Increased consumer awareness plus the significant advances being made in skin research means that today’s cosmetic formulation scientist requires a working knowledge of the basic principles of skin biology and skincare. Goals This unit will deal with products required for the cleansing, appearance and protection of the skin. Study time The study time for this part of the unit is 13 hours which should be allocated approximately as follows: Text:

10 hours

Activities:

3 ho hours

Acknowledgements We would like to thank the following for their contribution to the revision of this unit: Drom Fragrances International, European Flavours and Fragrances, Fragrance Oils and Mike Salmon. Sections 1 and 2 deal (Part 1) with various formulations which you can prepare for cleansers, toners and moisturisers according to skin types. There is an opportunity to do some practical formulation work in section 1. Before embarking on this practical activity activity,, make sure you have read the instructions carefully and that you have all the all the materials and equipment ready. ready . You will also be asked to visit a high street chemist or supermarket to find out about products on the market. If you have a busy schedule, perhaps you could plan it into your own shopping time. Practical Activities There are a number of practical activities within this Unit and they are located in the Unit itself or online, as indicated by the icon.

2


SKIN PRODUCTS


Overview The skin is a common substrate for the major disciplines within cosmetic science. Increased consumer awareness plus the significant advances being made in skin research means that today’s cosmetic formulation scientist requires a working knowledge of the basic principles of skin biology and skincare. Goals This unit will deal with products required for the cleansing, appearance and protection of the skin. Study time The study time for this part of the unit is 13 hours which should be allocated approximately as follows: Text:

10 hours

Activities:

3 ho hours

Acknowledgements We would like to thank the following for their contribution to the revision of this unit: Drom Fragrances International, European Flavours and Fragrances, Fragrance Oils and Mike Salmon. Sections 1 and 2 deal (Part 1) with various formulations which you can prepare for cleansers, toners and moisturisers according to skin types. There is an opportunity to do some practical formulation work in section 1. Before embarking on this practical activity activity,, make sure you have read the instructions carefully and that you have all the all the materials and equipment ready. ready . You will also be asked to visit a high street chemist or supermarket to find out about products on the market. If you have a busy schedule, perhaps you could plan it into your own shopping time. Practical Activities There are a number of practical activities within this Unit and they are located in the Unit itself or online, as indicated by the icon.

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SKIN PRODUCTS


CONTENTS PART 1 1 Formulating cleansing products 1.1 Cleansing for dry skin Activity 1 Preparation of a cold cream 1.2 Cleansers for normal and combination skins Activity 2 Advantages/disadvantages of toilet soap 1.3 Cleansers for oily skin 1.4 Skin toners Activity 3 Skin toner actives

4 4 5 6 7 11 12 12

2 Formulating moisturising products products 2.1 Moisturisation 2.2 Basic components of a moisterising product Activity 4 Product aesthetics Activity 5 Moisturising products – store checks 2.3 Moisturisers for dry and normal skin 2.4 Moisturisers for combination and oily skins 2.5 Extra protection products: Caring for hands and feet 2.6 Baby skin products: Caring for younger skin

14 14 16 16 17 17 23 23 23

Appendix Guideline formulations for Part 1

25

PART 2 3 Control of body odour and sweating 3.1 Body odour and sweating Activity 6 The causes of body odour Activity 7 Comparison of apocrine and eccrine sweat 3.2 Formulating deodorant and antiperspirant products Activity 8 Advantages and disadvantages of product formats 3.3 Active materials for antiperspirants Activity 9 Deodorant and antiperspirant evaluation

52 52 52 53 54 55 57 58

4 Sun protection 4.1 Sunlight and its effects on the skin Activity 10 Factors which affect light intensity Activity 11 Sunburn symptoms 4.2 Formulating suncare products Activity 12 Properties of suncare products Activity 13 SPF calculation Activity 14 Factors affecting SPF value

61 61 63 68 71 71 75 78

5 Removal of unwanted hair 5.1 Methods of hair removal 5.2 Shaving Activity 15 Wet shaving product properties 5.3 Aftershave products 5.4 Chemical depilatories Activity 16 Properties of a good depilatory product

82 82 83 83 86 86 86

Appendix Guideline formulations for Part 2

89

SUPPLEMENTARY BOOKLET Article 1 Article 2

3


103 107

SKIN PRODUCTS


1 FORMULATING CLEANSING PRODUCTS Aim In this section I aim to discuss the different categories of skin cleansing products on the market and present some examples of raw materials and formulations. Since toners are used for the final stages of the cleansing process, I have also included them in this section. Introduction There is a wide choice of cleansing formulations for the consumer to use. For example, skin can be cleansed with a traditional alkaline bar soap, oil in water or water in oil cream emulsion, or synthetic detergents. The choice of a suitable cleanser depends on the individual’s skin type and whether the person is wearing make-up or not. The consumer can also choose from a wide variety of product forms: bars, liquids, gels, creams, impregnated tissue wipes and aerosol mousses. Notes on the formulations In the remaining two sections, we will look at some guideline formulations which can be found in the appendix. Before we start, it is important that you understand the way they are presented. The information about the formula is divided into up to four columns as shown below. Phase

*INCI name/

Chemical description

% by weight

Function

**q.s.

Manufacture

*International Nomenclature Cosmetic Ingredient (INCI) **as required Note: Please remember that these are only guideline formulations and if you wished to use them, you would need to adapt them to meet your objectives and conduct the usual microbiological, stability and quality control tests. 1.1 Cleansers for dry skin Cleansing creams, lotions and milks can be oil-in-water or water-in-oil emulsions which combine the solvency of water and oils to effect cleansing of the skin. In doing this, they also leave a layer of emollient oil on the skin which keeps it smooth and supple rather than the dryness often left behind by the use of soaps and other synthetic detergent systems. Cleansing creams The original cleansing cream was based on one of the oldest known emulsions and is commonly known as a cold cream. It was traditionally based on a mixture of natural waxes and vegetable oils (beeswax and olive oil) stabilised with borax. At the turn of the century, mineral oil replaced the more unstable vegetable oils as shown in Appendix 1; Formula 1. In addition, mineral oil is excellent for make-up removal. In a cold cream, the proportion of fatty and oily material predominates. When it is applied, one experiences a pleasant cooling sensation which is produced from the slow evaporation of the water contained in the emulsion.

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To obtain different textures and consistencies, part of the mineral oil can be replaced with up to 16% of petrolatum. Further substitution with fatty acid esters such as isopropyl myristate helps the cream to thin down quickly when it is rubbed in, improving its spreading properties; this behaviour is described as thixotropy . In the next activity, you will learn how to formulate a modern cold cream. If you have never made one up before, then it is certainly worth trying out because cold creams provide a good starting point in formulating other emulsion-based products. If you are already f amiliar with such formulations then you may prefer to skip this activity.

ACTIVITY 1 Preparation of a cold cream This activity has been identified as a key activity for this unit. Please go to the online module to complete this activity, so that you can share your ideas and opinions with your fellow learners and benefit from their experience and knowledge in this area.

Cleansing lotions and milks Cleansing milks and lotions can be described as pourable, low viscosity alternatives to cleansing creams. They are applied to the skin with a tissue or cotton wool pad and so are often more economical than creams. In general these products contain Paraffinum liquidum (mineral oil) or vegetable oils such as Simmondsia chinensis (Jojoba) seed oil and fatty acid esters like isopropyl palmitate. Modern formulations are based on non-ionic emulsifiers such as sorbitan esters with their ethoxylated counterparts. Other examples include PEG-free systems such as the alkyl glucosides. This gives the formulator a great deal of flexibility, such that anything from a textured cream to pourable milk can be produced. Stearate soaps are still employed but to a lesser degree. Cetyl alcohol acts as an emollient and, like carbomers, it increases the viscosity of the product. Hydrocolloids such as cellulose derivatives, alginates, xanthan gum and magnesium aluminium silicate may be used to thicken the external phase of oil-in-water emulsions. A cleansing lotion is shown as Formula 02 and a foaming cleansing lotion as Formula 03 in Appendix 1. Rinse-off emulsions (foaming cleansers) Rinse-off emulsions are applied or massaged into the face and rinsed off with water rather than wiped off with a tissue. Some of these products will generate a small amount of lather whilst being washed off and are known as foaming cleansers. Such products incorporate some synthetic detergent to achieve this action. Consumers who enjoy using soap and water will prefer to use the products described in order to avoid the drying effects of soap or detergentbased cleansers.

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Bath Oils People with dry skin may prefer to bathe in bath ‘oils’ and essences, which clean the skin dissolving away the oily grime, leaving the skin feeling soft and moisturised. A number of choices are available on the market: • spreading or floating oils, which remain on the surface of the water • dispersible or blooming oils • soluble oils The ideal properties of bath oil is that it does not foam, that it contains effective perfume solubilisers, is mild to the skin and that it does not leave the bath too slippery. The main constituents are water-insoluble materials such as vegetable or mineral oil combined with nonionic surfactants and fragrance or essential oils. Formula 04 gives an example of a spreading bath oil. The dispersible bath oil shown in Formula 05 consists of emollients and fragrance with surfactants that disperse these materials to produce an emulsion in the bath water. The emulsion appears as a white cloud or ‘bloom’. Soluble bath oils consist of solutions of non-ionic surfactants in water with small amounts of emollient material and the low level of hydrophobic emollients allows these products to produce a little foam. Multiphasic bath oils are a novelty form but fun to make; an example of a triphasic product is shown in Formula 06 Bath Beads & Pearls Bath oils may also be packaged in gelatine capsules to make bath beads or pearls in a variety of shapes. Once added to the bath water, these capsules dissolve releasing their contents. 1.2 Cleansers for normal and combination skins Soap Traditionally soap, like the cold creams, represents another way of cleansing the skin. Soap results from the neutralisation of a mixture of fatty acids with an alkaline base such as sodium hydroxide in a process called saponification. The main components of a basic toilet soap bar are shown in Formula 07. Liquid toilet soaps are made using triethanolamine and potassium hydroxide to saponify the fatty acids. The next activity gives you the opportunity to think about some advantages and disadvantages in using toilet soaps.

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ACTIVITY 2 Advantages/disadvantages of toilet soap (Allow about 2 minutes) In the columns below, list some advantages and disadvantages of using toilet soap in terms of cost, properties in use (for example, foaming, ease of rinsing) and the after effects on the skin. You may like to draw some of your answers from your own experience. Advantages

Disadvantages

Cost

Properties in use

After effects on the skin

Soap is effective in removing grime and is relatively inexpensive. It produces a rich lather and can be easily rinsed off, leaving a squeaky-clean skin. On the other hand, the washing solution formed by soap is extremely alkaline (pH 9-10) and can cause irritation, dryness and scaling. In hard water it leaves scum deposits on the washbasin. The skin compatibility of soaps has been improved by the incorporation of various superfatting agents such as glycerin or the fatty alcohols. However, soap is gradually losing its popularity to synthetic, detergent-based products which tend to offer more flexibility in formulating. Synthetic detergent-based cleansers These types of products have brought versatility to the formulator and are available as bars, liquids, gels, aerosol mousses and impregnated tissue wipes. They are based on the use of synthetic surface active agents, or surfactants. Their main advantages over toilet soaps are that: • they are milder on the skin • they do not leave scum deposit films in hard water • they can be formulated to match the skin’s pH • a wider range of perfumes and water-soluble dyes (colours) can be used with them because of their lower pH. Unlike toilet soaps, however, synthetic detergent-based cleansers do not always produce the rich creamy lather and are a little more difficult to rinse off.

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Synthetic detergent bars Although synthetic detergent bars or syndet bars, as they are commonly known, are more expensive to manufacture than toilet soaps, they are very mild and produce a rich creamy lather. They are often sold at a premium price as facial cleansing bars. The main components of a syndet base, together with their typical use levels, are shown in table 3. Table 3: Syndet base INCI name

%w/w Prime function

Sodium cocoyl isethionate

25 -35 Surfactant

Stearic acid PEG-350

12.5- 17.5 Adds body and texture to 8 - 12 Refatting agent

Sodium isethionate

4- 6 Surfactant

Etidronic acid

0.05 Chelating agent

Zea mays (Corn) starch

2.00 Filler

Titanium dioxide [CI 77891]

0.30 Whitener

Sodium cocoyl glutamate

3 - 4 Thickening aid

Preservative, fragrance, colour etc.

q.s

Citric acid to pH 4.0 Water / aqua to 100% Many different types of additives can be incorporated into a syndet base to suit a wide range of applications. For example, soya lecithin can be used as a skin conditioning agent. Oatmeal can be incorporated as the active ingredient in a syndet bar for oily and combination skin. An example formulation is shown in Formula 08. The list of refatting or skin conditioning agents which can be used in these formulations is endless. Hydrolysed proteins, which are proteins that have been cut into shorter chains, are very substantive to the skin and are often used as skin conditioning agents Glycols like glycerin and propylene glycol are humectants and may moisturise the skin and also improve foam texture. Silicone derivatives have increased in popularity due to their ability to smooth the skin without leaving it sticky. Examples of silicones which can be used include PEG-n dimethicone where n is the number of moles of ethylene oxide and PEG/PPG-18/18 dimethicone, which contains an average of 18 moles of ethylene oxide and 18 moles of propylene oxide. The concept of natural products addresses consumer concerns for environmental issues. Natural oils and extracts are easy to incorporate as skin conditioners with the aid of non-ionic emulsifiers. Synthetic detergent liquids This category includes: • Shampoos (covered in Unit 15) • Facial cleansers. • Shower gels and body wash (which are used all over the body) • Liquid ‘soaps’ for hands and intimate areas • Foam baths The most popular combination of surfactants is the anionic/amphoteric/non ionic system. The structure and behaviour of these materials are explained in more detail in Unit 8, Surfactants. Examples of amphoteric surfactants are: • Alkyl betaines e.g. Lauryl betaine • Alkylamido betaines e.g. Cocamidopropyl betaine • Sulfobetaines (sultaines) e.g. Lauryl sultaine; lauryl hydroxysultaine

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• N-alkyl-amino propionates. e.g. Sodium lauriminodipropionate • Amphoacetates e.g. Sodium lauroamphodiacetate Examples of anionic surfactants are: • Alkoxylated carboxylic acids e.g. Laureth-5 carboxylic acid • Sarcosinates e.g. Sodium lauroyl sarcosinate • Isethionates e.g. Sodium cocoyl isethionate • Sulfosuccinates e.g. Disodium laureth sulfosuccinate • Mono alkyl phosphates e.g. C20-22 alkyl phosphate Examples of non-ionic surfactants are: • Lauryl glucoside • Decyl glucoside • Caprylyl/capryl glucoside • PEG-7 glyceryl cocoate Facial cleansers must be able to effect a mild yet thorough cleansing of the skin. Such formulations normally contain a mixture of surfactants which work synergistically. This means that they work better together than individually to provide better foaming, cleansing and mildness characteristics. Other ingredients may include refatting agents, a thickener, preservatives, perfume and water. The appearance of the product can be modified by using water-soluble dyes. Pearlescent agents such as glycol stearate or opacifying agents like titanium dioxide or copolymer latex emulsions are other possible additives. Transparent coloured gel systems are still very popular where the surfactant can be thickened with carbomers or other acrylate based materials; PEG-based thickeners such as PEG-7 glyceryl cocoate, or with sodium chloride. Other viscosity modifiers, which also provide a pleasant silky feel to the lather, can be used. These include cationic guar gums, cellulose derivatives, polyethylene glycol (PEG) esters and xanthan gum. (For further information see Unit 7, Gums, Thickeners and Resins). The final viscosity will of course depend on the dispensing system and the flow properties and consistency required. Facial scrubs Facial scrubs can be classed as exfoliating products, which involves the removal of the outermost layer of the stratum corneum. Scrub products are available as pastes, liquids, creams or gels in which tiny abrasive particles have been suspended. The suspending medium may be a low oil content emulsion or a mild synthetic detergent-based system. The product is applied to the face and massaged gently into the skin whilst avoiding the delicate eye area, then rinsed off with warm water to leave a smooth glowing skin. Facial scrubs are not recommended for frequent use since they may cause long-term physical damage to the skin and should be avoided by people who suffer from acne to prevent scarring from ruptured comedones. Commonly-used scrub agents include natural seeds from almonds, apricots and walnuts; ground loofah, corn cob and pumice and hydrogenated jojoba oil. Synthetic particles such as polythene powder are also widely used. The formula given in Formula 09 utilises Hydrogenated jojoba seed oil to provide a gentle scrubbing action plus some residual emolliancy. Foam bath The bathing ritual, which people have enjoyed for centuries, serves to cleanse the skin and relax body and mind. Foam bath is also known as bubble bath, crème bath, foaming bath essence or herbal bath. A foam bath is a carefully formulated surfactant blend that is added to running bath water to generate copious amounts of foam in soft and hard water. It also contains fragrance, which fills the bathroom with a pleasant odour and may include moisturisers, vitamins, minerals and natural extracts such as herbs. Menthol can be incorporated into the fragrance to produce a ‘breathe freely’ foam bath. When added to the bath water, it releases fragrance to help clear the nasal passages. Since consumers will spend a reasonable amount of time in the bath, foam bath must be safe on skin and mucous membranes. Fragrance has always been a key ingredient in foam bath, and for that matter a wide range of toiletries. However more recently marketers have used it to make stronger mood enhancing

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claims, linking use of these products to lifestyle and spiritual pursuits. Formula 10 shows a relaxing foam bath, containing water-dispersible hydrolysed oats as a moisturiser. Shower gels Shower gels, also known as body gels or body wash, were introduced in response to the installation of showers in the home. Shower gels contain similar ingredients to those employed in foam baths; however they do not need to foam as much but must be effective at cleansing. These products tend to be more viscous to enable the consumer to apply it more easily over the body. They can be applied to the skin by hand or with a body puff or loofah to generate creamy, stable foam, which rinses off to leave the skin feeling clean, soft and smooth. Once again fragrance lingers on the skin and in the room during and after the shower to enhance the experience. As brands become more global, it is vital to select fragrances that are well accepted in targeted markets. Shower products are often marketed as a range of variants with a different fragrance in each one. Multi functional shower gels, often known as 2-in-1’s, have grown in popularity, evolving from the success of the 2-in 1 hair shampoo and conditioning systems. The trend started with shower shampoos, which are formulated to clean the skin and hair and to provide residual conditioning on the hair. An example is shown in Formula 11. Another concept is shower gels which clean and moisturise. Nowadays milder surfactants with more skin substantive moisturisers make such a positioning easier to substantiate. A moisturising body wash is shown as Formula 12 Liquid hand soaps Liquid hand soaps were developed to compete with toilet soaps and so were positioned as more hygienic and convenient. True liquid hand soaps are based on saponified fatty acids but the majority are now based on synthetic surfactants. The liquid hand soap in Formula 13 is based on synthetic surfactants and uses glycol stearate to provide a rich pearly appearance These products have evolved into hygienic ‘dermoprotector’ products, formulated with antibacterial and skin conditioning agents. More recently ‘waterless’ hand cleaners, based on ethanol, have gained in popularity for travel and outdoor activities where water may not be readily available – see Formula 14.

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Intimate liquid soaps These products are used to clean the genital (intimate) areas and initially gained popularity in France and Italy, where bidets are in common use. Intimate products are formulated with low active level of mild surfactants. See Formula 15. Bath crystals Bath crystals are essentially sodium salts of weak acids. Commonly used ingredients include sodium carbonate crystals, sodium bicarbonate, sodium sesquicarbonate and disodium phosphate. Modern formulations incorporate herbal extracts and natural oils. The crystals can be coloured or tinted by spraying with aqueous/alcoholic solutions of dye or immersing them in a tank of the dye solution. Once the colour is evenly dispersed, perfume is added to the crystals in a tumble dryer- type mixer to ensure even distribution. The crystals are spread onto trays and allowed to dry before packing. If a water-soluble perfume is being used then the colouring and fragrancing operation can be performed in one step. Herbal extracts are usually added with the perfume. Bath bombs Bath bombs are effervescent bath crystals containing an organic acid and bicarbonate so that carbon dioxide is released when the product comes into contact with water. This gives the sensation of a natural carbonated spa. See Formula 16. 1.3 Cleansers for oily skin Frequent and effective cleansing is recommended for oily skin in order to keep the amount of sebum left on the skin to an absolute minimum and so avoid the development of spots and pimples. Emulsion cleansers are to be avoided since they tend to leave a layer of oil on the skin. Face masks and exfoliating lotions are used for exfoliation of acne-prone skin rather than facial scrubs since the latter can cause disruption of the comedones, which exacerbates the condition. A solution for the preparation of freshening and cleansing wipes is shown in Formula 17. Methyl gluceth-10 provides soft ‘feel’ whilst PEG-75 lanolin and oleth-20 provide gentle cleansing. The alcohol produces a cooling sensation along with some antibacterial properties. Microbiological testing of this type of product must be carried out extensively and monitored carefully during manufacture and after marketing. Gels have become a popular product form for cleansing and post-cleansing products. See the notes following Formula 17. Face masks and packs Masks are beauty treatments that may be used once or twice a week to provide a variety of effects: deep cleansing, stimulating, toning, hydrating and emollient. There are different types but the most widely used are peel-off and setting masks. The majority of formulations are the setting type, based on clay or Fullers earth mixed with a liquid. When setting masks are spread over the face and allowed to dry, they harden and contract, producing a tightening sensation, which stimulates blood flow to the skin. Peel off masks form a colloidal suspension that has a jelly-like consistency when applied to the face. The water evaporates from the mask to form a plastic film that is peeled off. This type of mask is used for sensitive, dehydrated and mature skins. Masks can be formulated to suit each skin type and examples of setting and peel off masks are shown in Formulas 18 & 19 respectively.

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1.4 Skin toners Skin toners are called by a variety of names, including tonics, fresheners, clarifying lotions and astringents, and are available as liquids and gels. When applied to the skin with a cotton wool pad, toners remove the final traces of grime, residues of soap or emulsion cleansers plus any loose flakes of dead skin. They leave the skin feeling clean, fresh and invigorated before a moisturiser or liquid foundation make-up is applied. For the next activity, you may like to give a little more thought to the active ingredients which are used in toners.

ACTIVITY 3 Skin toner actives (Allow about 3 minutes) The active component of these products is astringent. What do you think are the likely properties of such products? Give some examples of astringent materials if you can.

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The astringent will give the product the following properties to varying degrees: sensation of skintightening; erection of hairs (hairs stand on end); temporary reduction of skin pore size; removal and reduction in skin oiliness; antiperspirant action; rapid coagulation of blood from a fresh wound and skin healing (useful while shaving!). Materials with astringent properties can be classified as follows: • vegetable extracts containing tannins, for example, witch hazel • organic acids with low molecular weight, such as lactic acid and citric acid • metal salts of organic or inorganic acids, such as aluminium sulphate and aluminium lactate • short chain alcohols, for example, alcohol (ethanol), isopropyl alcohol (isopropanol) Basic skin toners will contain the astringent material, water, moisturiser and preservative. Alcohol (Ethanol) is commonly used as the astringent material at levels between 5-25%. Toners for oily skin Astringent lotions are useful in the control of very oily or acne-prone skin. These products often contain higher levels of ethanol or isopropyl alcohol, which exhibits stronger solvent properties. As well as its astringent properties ethanol is an effective germicide/antiseptic and its evaporation from the skin provides a pleasant cooling sensation. In products for acne, antibacterial agents can be included to minimise bacterial proliferation. Such agents include chloroxylenol, triclosan and benzalkonium chloride. Note: if the product is to be marketed within Europe these materials must be added within the limits permitted in Annex V of Regulation (EC) No 1223/2009 of the European Parliament. Other countries have their own regulations so attention must be paid to each individual marketing area. Keratolytic agents like salicylic acid that dissolve or break down the outer layer of skin (keratins) and promote the softening and peeling of the epidermis may be incorporated as exfoliants. Toners for normal and dry skin Toners for normal and dry skin are usually based on lower alcoholic strengths. Alcohol-free toners are often preferred since alcohol can leave the skin feeling dry and it does not project a natural image. Menthol can be used instead of ethanol to provide similar cooling sensations. A traditional skin tonic is shown in Formula 20. Formula 21 shows a low-alcohol freshener that uses alternatives to glycerin as moisturising agents as glycerin can leave an unpleasant sticky feel. There are many other moisturisers to choose from such as sodium hyaluronate, jojoba ethoxylates, panthenol and water-soluble vitamin E derivatives. Formula 22 contains sodium pyrrolidone carboxylate [INCI: Sodium PCa], which is one of the constituents of the skin’s natural moisturising factor, NMF, referred to in Unit 11. Toning solutions can be thickened to form attractive gels with carbomers and cellulose derivatives.

CHECKLIST You should now be able to: – classify the main types of cleansing formulations available on the market – recognise and recall the common active raw materials used for cleansing dry, normal and oily skins – describe the advantages and disadvantages of soaps, synthetic detergents and emulsions – give examples of the active raw materials which can be used in toners for dry, normal and oily skins.

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2 FORMULATING MOISTURISING PRODUCTS Aim In this section the aim is to introduce the concept of moisturisation, to describe the different classes of raw materials which provide moisturisation and to discuss formulations for different types of moisturising products. 2.1 Moisturisation Since dry or dehydrated skin lacks water, cosmetic formulations can temporarily reverse this by a process called moisturisation. Moisturisation is the ability of a preparation to increase the water content of the stratum corneum. Moisturising creams, gels and lotions are applied for the relief of the signs and symptoms of dry skin, leaving it soft, smooth and supple. The skin scales (corneocytes) become more pliable and transparent and therefore less visible, which gives a visually dramatic improvement. Moisturisers form the basis of other products such as rich night creams, suntan lotions, anti-ageing creams and barrier creams. There are several methods of achieving moisturisation, the most popular being the use of emollients and humectants. Emollients An emollient is a material such as an oil or wax which, when applied to the skin, makes it feel soft and smooth. Emollients often have an occlusive action. This means they behave like an extra barrier on the skin surface and so reduce transepidermal water loss (TEWL). This in turn increases the water content of the stratum corneum. The rapid reversal of the ‘rough’ feel in dry skin can be largely attributed to the emollients ability to fill the cracks in the horny layer and ‘glue down’ the protruding corneocytes. Humectants Humectants are materials which exhibit hygroscopic behaviour; this means that they can draw and hold onto a large amount of water. When an aqueous solution of a humectant is applied to the skin, it is thought to reduce trans-epidermal water loss by holding the water in the intercellular lipid matrix found between the corneocytes in the stratum corneum. Like emollients, humectants increase the water content of the stratum corneum and so keep it soft and supple. Humectants like glycerin and propylene glycol also inhibit water loss from oil-in-water emulsions. Other moisturising materials Materials such as hyaluronic acid and colloidal oatmeal act as a type of water blanket, providing protection as well as moisture to the skin. Amino acids and hydrolysed proteins are hygroscopic and substantive to skin. Penetration enhancers like urea soften the outer layers of the stratum corneum to improve its water-holding capacity and smoothness. Commonly-used emollients, humectants and moisturisers are listed in table 4 on the following page.

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Table 4: Raw materials commonly used in moisturising formulations Function

Class

Examples

Emollients

Esters

Isopropyl myristate, Isopropyl palmitate

Fatty acids

Linoleic acid, Stearic acid

Fatty alcohols

Cetyl, Stearyl & Cetearyl alcohol

Hydrocarbons

Paraffinum liquidum (Mineral oil), petrolatum

Triglycerides

Vegetable oils are triglycerides

Amino acids

Apricot kernel amino acids; Oat amino acids; Milk protein amino acids; Silk amino acids

Humectants

Lanolin & derivatives Lanolin, Lanolin oil and Lanolin alcohols Polyols

Glycerin; sorbitol

Protein

Collagen; Elastin; Vegetable proteins e.g. Lupinus albus protein; Triticum vulgare (Wheat) germ protein

Silicones

Dimethicone, cyclopentasiloxane

Sugars

Glucose; Xylitol; Xylose

Miscellaneous additives

includes biological and botanical additives; penetration enhancers, pH adjusters, antioxidants Emulsifying agents Ethers

.

.

Thickening agents Preservatives

15

Caviar extract; Fish cartilage extract; Hydrolysed collagen extract; Aloe barbadensis leaf juice; Urea; Sodium lactate; Lactic acid, BHT, Tocopherol, Ascorbic acid

Steareth-n; Ceteareth-n; Isosteareth-n where “n” = moles of ethylene oxide

Polymers

Acrylates/C10-30 alkyl acrylate crosspolymers; Polyacrylates e.g. Sodium polyacrylate

Silicones i.e. Silanes and siloxanes

Cetyl PEG-8 dimethicone; Lauryl PEG-8 dimethicone; PEG/PPG-18/18 dimethicone; PEG-9 dimethicone; Dimethicone/PEG-10/15 crosspolymer

Sterols

Lanolin alcohol; Lanosterol; Cholesterol; Soyasterol; Choleth-n; PEG-n phytosterols; PEG-n soy sterol

Surfactants; anionic: soaps and alkyl sulfates.

Fatty acid soaps e.g. Triethanolamine stearate. Sodium alkyl sulfates e.g. Sodium lauryl sulfate

Surfactants; anionic: replacing soaps and alkyl sulfates

Alkoxylated carboxylic acids e.g. Laureth-5 carboxylic acid. Alkyl phosphates and alkyl ether phosphates e.g. Stearyl phosphate; Potassium cetyl phosphate

Surfactants; amphoteric: seldom used for preparing skin care emulsions Surfactants; cationic: more commonly used for hair conditioning

Alkyl amino propionates e.g. Sodium lauriminodipropionate

PEG-15 cocamine; Stearalkonium chloride, Behentrimonium methosulfate

Surfactants; non-ionic Glycereth-n cocoate etc., C18-36 glycol ester etc., PEG-12 laurate / stearate etc. Glyceryl stearate etc., Polyglyceryl-4 isostearate, Sorbitan esters and their ethoxylated counterparts (Polysorbates) Sucrose cocoate / palmitate / stearate Carbomers; Xanthan gum; Cellulose gum; Sclerotium gum; Polyacrylates (see Unit 7) See Unit 6


SKIN PRODUCTS


2.2 Basic components of a moisturising product Unfortunately the majority of effective occlusive agents cannot be used without some modification because they are difficult to apply and can leave the skin feeling tacky or greasy. For example, Petrolatum is an excellent emollient but its skin-feel is unacceptable for a cosmetic product. For this reason, moisturisers are formulated into cosmetic emulsions stabilised with an appropriate emulsifier system. Moisturising products, like emulsion-based cleansers, are available as milks, lotions, creams, clear gels and aerosol mousses. A product may have excellent moisturising properties but if it does not have good aesthetics, in terms of appearance, fragrance and skin feel on application, the consumer is unlikely to buy it again. In the next Activity you will look at the aesthetics required for a good moisturiser.

ACTIVITY 4 Product aesthetics (Allow about 2 minutes) Write down a list of properties you would expect from a good moisturiser. e.g., easy to apply to the skin

A good moisturising formulation should be non-irritant, rub in easily without ‘soaping up’ and leave the skin feeling soft rather than sticky. The product should have a pleasant odour and if it is to be unperfumed there should be no fatty base odour. The basic components of a moisturising product include moisturiser(s), an emulsifier system, water, preservative(s) and antioxidants if necessary. Examples of commonly-used components are listed in table 4. Emulsifiers are fully described in Module 1, Units 3, 8 & 10. It is obvious that the extensive catalogue of components can generate an infinite number of formulations. The character of these formulations will therefore depend on the product type required and the choice and experience of the formulation chemist. The example formulations given in this section represent a basic guide and not an exhaustive account. It has already been pointed out that moisturisers are used to alleviate the symptoms of dry skin. At the same time, we should remember that people with normal, combination and oily skins still need to use a moisturiser to prevent their skin from becoming dry.

16


SKIN PRODUCTS


In the marketplace, moisturisers are often positioned under the following groups: – day facial products – night facial products – hand and body products – all-purpose products – extra protection/barrier products. The next Activity will help you to become familiar with the brands and claims associated with the above classification. It is worth incorporating it into your normal shopping time.

ACTIVITY 5 Moisturising products – store checks This activity has been identified as a key activity for this unit. Please go to the online module to complete this activity, so that you can share your ideas and opinions with your fellow learners and benefit from their experience and knowledge in this area.

Typical formulations for moisturising products 2.3 Moisturisers for dry and normal skin Moisturising products for every day application tend to be light, oil-in-water emulsions, which spread easily and rub into the skin quickly. These properties can be traced back to the traditional vanishing cream system which is a non-greasy, oil-in-water emulsion based on high quality stearic acid as the oil phase. Commercial stearic acid consists of a mixture of stearic and palmitic acids with a tiny amount of oleic acid. Partial neutralisation, that is saponification of the fatty acid with an alkaline base such as triethanolamine or potassium hydroxide, produces a soap which acts as the emulsifier by forming a type of gel which holds the cream together. Saponifying about 1621% of the stearic acid present in the formula is usually sufficient for a cream. The texture and viscosity of the product may be varied to make stiffer creams or lotions by altering the degree of saponification. An example of a simple day cream using this system is shown in Appendix 1 as Formula 23 however soap-based emulsions are no longer thought suitable for moisturisers and have been largely replaced by alkyl phosphates and alkyl ether phosphates e.g. Stearyl phosphate, Potassium cetyl phosphate and by non-ionic emulsifiers – see Formula 24. Products for night time application tend to have a richer feel than the day moisturisers and are often water-in-oil (w/o) emulsions, which leave a skin-softening occlusive film on the skin overnight. An advantage of w/o products is that the continuous oil phase has direct contact with the skin and forms a protective film immediately without any detergent action. In this way the dispersed water particles are trapped in the oil by the w/o emulsifier and the product is more resistant to being removed by washing. Traditionally w/o creams left a sticky after-feel on the skin attributed to the presence of waxes in the formulae, which were required to provide a rigid interfacial film that helps to hold the emulsion together. However by careful selection of the emulsifying system and by using emulsion stabilisers to thicken the continuous oil phase cosmetically elegant w/o creams are possible – see Formula 25. Non-ionic emulsifiers are: by far the predominant class of emulsifiers for skin care products. They include alkoxylated alcohols; fatty acid ethoxylates and glycol esters; ethoxylated carboxylic acids; glyceryl fatty acid esters and sorbitan esters and their ethoxylated counterparts (Polysorbates). The Hydrophilic-Lipophilic Balance (HLB) system of emulsifier selection generally works well with non-ionic emulsifiers and gives the formulation chemist a great deal of flexibility in the development of stable emulsions for varying oil/water combinations and they may be used to form both stable oil-in-water (o/w) and water-in-oil (w/o) emulsions. [For a complete explanation of the HLB System refer to Unit 10] Systems that form liquid crystals [see Unit 8, section 2.7] are of interest for moisturisers as they tend to penetrate further into the stratum corneum and moisturise at deeper levels than those

17


SKIN PRODUCTS


that form occlusive films on the surface. Examples of emulsifiers that form liquid crystals are as follows:• Cetearyl glucoside with cetearyl alcohol • Sorbitan olivate and cetearyl olivate • Sorbitan stearate with sorbityl laurate • Sorbitan stearate with sucrose cocoate • Polyglyceryl-3 methylglucose distearate • Potassium cetyl phosphate with hydrogenated palm glycerides • Lauryl glucoside with polyglyceryl-2 dipolyhydroxystearate See Formula 26 Cationic surfactants, such as stearalkonium chloride, are used to a much lesser extent as emulsifiers for skin care products. Because of their substantivity to the skin, however, they may be used to give an additional velvet-smooth skin feel after application but they are not compatible with anionic systems. Emulsifier systems for preparing w/o emulsions include the following:• Methoxy PEG-22/Dodecyl glycol copolymer • PEG-30 dipolyhydroxystearate • Polyglyceryl-10 decaoleate • Polyglyceryl-2 dipolyhydroxystearate • Polyglyceryl-3 diisostearate • Polyglyceryl-3 oleate • Polyglyceryl-3 polyricinoleate • Polyhydroxystearate/sebacate • There are many proprietary mixtures available; see suppliers web sites Improving emulsion stability Emulsion stability can be improved by including other materials which support the main emulsifier system. These materials are known as secondary emulsifiers and commonly-used examples are fatty alcohols such as cetyl and stearyl alcohol and self-emulsifying glyceryl monostearates (s/e GMS) but note that only those containing PEG-100 are stable at acid pH. For w/o systems lanolin alcohol and other sterols and glyceryl stearate may be used. Note: Throughout the text there is mention of cetyl alcohol, stearyl alcohol and cetearyl alcohol. Cetyl alcohol is C16, stearyl alcohol is C18 and cetearyl alcohol is a mixture of C16/C18 alcohols. All three are fatty alcohols and are white waxy solids. They are almost interchangeable provided the grade used for creating the original formula is maintained throughout product development, testing and manufacture. Increasing the viscosity of the continuous phase is commonly used to stabilise emulsions. For o/w emulsions carbomers, or Carbopol resins as they are commonly known, can be used to increase the viscosity of the water phase to inhibit coalescence of the dispersed oil droplets but carbomers are pH dependent and electrolyte intolerant. Other thickening aids include cellulose gum, xanthan gum and silicates and more on this can be found in Module 1; Units 9 & 10. For w/o emulsions increasing the volume of the disperse phase works well as does adding low melting point waxes to the oil phase. The oil phase can be thickened by adding silica or by various gelling agents like dextrin palmitate. Emulsions contain water therefore they must be adequately preserved. Although there are numerous antimicrobial materials that may work only those that appear in Annex V of Regulation (EC) No 1223/2009 of The European Parliament are permitted if the products are to be sold in Europe. Other countries have their own regulations so attention must be paid to each individual marketing area. Product aesthetics The ‘soaping-up’ or whitening effect found when applying oil-in-water products can be reduced or eliminated by using dimethicone or cyclopentasiloxane, which act as defoaming agents.

18


SKIN PRODUCTS


Dimethicone is also an effective moisturiser. The heaviness experienced with w/o creams can be improved by incorporating low viscosity “oils” like cyclopentasiloxane, isopropyl myristate, hexyl laurate and diethylhexyl carbonate to improve spreading on the skin. The use of silicone emulsifiers such as Cetyl PEG/PPG-10/1 dimethicone has proved popular. These can be used to produce stable water-in-oil formulations with up to 74% water with little or no wax. The resulting formulations exhibit excellent moisturising properties combined with improved aesthetics. An example of a formulation using this technology is given in Formula 27. This formula is particularly interesting since it contains a high level of Persea gratissima (Avocado) oil, which tends to be rather difficult to emulsify. Additives Natural additives Over the last 20 years, there has been a great demand by the consumer for ‘natural products’. Although a general consensus as to what constitutes a natural product has not yet been agreed, it is very difficult to develop a completely natural product. The cosmetic industry has responded in a number of ways. The most common method is to add small amounts of oils or water-soluble extracts from plants and display these prominently on the label. Although the list of naturals is endless they tend to be extracts of fruits, vegetables, herbs and seeds plus vitamins and amino acids. It is worth noting that the natural theme is applied to many skin care products today and can be used for cleansers, toners and moisturisers. Examples of natural extracts used in skin care are summarised in Table 5 but please note that this list is only a guide and more appear to be added every month or so. When using naturals in skincare formulations, it is worth noting that just because a material is of natural botanical origin it does not mean that it is safe for any particular consumer use. Naturals, like any other raw materials, must undergo strict quality control, preservation and toxicological tests. Finally, much research is currently under way to separate scientific facts on naturals from the herbal folklores on which much of their appeal is based. This has resulted in many active ingredients being offered to the cosmetic industry that may have beneficial effects on skin. Please note that this list is only a guide. .

19


SKIN PRODUCTS

DIPLOMA/CERTIFICATE IN COSMETIC SCIENCE MODULE 2 UNIT 16 Table 5. Natural extracts in skin care

Application in skin care n i k s y r D

Honey

n i k s y l i O

l a m r o N

n o i t a n i b m o C

t n a d i x o i t n A

o

t n a t i r r i i t n A

n t o n i t l a a u l u m c i r t i C s

o

Cornflower

o

Cucumber

o

Evening primrose Wheatgerm

l a i b o r c i m i t n A

o o

Seaweed

o

o

o

Cornelia

o

Sweet almond

o

Honeysuckle

o

Orange flower

o

Carrot

o

Avocado oil

o

Clary sage

o

Pineapple

o

Kukui nut Aloe vera

o o

o

Apricot kernel oil

o

Witch hazel

o

Chamomile Elderflower

o

o

o

Peach

o

Dandelion Borage

o

Orchid

o

o

Papaya

o

Bergamot

o

Lemon

o

Arnica

o

Balm mint

o

Sweet almond

o

Comfrey

o

o

Veronica

o

Lavender

o

Yarrow

o

Lime flower

o

Bamboo

o

Ginger

o

Green Tea

o

Gingko Biloba Ginseng

20

o o

o

o

o

o


o

SKIN PRODUCTS


Application in skin care n i k s y r D

n i k s y l i O

l a m r o N

n o i t a n i b m o C

t n a d i x o i t n A

Licorice

l a i b o r c i m i t n A

t n a t i r r i i t n A

n t o n i t l a a u l u m c r i t i C s

o

Grape seed

o

Oat

o

Tea Tree Cottonseed oil

o o

o

o

o

Special additives Consumer skincare needs have not really changed, however in the last 15 years, a number of new active ingredients have featured prominently on pack claims. The special additives, which are used in both day and night products, are becoming rather sophisticated and expensive. Examples include hydroxyacids, sunscreens, vitamins, proteins, essential fatty acids, alpha hydroxy acids and liposomes. Some of these raw materials are described below. Alpha and beta hydroxyacids are organic chemicals used in anti-ageing and some shaving products. Glycolic and salicylic acids are the most commonly used but lactic, tartaric, citric, malic and mandelic acids may also be found. Although these may be found naturally in willow bark, citrus fruits, sour milk and sugar cane the synthetic forms are normally used in formulations. These materials dramatically affect the epidermal renewal process of the skin as summarised below:1. Reduction of corneocyte adhesion in the basal layer of the stratum corneum (SC) by a process termed exfoliation. 2. Increase cell turnover rate, producing smoother looking skin. 3. Reduction in hyper pigmentation 4. Long-term increase in collagen and elastin synthesis. The most effective alpha hydroxyacids are lactic and glycolic used at levels of 1% to 5%. The disadvantage of these materials is that they can cause irritation because of their low pH, and should therefore be buffered to approximately pH 4.5. It is also recommended that exposure to the sun be limited if using products containing them. Salicylic acid is a beta hydroxy acid that tends to be milder to the skin with a long history of use as a peeling agent. More recent studies suggest that conjugating alpha hydroxy acids with amino acids could significantly reduce irritation. An example of a moisturising cream with glycolic acid is shown as Formula 28. Vitamins The use of vitamins in cosmetics has become ever more popular because it complements the holistic (body, mind and soul) approach to well being. So we move away from the myth that just slapping on some cream is enough. Instead, we take into consideration diet and exercise and emotional and spiritual factors. Therefore consumers not only take vitamin supplements but they also apply them topically. Vitamins E, A, C and panthenol are still the most widely used however Vitamin D is banned for use in cosmetics in the EU. Vitamin E (dl alpha tocopherol) found naturally in wheat germ, can be incorporated into formulations at up to 5% as an antioxidant/free radical scavenger. Free radicals such as lipid peroxides can be generated in the body during cell respiration and by exposure to ultraviolet light (sun light). This results in disruption of the cell membranes. The ester vitamin E acetate tends to be used as an emollient in skin care.

21


SKIN PRODUCTS


Vitamin A in its pure form is retinol but as this is unstable it is more usually found in cosmetics as its ester, either retinyl acetate or retinyl palmitate. Retinoids at levels of 0.025-0.05% have been used to treat sun or photo-damaged skin. They normalise epidermal activity and reduce hyperpigmentation. Retinoids such as tretinoin also have a number of undesirable side effects such as erythema, dryness and itching and are not permitted for use in cosmetics within the EU. Vitamin C or ascorbic acid is a natural anti-oxidant that regulates collagen biosynthesis and the body’s wound healing processes. Collagen, [see Module 1, Unit 11] is one of the structural proteins found in the connective tissue of the dermis. Until recently it has been difficult to apply vitamin C topically because it is readily oxidised when in solution. However, it can be stabilised in microcapsules or liposomes and presented as ascorbyl dipalmitate, which is lipo-soluble. NOTE: It should be noted that according to the FDA cosmetics declaring ingredients as vitamins as, for example, tocopherol as vitamin E, convey the misleading impression that these ingredients and products offer a nutrient or health benefit and may therefore be deemed misbranded. The INCI Dictionary, the currently recognized source of cosmetic ingredient names, lists “vitamin” ingredients by their respective chemical names. Essential fatty acids An intact skin barrier is vital to the overall health of the body. Ceramides found in the stratum corneum (SC) play a fundamental role in the functioning and hydration of the barrier. Ceramides account for at least 40% of the intercellular lipids found between the corneocytes. Essential fatty acids (EFAs) such as linoleic and gamma-linolenic acid are important building blocks of ceramides in man. The former is found in plants (borage, evening primrose and grape seed) and in fish oils. EFAs are also important in the regulation of keratinisation and the metabolism of prostaglandins, which play a crucial role in the body’s immune system. A deficiency in EFAs has been linked to abnormal dryness of the skin or mucus membranes (xerosis), and increased TEWL. When applied topically, EFAs can become incorporated into the SC structural lipids, improving the skin’s suppleness and flexibility. Macromolecules Proteins: Protein derivatives such as hydrolysed protein (milk, silk and marine), amino acids and glycosaminoglycans, are very substantive to the skin, leaving it feeling soft and smooth. Glycosaminoglycans including hyaluronic acid and chondroitin sulphate have a large number of hydroxyl groups that allow them to absorb and retain considerable amounts of water. They are too large to penetrate the SC but can form a hygroscopic, semi permeable film on the skin surface.

Polysaccharides Beta-glucans are polysaccharides derived from oats, wheat and baker’s yeast. They can be chemically modified to make them more hydrophilic. When used in skin creams, beta-glucans can affect the skin in a number of ways including reduction of irritation caused by detergents; increasing cell turnover in the SC, stimulation of collagen synthesis and reduction of fine wrinkles.

Delivery vehicles Over the years, there has been much progress in the way active materials are delivered into the SC. Delivery systems have expanded from single emulsions and microcapsules to multiple emulsions, cyclodextrins, liposomes, polymeric systems, wipes and patch technology. Liposomes can be defined as microscopic bubbles known as vesicles. The walls of these vesicles bear a close resemblance to animal and plant cell membranes which are organised into bilayers. The membranes of true liposomes consist of phospholipids, which are important building blocks for animal and plant cell membranes. On the other hand, vesicles whose walls consist of nonionic surfactants are called niosomes. Liposomes are very compatible with t he skin and because of their size (15-3500 nm); they are able to penetrate the skin efficiently, unlike classical emulsions.

22


SKIN PRODUCTS


Plant phospholipids (lecithin) tend to be used more than animal phospholipids because of their high content of esterified polyunsaturated fatty acids such as linoleic acid. As a type of microencapsulation technology, liposomes offer a safer way of delivering actives such as moisturisers and vitamins to the deeper layers of the skin (see K. Suzuki and K. Sakon, 1990, Cosmetics & Toiletries, Vol. 105, No. 61). Liposomes have been used to tackle cosmetic problems such as dry and oily skin, age spots, and skin ageing. A moisturising lotion with liposomes is shown as Formula 29. Hand and body lotions Products for use on the hands and body tend to be similar in formulation to the day moisturisers. They normally exist as lotions and sometimes aerosol mousses rather than creams for ease of application. These lotions will have an initially rich texture which breaks down easily without leaving a greasy feel. This behaviour can be achieved by increasing the viscosity of the water phase with agents like the carbomers and cellulose derivatives. Formula 30 is a formula that uses cocoa butter and lanolin oil, which is rich in cholesterol, to provide excellent emolliancy. The emollient Caprylic/capric triglyceride is a reconstituted vegetable oil that improves the spreading properties of the cream on the skin. An antioxidant should be included to prevent any rancidity from the cocoa butter. All-purpose products As their name suggests, all-purpose products can be used as a moisturiser or as a cleanser on the face, hands and body. All-purpose milks have become popular because of their light texture and ease of spreading. In Formula 31 isohexadecane, cyclopentasiloxane and PPG-15 stearyl ether together with Paraffinum liquidum (Mineral oil) are used for their emolliancy; sorbitan stearate and Polysorbate 60 form the emulsifier system. Urea is included for its moisturising properties. Talcum powder or dusting powder is often used after bathing to absorb moisture and perfume the skin, leaving it feeling soft and silky. In warm weather it absorbs perspiration to help cool the body. Formulations are based on the mineral talc with hydrous magnesium silicate, to provide the slippery skin feel. It is important that the talc, a natural product, is sterilised before use to minimise risk form microbial contamination. In Formula 32 zinc stearate is included for lubricity and its mild antiseptic properties. Soothing agents such as aloe and allantoin can be added, to help relieve minor skin irritations and the discomfort caused by prickly heat rash and sunburn. Magnesium carbonate provides absorbency and fluffiness. Some “talcum” powders may contain modified starch. 2.4 Moisturisers for combination and oily skins The use of too many oily/fatty components in moisturisers for combination and oily skin must be avoided for obvious reasons. Formula 33 gives a light moisturising milk for combination skin.

2.5 Extra protection products: Caring for hands and feet Care of hands and nails has always been important, because like the face they are exposed to environmental conditions. Regular contact with detergents and industrial chemicals makes the hands the most vulnerable part of the body, exhibit early signs of ageing. Barrier creams, such as hand creams, are protective products. However, in addition to this, they prevent external materials from passing through the skin. External materials will include water, defatting solvents, soil and dirt. The formulation of barrier creams will be determined by the type of external materials from which the end-user requires protection. Two types of protection are discussed below. Protection from water These formulations have water-repellent properties and can be based on petroleum jelly, lanolin or silicones. An aerosol mousse, as an alternative, offers a product which is hygienic and easy to apply. Kaolin may be included as a skin protectant. Glyceryl stearate allows the product to be easily washed off after use (see Formula 34).

23


SKIN PRODUCTS


Protection from oils Non-oil soluble film formers such as tragacanth, sodium alginate or gum acacia can be used to provide oil repellence. Glycerin helps to plasticise the gum film. An example is shown in Formula 35. Feet are often the most neglected area of the body, where people usually only purchase such products at the beginning of summer or if they have a specific problem. However some innovative products are now available in the market place, see Formulas 36 & 37. 2.6 Baby Skin Products: Caring for younger skins Caring for baby skin involves general cleansing of excreta, protection from nappy rash and exposure to ultraviolet light. A baby’s skin makes up a higher percentage of the body weight than adult skin. The higher surface area to weight ratio makes babies and infants more susceptible to increased trans-epidermal water loss, percutaneous absorption of topically applied materials, infection, and heat loss, therefore, it is extremely important that raw materials are chosen carefully and that pharmacopoeia grade materials are used. Formula 38 is a simple emollient bath oil that provides gentle cleansing and leaves the skin feeling soft and moisturised. Wet wipes have grown in popularity and are used in many different products areas. They should be able to remove excreta and fatty deposits from previously applied creams and lotions. Traditionally baby wipes are made from paper, impregnated with a mild surfactant solution. Recently, more premium products have entered the market. These products consist of spun lace (polyester/viscose) that offers a softer feel, impregnated with a low viscosity lotion. The latter provides cleansing and moisturisation in one step. Fragrance-free wipes have also gained considerable market share. A lotion wet-wipe is shown as Formula 39. After cleansing the nappy area, protective creams or baby powder may be applied. The use of liquid talc, as shown in Formula 40 is a safer alternative to traditional baby powder because it overcomes the risk of inhalation of airborne particles. Formula 41 is a barrier cream which can be applied to the nappy area for protection against chemical attack from excreta and decomposition products. This helps to prevent nappy rash and chafing. Zinc oxide is the active ingredient known for its protective and anti-inflammatory properties.

CHECKLIST You should now be able to: – define the terms, humectant, emollient and moisturisation – give examples of raw materials which are commonly used as moisturisers – list the basic components of moisturising products – classify the moisturising products available on the market – outline some of the new functional materials which are now available as special additives.

24


SKIN PRODUCTS


APPENDIX GUIDELINE FORMULATIONS FOR PART 1 Appendix 1 contains formulations that are referenced in Unit 16 Part 1. The INCI (International Nomenclature of Cosmetic Ingredients) system has been used to name the materials with occasional explanations in brackets to help identify them further. Short explanations of how the formula is created are given; it should be remembered that the function of the ingredients is in part dependent on the total composition in which they are incorporated. The formulations are given to illustrate the text and should only be considered as starting points with which to experiment and customise to your own requirements. Virtually all of them require a carefully selected preservative system. Aqua (Water) is preferably deionised and should be free of microbial contamination. Disodium EDTA is incorporated in some formulations as a sequestrant or chelating agent. It chelates heavy metal ions and may prevent discolouration. It also has some microbiological activity so may be considered a useful addition to other formulations containing water. Throughout the appendix, alcohol is ethanol and is suitably denatured, i.e. made undrinkable by the inclusion of a suitable ingredient. In the EU, alcohol is denatured with denatonium benzoate and tertiary butyl alcohol and it is referred to as Alcohol denat. on labels. WARNING: Alcohol is highly flammable and must always be handled with care according to safety instructions. Formula 01: Cold cleansing cream [Note: this is a Key Activity formula] Stage INCI Name

%w/w Prime function

A

Paraffinum liquidum (Mineral oil)

40.00 Soil/makeup remover

A

Cera alba (Beeswax)

16.00 Emulsifier/thickener

A

Isopropyl myristate

5.00 Moisturiser

A

Petrolatum

5.00 Moisturiser

B

Sodium borate

1.00 Emulsifier

B

Aqua (Water) to 100%

33.00 Solvent

C

Parfum (fragrance)*

q.s.** See Unit 13

C

Preservative*

q.s.** See Unit 6

Preparation 1. Heat A to 75°C. 2. In a separate container, heat B to 75°C. 3. Add B to A slowly whilst stirring. 4. Cool to 35°C and add C. * Not required for Activity 8 ** Where q.s. appears it translates to “quantity sufficient” and is used where the level of material to be added is either to meet a subjective requirement, like dye or perfume, or to adjust pH or to adequately preserve the final composition. In Formula 01 fatty acids present in Cera alba (beeswax) are partially saponified by the sodium borate (borax) to form a soap-type emulsifier. The Paraffinum liquidum (Mineral oil) is the principal solvent for make-up and facial grime, helped by the isopropyl myristate, which also reduces some of the oiliness caused by the petrolatum, which is added to give body to the cream.

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SKIN PRODUCTS


Formula 02: Cleansing lotion Stage INCI Name

%w/w Prime function

A

Steareth-100

3.00 Surfactant - cleansing

A

Glycol stearate

3.00 Pearliser

A

PPG-15 stearyl ether

3.00 Emollient

A

Isohexadecane

7.00 Emollient

A

Cetearyl alcohol

1.00 Thickening

B


B


B

Polysorbate 20

C

Preservative

q.s. See Unit 6

C

Parfum (Fragrance)

q.s. See Unit 13

q.s. 10.00 Surfactant - cleansing 3.00 Emulsifier

Preparation 1. Heat A, the oil phase, to 70°C to dissolve all waxes. 2. In a separate vessel heat water in B to 70°C to dissolve the sodium cocoyl isethionate. Add the remaining ingredients in phase B. 3. Add A to B slowly with intensive stirring. 4. Cool to 35°C, adding preservative and perfume whilst stirring. NOTE: The composition can be thickened by the addition of 1% hydroxyethylcellulose. Retain about 10% water from Stage A and dissolve the hydroxyethylcellulose at about 35C and add it to the mix at 35C. In Formula 02 sodium cocoyl isethionate is the principal cleansing agent in association with steareth-100. Polysorbate 20 is the principal emulsifier. Glycol stearate forms pearly crystals when dissolved in surfactant systems and then allowed to cool. Cetearyl alcohol is a thickener and emulsion stabiliser and also adds skin feel while isohexadecane and PPG-15 stearyl ether add emolliancy.

26


SKIN PRODUCTS


Formula 03: Foaming cleansing lotion Stage INCI Name

%w/w Prime function

A


q.s.

A


B

Stearic acid

1.00 Emollient

B

Glycol stearate

3.00 Pearlising agent

B

Cetearyl alcohol

4.00 Emollient/thickener

B

Ethylhexyl hydroxystearate

2.00 Emollient/thickener

B

Lauramide MIPA

3.00 Foam thickener/ booster

B

Stearamide MIPA

3.00 Foam thickener/ booster

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s. See Unit 6

30.00 Surfactant

Preparation 1. Heat water to 70°C, add sodium cocoyl isethionate and stir until dissolved. 2. In a separate vessel, combine ingredients in B and heat to 65 - 70°C. 3. Add B to A and stir until cool. 4. Add C. In Formula 03 the foaming agent is sodium cocoyl isethionate and the lauramide MIPA and stearamide MIPA boost the foam and make it thicker and creamier. The formula is selfemulsifying; stearic acid adds emolliancy and glycol stearate forms pearly crystals when dissolved in a hot surfactant system and allowed to cool. Cetearyl alcohol thickens the lotion and adds emolliancy to skin. Formula 04: Spreading bath oil Stage INCI Name

%w/w Prime function

A


45.00 Emollient

B


49.00 Emollient

C

PEG-40 sorbitan peroleate

1.00 Surfactant/dispersal agent

D

Parfum (Fragrance)

5.00 See Unit 13

Preparation Mix all items together in a clean, dry vessel. In this formula the PEG-40 sorbitan peroleate disperses the other ingredients as a floating film on the surface of the bath water. No preservative is needed as there is no water in the formulation.

27


SKIN PRODUCTS


Formula 05: Blooming bath oil Stage A B C D E

INCI Name PEG-40 sorbitan peroleate PPG-15 stearyl ether Ethylhexyl palmitate Prunus amygdalus dulcis (Sweet almond) Oil Parfum (Fragrance)

%w/w 30.00 15.00 50.00 5.00 5.00

Prime function Surfactant/dispersal agent Emollient Emollient Emollient See Unit 13

Preparation 1. Mix all items together in a clean, dry vessel. In this formula the PEG-40 sorbitan peroleate disperses the other ingredients as a cloud or “bloom” in the bath water. Other vegetable oils may be substituted for the sweet almond oil. No preservative is needed as there is no water in the formulation but adding an antioxidant like tocopherol or BHT should be considered. Formula 06: Triphasic Bath Oil Stage INCI Name

%w/w Prime function

A

PEG-7 glyceryl cocoate

30.00 Emollient

B

Glycerin

34.00 Forms separate phase

C

Paraffin liquidum (Mineral oil)

33.00 Emollient

D

Aqua (Water)

3.00 Dissolves Blue 1

E

Parfum (Fragrance)

5.00 See Unit 13

F

Chlorophyll

qs Colours upper phase

G

CI 47005 (Yellow 10)

qs Colours middle phase

H

CI 42090 (Blue 1)

qs Colours lower phase

Preparation Add each item in turn to a clean, dry vessel, stirring with each addition. Mix well until clear and it should separate into 3 distinctive layers. Although it contains a little water the glycerin will effectively shield this from microbial spoilage. The perfume may upset the balance so try without it first.

28


SKIN PRODUCTS


Formula 07: Bar toilet soap Stage INCI Name

%w/w Prime function

A

Soap chips

84.60 Soap cleanser

B

Etidronic acid

0.20 Sequestering agent

C

BHT

0.20 Antioxidant

D

Glycerin

E

CI 77891 (Titanium dioxide)

1.50 Whitener

F

Parfum (Fragrance)

1.00 See Unit 13

12.50 Humectant

Preparation 1. Add all materials to soap chips. 2. Pass through a triple roll mill. 3. Feed mixture into a toilet soap amalgamator 4. Refine, extrude, cut and stamp. Soap chips are purchased from small quantity suppliers that may be found on-line. The mixing, milling and extruding equipment is quite specialised and also may be found on-line. Etidronic acid sequesters (chelates) iron ions to prevent discolouration. Glycerin is primarily to stop the bar soap drying out but also to give the right consistency. CI 77891 (Titanium dioxide) is to make the bar white and it also has a hardening effect. The anatase form may be dispersed in glycerin before addition to the mix to ensure even distribution. Perfumes often cause discolouration in soaps so make sure the supplier knows the end-use and check stability at 40°c and in daylight. Formula 08: Syndet bar for oily skin Stage INCI Name

%w/w Prime function

A


30.00 Surfactant

B

Stearic acid

15.00 Adds body and texture to

C

PEG-350

10.00 Refatting agent

D

Sodium isethionate

5.00 Surfactant

E

Etidronic acid

0.05 Chelating agent

F

Colloidal oatmeal

8.00 Soft scrub agent

G

CI 77891 [Titanium dioxide]

0.30 Whitener

H

Glycerin

2.00 Humectant

I

Sodium cocoyl glutamate

3.50 Thickening aid

J

Preservative, fragrance, colour etc.

q.s.

K

Citric acid to pH 4.0

q.s.

L


q.s.

Preparation 1. Place all the materials into a soap bar kneader and mix until homogenous. 2. Pass through a triple roll mill. 3. Feed mixture into a toilet soap amalgamator or return to the kneader for further mixing. 4. Press into suitable moulds.. The kneading, milling and extruding equipment is quite specialised and may be found on-line. Etidronic acid sequesters (chelates) iron ions to prevent discolouration. Colloidal oatmeal imparts a gentle scrubbing action when hand washing. Glycerin is primarily to stop the bar soap drying out but also to give the right consistency. CI 77891 (Titanium dioxide) is to make the bar white. The anatase form may be dispersed in glycerin before addition to the mix to ensure even distribution. Perfumes often cause discolouration in soaps so make sure the supplier knows the end-use and check stability at 40°c and in daylight.

29


SKIN PRODUCTS


Formula 09: Body polishing scrub Stage INCI Name

%w/w Prime function

A

Aqua to 100%

qs

B

Sodium olefin sulfonate (37%)

B

PEG-80 jojoba acid

B

Sodium laureth sulfate (28%)

B

Cocamidopropyl betaine (30%)

C

Aqua (Water)

C

Hydroxyethylcellulose (HEC)

1.00 Thickener

D

Hydrogenated jojoba seed oil

6.00 40/60 mesh - scrub agent

D

Triethanolamine or citric acid

q.s. To pH 6.5 – 7.5

D

Parfum (fragrance)

q.s. See Unit 13

D

Preservative

q.s. See Unit 6

D

Water-soluble colour

q.s.

15.00 Surfactant 1.00 Thickener/foam stabiliser 15.00 Surfactant 5.00 Surfactant 10.00

Preparation 1. Heat water A to 70°C. 2. Add ingredients in phase B in order listed whilst mixing. 3. In a separate vessel, Add HEC in phase C to water in phase C with high speed propeller agitation and mix for 30 minutes at moderate speed. 4. Add phase C to phase A-B. 5. Cool to 35°C and add phase D. In Formula 09 the HEC acts as a suspending agent for the hydrogenated jojoba seed oil, which confers a mild scrubbing action to the formula. Sodium olefin sulfonate and sodium laureth sulfate are the main foaming agents and cocamidopropyl betaine adds mildness to the composition. PEG-80 jojoba acid improves foam stability and foam density.

30


SKIN PRODUCTS


Formula 10: Relaxing foam bath Stage INCI Name

%w/w Prime function

A

Aqua To 100%

q.s.

A

Sodium laureth sulphate (28%)

A

Sodium lauroyl sarcosinate (30%)

7.50 Surfactant

A

PEG-9 cocoglycerides

4.00 Emollient

A

PEG-75 lanolin

3.00 Solubiliser/emollient

A

Glycol stearate

1.50 Pearlising agent

B

Lactic acid to pH 6.5 – 7.0

B

Hydrolysed oats (50% active)

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s. See Unit 6

C


q.s.

30.00 Surfactant

q.s. pH adjuster 2.50 Moisturiser

Preparation 1. Measure out water and add all Stage A ingredients in turn and heat to 75-80°C. 2. Mix until homogeneous. 3. Stir to cool. Adjust pH to 6.5-7.0 with lactic acid. 4. At 35-40°C, add hydrolysed oats and perfume. 5. Add preservative and colour as required. The sodium laureth sulphate provides good and copious foam and the sodium lauroyl sarcosinate makes it creamier and more stable. PEG-9 cocoglycerides and PEG-75 lanolin each provide emolliancy and the glycol stearate is a pearlising agent. It crystallises out of hot surfactant solutions to give a pearly effect. If a pearly finish is not required leave out the glycol stearate and heat just enough to mix all Stage A ingredients to give a clear solution. Herbal extracts may be added to suit the demand for products with natural ingredients. Formula 11: All-in-one shampoo and shower gel Stage INCI Name

%w/w Prime function

A

Aqua To 100%

q.s.

A


40.00 Surfactant

B


12.00 Surfactant

B

PEG-120 methyl glucose dioleate

2.50 Thickener

B


2.00 Thickener

B

Panthenol

0.40 Hair benefit agent

C

Triethanolamine/citric acid

q.s To pH 6.5- 7.0

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s. See Unit 6

C


q.s. Optional

Preparation 1. Add sodium laureth sulphate to water, with moderate mixing. 2. Add Stage B ingredients to Stage A. 3. Adjust pH to 6.5-7.0. 4. Add perfume, preservative and colour as required. Sodium laureth sulphate provides copious foam and cocamidopropyl betaine makes foam richer and creamier and is said to reduce the irritation potential of sodium laureth sulphate. PEG-120 methyl glucose dioleate and PEG-7 glyceryl cocoate each further enrich the foam and skin feel and add residual conditioning to hair. Panthenol is a small molecule that is proven to penetrate and add moisture to hair although whether it is of benefit in this formulation is debateable.

31


SKIN PRODUCTS


Formula 12: Moisturising body wash Stage INCI Name

%w/w Prime function

A


q.s.

B

Sodium lauroyl sarcosinate (30%)

14.00 Surfactant

B

Sodium laureth sulfate (28%)

13.00 Surfactant

B

Cocamidopropylamine oxide (30%)

4.00 Surfactant/foam stabiliser

B


2.00 Surfactant/.emollient

B C

PEG-150 pentaerythrityl tetraisostearate Parfum (Fragrance)

2.00 Thickener 1.00 See Unit 13

C

1.00 Moisturiser

D

Cocodimonium hydroxypropyl hydrolyzed wheat protein Citric acid to pH 6.5 – 7.0

D

Sodium chloride

q.s. Thickener

D

Preservative

q.s. See Unit 6

q.s. pH adjustment

Preparation 1. Measure out the water into a suitable vessel and start heating to 65 – 70°c. 2. While heating add items in Stage B in turn to the hot water, stirring until clear but avoid aeration. 3. When solution is below 35°C add each Stage C item in turn, with careful stirring 4. Finally adjust pH to 6.5 to 7.0, thicken with sodium chloride if necessary and add a preservative to ensure adequate protection from microbial contamination. Sodium lauroyl sarcosinate is a mild anionic surfactant; in this formulation it improves lather, mildness and after-feel. Sodium laureth sulfate is included for its ability to provide instant foaming. Cocamidopropylamine oxide is included as a foam stabiliser, while PEG-7 glyceryl cocoate is incorporated as a non-ionic mildness additive, which also functions as a water soluble emollient. PEG-150 pentaerythrityl tetraisostearate is a complex high molecular weight ester that is an effective thickener for aqueous detergent systems. The quaternary wheat protein derivative, cocodimonium hydroxypropyl hydrolyzed wheat protein, is a highly substantive conditioning agent included to moisturise the skin. Citric acid is added to adjust pH to 6.5 – 7.0 and a preservative is required to adequately preserve the finished composition.

32


SKIN PRODUCTS


Formula 13: Liquid hand soap Stage INCI Name

%w/w Prime function

A

Aqua To 100%

q.s.

A


7.50 Surfactant

A


25.00 Surfactant

A

PEG-55 propylene glycol oleate

2.00 Skin conditioner

A

Glycol distearate

2.00 Pearl effect

A

Cocamide MEA

2.50 Non-ionic surfactant

A

PEG-150 distearate

0.50 Thickener

B

Parfum (Fragrance)

1.00 See Unit 13

B

Hydrolyzed wheat protein

1.00 Moisturiser

C

Citric acid to pH 6.5 – 7.0

q.s. pH adjustment

C

Preservative

q.s. See Unit 6

Preparation 1. Heat the water to 60°C. Add ingredients in StageA in order and mix between each addition, being careful to avoid aeration. 2. Cool to 30 – 35C and add ingredients in B. Mix well, avoiding air entrapment. 3. Finally adjust pH to 6.5 – 7.0 and add a preservative to ensure adequate protection from microbial contamination. Sodium laureth sulphate provides copious foam and cocamidopropyl betaine makes foam richer and creamier and is said to reduce the irritation potential of sodium laureth sulphate. The PEG55 propylene glycol oleate has a skin conditioning effect; glycol distearate crystallises from hot surfactant solution to impart a pearly effect. Cocamide MEA stabilises the foam and makes it feel richer and creamier. PEG-150 distearate is a very effective thickener for surfactant systems and hydrolyzed wheat protein has a moisturising effect. Formula 14: Waterless hand cleaner Stage INCI Name

%w/w Prime function

A


q.s.

A

Disodium EDTA

0.10 Sequestrant

A

Acrylates/C10-30 Alkyl acrylate crosspolymer

0.50 Thickener

B

Glycerin

10.00 Humectant

B

Alcohol (Ethanol)

50.00 Antimicrobial solvent

B

Triclosan

0.30 Antimicrobial agent

B

Parfum (Fragrance)

0.30 See Unit 13

C

Sodium hydroxide solution to pH 6.5 – 7.0

q.s. pH adjustment

Preparation 1. Measure the water into a suitable vessel and dissolve the Disodium EDTA and carefully disperse the Acrylates/C10-30 alkyl acrylate crosspolymer. Warming to 30°C speeds the process. 2. Mix the items of stage B together and add to Stage A with stirring. 3. Finally adjust pH to 6.5 – 7.0 by careful addition of sodium hydroxide solution – this will gel the mix. The alcohol sterilises the skin and rapidly evaporates. The glycerin stops the ethanol from being too drying; triclosan is an antimicrobial agent that will stay on the skin. When acrylates/C10-30 alkyl acrylate crosspolymer is neutralised to pH 6.5 – 7.0 it forms a clear gel. Because of the high alcohol content a preservative is not required. The perfume is optional.

33


SKIN PRODUCTS


Formula 14: Waterless hand cleaner Stage INCI Name

%w/w Prime function

A


q.s.

A

Disodium EDTA

0.10 Sequestrant

A

Acrylates/C10-30 Alkyl acrylate crosspolymer

0.50 Thickener

B

Glycerin

10.00 Humectant

B

Alcohol (Ethanol)

50.00 Antimicrobial solvent

B

Triclosan

0.30 Antimicrobial agent

B

Parfum (Fragrance)

0.30 See Unit 13

C

Sodium hydroxide solution to pH 6.5 – 7.0

q.s. pH adjustment

Preparation 1. Measure the water into a suitable vessel and dissolve the Disodium EDTA and carefully disperse the Acrylates/C10-30 alkyl acrylate crosspolymer. Warming to 30°C speeds the process. 2. Mix the items of stage B together and add to Stage A with stirring. 3. Finally adjust pH to 6.5 – 7.0 by careful addition of sodium hydroxide solution – this will gel the mix. The alcohol sterilises the skin and rapidly evaporates. The glycerin stops the ethanol from being too drying; triclosan is an antimicrobial agent that will stay on the skin. When acrylates/C10-30 alkyl acrylate crosspolymer is neutralised to pH 6.5 – 7.0 it forms a clear gel. Because of the high alcohol content a preservative is not required. The perfume is optional. Formula 15: Intimate foaming cleanser Stage INCI Name

%w/w Prime function

A


q.s.

A


A

Capryl/capramidopropyl betaine

A

Glycerin

B

Citric acid

q.s To pH 6.5- 7.0

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s. See Unit 6

2.00 Surfactant/.emollient 17.00 Surfactant 3.00 Humectant

Preparation 1. Measure the water into a suitable vessel and dissolve the EDTA, Disodium salt and stir in the PEG-7 glyceryl cocoate, Capryl/capramidopropyl betaine and glycerin. 2. Adjust pH to 6.5 – 7.0 by careful addition of citric acid. 3. Finally add perfume if required and add a preservative to ensure adequate protection from microbial contamination. Pack into a pump-type foamer. This formula uses mild surfactants that will not irritate mucous membranes and that will foam when dispensed from a suitable applicator.

34


SKIN PRODUCTS


Formula 16: Effervescent bath crystals Stage INCI Name

%w/w Prime function

A

Sodium sesquicarbonate

70.00. Bath salts

B

Sodium bicarbonate

C

Tartaric acid

D

Sodium methyl oleoyl taurate (Powder)

E

Parfum (Fragrance)

5.00 Bath salts 20.00 Reacts with the carbonates 5.00 Foaming agent q.s. See Unit 13

Preparation 1. Mix together in a clean, dry powder blender. Compress into suitable moulds. Formula 17; Skin cleansing wipes Stage INCI Name

%w/w Prime function

A


q.s.

A

Methyl gluceth-10

5.00 Cleansing/skin feel

A

PEG-75 lanolin

3.60 Cleansing/skin feel

A

Citric acid

0.20 pH adjustment

A

Oleth-20

1.00 Surfactant

C

Alcohol (Ethanol)

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s. See Unit 13

15.00 Antimicrobial/astringent

Preparation 1. Combine all the ingredients except alcohol, perfume and preservative. 2. Stir until homogeneous. 3. In a separate vessel, mix together alcohol, perfume and preservative and stir until homogeneous then add to main mix. Pack in sealed sachets, ensuring that wipes are completely saturated. Methyl gluceth-10 provides soft ‘feel’; PEG-75 lanolin and oleth-20 provide gentle cleansing but the alcohol is the prime cleansing agent. This solution may be gelled using a carbomer or Acrylates/C10-30 alkyl acrylate crosspolymer at 0.60 – 1.00%. Leave out the citric acid and neutralise to pH 6.5 – 7.0 with a suitable alkali.

35


SKIN PRODUCTS


Formula 18: Cream setting mask Stage INCI Name

%w/w Prime function

A

Kaolin

14.00 Absorbent powder

A

Bentonite

10.00 Thickener /absorbent

A

Light magnesium carbonate

8.00 Toning / bulking agent

A

CI 77981 [Titanium dioxide]

1.00 Whitener

B

Ceteareth-20

3.00 Emulsifier

B

Cetearyl alcohol

0.80 Emollient

B


5.00 Emollient

B

Isopropyl palmitate

2.50 Emollient

C

Glycerine

5.00 Humectant

C

Preservative

q.s. See Unit 5

D


q.s.

E

Parfum (Fragrance)

q.s. See Unit 13

E

Alcohol (Ethanol)

15.00 Drying agent

Preparation 1. Sieve mixed powders in phase A. 2. Heat B to 70°C. 3. Dissolve preservative in glycerin at 70°C and add to water (phase D) at 70°C. 4. Add B to the water phase and mix to form a cream 5. Add A to batch slowly to expel as much air as possible. 6. When cool stir in a mixture of ethanol and perfume. The kaolin absorbs sebum and facial grime; the bentonite thickens the mix, light magnesium carbonate adds bulk to the powders and titanium dioxide whitens them. The items of Stage B form an oil-in-water emulsion with the water phase. Alcohol ensures the mask drying in a reasonable time frame but glycerin stops t he mask from becoming too dry. The ratio of these two ingredients may be varied to obtain the effect desired. Formula 19: Peel-off mask Stage INCI Name

%w/w Prime function

A

Polyvinyl alcohol (PVA)

10.00 Gelling agent

A


55.00

B

Alcohol (Ethanol)

25.00 Drying agent

B

PEG-6 methicone acetate

2.00 Emollient

C

Triethanolamine, 99%

3.00 Neutralising agent

D

Preservatives, parfum, pigments

5.00

Preparation 1. Mix polyvinyl alcohol into hot water and stir until fully dissolved, cool to <40°C. 2. In a separate vessel, mix together the alcohol and PEG-6 methicone acetate and add to A when below 40°C. 3. Adjust pH to 6 - 7 4. Add perfume, pigments and preservative(s) whilst stirring. The polyvinyl alcohol is the setting agent that forms a “skin” on the skin’s surface as the alcohol and water evaporate. The mask may be peeled off when fully set, removing dead skin cells at the same time. Experiment may be needed to obtain the best results.

36


SKIN PRODUCTS


Formula 20: Astringent lotion for oily skin Stage INCI Name

%w/w Prime function

A

Oleth-10

0.50 Solubiliser

A

Parfum (Fragrance)

0.20 See Unit 13

B


C

Propylene glycol

5.00 Humectant

C

Methylparaben

0.20 Preservative

D

Alcohol (Ethanol)

E

Sodium lactate

E


q.s.

20.00 Astringent 0.30 pH buffer q.s. pH adjustment

Preparation 1. Pre-disperse perfume in oleth-10 with gentle warming. 2. Add to the water with vigorous stirring. 3. Dissolve the methylparaben in the propylene glycol and add to main mixture. 4. Stir well and add ethanol. 5. Add sodium lactate then add lactic acid to adjust pH to 5.3 – 5.8 Sodium lactate has moisturising activity and buffers the pH on the addition of lactic acid. This is a basic formulation to which suitable extracts can be added, including Hamamelis virginiana (Witch hazel) extract. Methylparaben is the preservative of choice for this mixture although others may be suitable. Formula 21: Toning lotion for normal/dry skin Stage INCI Name

%w/w Prime function

A


q.s.

A

Glycerin

A

Hydrolyzed silk protein

1.00 Skin conditioner

B

Alcohol (Ethanol)

5.00 Astringent/solvent

B

Polysorbate 20

1.25 Solubiliser

B

Parfum

B

Methylparaben

0.25 Preservative

C

Sodium lactate

0.30 pH buffer

C


10.00 Humectant

q.s. See Unit 13

q.s. pH adjustment

Preparation 1. Mix together items of Stage A 2. In a separate vessel, mix together items of Stage B 3. Add Stage B to stage A while mixing 4. Add sodium lactate then add lactic acid to adjust pH to 5.3 – 5.8. This formulation has reduced alcohol content for less astringency and a high glycerin content to inhibit the skin drying effect of the alcohol. Hydrolyzed silk protein is added to improve the feel of skin. Sodium lactate has moisturising activity and buffers the pH on the addition of lactic acid. This is a basic formulation to which suitable extracts can be added, including Hamamelis virginiana (Witch hazel) extract. Methylparaben is the preservative of choice for this mixture although others may be suitable.

37


SKIN PRODUCTS


Formula 22: Toning lotion for normal/dry and sensitive skin Stage INCI Name

%w/w Prime function

A


q.s.

A

Sodium PCA

A

Hamamelis virginiana (Witch hazel) extract

1.00 Astringent

A

Cucumis sativus (Cucumber) fruit extract

5.00 Moisturising

B

Polysorbate 20

1.25 Solubiliser

B

Parfum

C

Methylparaben

0.25 Preservative

C

Propylene glycol

5.00 Solvent

D

Sodium lactate

0.30 pH buffer

D


10.00 Humectant

q.s. See Unit 13

q.s. pH adjustment

Preparation 1. Mix together items of Stage A. 2. In a separate vessel, mix together items of Stage B. 3. Add Stage B to stage A while mixing. 4. Dissolve methylparaben is propylene glycol and stir into main mix. 5. Add Sodium lactate then add lactic acid to adjust pH to 5.3 – 5.8. This formulation has Hamamelis virginiana (Witch hazel) extract for low astringency and Cucumis sativus (Cucumber) fruit extract for moisturising claims. Sodium lactate has moisturising activity and buffers the pH on the addition of lactic acid. This is a basic formulation to which suitable extracts can be added, including sodium hyaluronate, jojoba ethoxylates, panthenol and water-soluble vitamin E. Methylparaben is the preservative of choice for this mixture although others may be suitable. Formula 23: Stearic acid type vanishing cream Stage INCI Name

%w/w Prime function

A

Isopropyl palmitate

2.00 Emollient/Occlusive

A

Wheatgerm oil

1.00 Emollient/Occlusive

A

Stearic acid

B


B

Triethanolamine

1.40 Neutraliser

B

Glycerin

6.00 Humectant

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s See Unit 6

23.00 Emollient/Occlusive q.s.

Preparation 1. Heat A and B independently to 75°C. 2. Add B to A slowly with continuous stirring. 3. Cool to 35°C and add perfume and preservative. This illustrates a traditional vanishing cream and is now unlikely to be used for a commercial product. The triethanolamine will saponify part of the stearic acid to form a soap, which is an anionic emulsifier, so the emulsion will be an oil-in-water (o/w) type. Over the course of a day or two the stearic acid will form pearl-like crystals and the cream will soften. This process can be encouraged by gentle stirring after 24/48 hours.

38


SKIN PRODUCTS


Formula 24: Moisturising cream Stage INCI Name

%w/w Prime function

A

Caprylic/capric triglyceride

8.00 Emollient

A

Dimethicone

3.00 Emollient/occlusive

A

Ethylhexyl palmitate

5.00 Emollient

A

Cetearyl alcohol


A2

Potassium cetyl phosphate

3.00 Emulsifier

B


B

Glycerin

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s See Unit 6

q.s. 5.00 Humectant

Preparation 1. Heat A (Oil Phase) to 80°C then when clear stir in A2 (Potassium cetyl phosphate) and stir until melted. 2. Heat B (Aqueous Phase) to 80°C then slowly add oils to water with stirring, briefly homogenise, 3. Cool with stirring and add C (perfume and preservative) when below 35°C and homogenise. Formula 24 is a more modern version of a moisturising day cream, suitable for day time use. The caprylic/capric triglyceride is a stabilised form of vegetable oil with a pleasant skin feel. The dimethicone improves application and is part of the moisturising system as it forms an occlusive film on the skin. The cetearyl alcohol has a similar function but is also an emulsion stabiliser. Glycerin is the humectant and ethylhexyl palmitate is a light spreading ester that reduces the oily feel of the composition on application. This formula can form the basis of a good moisturising cream to which can be added other moisturising agents like Sodium PCA; herbal extracts for natural claims and a UV absorber for sun protection.

39


SKIN PRODUCTS


Formula 25: A w/o night cream Stage INCI Name

%w/w Prime function

A

Octyldodecanol

15.00 Emollient

A

Theobroma cacao (Cocoa) seed butter

2.00 Thickens oil phase

A


8.50 Emollient

A

PEG-30 dipolyhydroxystearate

2.00 w/o emulsifier

A

Cera alba (Beeswax)

3.00 Emulsion stabiliser

A

Prunus amygdalus dulcis (Sweet almond) oil

5.00 Emollient

A

BHT (Butylated hydroxytoluene)

0.05 Antioxidant

B


B

Magnesium sulfate


B

Glycerin

5.00 Humectant

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s. See Unit 6

q.s.

Preparation 1. Heat A (Oil Phase) to 80°C with stirring until waxes have melted. 2. Heat B (Aqueous Phase) to 80°C then slowly add Aqueous Phase to Oil Phase with stirring, briefly homogenise, cool with stirring. 3. Add C (perfume and preservative) when below 35°C and homogenise This is an example of a w/o emulsion containing natural oil (Prunus amygdalus dulcis (Sweet almond) oil) and natural waxes (Theobroma cacao (Cocoa) seed butter & Cera alba (Beeswax). The emulsifier is PEG-30 dipolyhydroxystearate and w/o emulsion stability is enhanced by the addition of magnesium sulfate in the aqueous phase. An antioxidant is required to prevent rancidity of natural oils and waxes; BHT is suggested but there are other ones that are suitable e.g. tocopherol. The waxes give structure to the oil phase and the octyldodecanol and ethylhexyl palmitate reduce the heavy feeling of the oils/waxes on application.

40


SKIN PRODUCTS


Formula 26: A moisturiser with liquid crystal emulsifier system Stage INCI Name

%w/w Prime function

A


6.00 Emollient

A

Cetearyl alcohol


A

Cetearyl glucoside

1.00 Emulsifier

A

Vitis vinifera (Grape) seed oil

4.00 Emollient

A

Tocopherol

0.10 Antioxidant

A2

Cyclopentasiloxane

0.20 Prevents “soaping”

B


B

Disodium EDTA

0.08 Sequestrant

B

Xanthan gum

0.15 Rheology modifier

B

Glycerin

5.00 Humectant

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s See Unit 6

q.s.

Preparation 1. Heat A (Oil Phase) to 70°C and stir until ALL melted. Just prior to mixing the two phases together add A2 (cyclopentasiloxane), which is volatile. 2. Heat B (Aqueous Phase) to 30°C, dissolve the disodium EDTA and then disperse the xanthan gum before heating to 70°C. 3. Slowly add oils to water with stirring, briefly homogenise, cool with stirring and add C (perfume and preservative) 4. When below 35°C add perfume and preservative with stirring. Do not homogenise as this disrupts the formation of liquid crystals. This is a basic formula to illustrate an emulsifier system (cetearyl glucoside & cetearyl alcohol) that forms liquid crystals in o/w emulsions. The combination of caprylic/capric triglycerides give a nice skin feel on application, which is further enhanced by the cyclopentasiloxane. The xanthan gum helps stabilise the emulsion and glycerin is the humectant. The formula may be readily adapted to use any of the emulsifier combinations suggested in the main text for forming liquid crystals and herbal extracts and moisturising agents may be added.

41


SKIN PRODUCTS


Formula 27: w/o emulsion using a silicone-based emulsifier Stage INCI Name

%w/w Prime function

A

Persea gratissima (Avocado) oil

25.50 Emollient

A

Cetyl PEG/PPG-10/1 dimethicone

2.50 Silicone emulsifier

A

Hydrogenated castor oil

0.80 Soft wax

A

Cera alba (Beeswax)

1.20 Wax

A

BHT (Butylated hydroxytoluene)

0.10 Antioxidant

B


B

Sodium chloride


B

Glycerin

5.00 Humectant

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s See Unit 6

q.s.

Preparation 1. Heat A (Oil Phase) to 75°C with stirring until waxes have melted. 2. In a separate vessel heat B (Aqueous Phase) to 75°C then slowly add Aqueous Phase to Oil Phase with stirring, briefly homogenise, cool with stirring. 3. Add C (perfume and preservative) when below 35°C and homogenise when at 25°C. Cetyl PEG/PPG-10/1 dimethicone is the primary emulsifier with stability improved by the incorporation of hydrogenated castor oil and beeswax. Formula 28: Alpha-hydroxy cream Stage INCI Name

%w/w Prime function

A

Cetearyl alcohol

2.80 Emollient

A

PEG-20 glyceryl stearate

4.30 Emulsifier

A

Stearic acid

1.40 Emollient

A

Isopropyl palmitate

4.20 Emollient

A

Paraffinum liquidum

4.30 Emollient

A

Cetyl dimethicone

1.40 Emollient

B


B

Sodium magnesium silicate

1.00 Thickener

B2

Glycerin

4.50 Humectant

B2

Glycolic acid (50%)

7.10 Alpha-hydroxy acid

B3

Sodium hydroxide to pH 4.5

q.s. pH buffer

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s See Unit 6

q.s.

Preparation 1. Heat A (Oil Phase) to 75°C and stir until melted. 2. In a separate vessel heat water to 30°C and disperse Sodium magnesium silicate with vigorous stirring then bring temperature to 75°C, adding B2 ingredients while heating and stirring. 3. When Aqueous Phase is at 75°C slowly add oils to water with stirring, briefly homogenise then continue stirring while cooling to 40°C. 4. Add B3 (Sodium hydroxide 25% solution) to adjust pH to 4.5 +/- 0.2 5. Continue cooling with stirring and add C (perfume and preservative) when below 35°C and homogenise. PEG-20 glyceryl stearate is an acid stable emulsifier; further stability is conferred by the presence of cetearyl alcohol and cetyl dimethicone and these plus the other emollient oils help protect the skin from irritation as the alpha-hydroxy acid dislodges dead skin cells. 42


SKIN PRODUCTS


Formula 29: Moisturising cream with liposomes Stage INCI Name

%w/w Prime function

A

Acrylates/C10-30 alkyl acrylates crosspolymer


A

Carbomer


A


3.00 Emollient

A

Ethylhexyl stearate

8.00 Emollient

A


7.00 Emollient

B


B

Glycerin

2.00 Humectant

B

Sodium hydroxide (18% solution)

0.50 pH adjuster

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s See Unit 6

D

Liposome [Phospholipids + active]

q.s.

3.00 Delivery system

Preparation 1. Combine ingredients in phase A in final vessel, stirring rapidly to disperse the polymers. 2. In a separate vessel combine the ingredients in phase B, mix until homogeneous. 3. Add three-quarters of Phase B to A slowly, with rapid stirring for 20 minutes to swell polymers. 4. When emulsion is smooth and white, add part of the sodium hydroxide solution and bring to pH 7.0, then continue mixing. 5. Slowly add the remainder of Phase B with moderate mixing. 6. Add the rest of the sodium hydroxide solution. 7. Add C, the perfume and preservative and mix. 8. Add D, the liposomes whilst stirring very slowly to avoid rupturing them. 9. Mix until uniform. Mixing the polymers in the oil phase is a way of avoiding the problems of dispersing them in water and it can be very successful, as long as the oils and mixing vessel are perfectly dry. The Liposome can be any that is commercially available from a supplier.

43


SKIN PRODUCTS


Formula 30: Moisturising cream with Cocoa seed butter Stage INCI Name

%w/w Prime function

A


2.00 Emollient

A

Theobroma cacao (Cocoa) seed butter

2.00 Emollient

A

Lanolin oil

1.00 Emollient

A

Stearic acid

2.00 Emulsifier

A

Glyceryl stearate SE

2.00 Emulsifier

A

Dimethicone

1.00 Occlusive emollient

B


B

Glycerin

4.00 Humectant

B

Triethanolamine

0.93 pH adjuster

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s See Unit 6

q.s.

Preparation 1. Heat A (Oil Phase) to 70°C and stir until melted. 2. In a separate vessel heat B (Aqueous Phase) to 70°C 3. Slowly add oils to water with stirring, briefly homogenise, 4. Cool with stirring and add C (perfume and preservative) when below 35°C and homogenise. The glyceryl stearate SE is a self-emulsifying grade which has been partially saponified with sodium or potassium hydroxide to form an anionic soap-type emulsifier. It must only be used at pH 7.0 and above. Further emulsifier is formed between the stearic acid and triethanolamine within the formula. The result is a non-greasy emulsion that protects the hands but it can be readily removed by washing.

44


SKIN PRODUCTS


Formula 31: All-purpose moisturising milk Stage INCI Name

%w/w Prime function

A

Isohexadecane

6.00 Emollient

A


2.00 Emollient

A


A

Sorbitan stearate

3.00 Emulsifier

A2

Cyclopentasiloxane

1.50 Improves application

B


B

Disodium EDTA

0.08 Sequestrant

B

Xanthan gum


B

Glycerin

4.00 Humectant

B

Polysorbate 60

2.50 Emulsifier

B

Urea

5.00 Moisturiser

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s. See Unit 6

10.00 Emollient

q.s.

Preparation 1. Heat A (Oil Phase) to 70°C and stir until ALL melted. Just prior to mixing the two phases together add A2 (cyclopentasiloxane), which is volatile. 2. In a separate vessel heat B (Aqueous Phase) to 30°C, dissolve the disodium EDTA and then disperse the xanthan gum before heating to 70°C. 3. Slowly add oils to water with stirring, briefly homogenise, cool with stirring and add C (perfume and preservative) In formula 31, isohexadecane, cyclopentasiloxane and PPG-15 stearyl ether t ogether with Paraffinum liquidum (Mineral oil) are used for their emolliancy; sorbitan stearate and polysorbate 60 is the emulsifier system. Urea is included for its moisturising properties. The formula may be made less oily by substituting an emollient ester for some or all of the Paraffinum liquidum. Moisturising additives like sodium hyaluronate or sodium PCA may also be included. As an exercise check the required HLB of the oil phase and see if the emulsifiers satisfy the HLB system. Formula 32: Talcum powder Stage INCI Name

%w/w Prime function

1

Parfum (Fragrance)

q.s. See Unit 13

2

Magnesium carbonate (light)

3

Zinc stearate

5.00 Adds lubricity

4

Zinc oxide

4.00 Soothing agent

5

Talc to 100%

15.00 Absorbent powder

q.s. Absorbency and slip

Preparation 1. Mix perfume with magnesium carbonate 2. Add remaining ingredients and mix in a suitable blender Zinc stearate is included for lubricity and its mild antiseptic properties. Soothing agents such as Aloe barbadensis leaf juice and allantoin can be added, to help relieve minor skin irritations and the discomfort caused by prickly heat rash and sunburn. Magnesium carbonate provides absorbency and fluffiness. Some “talcum” powders may contain modified starch.

45


SKIN PRODUCTS


Formula 33: Moisturising milk for combination and oily skin Stage INCI Name

%w/w Prime function

A

PEG-5 glyceryl stearate

1.50 Emollient

A

Steareth-10

1.50 Emollient

A

Cetearyl alcohol

0.80 Emollient

A


5.00 Emollient

A


8.00 Emollient

A2

Cyclopentasiloxane


B


B

Disodium EDTA

0.08 Sequestrant

B

Carbomer


B

Glycerin

3.00 Humectant

B

Triethanolamine

0.15 neutraliser

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s. See Unit 6

q.s.

Preparation 1. Heat A (Oil Phase) to 70°C and stir until ALL melted. Just prior to mixing the two phases together add A2 (cyclopentasiloxane), which is volatile. 2. In a separate vessel heat B (Aqueous Phase) to 30°C, dissolve the disodium EDTA and then disperse the Carbomer before heating to 70°C. 3. Slowly add oils to water with stirring, briefly homogenise 4. Cool with stirring and add C (perfume and preservative) The emolliancy can be modified by substituting Paraffinum liquidum for some or all of the ethylhexyl palmitate. The viscosity can be modified by increasing or decreasing the carbomer content, in which case add sufficient triethanolamine to neutralise to pH 6.5 – 7.0 Formula 34: Barrier cream for foot protection against water and water-borne pollutants Stage INCI Name

%w/w Prime function

A



A

Glyceryl stearate SE

5.00 Emulsifier

A

Cetearyl alcohol

0.80 Emollient

A

Dimethicone 200cs

5.00 Waterproofing

B


B

Glycerin

B

Kaolin

C

Parfum (Fragrance)

q.s. See Unit 13

C

Preservative

q.s See Unit 6

q.s. 3.00 Humectant 35.00 Barrier agent

Preparation 1. Heat A (Oil Phase) to 70°C and stir until ALL melted. 2. In a separate vessel heat B (Aqueous Phase) to 70°C 3. Slowly add oils to water with stirring, briefly homogenise 4. Add kaolin with continuous mixing, allow air to dissipate and keep mixing until a smooth consistency is obtained. 5. Cool with stirring and add C (perfume and preservative) This formula is suggested as protection against water and water-borne pollutants. The kaolin, Paraffinum liquidum and dimethicone will form a protective film on the foot surface.

46


SKIN PRODUCTS


Formula 35: Barrier cream for foot protection against oil and oil pollutants Stage A A B B

INCI Name Acacia senegal gum Aqua (Water) to 100% Glycerin Astragalus gummifer gum Preservative

%w/w 5.00 q.s. 2.50 5.00 q.s.

Prrime function P Barrier film former Plasticiser Barrier film former See Unit 6

Preparation A. Dissolve the Acacia Senegal gum gum in the water water,, warming may may help.. B. Diss Dissolve olve the Astragal Astragalus us gummifer gummifer gum gum in the glycerin. glycerin. C. Add B very slowly to A with continuous continuous stirring then add preservative preservative This formula is suggested as protection against water and water-borne pollutants however it is added here more for interest than practical application and the use of modern film forming g resins would provide a more elegant product. Acacia senegal gum is also known as gum arabic and astragalus gummifer gum as gum tragacanth. Formula 36: Liquid powder for feet Stage INCI Name

%w/w Pr Prime function

A


q.s.

A

Disodium EDTA

0.10 Sequestrant

A

Acrylates/C10-30 alkyl ac acrylate cr crosspolymer

0.45 Rheology mo modifer

B

Alcohol (Ethanol)

B

Dichlorobenzyl alcohol

0.10 Fungicide

B

Cyclopentasiloxane


B

Melaleuca alternifolia (Tea tree) leaf oil

0.15 Essential oil/fragrance

B

Menthol

0.10 Cooling agent

B

Mentha piperita (Peppermint) oil

0.10 Essential oil/cooling

C

Tapioca starch

20.00 Ab Absorbent powder

D

Triethanolamine

0.140 Ne Neutraliser

D

Aqua (Water)

35.00 Solvent

0.50

Preparation 1. Warm water to 40°C, 40°C, dissolve disodium disodium EDTA EDTA and disperse acrylates/C10-30 acrylates/C10-30 alkyl acrylate crosspolymer crosspol ymer (Use propeller stirrer). Cool A to below 30°C. 2. Mix together items items of Stage B. B. When main mix below 30°C stir in Stage B mix. 3. Stir in tapioca flour; this must must disperse well and be smooth and and homogenous. homogenous. 4. Finally; when a smooth smooth homogenous homogenous main mix is obtained thicken thicken it by the addition of a water/triethanolamine solution to adjust pH to 6. – 7.0. This applies as a thickened liquid but during application the alcohol evaporates leaving the foot coated with absorbent powder. powder. It is cooling and pleasant to use. The alcohol content is the preservative and dichlorobenzyl alcohol has fungicidal properties.

47


SKIN PRODUCTS


Formula 37: Cooling foot spray Stage INCI Name


A

Alcohol (Ethanol)

55.00 Solvent

B

Dichlorobenzyl alcohol

0.10 Fungicide

B

Propylene glycol

5.00 Rh Rheology modifer

B

Melaleuca alternifolia (Tea tree) leaf oil

0.15 Essential oil/fragrance

B

Menthol

0.10 Cooling agent

B

Mentha piperita (Peppermint) oil

0.10 Essential oil/cooling

C

Aqua (Water)

C

Sodium lactate

0.20 pH buffer

C

Lactic acid (88%)

0.10 pH pH adjustment

D


20.00

q.s.

Preparation 1. Disp Dispense ense the alcohol alcohol – warning warning highly highly flammabl flammable. e. 2. Mix together together the the Items of Stage Stage B and add add to alcohol. alcohol. 3. Slowly add water water C to main mix with vigorous vigorous stirring then add sodium sodium lactate and lactic acid to adjust pH to 4.8 – 5.8. 4. Slow Slowly ly add water water D to main mix with vigoro vigorous us stirring. stirring. This formula is suitable for packing in a pump spray. The alcohol content is the preservative and dichlorobenzyl dichloro benzyl alcohol has fungicidal properties. Formula 38: Emollient baby bath oil Stage INCI Name


1


80.00 Emollient

2

Polysorbate 80

20.00 Cleansing

Preparation Mix together in a clean dry vessel. Formula 28 will disperse in the bath water making it easy to clean the baby and imparting an emollient film to the skin. Beware – the baby may be slippery after bathing! No preservative is required as there is no water in the product and it can be left unperfumed or a suitable parfum/fragrance obtained for use in baby products.

48


SKIN PRODUCTS


Formula 39: Lotion for wet wipe Stage INCI Name


A


1.50 Em Emollient

A

Cetearyl stearate

0.50 Emollient

A


A

Sorbitan stearate

1.50 Emulsifier

A2

Cyclopentasiloxane


B


B

Glycerine

3.00 Humectant

B

Polysorbate 60

1.50 Emulsifier

C

Preservative

q.s. See Unit 6

C

Parfum (Fragrance)

q.s. Se See Unit 13

10.00 Em Emollient

q.s.

Preparation 1. Heat A (Oil Phase) Phase) to 70°C and stir until ALL melted. Just Just prior to mixing mixing the two phases together add A2 (Cyclopentasiloxane), which is volatile. 2. In a separate separate vessel vessel heat B (Aqueou (Aqueouss Phase) Phase) to 70°C. 70°C. 3. Slow Slowly ly add oils to water with stirring stirring,, briefly homogen homogenise ise 4. Cool with stirring and add add C (perfume and preservative) preservative) when below below 35°C This formula is suitable for application on wet wipes .Caprylic/capric triglyceride could be substituted for the Paraffinum liquidum and the lotion could be made without fragrance. Formula 40: Liquid talc for babies Stage INCI Name


A


q.s.

A

Carbomer

B


B

Cetearyl alcohol

0.60 Emollient

C

Cyclopentasiloxane


D

Maize or tapioca starch

3.00 Humectant

D

Talc

E

Triethanolamine (50%) to pH 7.0

q.s. Neutraliser

E

Preservative

q.s. See Unit 6

E

Parfum (Fragrance)

q.s. Se See Unit 13

0.50 Suspending agent 10.00 Emulsifier

10.00 Emulsifier

Preparation 1. Heat the water (A) to 30°C and and disperse the carbomer then bring to 70°C 70°C with stirring. stirring. 2. When at 70°C 70°C stir in the PEG-7 glyceryl cocoate cocoate and then then the cetearyl alcohol. alcohol. Make sure sure this completely dissolves in the hot emulsion. 3. Cool to 60°C 60°C and stir in the the cyclopentas cyclopentasiloxa iloxane ne (C). 4. Stir in the starch and and talc (D) and continue continue to cool with stirring. 5. At about 40°C 40°C add the the preservative and and then triethanolamine triethanolamine as a 50% solution solution in water; water; this will gel the mix. 6. If to be fragranced add when when mix is below 35°C and make sure sure fragrance is considered considered safe for babies. This is very much a guide formulation, which will need f urther work to ensure its stability. stability. The cetearyl alcohol is added to hot water as there is insufficient oil phase to add separately. separately.

49


SKIN PRODUCTS


Formula 41: Protective baby cream Stage INCI Name

%w/w Prime function

A

Microcristallina cera

3.50 Thickener

A

Petrolatum

A

Sorbitan stearate

A


B


B

Glycerin

5.00 Humectant

B

Allantoin

0.10 Soothing agent

C

Zinc oxide

7.00 Skin protectant

D

Preservative

q.s. See Unit 6

D

Parfum (Fragrance)

q.s. See Unit 13

13.50 Emollient/occlusive 2.00 Emulsifier 14.50 Emollient/occlusive q.s.

Preparation 1. Heat the items of Stage A, the oil phase, to 70°C until all melted. 2. In a separate vessel heat the items of Stage B, the aqueous phase to 70°C. 3. Add Stage B to Stage A with mixing. 4. Cool to 60°C with stirring and sift in the zinc oxide. 5. Mix to a smooth consisentcy and continue mixing to room temperature, adding preservative and then perfume if required. Homogenise if possible. Zinc oxide is a traditional additive for creams for babies’ bottoms. It has soothing properties and helps keep the area dry. This is a product where the occlusive properties of petrolatum and Paraffinum liquidum are particularly beneficial as they provide a barrier against babie’s urine.

50


SKIN PRODUCTS

PART 2



Unit 16

Prepared by Grace Abamba Amended by Paul Hebditch and John Woodruff



3 CONTROL OF BODY ODOUR AND SWEATING 3.1 Body odour and sweating

In the hustle and bustle of everyday living, with overcrowded trains and stuffy meeting rooms, one becomes highly aware of the next person’s smell or body odour, which can vary from quite attractive to positively nauseating. Having a socially acceptable smell is very important. In addition, sweat-stained armpits on clothing are perceived to be a sign of anxiety. Body odour in cosmetic terms refers specifically to armpit (or axillary) odour which tends to have a characteristic smell.

ACTIVITY 6 The causes of body odour (Allow about 5 minutes) In the space below, write down what you think are the common causes of body odour and sweating. I have given you an example of each. Body odour

52

Sweating

1 Lack of washing 1

Vigorous exercise

2

2

3

3


SKIN PRODUCTS


Hot weather, exercise, anxiety/emotional stress makes us hot and therefore sweat. Lack of washing to remove sweat and skin debris, and eating certain foods such as garlic contribute to underarm odour. Underarm hair tends to trap and concentrate any odour produced. Sweat glands and skin bacteria In the first part of this unit, we discussed the two types of sweat glands and how apocrine sweat in particular is broken down by skin bacteria to cause body odour. You may like to go over that section again if you cannot recall this material. There are specific groups of skin bacteria which act on apocrine sweat to produce characteristic malodours. For example, the Gram-positive Coryneforms produce a pungent, acrid odour; on the other hand, Micrococci and Gram-negative bacteria such as E. coli produce sweaty smells. For further information read chapter 8 in the reference book on antiperspirants and deodorants given at the beginning of this unit.

ACTIVITY 7 Comparison of apocrine and eccrine sweat (Allow about 5 minutes) Since the secretion of body fluids (sweat) is the primary source of body odour, we need to be aware of how it is produced and the nature of its composition. Apocrine sweat composition

%

Eccrine sweat composition

%

Protein

1.56

Sodium chloride

Amino acids

0.97

Acetic acid

0.0096

Lipids

0.03

Propionic acid

0.0002

Carbohydrates

0.10

Caprylic acid and caprionic acid

0.0046

Water

to 100

0.70

Lactic acid

0.10

Citric acid

0.14

Urea

trace

Water

to 100

How would you say that the two types of sweat differed?

Eccrine sweat consists of mainly common salt (sodium chloride) and short chain organic acids. However, we can see that apocrine sweat produces the main source of nutrients for bacterial growth. The other contributory factors which result in axillary odour are summarised in figure 6 on the following page.

53


SKIN PRODUCTS


Apocrine glands

Eccrine glands

Proteins, lipids, carbohydrates

Water, minerals, electrolytes

Bacterial growth

Semi-occluded environment

Lipid mixture

Sebaceous glands

Odour

Anatomy of axillae

Figure 6. Contributory factors to axillary odour

As you can see, the anatomy of the underarm area provides a partially closed environment where bacteria can thrive on the nutrients provided by the three major glands. The sebaceous and apocrine glands secrete lipids, proteins and carbohydrates while the eccrine glands provide water, minerals and electrolytes. 3.2 Formulating deodorant and antiperspirant products Aims In this section, I aim to discuss the products used to combat underarm odour and sweating, namely deodorants and antiperspirants; and explore methods for evaluating their efficiency. Introduction You may like to think that a good wash in the morning is all you need to prevent body odour later in the day, but often this is not the case. Depending on the type of work or activity we are involved in during the day, we may need to reduce or disguise our body odour. The cosmetics and toiletries industry has developed products, namely deodorants and antiperspirants, which can do this job. Let us start this section by defining exactly what we mean by the terms antiperspirant and deodorant. A deodorant is a cosmetic product which masks, reduces and/or removes or prevents the development of body odour. An antiperspirant is a chemical that when applied topically to the underarm will reduce the production of sweat at that site. In the USA, antiperspirants are classified as over-the-counter (O.T.C.) drugs and are regulated by the Federal Drug Administration (FDA); this is not the case in Europe. Product formats Before we begin to look more closely at formulations, it is important to note that deodorants and antiperspirants are available in at least four different formats: aerosols, roll-ons, pumps, and sticks/solids. In recent years, there has been an increased interest in creams and the more recent deo-wipe format. Some of these formats are shown in figure 7 on the following page. The product format chosen will obviously determine the nature of the finished formulation, even though the same active material is being used.

54


SKIN PRODUCTS


Aerosol

Roll-on

Pump

Stick

Figure 7. Packaging for deodorants and antiperspirants

ACTIVITY 8 Advantages and disadvantages of product formats This activity has been identified as a key activity for this unit. Please go to the online module to complete this activity, so that you can share your ideas and opinions with your fellow learners and benefit from their experience and knowledge in this area. Formulations I shall now look at active materials for deodorants. There are three mechanisms for achieving deodorancy: odour modification; odour reduction and/or removal; and odour prevention. Odour modification. In the absence of frequent bathing, the use of fragrances to modify body odour was extremely common until the use of soap became popular. Odour modification by fragrances can be done in a number of ways. The fragrance can change a malodour to give it a more pleasant character in a process called masking.

55


SKIN PRODUCTS


Perfume raw materials which can be used include the terpenes, such as citrals, alphaionone and geranyl formate. These volatile materials are effective at extremely low concentrations and work by competing with the malodorous chemicals to volatilise; so we smell the odour-masking substance rather than the malodour. Use of encapsulation technology provides controlled release of fragrances over a period of time. This allows manufacturers to make stronger efficacy claims such as 24 hour deodorancy. A fragrance can also reduce the intensity of the malodour by counteraction. Odour counteraction can be explained as follows. Consider two odours A and B, where each is given a perceived odour intensity score on an arbitrary scale. A represents the malodour with a perceived intensity score of 8 and B represents a fragrance compound with a score of 3. When the two odours are combined, their perceived odour intensity score is reduced to 5 or even 2. As a result, there is a perceived reduction in the malodour. Odour removal . Physical methods involve good skin hygiene such as daily washing, which helps to remove skin debris and malodorous chemicals, and reduces the total number of bacteria on the skin. Chemical substances such as sodium bicarbonate, zinc glycinate and magnesium oxide work by chemical neutralisation of the short chain fatty acids such as isovaleric and butyric acids, in the axillae. Odour absorbents capture and retain odour molecules inside their structure. On the other hand, odour adsorbents retain the molecules on the surface of their structure. Examples of these materials include zinc ricinoleate and patented materials such as aluminium and potassium double sulfate. Odour prevention. The most common method of achieving deodorancy is to combine perfume with an antimicrobial agent. These work by eliminating skin bacteria including those responsible for breaking down apocrine sweat in the axillae. These materials are often used as preservatives in cosmetic formulations. The earliest examples of such materials include cresylic acid (used in Lifebuoy soap, 1895), zinc oxide (used in Mum, 1902), hexachlorophene (used in Dial Soap, 1948) and later benzethonium chloride. Nowadays trichloro hydroxy diphenyl ether or Triclosan is widely used. In addition, aluminium salts, which are primarily used as antiperspirant actives, have very good antibacterial properties too. We will discuss antiperspirants in more detail in the next section. The use of bacterial enzyme inhibitors represents an alternative way of controlling body odour to using antimicrobial agents which tend to be non-specific and can cause skin irritation in sensitive skins. These enzyme inhibitors are usually esters of hydroxycarboxylic acids; one example is triethyl citrate (at 1-1.5% w/w). They work as follows: 1 Bacterial enzymes known as esterases normally attack a variety of esters in apocrine sweat. 2 In the presence of triethyl citrate, the esterases attack the triethyl citrate and hydrolyse it to citric acid. 3 Citric acid will reduce the skin pH. Now esterases cannot work in highly acidic conditions and so do not metabolise apocrine sweat; hence the malodorous chemicals are not produced. A disadvantage with the use of enzyme inhibitors is that once they are used up or diluted by eccrine sweat, then the skin pH will return to normal and the bacterial esterases will start working again. There fore the product containing such inhibitors has to be reapplied fairly often. Examples of deodorant formulations are given in formulae 42 and 43.

56


SKIN PRODUCTS


3.3 Active materials for antiperspirants The first antiperspirant on the market used aluminium chloride as the active. However, it is highly acidic and became extremely unpopular because it was a skin irritant which stained fabrics and led to their eventual disintegration. Nowadays, the most commonly used active ingredients are aluminium chlorohydrate (ACH) and aluminium zirconium chlorohydrate (AZCH). These are buffered astringent salts with an approximate pH 4. A combination of magnesium hydroxide and glycine produces a good buffering system. Mode of action There are a number of hypotheses to explain how antiperspirants reduce axillary sweating. The most widely accepted one is the hydroxide plug hypothesis which involves the diffusion of the soluble antiperspirant into the sweat duct. The acidic metal salt is gradually neutralised to form a polymeric aluminium hydroxide gel. The latter partially blocks the opening of the sweat duct and so reduces the amount of sweat delivered to the skin (see figure 8).

Stratum corneum

Hydroxide gel plugs of Aluminium-Zirconium antiperspirant Eccrine sweat duct

Epidermis

Figure 8. Blockage of the sweat duct by antiperspirant salts

Active ingredient forms ACH and AZCH complexes are available commercially as: – solutions - ACH and AZCH are available as 50% and 35% aqueous solutions respectively – powders of various particle sizes: macrospheres of ACH for aerosols; fine powders for sticks and roll-ons – granules - ACH only. Activated aluminium compounds The introduction of ‘activated’ or enhanced forms of ACH and AZCH is the most recent development in antiperspirant technology. The process involves modification of the distribution of the active molecular species within the complex, which significantly improves its antiperspirancy compared to the unactivated salt. It is beyond the scope of the module to discuss the chemistry of these materials. Further information can be found in chapter 6 of L. Karl and C. B. Felger, Antiperspirants and deodorants.

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Legislation The use of antiperspirants, like antimicrobial actives, is regulated by the EU Cosmetics Directive in Europe, and the FDA’S OTC Review Panel in USA. See table 6 below. Table 6. Regulation of antiperspirant actives

Active

Maximum use level (anhydrous)

Exclusions

ACH

25%

None

AZCH*

20%

Not permitted in aerosols due to inhalation risk

Normal use levels are 3 - 10% in aerosols and 15 - 20% in sticks and roll-ons. AZCH tends to be about 30% more active than ACH on a weight for weight basis. In order for a product to be registered as an antiperspirant , it must be shown to reduce sweating by a minimum of 20% in at least 50% of the test population. The following table illustrates the relative efficiency of antiperspirant actives in different product forms. Table 7. The efficiency of antiperspirant actives

Active

Product form

% Sweat reduction

ACH (20% aqueous)

Stick/roll-on

35-40

AZCH (20% aqueous)

Stick/roll-on

55-60

ACH (standard)

Aerosol

20-25

ACH (activated)

Aerosol

35-40

Formulations Examples of antiperspirant formulations are given in formulae 44 - 46.

Evaluating the efficacy of deodorants and antiperspirants Evaluation of deodorants and antiperspirants involves rather complicated processes which must be strictly controlled in order to obtain meaningful results.

ACTIVITY 9 Deodorant and antiperspirant evaluation (Allow about 50 minutes) Standard methods for evaluating the efficacy of deodorants and antiperspirants are given in the extract contained in the Supplementary Booklet. Read the extract carefully, and make notes on it. There is no need to dwell on the statistical methods employed at this stage, since statistics will be covered in a later module. The original text contained further references which have been omitted in this extract. You will need to obtain a copy of the textbook to find these references. When you make notes, use as a guide the questions which follow.

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1 List the two main methods for evaluating deodorant efficacy in vivo.

2 Describe the Baxter and Reed Olfactory Method of assessing deodorant efficacy.

3 Summarise the indirect method for deodorant efficacy measurement.

4 Describe the gravimetric method for assessing antiperspirant efficacy.

5 Summarise the alternative methods for measuring antiperspirant efficacy, namely thermography and hygrometry.

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Summary To conclude this section, I have summarised in figure 9 the various factors which contribute to body odour and the cosmetic formulations used to control and prevent it. Factors affecting production Emotion

Apocrine sweat

+

Heat

Underarm hair

Exercise

Washing

Eccrine + sweat

Skin bacteria

Control measures

+

Skin debris

Diet

Underarm odour

Washing Antiperspirant

Antibacterial

Perfume Absorbent

Figure 9. The production and control of body odour

CHECKLIST You should now be able to: – list the major factors which cause underarm odour – explain the difference between apocrine and eccrine sweat in terms of composition – define the function of a deodorant and an antiperspirant – describe the various product and packaging forms available for deodorants and antiperspirants – list the common active materials used in deodorants and antiperspirants – list other basic components found in deodorant and antiperspirant formulations.

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4 SUN PROTECTION 4.1 Sunlight and its effects on the skin Aims In this section, I aim to discuss the physical nature of sunlight and how it interacts with the skin to cause tanning and less favourable effects such as sunburn, premature ageing (photo-ageing) and skin cancer. Introduction As well as promoting a feeling of well-being and enabling the synthesis of vitamin D, the sun causes white skin to turn brown in a process called tanning. People who are born with brown skin tend to get darker in more intense sunlight. Until the turn of the century, tanned skin was viewed quite differently from the way it is today. A person with tanned skin was likely to come from a poor background, which meant that they were engaged in menial outdoor work. The rich made efforts to protect their skin from the sun and even bleached it, at their own peril, with mercurybased products. With a change in social attitudes, a good tan signifies wealth and the fact that one has been away on holiday. This has resulted in an increase in sunburn, skin cancer and young people with prematurely aged skin. The cosmetics industry has responded with a plethora of suncare products and, more recently, anti-ageing products. The function of suncare products has shifted from just an aid for developing a good tan to an essential protective measure against the ill-effects of the sun. Products for consumers with dark skins are also emerging. Increased consumer awareness about sun-related diseases has led to a phenomenal growth in European sun product sales exceeding € 1.48 billion in 2010, up 4.2% on the previous year in the ‘Big 5’ (France, Germany, Italy, Spain and the UK) alone. Electromagnetic spectrum Let us have a closer look at the nature of sunlight. The sun emits electromagnetic radiation as waves from its surface, which can be divided into 8 major wavelengths, as shown in table 8. Table 8. Solar radiation

Type of radiation Cosmic rays

Wavelength range (m)

Energy range

10-15

Highest energy

105

Lowest energy

Gamma rays X-rays Ultraviolet rays Visible light Infra-red Microwaves Radio waves

The ultraviolet (uv) radiation is the waveband that concerns us, and can be divided into 3 main wavelengths: UVC (200 - 290 nm), UVB (290 - 320 nm), and UVA (320 - 400 nm). UVC rays never enter the earth’s atmosphere because they are filtered out by the ozone layer unlike UVA and UVB rays. Ultraviolet A is able to penetrate glass whereas UVB cannot. Both UVB and UVA can penetrate the ozone layer. Although UVB has much higher energy than UVA, it does not penetrate glass. UVB will penetrate the epidermis, but it is mostly absorbed just above the dermis. UVA penetrates into the dermis and beyond. Going one step further, visible light and infra-red, which is detectable as heat, can penetrate more deeply into the body. The energy that UVA and UVB transmit to cellular structures is responsible for damaging effects on the skin ranging from acute symptoms of sunburn and tanning to chronic skin cancer and premature ageing (see figure 10 on the following page).

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DIPLOMA/CERTIFICATE IN COSMETIC SCIENCE MODULE 2 UNIT 16 UV - A (down to the dermis)

Reflection from skin surface (5%)

UV - B (above the dermis)

Incident radiation

Thickness (in µ) Stratum corneum (8-15µ)

0

Granular cell layer (2-4µ)

20

Dermal reflection

40 Squamous cell layer (50-150µ)

60 Absorption Melanocyte

80

100 Basal cell layer (5-10µ)

Diffraction

120

140 Dermis (1000-4000µ)

Capillaries

160

200

Veinlet

Arteriole

Figure 10. Diagrammatic cross-section of the skin showing the penetration of UV radiation (courtesy Givaudan-Roure)

Light intensity The two major factors which influence skin colour (pigmentation) and how it reacts to exposure to sunlight are the intensity of light and the person’s skin type. The intensity of light reaching the skin will be determined by a number of environmental factors.

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ACTIVITY 10 Factors which affect light intensity (Allow about 3 minutes) Note down some of the environmental factors which would affect the amount of light reaching the skin. Which factors (for example, the time of day) will increase the amount of light reaching the skin and which will decrease it? Environmental factors e.g., depletion of ozone layer

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Effect e.g., increased radiation from sun


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Light intensity is affected by the seasons, the time of day, and how long the skin is exposed to sunlight. The part of the world, in terms of both latitude and altitude, is also important. In addition, the amount of light which is being transmitted and reflected will depend on factors such as the weather, the type of clothes being worn, and whether one is swimming in the sea or in a pool. Indoors, the amount of light passing through glass windows is significant. In general, glass, water, clothing and cloudy weather will reduce the amount of light reaching the skin. Higher altitudes, and reflection from rain, snow, sand and grass will increase the intensity of light reaching the skin. If you have ever been skiing, you will know how important it is to protect your skin and eyes from the reflected rays of the sun. Skin types Human skin can be classified into 6 major types based on the colour of unexposed skin and the ease of burning and tanning (see table 9, on page 75, for a summary, and refer to photos 1 to 5), the scale being developed in 1975 by T.B. Fitzpatrick, a Harvard dermatologist. It is useful to have this information when setting up a consumer panel to measure the efficacy of suncare products and labelling products. Pigmentation As mentioned in the first module, the melanin pigment in the skin functions as the skin’s natural sunscreen as well as being the major determinant of skin colour. The amount of protection gained from the melanin will depend on the amount present and the size and activity of the melaninproducing cells (melanocytes). Obviously, this will differ from race to race. For instance, in black skin, the melanin particles are larger and more widely distributed in the epidermis compared to white skin. Black skin offers about ten times more protection from the sun’s rays than white skin.

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65

Photo 1: Skin type I (see Table 9)

Photo 2: Skin type II

Photo 3: Skin type III

Photo 4: Skin type IV


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Photo 5: Skin type V

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Photo 6: Skin type VI


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DIPLOMA/CERTIFICATE IN COSMETIC SCIENCE MODULE 2 UNIT 16 Table 9. Skin types I - VI

Skin type

Sunburn and tanning history * Example

I

Always burns easily; never tans. People most often with fair skin, blue eyes, freckles; unexposed skin is white.**

II

Always burns easily; tans minimally.

People most often with fair skin, red or blond hair, blue, hazel or even brown eyes; unexposed skin is white.

III

Burns moderately; tans gradually and uniformly (light brown)

Normal average white person; unexposed skin is white.

IV

Burns minimally; always tans well (moderate brown)

People with white or light brown skin, dark brown hair, dark eyes (e.g., Hispanics, Mediterraneans, Monogoloids, Orientals); unexposed skin is white to light brown.

V

Rarely burns, tans profusely (dark brown)

Brown skinned persons (e.g. American Indians, East Indians, Hispanics, AfroCaribbeans, African Americans); unexposed skin is brown.

VI

Never burns; deeply pigmented (black)

Blacks (e.g. Afro-Caribbeans, African Americans, Australian Aborigines and South Indians); unexposed skin is black.

* Based on first 30 to 80 minutes sun exposure after winter season or no sun exposure. ** These people may be of Celtic descent (Irish or Scottish); others may have dark hair and brown eyes.

Tanning A suntan develops in two stages and will depend on the person’s skin type and the intensity of sunlight. An immediate tan develops after about an hour’s exposure to sunlight and is the result of the darkening of the melanin precursors and bleached melanin already present in the epidermis. It does not prevent skin reddening which normally occurs before tanning, but it is thought to protect genetic material in the basal layer. So a cap of melanin covers the nucleus in each keratinocyte. Delayed tanning begins after two days’ exposure and peaks after 4 to 10 days. UV radiation stimulates the production of melanocytes, which in turn produce more melanin. At the same time, there is an increased cell division at the basal layer resulting in more keratinocytes which can carry more melanin to the stratum corneum. The stratum corneum becomes tanned and thicker and offers 2 to 4 times more protection than untanned skin. A full tan develops in about 14 days and will last for the lifespan of the epidermis. Skin damage Skin damage reveals itself in the following ways: – sunburn – premature ageing – skin cancer. Sunburn can result in real agony, as those of us who have fallen asleep in the sun can testify! In the next activity, we will describe the symptoms of sunburn.

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ACTIVITY 11 Sunburn symptoms (Allow 2 minutes) Take a few minutes to write down the signs of sunburn; you may not have experienced it but you may know someone who has.

Sunburn occurs in two stages: 1 Reddening of the skin, (erythema). In darker skins, this is not readily visible. Erythema is the result of an increased blood flow to the skin. In paler skin, it can be seen as a slight pink/red skin colouring after 20 minutes’ exposure, or in severe cases, a vivid lobster-red colour accompanied by swelling after 90 minutes. 2 Blistering and peeling of the skin, accompanied by a lot of pain, after 3 hours’ exposure. If the skin is well looked after, severe sunburn will heal within 10 days but is often accompanied by unsightly peeling of the skin as inflammation subsides. Premature ageing, also known as photoageing, involves the degeneration of the dermal connective tissue, particularly collagen fibres and their synthesis, to produce the following changes to the skin: – dryness – fine wrinkling – loss of skin elasticity – thinned epidermis – hyperpigmentation patches. Although it is difficult to separate UVA and UVB unless under controlled conditions, premature ageing is thought to be caused mainly by UVA which can penetrate into the dermis. Premature ageing used to be prevalent in outdoor workers such as sailors, construction workers and farmers, but nowadays it is also seen in the so-called ‘sun worshippers’ who stay too long in the sun or under UV lamps. In normal ageing, photoageing still plays an integral role, as can be seen when comparing exposed and unexposed areas of skin. ‘Normal’ aged skin will display the same features as listed above. Hyperpigmentation patches are known as age spots. However, there are other factors involved such as changes in the immune system, changes to the genes and in the general metabolism. These changes affect the ageing of the person as a whole. Skin cancer : the incidence of this has increased over the years especially among white people living in subtropical and tropical climates. UVB is chiefly responsible for producing melanoma and other skin cancers. It is beyond the scope of this module to elaborate further on this subject.

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Mechanism of UV damage to the skin When UV radiation penetrates the skin, it produces highly reactive chemicals called free radicals which cause extensive damage to the genetic material (DNA and RNA, which tend to absorb UV radiation) and to the cell membranes. Free radicals are not unknown to cells because they are mainly produced during cellular respiration in the presence of oxygen. Although the cell contains its own mopping-up mechanisms for removing most of the free radicals, they are known to play a role in normal ageing and diseases such as arteriosclerosis. Free radicals are very unstable compounds containing an odd number of electrons. Examples include superoxides, hydroperoxides and hydroxy radicals. The following chemical reactions show how different free radicals can be formed. These free radicals go on to damage cellular structures. —

O2 + e

O2

Superoxide radical O2

+

H

+

HO 2

Hydroperoxide radical —

H2 O 2 + e

H2 O 2 + O 2

HO O 2 + H O- + H O

Hydroxy radical Control of free radical formation As mentioned above, the cells have natural methods of controlling the production of free radicals and the damage they can cause. These methods involve enzymes such as catalase and glutathione-S-transferase which prevent free radical formation from hydrogen peroxide. Superoxide dismutase enzymes have the important job of mopping up the superoxide and hydroperoxide radicals in the cell. Black skin The types of adverse effects described above are reported mainly, though not exclusively, in people with white or light brown skin (types I, II and III). Black skin (types IV and V) suffers other problems as a result of its highly pigmented nature. Cosmetic formulators should take note of these problems when developing products for black skin. Although normal, untraumatised black skin has the same thickness as white skin, it has a thicker, more dense stratum corneum. However, it reflects light to the same degree as white skin. It tends to absorb 30 per cent more heat than white skin and this is compensated for by more sweating, which cools the body faster in tropical climates. Melanin tends to be distributed freely throughout the epidermis and stratum corneum. This phenomenon is also seen in whites with deeply tanned skin. Since it is so good at screening UV radiation, this unfortunately reduces final synthesis of vitamin D. This poses a problem to blacks living in temperate climates who may then be prone to develop rickets. Black skin has a tendency to get darker (hyperpigment) and to form keloids in areas which have been inflamed, damaged or scarred. For example, the use of very strong detergents, skin lighteners, and peeling agents such as benzoyl peroxides, retinoic acid and fruit acids can leave unsightly patchy skin colour. Keloids are hard raised, smooth and shiny outgrowths (papules and nodules). They itch and can be painful and tender. They do occur in other skin types but are prevalent in black skin. Although keloids are treated medically, the cosmetic formulator can minimise irritation by making sure that products undergo rigorous safety test on black skin.

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Summary In this section we have looked at the nature of sunlight and identified UV radiation as the major waveband in causing tanning and adverse reactions. Short-term effects of exposure to UV radiation are sunburn and tanning. Long-term overexposure causes photoageing and skin cancers. The way skin reacts to UV radiation depends largely on the light intensity and skin type in question. Finally, black skin which offers better protection from sunlight can suffer from hyperpigmentation and keloids as a result of irritation.

CHECKLIST You should now be able to: – list the 8 main components of the sun’s electromagnetic spectrum – list the 3 main types of ultraviolet light plus their corresponding wavelengths – explain how sunlight interacts with the skin – classify skin into six main types in terms of their normal pigmentation, sunburn and tanning characteristics – describe how the skin develops a tan – summarise the effects of long term chronic exposure of the skin to ultraviolet radiation, using premature ageing as an example.

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4.2 Formulating suncare products Aims The aim of this section is to explore the types of products which can be used to protect the skin from over exposure to ultraviolet radiation and methods of evaluation of their efficacy. Sunscreens There are two main types of active ingredients used in suncare formulations to control the amount of UV light penetrating the skin: chemical sunscreens and physical sunscreens. Chemical sunscreens can be added to skin care products to chemically absorb ultraviolet light. On the other hand, physical sunscreens work by reflecting and scattering UV light. The extent of protection is variable and depends on three major factors: – the type of sunscreen and which wavelength of UV light it absorbs – the level of sunscreen used in the product – the product base used as a vehicle for the sunscreen, e.g., gel, emulsion or oil. – ideally any sunscreen used on human skin must be photo-stable, in that it should not degrade, or cause other sunscreens present in the formulation, to degrade under irradiation. In the next activity you may like to think about the properties required for a good suncare product.

ACTIVITY 12 Properties of suncare products (Allow 2 minutes) Make a list of desirable properties for the ideal suncare product, in terms of formulation, aesthetics and performance.

An ideal sunscreen is one that would bind well to the stratum corneum, resist ruboff and washoff by water and sweat, and be non-staining and non-toxic. It should absorb light effectively over a broad spectrum at low concentrations to minimise risks of allergy and irritation. When evaluating sunscreen agents we need to determine which wavelength of ultraviolet light it absorbs best.

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DIPLOMA/CERTIFICATE IN COSMETIC SCIENCE MODULE 2 UNIT 16 1 cm E1%

UV-C

UV-B

UV-A

1000 900 800 700 600 500 400 300 200 100 0 260 270 280 290 300 310 320 330 340

Wavelength (nm)

Figure 11. Absorption spectrum for a sunscreen

An absorption spectrum shows how a chemical absorbs and transmits light at different wavelengths. The graph in figure 11 shows the absorption spectrum for a chemical sunscreen. The chemical shown in figure 11 absorbs light best at 308 nm (i.e., has an absorption maximum at 308 nm), which makes it a good UVB absorber. This chemical sunscreen is known as Ethylhexyl Methoxycinnamate and is widely used in suncare products. The structure and absorption maximum for some widely used chemical sunscreens are shown in table 10. Chemical sunscreens There is a range of approved chemical sunscreens available which can be used at regulated levels. Table 10 gives some examples.

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DIPLOMA/CERTIFICATE IN COSMETIC SCIENCE MODULE 2 UNIT 16 Table 10. Approved structure of some chemical sunscreens

Sunscreen (CTFA name) and structure

Absorption maximum (nm)

Isoamyl Methoxycinnamate

308

O C

O

C5H 11

H3CO

Ethylhexyl Salicylate O

305

C2H 5

C

O

CH 2

CH

C 4H9

OH

Butyl Methoxydibenzoylmethane O

355

O

O

Benzophenone-3 O

286 and 325

OH

C

O

CH 3

Physical sunscreens Physical sunscreens employed in suncare products are inorganic pigments and minerals such as talc, kaolin, mica and metallic oxides. Titanum dioxide and zinc oxide are the most popular physical sunscreens. Until recently, products formulated with these materials offered poor aesthetics due to their large particle size (~200 nm). So for instance when applied, they gave the skin a greyish white, tacky sheen, as seen on vivid lips of skiers. However, micronised versions offering much smaller particle sizes are now available and certainly improve the appearance of the final product on the skin. A combination of zinc oxide, titanium dioxide with organic sunscreens, when formulated correctly, can provide excellent synergistic effects. Unfortunately, finer particle sizes reduce the reflective properties of the metallic oxide. To aid dispersion of physical sunscreens during manufacture and to resist re-agglomeration of the individual particles during storage, physical sunscreens are often coated to make them more hydrophobic.

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Choice of sunscreens (UV filters) There is a wide range of sunscreens available but only some of these are approved in the major markets of Europe, the USA, Australia and Japan. Some examples are shown in table 11. Table 11. EU Permitted filters in USA INCI Name

Annex Ref. No.

Max. conc. % w/w

Range of wavelengths absorbed

UVA/B

USA (drug name)

Camphor benzalkonium methosulfate

1.2

6

max 284nm

UVB

No

Homosalate

1.3

10

max 305nm

UVB

15% Homosalate

Benzophenone-3

1.4

10

max 287nm

UVB/A

6% Oxybenzone

Phenylbenzimidazole sulfonic acid

1.6

8(a)

max 307nm

UVB

4% Ensulizole

Terephthalylidene dicamphor sulphonic acid

1.7

10(a)

max 345nm

UVA

No

Butyl Methoxydibenzoylmethane

1.8

5

max 355nm

UVA

3% (b) Avobenzone

Benzylidene camphor sulfonic acid

1.9

6(a)

max 294nm

UVB

No

Octocrylene

1.10

10(a)

max 302nm

UVB

10% Octocrylene

Polyacrylamidomethyl benzylidene camphor

1.11

6

max 295nm

UVB

No

Ethylhexyl methoxycinnamate

1.12

10

308-310nm

UVB

7.5% Octinoxate

PEG-25 PABA

1.13

10

max 307nm

UVB

No

Isoamyl p-methoxycinnamate

1.14

10

max 308nm

UVB

No - TEA (c) [Amiloxate @ 10%]

Ethylhexyl triazone

1.15

5

max 312nm

UVB

No - TEA (c) [Octyl traizone @ 5%]

Drometrizole trisiloxane (g)

1.16

15

?

UVA

No

Diethylhexyl butamido triazone

1.17

10

max 311nm

UVB

No

4-Methylbenzylidene camphor

1.18

4

max 303nm

UVB

No - TEA (h) [Enzacamene @ 4%]

3-Benzylidene camphor

1.19

2

max 290nm

UVB

No

Ethylhexyl salicylate

1.20

5

max 306nm

UVB

5% Octisalate

Ethylhexyl dimethyl PABA

1.21

8

max 310nm

UVB

8% Padimate O

Benzophenone-4 (for the acid)

1.22

5(a)

max 285nm

UVB

10% Sulisobenzone

Benzophenone-5 (for the salt)

1.22

5(a)

max 285nm?

UVB

No

Methylene bis-benzotriazoyl tetramethylbutylphenol (MBBT)

1.23

10

max 370nm

UVA

No - TEA (c) [Bisoctrizole @ 10%]

Disodium Phenyl Dibenzyimadazole Tetrasulfonate (DPDT)

1.24

10 (a)

max 335nm

UVA

No

Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine (BEMT)

1.25

10

max 341nm

UVA

No - TEA (c) [Bemotrizinol @ 10%]

Polysilicone-15

1.26

10

max 312nm

UVB

No

Titanium Dioxide

1.27

25

max 290-300nm

UVB/ UVA

25% Titanium Dioxide

Diethylamino Hydroxybenzoyl Hexyl Benzoate

1.28

10 max 360-370nm

UVA

25% Zinc Oxide

Zinc Oxide

NOTES: a) the conc. is calculated as the conc. of the acid. b) Avobenzone is only permitted in combination with some UV filters. c) Approval has been requested via a Time & Extent Application. Antioxidants Sun care formulations can be enhanced by incorporating free radical scavengers. The latter tend to be antioxidants such as vitamin E, magnesium ascorbyl phosphate (vitamin C derivative) and, more recently, grape skin extracts.

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Measuring the efficacy of sunscreen products Historically, most countries had their own methods for the determination the efficacy of sunscreen products. One is to measure the UVB protection in terms of Sun Protection Factor (SPF), with the main international methods being the German DIN, American FDA, Australia, Japan and COLIPA. Each method used a slightly different procedure and generated different SPF numbers. Recent developments have concentrated in harmonisation of the various method, culminating in the publication of International Sun Protection Factor (SPF) Test Method (May 2006) this being initially adopted by the USA, Europe, Japan and South Africa. Earlier work concentrated on the acute effects of UVB radiation on the skin, namely erythema, sunburn and tanning. The advent of safe tanning led to the development of the sun protection factor test for new products. This method is based on the ability of UVB to cause erythema in the skin. The test relies on the accurate detection of the first sign of erythema by measuring the minimal erythemal dose (MED). The Minimal Erythemal Dose in human skin is defined as the lowest ultraviolet (UV) dose that produces the first perceptible unambiguous erythema with defined borders appearing over most of the field of UV exposure, 16 to 24 hours after UV exposure (International Sun Protection Factor (SPF) Test Method 2006). The sun protection factor or SPF of a product indicates how much longer the protected skin can be exposed to ultraviolet light before reddening occurs. This can be summarised by the following equation: SP F

MED with sunscreen MED without sunscreen

= ----------------------------------------------------------

The higher the SPF number on the product, the higher the protection from UVB radiation. The equation could also be written as SP F

Time to produce erythema in protected skin Time to produce erythema in unprotected skin

= --------------------------------------------------------------------------------------------------------------

ACTIVITY 13 SPF calculation (Allow 2 minutes) Using the equation above, see if you can work out the SPF required from a suncare product. On the first day of his holiday, Joe Smith forgets to put on any suntan lotion and it takes just 15 minutes in the sun for his skin to start turning red. The following day he remembers to use his suntan lotion. It takes two hours before his skin starts to turn red. What is the SPF rating of his suntan lotion?

In order to calculate the SPF, you simply enter the times taken to produce erythema into the formula. The MED with sunscreen was two hours or 120 minutes; the MED without sunscreen 15 minutes. The SPF is thus 120 divided by 15, which is 8. Therefore, for Joe Smith, the SPF for that particular sunscreen would be 8.

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DIPLOMA/CERTIFICATE IN COSMETIC SCIENCE MODULE 2 UNIT 16 Photo 9: Solar simulator lamp

Photo 10: Selection of test sites

Photo 11: Exposure to UV radiation

Photo 12: Reaction to UV radiation

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Procedure for measuring SPF in human test volunteers The determination of SPF values for a product must be done under controlled conditions, in order to produce reliable results. The procedure should be performed by trained and qualified personnel in order to avoid and damage to the skin of volunteers involved in the study. The general method involves a number of steps. The International SPF Test Method is a laboratory method that utilises a xenon arc lamp solar simulator (or equivalent) of defined and known output. To determine the Sun Protection Factor, incremental series of delayed erythemal responses are induced on a number of small sub-sites on the skin of selected human subjects. The test is restricted to the area of the back between waist and shoulder-line. An area of each subject’s skin is exposed to ultraviolet light without any protection and another (different) area is exposed after application of a test sun protection product. Furthermore at least one further area is exposed after application of an SPF reference sunscreen formulation. By incrementally increasing the UV dose, varying degrees of skin erythema (redness due to superficial vasodilatation) are generated. These delayed erythemal responses are visually assessed for redness intensity 16 to 24 hours after UV radiation, by the judgement of a trained evaluator. The minimum erythemal dose (MED) for unprotected skin and that obtained after application of a sun protection product must be determined on the same subject on the same day. More than one product may be tested on the same subject in any single test. An individual sun protection factor (SPFi) for each subject tested is calculated as the ratio of protected and unprotected MEDs. The sun protection factor for the product (SPF) is the arithmetic mean of all valid SPFi results from each and every subject in the test and should be expressed to one decimal place. A minimum of 10 valid results and a maximum of 20 shall be used for the calculation of SPF. Confidence limits (95% Confidence Interval) for the mean SPF should fall within the range of ± 17% of the mean SPF. Every test shall include an appropriate high or low SPF reference sunscreen formulation depending on the expected SPF of the test formulations with the obtained SPF for the reference sunscreen falling within the expected range. The principle of the water resistance test is to compare the Sun Protection Factor for a sunscreen product after a period of immersion in water with the original, static SPF of the product determined according to the International Sun Protection Factor (SPF) Test Method. To determine the wet SPF (SPFw), the International Sun Protection Factor (SPF) Test Method is followed to the point where the product under test has been applied to the volunteer’s skin. Product treated skin is then immersed in water according to the following schedule: • Allow 15 to 30 minutes drying time after product application • First 20 minute immersion in water • Allow 15 minutes drying time (no towelling) • Second 20 minute immersion in water • Allow to dry for 15 minutes or until completely dry (no towelling) Water immersion takes place in a spa-pool, Jacuzzi, bathtub or equivalent after which the wet SPF is determined. Individual Percentage Water Resistance Retentions are determined and a mean retention calculated for up to 25 volunteers. A Water Resistant product should have a Mean Retention of greater than 50% and a Very Water Resistant product should have a Mean Retention of greater than 50% when subjected to four 20 minute water immersions.

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Now that we have been through the steps involved in measuring SPFs you may have already started to think of factors will affect the final SPF rating for the product tested. There are about twelve factors. See how many you can think of in the next activity.

ACTIVITY 14 Factors affecting SPF value This activity has been identified as a key activity for this unit. Please go to the online module to complete this activity, so that you can share your ideas and opinions with your fellow learners and benefit from their experience and knowledge in this area. UVA and broad spectrum protection A suncare product must offer UVB and UVA protection to combat both short and long term effects of exposure. The SPF method described above cannot be used to measure the degree of protection from UVA because UVA has a longer wavelength than UVB and so would require higher doses of UVA or longer exposure times in order to produce measurable skin effects. An alternative method must be used to determine UVA protective properties of a product. In the past, photosensitises such as were used to increase skin’s sensitivity to UVA-induced erythema. This is extremely distressing and irritating to volunteers and is quite unethical. Workers have also investigated the use of both immediate and permanent pigment-darkening effects of UVA. Light protection index An in vitro method was developed by Jack Ferguson and co-workers to measure the wavelengths of radiation that a particular sunscreen is likely to protect against. This method uses a synthetic skin cast which is a replica of the skin surface and which is transparent to light. The skin cast is irradiated by a solar stimulator such as a Xenon arc lamp. The amount of radiation passing through the cast without sunscreen is measured by a UV meter and processed through a computer program in order to relate the results to real life conditions. The sunscreen product is then applied to the skin cast and the process is repeated to give a light protection index: Light protection index (LPI)

Amount of light passing through with protection Amount of light passing through without protection

= ---------------------------------------------------------------------------------------------------------------------------

The cast was found to be susceptible to chemical attack by the sunscreen actives, and has since been superseded by a special adhesive tape developed by Brian Diffey and coworkers. Roughened glass quartz plates or PMMA can also be used. In one method, transmission measurements at six discrete regions of the glass plate are taken at 5 nm increments from 290 nm to 400 nm by a computer-controlled scanning monochromator with a photomultiplier mounted directly below the glass. This procedure is carried out three times for each product being tested. Three UVA/UVB ratios are generated for each product, from which the mean and standard deviation are calculated. These ratios are categorised using a consumer friendly symbol system originally developed by Boots the Chemist. The original scale had 4 categories of protection:Mean UVA/UVB ratio

UVA protection category (star rating)

0 to <0.2

too low to make a UVA claim

0.2 to <0.4

moderate (*)

0.4 to <0.6

good (**)

0.6 to <0.8

superior (***)

0.8+

maximum (****)

This has been modified over time to firstly include a 5 Star Category with a ratio above 0.9 and more recently to align the method with the EU Commission Recommendation of 22nd September

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2006 "on the efficacy of sunscreen products and the claims made relating thereto" (2006/647/EC). This later change has included a re-irradiation step in the test method and removal of the bottom 2 categories. The Diffey method forms the basis of the Boots star rating system as a guide for consumers choosing a sunscreen product to suit their skin type (see B.L. Diffey, J. Robson, A new substrate to measure sunscreen protection factors throughout the ultraviolet spectrum, J. Soc. Cos. Chem., 40, 127 - 133 (May/June 1989). Table 13. Advantages and disadvantages of the Diffey method

Advantages

Disadvantages

Measures UVA and UVB protection

Not measured on real volunteers

Quick, reproducible

Can’t predict safety on skin and eyes

Good screening tool

Used for emulsions not for hydroalcoholic/oil based formulations

Good correlation with SPF measurements

Suncare formulations Suncare products are now available in various forms such as emulsions (creams, lotions and milks), mousses, sticks, gels and oils. We will now look at some examples of such formulations. Gels. The clarity and cooling sensation offered by alcoholic-based gels are very attractive to the consumer. Unfortunately, the alcohol can be both irritating and drying to the skin. In addition, gels do not achieve very high SPFs. However, the emergence of alcohol-free gels may help to improve their acceptability. Formula 47 is an example of an alcohol-free sunscreen gel which uses PMV/MA decadiene cross polymer to produce and stabilise the gel structure. Emulsions are the most popular type of formulation for suncare systems. They can either be oil-inwater (o/w) or water-in-oil (w/o) (see the module on Emulsions). They can produce very high SPFs leaving an opaque film on the skin. Formula 48 gives an o/w cream containing nonionic emulsifiers and carbomers. The carbomers provide quickbreaking properties to help with spreading the product onto the skin. Formula 49 uses physical sunscreen, microfine titanium dioxide and zinc oxide, which are available in very small particle sizes down to 50 nanometres. Water-resistant properties of emulsions, especially the o/w type, can be improved by including film-forming raw materials such as silicones and polyvinylpyrrolidones at 2 - 3% w/w. Sticks. The nature of sticks allows them to be directed at specific areas of the body such as lips, nose, forehead and nipples. They provide good water-proofing properties and work best with opaque, physical sunscreens. In the formula in formula 50, chemical sunscreens are combined with beeswax and carnauba to provide plasticity and hardness respectively. Oils. The use of these provides high water resistance and good ease of application. The major drawback with oils is that they are sticky and do not achieve very high SPFs because they leave a thin, transparent film on the skin. Formula 51 provides a formulation. These products can only provide minimal protection against serious burning. Emollients and solvents. The choice of emollients and solvents for sunscreens is very important in ensuring good skin feel, spreading and protection properties. Branched chain esters are excellent emollients for use in suncare products. The type and polarity of commonly used solvents such as mineral oil, propylene glycol and ethanol will affect the final absorption maximum achieved by the sunscreen. Formulations may include dicaprylyl carbonate as an emollient that also improves solubility of crystalline filters and spreadability of the product on the skin. Formats Lotions are still the most popular format, although trigger sprays and wipes offer improved ease of use and less greasy formulations. Aerosol mousses offer a novel way to apply sunscreen. Unfortunately, they are oil based which makes them more expensive and less effective than other formats. 79


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Children’s products Although a child’s skin has identical barrier properties to that of adult skin, it tends to be thinner and more susceptible to moisture loss. Suncare products for children should be easy to apply, highly protective and moisturising with very little, if any, perfume, to avoid irritation and sensitisation. Emulsion-based products provide the best vehicle for sunscreens in this type of product. The use of physical sunscreens without organic sunscreens is becoming the preferred route for formulating children’s products because they exhibit a low potential for causing irritant/allergic skin reactions. Anti-ageing products The anti-ageing sector of the market has shown significant growth. Many of these products are based on moisturising formulations with low levels of sunscreens to provide daily protection all year round. Other sophisticated ingredients such as hyaluronic acid, soluble collagen and ceramides may also be included to improve the water binding properties of ageing skin. More recently, another class of materials known as the fruit acids or alpha hydroxy acids (AHAs) have received a lot of attention. Examples include lactic and glycollic acid. These work by stimulating cell renewal activity in the epidermis, resulting in increased exfoliation. Over a period of time, they are claimed to reduce the appearance of fine wrinkles and so keep the skin looking smooth. The formula in formula 52 shows an example of an anti-ageing cream using fruit acids. These materials can cause irritation and hyperpigmentation in sensitive skins so appropriate skin safety tests must be conducted. There has been renewed interest in the use of anti-oxidants, vitamins and active ingredients from oats and wheat. After sun products After sun products are used after sun exposure which may have resulted in mild t o moderate sunburn. Obviously, severe sunburn would require medical treatment. Such products tend to be similar to moisturising milks and lotions discussed in the first part of this module. In addition, they contain soothing and healing agents such as allantoin, aloe vera gel, calamine and vitamins A and E. Inclusion of emollients will help to cover the appearance of unsightly flaking and peeling skin. Cooling agents such as menthol can also be used. Artificial tanning and self tanning products A separate class of products exists which are aimed at people that never tan but instead burn easily (skin type 1), or who may be allergic to sunlight or may just want to look tanned all year round. These products do not offer any protection but give a tanned appearance so they should be used with the appropriate suncare product when skin is exposed to sunlight. There are three major approaches to formulating such products: Dihydroxyacetone. The best known method uses a chemical called dihydroxyacetone at a use level of 5%. The latter reacts with free amino acids to form dark-coloured melanoids. The tanned effect appears just several hours after application. The next time you visit the chemist, you may like to buy some and apply it to a small part of your skin, and see if it really works. See formula 53 for a crystal clear gel spray. Pigmented face powders. Heavily pigmented face powders can be applied to imitate the tanned appearance of the skin. Tanning accelerators. Melanin precursors, tyrosine and riboflavin mixtures are commercially used in suncare products to speed up the tanning process. When the skin is exposed to light, riboflavin oxidises the tyrosine in the skin and in the formulation to form melanin.

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Summary In this section I have discussed the use of chemical and physical sunscreens to reduce or prevent the deleterious effects of UV radiation on the skin, and dealt with the methods used for measuring the efficacy of UVB sunscreens, namely SPF numbers and UVA sunscreens with the Diffey method. The advantages and disadvantages of various product formats for suncare products were described. Finally, the emergence of the anti-ageing sector as an extension of suncare and moisturising products was highlighted.

CHECKLIST You should now be able to: – define what is meant by the term sunscreen – explain the difference between a chemical and a physical sunscreen in terms of their mode of action – list the characteristics of an ideal sunscreen product in terms of formulation aesthetics and performance – give examples of UVA and UVB sunscreens – describe how the efficacy of UVA and UVB sunscreens can be measured – list and describe the other basic components used in suncare products – describe the active ingredients used in after sun, anti-ageing products and artificial tanning products – explain how a sun protection factor (SPF) is calculated – list and describe the variables that influence the calculation of the SPF number for a product.

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5 REMOVAL OF UNWANTED HAIR Aims The aim of this section is to discuss the removal of unwanted hair from the skin using cosmetic products. I begin by highlighting the various methods available for hair removal, and then concentrate on shaving products and chemical depilatories. Introduction We remove hair from various parts of our body (underarm, legs, face and genital area) for a number of reasons. The major reason is to improve our appearance and social acceptability. In our society a clean-shaven look is perceived to be more respectable than an untidy beard. Women are often embarrassed when they grow hair in parts which our culture does not accept, such as on the face, legs and in the armpit area. However, certain circumstances cause excessive growth of hair in these areas. Examples include hormonal changes (puberty, pregnancy, menopause), various drugs (contraceptive pill, steroids), and diseases (tumours). Normal and abnormal hair growth is covered in Unit 12. 5.1 Methods of hair removal The process of hair removal from below t he skin’s surface is called epilation. The other term, depilation, describes the temporary removal of hair from the surface of the skin. Methods for removing hair can be divided into 2 groups as shown below. Table 14. Methods for removing unwanted hair

Mechanical hair removal

Chemical hair removal

Tweezing

Thioglycollates

Threading

Enzymes

Electrical epilation Electrolysis Sugaring Waxing Shaving

Chemical hair removal will be discussed later in this section. Let us look first at the various methods of removing unwanted hair mechanically. Tweezing involves pulling out individual hairs with tweezers. In threading, a piece of thread is wound around each individual hair and then pulled. Electrical epilation involves the use of an appliance designed with rotating coils, which pull out the hair by the roots. Apparently with continued use, any hair from the new growth becomes finer, softer and more sparse. Electrolysis involves passing a fine needle into the hair follicle and destroying the bulb by passing an electric current through it. The hair is loosened and then plucked from the follicle. Although it is possible to buy an apparatus for home use, most electrolysis is undertaken in salons by professionally qualified personnel. As such, it is a time-consuming and costly procedure, and is mostly used for the removal of small amounts of coarse facial hair.

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Waxing is one of the most common methods used for hair removal. There are two types. Hot waxing involves the application of molten wax to the skin. When the wax cools, it hardens and is then stripped off, bringing the hair with it. In strip waxing, the molten wax is applied to the hair and a strip of paper or fabric is pressed into the wax. Once the wax cools and hardens, the paper is pulled off, taking the unwanted hair and wax. As you can imagine, hot waxing is extremely painful and has been largely superseded by strip waxing. After the waxing process, products containing emollients and soothing agents are then applied. Sugaring. A ‘new’ method called sugaring has recently arrived in salons and is undertaken by beauticians who are members of the Federation of Professional Sugaring. It originated from African and Middle Eastern practices. It is based on a mixture of sugar, lemon juice and water, with a putty-like consistency. The latter is applied in the direction of hair growth. The hair is removed by flicking off the dried putty with the fingers. Kits for home use are now available. 5.2 Shaving During his adult life, the average male shaves off about 28 feet of hair. Shaving involves the use of a sharp razor blade or electric razor to cut the hair just below the skin surface. There are two methods, wet shaving and dry shaving. We will start by discussing the products which can be used in wet shaving. Wet shaving In wet shaving, the hair must first be softened with soap and water or other shaving products and then a mechanical razor blade used to remove the hair. In terms of formulations, there are two types of wet shaving products: – soap-based, available as sticks /cakes, lather creams and aerosols – emulsion-based brushless shave creams. In the next activity, it is worth considering the desired properties from a wet shaving product. If you do shave then you will have first-hand knowledge of what you want from such a product.

ACTIVITY 15 Wet shaving product properties (Allow 2 minutes) What are the ideal properties of a wet shaving product? See if you can fill in the table below. Properties

Details

Foaming

Foams quickly and copiously. Also…

Effect on hair

Effect on skin

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The product must foam quickly and copiously and must be stable enough to last throughout shaving process. The foam must surround, separate and hold hairs. In addition, the product should soften and swell hairs and lubricate the skin to reduce blade resistance thus preventing razor burn. As with other cosmetic products, it must be non-irritating to the skin and should have a pleasant fragrance. Components of soap-based formulations Soap-based shaving products contain a mixture of long- and short-chain fatty acids which are saponified using a choice of bases to form soap of varying consistencies. They also contain a humectant such as glycerine to stabilise the foam and prevent it from drying out. A useful summary is given in table 15 which describes the effect of the various components on the final soap and the foam. Table 15. Soap-based shaving product ingredients and their effects

Ingredient

Effect on soap

Effect on foam

Short chain fatty acids (e.g. C12 - C14)

Softening - more irritant to skin

Large quantity of loose, quickly produced foam

Long chain fatty acids (e.g. C16 - C18)

Hardening

Small quantity of thick foam

Triethanolamine (T.E.A.)

Soft soap

Fast copious foam

Potassium hydroxide solution

Soft soap

Copious foam

Sodium hydroxide solution

Hard soap

Moderate foam

Glycerin

Softens soap

Stabilises foam and prevents it from drying out

Blends of the ingredients are selected to give the desired physical and performance properties as shown below in table 16. Table 16. Ingredients for shaving product formulations

Aerosol

PRODUCT FORMAT Cream

Stick/cake

Lauric acid (C12)

1.00

10.00

18.00

Stearic acid (C18)

5.7

30.00

65.00

Glycerin

1.9

10.00

5.00

Triethanolamine

2.85

Sodium hydroxide

0.6

1.7

Potassium hydroxide

2.4

4.3

47.0

6.0

Ingredient (%w/w)

Water

83.55

Butane/propane

5.0

Now that you have read about the basic components of soap-based formulations, here are a few more points which you have to consider when formulating sticks, creams and foams.

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Lather shaving stick/cake. As you can see from the table, shaving sticks and cakes contain the highest level of soap. Once saponification is complete, the soap chips are mixed with opacifiers, colour and perfumes, passed through a mill and moulded into the required shape with a soap plodder. Lather shaving creams. Lather shave creams are usually sold in tubes or more recently pumps, and are extremely economical to use. When formulating such products, it is wise to leave a small excess of fatty acids after the saponification reaction. Fatty acids help to neutralise any pockets of base/alkali which may remain. So always check the level of excess or free fatty acids during quality control procedures. Aerosol shaving foams. Aerosol shave foams have become more popular than cream shaves, owing to their convenience. Once the beard or hair is wetted, the foam is applied to it. More recently the introduction of the post-foaming shave gels in a barrier pack has helped to further revitalise what had become a stagnant market. Post-foaming gels. Barrier packs used for post foaming gels are based on the separation of the liquid concentrate from the propellant (see the Aerosols module). The product is dispensed from the aerosol can as a clear stable gel. The gel is a soap solution gelled with a water-soluble polymer thickener such as carboxymethyl cellulose. A small amount of hydrocarbon (like isopentane) is introduced into the mixture. The hydrocarbon vaporises when the product is rubbed into warm skin, causing the product to foam on the face. Post-foaming gels are said to provide better wetting and lubrication, offering a more comfortable shave. The reasons are as follows: other ingredients may be added to improve the aesthetics and skin compatibility; antimicrobials are included to prevent infections in minor cuts; polymers such as polyvinyl pyrrolidone, natrosol or cocamide diethanolamide give a thicker product; silicones such as dimethicone, mineral oil, or lanolin oil are added as lubricants and emollients; allantoin may be added to heal minor cuts and nicks; and menthol gives a fresh cooling sensation on the skin as it evaporates. It is important to separate the propellant from the liquid. If the propellant is not separated from the liquid, the product will behave as an ordinary aerosol foam. In other words, as it is dispersed it will start foaming, thus losing its product plus. Brushless shave creams. Brushless shaves are essentially oil-in-water emulsions. When rubbed into beard hair, they surround the hair with oil bubbles instead of air bubbles produced by soapbased products. Brushless shaves are usually formulated to a lower pH of 7.5-8.5 (compared to pH 9-10 in soap-based products). The advantages of these products are that they give a very comfortable shave and they are good for people with dry skin. Unfortunately, the hair has to be presoftened with soap and water and they are not as economical as soap-based products. Formula 54 gives an example of a brushless shave. Dry shaving products Dry shaving products, or pre-electric shaves as they are commonly known, are used in conjunction with electric razors. The hair must be dry and stiff to give a good shave with an electric razor. Shaving bumps and Pseudofolliculitis barbae Dry shaving products tend to be used by people who suffer from acne, shaving bumps or the more severe condition known as Pseudofolliculitis barbae. The latter tends to be common in men with very curly hair such as African Americans and Afro-Caribbeans. In this condition, after shaving, the hair starts to grow back and because of the curliness and sharp edge, it grows back into the skin. This causes inflammation of the skin with varying degrees of severity. It becomes virtually impossible to shave and, at this stage, the only solution is to grow a beard and allow the skin to heal up.

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Pre-electric shaves serve a dual function by removing perspiration and lubricating the skin to reduce friction between the skin and razor, thus avoiding razor burns. Typical formulations contain a mixture of denatured alcohol and emollients. Some formulations will also contain astringents such as aluminium chlorohydrate or lactic acid to tighten the skin pores in order keep the hairs standing upright. An antibacterial is also included to minimise the chances of infection and inflammation. See formula 55 for a formulation. 5.3 Aftershave products The shaving process can be quite traumatic and often results in small cuts. Aftershave products are used after shaving to moisturise, cool and refresh the skin and also to reduce the risk of bacterial infection at injured sites. Aftershaves are available as lotions gels, balms, powders and foams. Traditional aftershave lotions are clear products based on quite a high level of denatured ethanol (40-60%). They also contain emollients, humectants and antimicrobial agents. They also contain up to 3% perfume and, depending on the ethanol/water ratio, a solubiliser may be necessary. See formula 56 for an example of an aftershave lotion. Aftershave balms are oil in water emulsions with little or no alcohol (ethanol) which makes them suitable for sensitive or dry skins. More recent formulations will contain sunscreen agents for uv protection. See formula 57. 5.4 Chemical depilatories Chemical depilatories are widely used in the home for the removal of unsightly body hair. These products are sometimes used by men prone to Pseudofolliculitis barbae. They used to be packaged primarily in tubes which came with a plastic spatula-like applicator. Nowadays, they are available in more convenient packs such as roll-ons, sachets and aerosols to suit the end use. So, for instance, roll-ons are more convenient for underarm use.

ACTIVITY 16 Properties of a good depilatory product This activity has been identified as a key activity for this unit. Please go to the online module to complete this activity, so that you can share your ideas and opinions with your fellow learners and benefit from their experience and knowledge in this area. How depilatories work Thioglycollate-based depilatories work in a similar way to permanent waving lotions, by breaking disulphide linkages in the keratin hair fibres. However, depilatories go one step further than perms and totally disintegrate the hair. Other actives such as inorganic sulphides of strontium or calcium are also available but are under restricted use. Formulations Formula 58 gives a detailed formulation. Perfuming these products is quite a challenge because of the sulphurous odour produced whilst depilation is taking place. High pH and the strong reducing properties narrows the choice of perfumes available. It is therefore vital to work with the perfumer at the very early stages of development. Safety Since both hair and skin consist of keratin protein, adverse skin reactions are a major problem with depilatories. A lot of work has been conducted to reduce the irritation potential of these products. For instance, it has been found that inclusion of materials such as urea, thiourea and guanidine is supposed to increase the rate of the thioglycollate reaction, thus reducing contact time with the skin. In addition, redoxin has been found to reduce the required amounts of thioglycollate required for efficient hair removal. 86


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Finally, depilatories must carry adequate cautions such as not to be used on broken or inflamed skin or after using other products such as soap or perfumes. Enzyme depilatories Preparations containing protein-digesting enzymes such as papain (from the papaya tree) can be used to treat empty hair follicles after waxing. They progressively reduce hair growth over a number of months. Summary In this section, we looked at two major ways of removing unwanted hair, namely mechanical and chemical methods. Mechanical methods include tweezing, threading, electrical epilation, sugaring, waxing and shaving. A variety of shaving and aftershave formulations were described. With regard to chemical methods, I discussed the importance of thioglycollate-based products and the emergence of newer products based on enzymes.

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CHECKLIST You should now be able to: – distinguish between mechanical and chemical methods of hair removal – explain the differences between wet and dry shaving – list the desired properties of a good wet shaving product – list the three main types of wet shaving products currently available on the market – describe the basic components of soap-based and emulsion-based shaving products – list the function and components of a dry shaving preparation – define the functions of an aftershave product – list the major components in an aftershave product – list the requirements of a chemical depilatory – explain the active ingredients used in a chemical depilatory – explain how a thioglycollate-based depilatory works – describe how enzymes and sugaring are used for hair removal.

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APPENDIX GUIDELINE FORMULATIONS FOR PART 2 Appendix 2 contains formulations that are referenced in Unit 16 Part 2. The INCI (International Nomenclature of Cosmetic Ingredients) system has been used to name the materials with occasional explanations in brackets to help identify them further. Short explanations of how the formula is created are given; it should be remembered that the function of the ingredients is in part dependent on the total composition in which they are incorporated. The formulations are given to illustrate the text and should only be considered as starting points with which to experiment and customise to your own requirements. Virtually all of them require a carefully selected preservative system. Aqua (Water) is preferably deionised and should be free of microbial contamination. Disodium EDTA is incorporated in some formulations as a sequestrant or chelating agent. It chelates heavy metal ions and may prevent discolouration. It also has some microbiological activity so may be considered a useful addition to other formulations containing water. Throughout the appendix, alcohol is ethanol and is suitably denatured, i.e. made undrinkable by the inclusion of a suitable ingredient. In the EU, alcohol is denatured with denatonium benzoate and tertiary butyl alcohol and it is referred to as Alcohol denat. on labels. WARNING: Alcohol is highly flammable and must always be handled with care according to safety instructions. Formula 42: Deodorant Stick Stage INCI Name A

Alcohol (Ethanol)

A

Aqua (Water)

B

Methyl gluceth-20 stearate

B

Propylene glycol

C

Stearic acid

D

Triclosan

E

Parfum (Fragrance) & colour

%w/w Prime function 65.00 Solvent 5.00 10.00 Emulsifier 7.00 Lubricant 6.0 Gelling agent 0.20 Antimicrobial q.s. See Unit 13

Preparation 1. Mix together the items of Stage A and heat to 65°C. 2. In a separate vessel mix together the items of Stage B and add to main mix, maintaining temperature at 65°C. 3. Add Stage C, stearic acid, to Stage A+B with mixing and mix until clear. 4. Add D, Triclosan and E, perfume; mix until clear then pour into suitable moulds and allow to cool. The alcohol is cool and refreshing and has an instant antimicrobial effect on the skin. The stearic acid is a gelling agent in this formulation. The triclosan remains on the skin as an antimicrobial agent.

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Formula 43: Deodorant pump spray Stage INCI Name

%w/w Prime function

A

Alcohol (Ethanol)

50.00 Solvent

A

Triclosan

0.05 Antimicrobial

B


2.00 Lubricant

B

Isopropyl myristate

1.00 Emollient

B

Parfum (Fragrance)

q.s. See Unit 13

C


q.s.

Preparation 1. Measure out alcohol and stir in triclosan until clear. 2. Add items B in order with mixing. 3. When main mix is clear add water [C] slowly with stirring until clear. The alcohol is cool and refreshing and has an instant antimicrobial effect on the skin. The triclosan remains on the skin as an antimicrobial agent and the PPG-15 stearyl ether is a lubricant and it also reduces stickiness. Formula 44: Antiperspirant roll-on (Water-in-volatile silicone emulsion) Stage INCI Name

%w/w Prime function

A

Cyclopentasiloxane

20.00 Volatile silicone

A

Parfum (Fragrance)

0.50 See Unit 13

A

Polyglyceryl-10 palmitate

2.00 Lubricant

A

PEG/PPG-18/18 dimethicone

10.00 Silicone emulsifier

B

Aluminum chlorohydrate (50%)

38.00 Antiperspirant active

B


q.s.

Preparation 1. Mix together items of Stage A until clear. 2. Mix together items B, aluminum chlorohydrate solution and water. 3. Add Stage A to Stage B with constant stirring then homogenise with a high shear mixer. 4. Fill into suitable roll-on packs. The cyclopentasiloxane is cool and refreshing; the polyglyceryl-10 palmitate is a lubricant and the PEG/PPG-18/18 dimethicone is a water-in-silicone (w/Si) emulsifier. Aluminum chlorohydrate is the antiperspirant active material, which is usually available as a 40% or 50% solution in water.

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Formula 45: Antiperspirant dry stick Stage INCI Name

%w/w Prime function

A

Cyclopentasiloxane

46.00 Volatile silicone

B

PEG-400 distearate

6.00 Emollient/gelling agent

B

PEG-32

2.00 Gelling aid

B

PEG-1000

2.00 Gelling aid

B

Stearyl alcohol

B

Silica

C

Aluminum zirconium tetrachlorohydrex Gly

D

Parfum (Fragrance)

20.00 Gelling aid 1.00 Suspending agent 20.00 Antiperspirant active 2.00 See Unit 13

Preparation 1. Weigh the cyclopentasiloxane into a suitable vessel and heat to 70°C. Note this material is volatile. 2. Add items of stage B in order, maintaining the temperature at 70°C and with continuous stirring. 3. After 10 minutes stirring add the Aluminum zirconium tetrachlorohydrex Gly; this is available as a microfine powder. 4. Cool to 60°C; add perfume and fill into suitable containers. The cyclopentasiloxane is cool and refreshing; the PEG-400 distearate, PEG-32 and PEG-1000 all gel the stick and add some emolliancy. The stearyl alcohol thickens and solidifies the stick and the silica acts a suspending aid for the aluminum zirconium tetrachlorohydrex Gly powder, which is the antiperspirant active. Formula 46: Aerosol antiperspirant spray Stage INCI Name A

Disteardimonium hectorite

A

Cyclopentasiloxane

B

Dimethicone

C

Aluminum zirconium tetrachlorohydrex Gly

D

Parfum (Fragrance)

E

Isobutane

%w/w Prime function 1.00 Suspending agent 11.80 Volatile silicone 4.00 Emollient 10.00 Antiperspirant active 0.20 See Unit 13 73.00 Propellant

Preparation 1. Stage A; weigh the cyclopentasiloxane into a suitable vessel and disperse the disteardimonium hectorite into it using a high shear mixer, continue mixing on high shear for 20 minutes then change to a low shear mixer. 2. Stage B: add the dimethicone while mixing and mix for 10 minutes. 3. Stage C: blend in the aluminum zirconium tetrachlorohydrex Gly powder. 4. Pass the suspension through an in-line homogeniser, add perfume and when mixed fill into aerosol containers and charge with isobutane, E. The cyclopentasiloxane is cool and refreshing; the disteardimonium hectorite is a suspending agent and dimethicone adds emolliancy. The aluminum zirconium tetrachlorohydrex Gly is the antiperspirant active and a microfine powder must be used.

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Formula 47: Sunscreen gel (non-alcoholic) Stage INCI Name

%w/w Prime function

A


q.s.

A

PVM/MA decadiene crosspolymer

0.45 Water-proofing/thickener

B

Sodium hydroxymethylglycinate

0.40 Preservative

B

Phenoxyethanol

0.60 Preservative

C

Aloe barbadensis (Aloe) leaf juice

1.00 Anti-inflammatory agent

C

Tocopherol acetate

0.05 Free-radical scavenger

C

Ethylhexyl methoxycinnamate

5.50 UVB absorber

C

Helianthus annuus (Sunflower) seed oil

1.00 Emollient

C

Parfum (Fragrance)

q.s. See Unit 13

Preparation 1. Stage A; measure the water into a suitable vessel, stir in the PVM/MA decadiene crosspolymer and heat to 80°C with mixing until homogeneous. 2. Cool to 60°C and stir in Stage B: the two preservatives. 3. While mixing add each item of Stage C in turn. The PVM/MA decadiene crosspolymer is the gelling agent and should hold the oil droplets of tocopherol acetate, ethylhexyl methoxycinnamate and Helianthus annuus (Sunflower) seed oil in suspension. In theory the composition is SPF6 and does not provide any UVA protection so does not meet international standards; however it may serve as a starting point for a more advanced formulation. Unfortunately ethylhexyl methoxycinnamate destabilises butyl methoxydibenzoylmethane, which is one of only two globally accepted UVA absorbers. The other is terephthalylidene dicamphor sulfonic acid, which is permitted globally to a maximum of 3%. In theory this addition would give SPF15 but insufficient UVA protection to meet international expectations.

92


SKIN PRODUCTS


Formula 48: Sunscreen cream, SPF 10 Stage INCI Name

%w/w Prime function

A

Ethylhexyl dimethyl PABA

7.50 UVB absorber

A

Benzophenone-3

3.50 UVB/UVA absorber

A

Steareth-21

0.50 Emulsifier

A

Steareth-2

1.50 Emulsifier

A

Ceteareth-20

2.00 Emulsifier

A

Cetearyl alcohol


A

Tocopherol acetate

2.00 Free-radical scavenger

B


B

Carbomer

B2

Preservative

B2

Triethanolamine (50%)

C

Parfum (Fragrance)

q.s. 0.80 Rheology modifier q.s. See Unit 6 1.60 Neutraliser q.s. See Unit 13

Preparation 1. Weigh the oil phase (A) into the smaller vessel and heat to 70 – 75°C. 2. Start warming the water in the main mixing vessel and when at about 30°C slowly add the carbomer with fast stirring; when fully dispersed heat to 70°C. 3. When both phases are at 70°C slowly pour the hot oil phase into the aqueous phase while stirring, when fully mixed start cooling with slow speed stirring. 4. When cooled to about 60°C add the preservative then slowly add the triethanolamine as a 50% solution, which will gel the mix. The pH should be 6.0 – 7.0. 5. Continue slow mixing to 35°C and stir in the perfume and continue mixing while cooling to ambient temperature In theory the composition is SPF10 but it provides little UVA protection so does not meet international standards; however it may serve as a starting point for a more advanced formulation although ethylhexyl dimethyl PABA and benzophenone-3 are seldom used in modern formulations. In the EU high protection refers to SPF > 30 and very high protection is SPF >50. The EU authorities also recommend that the UVA protection factor measured at 370nm should be at least 1/3rd of the declared SPF. European recommendations SPF rating

Protection level

UVA protection

Boots stars

SPF 4 to <15

Low Protection

UVA Low

*

SPF 15 to <30

Medium Protection

UVA Medium

**

SPF 30 to <50

High Protection

UVA High

***

SPF 50+

Very High Protection

UVA Highest

****

USA recommendations are very similar and the FDA rules that the SPF must be above 15 in order to make the claim that “sunscreen reduces the risk of skin cancer and early skin aging when used as directed” The FDA also proposes to limit the maximum SPF on sunscreen labels to 50+ as it believes that there is insufficient data to show products with SPF values higher than 50 provide greater protection for users than products with an SPF of 50. Canadian legislation requires that all broad spectrum sunscreen products contain both a recognized UVA and a UVB absorber; be minimum SPF 15 and to have a critical wavelength protection of at least 370 nm with a UVA:UVB ratio not be less than 1:3.

93


SKIN PRODUCTS


Australia allows for labelling of sunscreen products with a rating of up to SPF 50+, as it is understood that SPF 50+ sunscreens allow much less UVA radiation, which is largely responsible for melanomas and skin cancer, to pass through a layer of sunscreen. Formula 49: Sunscreen cream SPF 25, broad spectrum Stage INCI Name

%w/w Prime function

A


q.s.

A

Acrylates/C10-30 alkyl acrylate crosspolymer

0.38 Emulsifier/thickener

A

Propylene glycol

5.00 Solvent/humectant

A

Disodium EDTA

0.01 Sequestrant

B

Neopentyl glycol diheptanoate

5. 00 Emollient

B

Butyl methoxydibenzoylmethane

3.00 UVA absorber

B

Homosalate

B

Ethylhexyl salicylate

B

Octocrylene

10.00 UVB absorber

B

Tocopherol

0.20 Antioxidant

C

Triethanolamine (50% solution)

0.70 Neutraliser

C

Preservative

q.s. See Unit 6

C

Parfum (Fragrance)

q.s. See Unit 13

10.00 UVB absorber 5.00 UVB absorber

Preparation 1. Start warming the water in the main mixing vessel and when at about 30°C slowly add the polymer with fast stirring; when fully dispersed heat to 70°C and add remaining Stage A ingredients. 2. Weigh the oil phase (A) into a separate vessel and heat to 70° – 75°C. 3. When both phases are at 70°C slowly pour the hot oil phase into the aqueous phase while stirring; when addition is complete mix at high shear for 3 minutes then start cooling with slow speed stirring. 4. When cooled to about 60°C add the preservative then slowly add the triethanolamine as a 50% solution, which will gel the mix. The pH should be 6.0 – 7.0. 5. Continue slow mixing to 35°C and stir in the perfume and continue mixing while cooling to ambient temperature All the UV absorbers are within permitted levels for global acceptance and in theory the composition is SPF25 and provides sufficient UVA protection to comply with international standards. The UV absorbers are not the most effective and better ones, like the triazines, are available but are not accepted world-wide.

94


SKIN PRODUCTS


Formula 50: Sunscreen stick; SPF 15, broad spectrum Stage INCI Name

%w/w Prime function

A


65.00 Emollient

B

Cera alba (Beeswax)

11.00 Hardening wax

C

Copernicia cerifera (Carnauba) wax

11.00 Hardening wax

D


E

Octocrylene

3.00 UVA absorber 10.00 UVB absorber

Preparation 1. Melt the waxes in the caprylic/capric triglyceride at 85°C. 2. Add Butyl methoxydibenzoylmethane and stir until dissolved. 3. Add Octocrylene and stir until dissolved. 4. Pour into mould at a temperature just before the cloud point (the temperature at which the mixture starts to look cloudy). 5. Cool to room temperature. The waxes harden the stick to make a lip salve and in theory it will provide SPF15 and sufficient UVA protection to comply with international standards for broad spectrum protection. The two UV absorbers are included at their maximum permitted levels and additional filters would be required to achieve a higher SPF. Formula 51: Sunscreen oil; SPF 15, broad spectrum Stage INCI Name

%w/w Prime function

A


65.00 Emollient/solvent

B

Diisopropyl adipate

10.00 Emollient/solvent

C

Petrolatum

10.00 Emollient

D


E

Octocrylene

3.00 UVA absorber 10.00 UVB absorber

Preparation 1. Measure out the caprylic/capric triglyceride and add the diisopropyl adipate; add the petrolatum and warm with stirring until a clear liquid is obtained. 2. Stir in the butyl methoxydibenzoylmethane and octocrylene and mix until clear. 3. Cool and pack into suitable bottles. In theory this composition will provide SPF15 and sufficient UVA protection to comply with international standards for broad spectrum protection although when sprayed as a thin film of oil on the skin actual performance is likely to be less. The two UV absorbers are included at their maximum permitted levels and additional filters would be required to achieve a higher SPF. No preservative is required because the product does not contain water. Sun protection products are by far the most interesting and arguably the most useful type of cosmetic product to formulate. It is a dynamic area with constant improvements being made but many of these involve the use of speciality mixtures, which have no place in this unit. For further reading look at: http://www.creative-developments.co.uk/8papers.html For a (somewhat outdated) background to the challenges of formulating effective sun protection products see: http://www.creativedevelopments.co.uk/papers/Factors%20affecting%20sun%20care%20formulations.html For the BASF sunscreen simulator, which calculates theoretical SPF and UVA results go to: http://www.personal-care.basf.com/europe/by-market-segment/sun-care/basf-sunscreen-simulator

95


SKIN PRODUCTS


Formula 52: Anti-ageing cream with alpha hydroxy acids (AHAs) Stage INCI Name

%w/w Prime function

A


10.00 Emollient

A

Glyceryl stearate

5.00 Emulsifier

A

Polysorbate 60

2.00 Emulsifier

A

Cetearyl alcohol


A

Tocopheryl acetate

1.50 Emollient

A

Cera alba (Beeswax)

0.50 Thickener/emollient

A

Myristyl alcohol

0.50 Thickener/emollient

B

Aqua (Water)

B

Lactic acid

C

Preservative

q.s. See Unit 6

C

Parfum (Fragrance)

q.s. See Unit 13

q.s. 2.00 AHA

Preparation 1. This is a water to oils mix. Add the items of Stage A to the main vessel and heat to 70°C with occasional stirring. Make sure all the waxes are melted. 2. In a separate vessel, heat the aqueous phase to 70°C. 3. Add the aqueous phase ‘B’ to the oil phase ‘A’ while stirring, mix well then cool to room temperature with constant mixing, adding the preservative below 50°C and the perfume below 35°C, followed by homogenising. This is a w/o emulsion formed using a low HLB emulsifier, glyceryl stearate, with a higher HLB emulsifier, Polysorbate 60. The aqueous phase is added to the oil phase to encourage the formation of the w/o emulsion but the phase ratio looks rather low and more oil may be required; a suggestion would be to add 10% caprylic/capric triglyceride and to reduce the water accordingly. The oil phase will leave an occlusive film on the skin, encouraging hydration by retarding transepidermal water loss (TEWL) and the lactic acid will be entrapped in the oil film and may help to dislodge dead skin cells. A more modern approach to anti-ageing creams is to use a good quality moisturising cream as the base and to provide SPF15 and a high level of UVA protection for daytime use and to apply a w/o emulsion that includes a higher level of hydrating actives for night use. The use of AHAs should be restricted to once weekly use. Where AHAs are being used to exfoliate the skin the following warning is required in order for the product to be both EU and USA compliant:This product contains an alpha hydroxy acid (AHA) that may increase your skin’s sensitivity to the sun. Use a sunscreen, wear protective clothing and limit sun exposure during usage of the product and for a week after use of the product has stopped. Avoid contact with the eyes. If product gets into eyes rinse well with water immediately. A Cosmetic Ingredient Report (CIR) published in summer ‘97 concludes with the following:“Based on the available information included in this report, the CIR Expert panel concludes that glycolic and lactic acids, their common salts and their simple esters are safe for use in cosmetic products at concentrations of <10% at final f ormulation pH >3.5, when formulated to avoid increasing sun sensitivity or when directions for use include the daily use of sun protection.

96


SKIN PRODUCTS


Formula 53: Self-tanning gel spray Stage INCI Name

%w/w Prime function

A

Aqua (Water)

A

Disodium EDTA

A

Preservative

B

Dihydroxyacetone (DHA)

5.00 Tanning agent

C

Acrylates/aminoacrylates/C10-30 alkyl PEG-20 itaconate copolymer Citric acid to pH 3 – 3.5

7.60 Gelling agent

D

q.s. 0.10 Sequestrant q.s. See Unit 6

q.s. pH modifier

Preparation 1. Measure out the water and dissolve items of Stage A. 2. Add B, dihydroxyacetone, with stirring 3. Add C, Acrylates/aminoacrylates/C10-30 alkyl PEG-20 itaconate copolymer, with rapid stirring and make sure it is fully dispersed 4. Add a solution of citric acid to adjust to pH 3 – 3.5 Although gelled this should provide a spray from a suitable pump spray applicator. It will turn any skin with which it comes into contact a shade of brown. A much improved product is obtained if about 2% erythrulose is included with the DHA but all self-tanning lotions need to be applied to clean, unblemished skin that has recently had an exfoliant treatment for best results. Formula 54: Brushless shaving cream Stage INCI Name

%w/w Prime function

A

Stearic acid

8.00 Forms soap with TEA

A

Lanolin oil

2.00 Emollient

A


2.00 Emollient

A

Glyceryl stearate s/e (Acid stable)

3.00 Emulsifier

A

Cetearyl alcohol


B

Aqua (Water)

B

Disodium EDTA

0.10 Sequestrant

B

Polysorbate 20

3.00 Emulsifier

B

Glycerin

3.00 Humectant

B

Triethanolamine (TEA)

0.75 pH modifier/neutraliser

C

Preservative

q.s. See Unit 6

C

Parfum (Fragrance)

q.s. See Unit 13

q.s.

Preparation 1. Weigh out the items of Stage A and heat to 70°C. 2. Measure out the water of Stage B into a separate vessel, add the remaining ingredients of Stage B and heat to 70°C. 3. When both phases are at 70°C and all waxes have fully melted slowly add A to B with careful mixing. 4. Mix for 5 minutes at 70°C then start cooling with slow mixing. 5. When below 50°C add the preservative and add the perfume below 35°C; continue mixing to ambient temperature. The stearic acid is semi-saponified with the triethanolamine to form a soap to wet the skin and it is also an anionic emulsifier. The glyceryl stearate s/e must be an acid stable version of selfemulsifying glyceryl stearate; it will contain PEG-100 stearate as the emulsifier. This product will develop a pearly sheen over time and soften as the stearic acid crystallises; a slow and careful mix before filling into tubes will increase this effect but beware of entrapping air in the product – it will never come out! 97


SKIN PRODUCTS


Formula 55: Pre-electric shave lotion Stage INCI Name

%w/w Prime function

1

Alcohol (Ethanol) to 100%

q.s. Astringent

2

Diisopropyl adipate

8.00 Emollient

3

PEG-6 caprylic/capric triglycerides

4.00 Emollient

4

Glycerin

3.00 Humectant

5

Parfum (Fragrance)

q.s. See Unit 13

Preparation Weigh each item in turn into the mixing vessel and mix until clear. This product is applied prior to an electric shave to assist in the beard cutting process. It is selfpreserving because of the high alcohol content. Formula 56: After-shave lotion Stage 1 2 3 4

INCI Name Alcohol (Ethanol) to 100% Propylene glycol Allantoin Parfum (Fragrance)

%w/w q.s. 5.00 0.05 q.s.

Prime function Astringent Emollient Healing agent See Unit 13

Preparation Weigh each item in turn into the mixing vessel and mix until clear. This product is applied after a wet shave to assist in the beard cutting process. It is intended to sterilise nicks and cuts caused by the shaving process. Allantoin is a recognised healing agent but “healing” is not a claim that can be applied to cosmetic products. The main purpose of after shave lotions is to provide the user with a pleasant perfume.

98


SKIN PRODUCTS


Formula 57: After-shave balm Stage A A A A B B B B C D D D

INCI Name Aqua (Water) to 100% Disodium EDTA Carbomer Glycerin Isopropyl palmitate Methyl gluceth-20 distearate Ceteareth-20 Cetearyl alcohol Triethanolamine (10%) Alcohol (Ethanol) Preservative Parfum (Fragrance)

%w/w q.s. 0.08 0.20 3.00 2.00 2.00 2.00 0.50 2.00 15.00 q.s. q.s.

Prime function Sequestrant Gelling agent Humectant Emollient Emollient Emulsifier Emulsion stabiliser Neutraliser Astringent See Unit 6 See Unit 13

Preparation 1. Measure out the water and warm to about 30°C to facilitate dissolving the disodium EDTA and dispersing the carbomer. Stir in the glycerin and heat to 70°C. 2. In a separate vessel heat the items of Stage B, the oil phase, to 70°C and make sure all the ingredients are properly melted. 3. Add the hot oils to the hot aqueous phase with mixing, 4. Add triethanolamine solution, which will thicken the mix then commence cooling with slow mixing. 5. Dissolve the preservative and perfume in the alcohol and sir into the main mix when at 30°C. This has less “sting” than the previous formula but serves much the same purpose of tightening the skin and providing an immediate but transitory antimicrobial action. At 15% the alcohol is not sufficient to preserve the composition and a suitable one needs to be added. Such products are being superseded by men using a light facial moisturiser with additional skin care benefits and possibly adding UVB/UVA protection.

99


SKIN PRODUCTS


Formula 58: Thioglycolate depilatory cream Stage A A A A B B B B C C D E D

INCI Name Aqua (Water) to 100% Tetrasodium EDTA Urea Glycerin Paraffinum liquidum (Mineral oil) Decyl oleate Ceteareth-12 Cetearyl alcohol Calcium thioglycolate Calcium hydroxide Mica Potassium hydroxide solution Parfum (Fragrance)

%w/w q.s. 0.08 4.00 3.00 1.00 3.00 2.00 10.00 7.50 1.50 5.00 q.s. q.s.

Prime function Sequestrant Gelling agent Humectant Emollient Emollient Emulsifier Emulsion stabiliser Depilatory agent pH modifier Opacifier See Unit 13

Preparation 1. Measure out the water and other ingredients of Stage A and heat to 75°C. 2. Weigh the items of Stage B, the oil phase, into a separate vessel and heat to 75°C 3. When both phases are at 75°C and all waxes are melted add the oil phase B to the aqueous phase, A, with mixing. 4. Mix with cooling to 40°C and mix in Stage C items. 5. Mix well and add mica and continue slow mixing to ambient temperature. 6. Finally make a 10% solution of potassium hydroxide [with great care & wearing proper safety equipment] in water and adjust pH of mix to 12.5 7. A perfume may be included but few are stable in this system. WARNING: This is a corrosive product, be careful; it will dissolve hair, skin, eyes and carpets. Any traces of iron will turn it purple. The tetrasodium EDTA will chelate iron ions; urea softens the hair and other ingredients provide some protection to the skin against the irritating effects of the depilatory. This formula is added for interest and anyone wishing to make a depilatory product is advised to seek expert advice. That is the end of the illustrative formulations for Unit 16. They have been included for interest and are not meant to be commercially acceptable final compositions.

100


SKIN PRODUCTS


SUPPLEMENTARY BOOKLET



Unit 16 101

Prepared by Grace Abamba Amended by Paul Hebditch


SKIN PRODUCTS


CONTENTS

102

Article 1 Efficacy testing of deodorants

103 103

Article 2 Skin care technologies

107 107


SKIN PRODUCTS


Efficacy testing of deodorants Both in vivo and in vitro methods have been employed for screening potential deodorant systems. In vitro techniques do not, however, provide a reliable indicator of clinical effectiveness. The well designed clinical trial must therefore be regarded as the most valid approach to deodorant evaluation. The two principal methods for the in vivo evaluation of deodorant efficacy are: – determination of the effect of treatment on the skin microflora; and – olfactory assessment of the effects on skin odours. Techniques used to quantify microflora include tape stripping, contact plates, velvet replicate pads, swabbing, scrubbing and pressurised spray methods. It must be stressed, however, that none of these techniques are of use in the evaluation of actives such as odour suppressors, modifiers or neutralisers which take effect after the formation of odorous substances by bacteria. They are also of little value in evaluation deodorant formulations based on bacteriostats as, once the bacterial population has been sampled and the organisms removed from the axilla, the inhibitory effects of the antimicrobial are lost and the bacteria flourish normally. In these cases, we must again resort to subjective sensory techniques for the evaluation of product efficacy. Olfactory assessment of the effect of deodorants on body odours may be performed by direct armpit sniffing or by indirect sniffing of pads or other sampling vehicles. The sensory evaluation may be performed by panels of trained assessors, by the panellists themselves or by a combination of both methods. These techniques are suitable for evaluation both materials which act by inhibiting formation of axillary odour and those which act by reducing perception of malodour once it has been produced. The technique of Gee and Seidenberg for evaluation of deodorant soaps involves assessment of intensity of odour by sniffing the axillae directly and assigning a numerical value. The method has been widely used and lends itself to statistical analysis. A more recent adaptation of the method is described by Baxter and Reed. The test panel involves 20 - 40 subjects, each panellist testing each product in crossover fashion. Potential subjects are screened for the amount of odour they produce following several days’ abstention from use of underarm products, except for daily washing with an unperformed control soap. Male subjects are generally preferred since they object less to persevering with ineffective (placebo) products and tend to generate higher odour levels owing to the presence of axillary hair. While taking part in the trial, subjects are forbidden to use any products in the axillae, such as antiperspirants, talcs, perfumes, etc., other than those supplied by the tester. They are provided with two flannels, colour-coded for each axilla, and instructed to use separate volumes of water for washing each axilla to minimise the possible cross-transfer of actives. The usual procedures of a double-blind clinical trial, balanced randomised order of product use and incorporation of positive and negative controls, are observed. If non-perfumed, specific actives are being evaluated, the test products are formulated without perfume for the purpose of testing. Each cross-over period lasts for three weeks. The first week constitutes a pre-treatment phase when the panellist is instructed to wash the axillae once daily with control soap. All subjects use placebo products during this week. During the second week subjects are given one of the following combinations of products (or placebo again) to use, one on each axilla, once daily after washing: Axilla A Axilla B Placebo Placebo Positive control Vehicle Test product Vehicle

103


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In the final week, subjects do not wash or apply deodorant at home and washing is performed at the laboratory, the same product combination being applied by test personnel. Axillary odour is assessed each morning prior to washing and applying product and again in the afternoon, approximately approxim ately six hours after aft er the previous application. As subjects are then in their second week of treatment, these assessments are taken to represent the plateau for efficacy efficacy.. Where appropriate, bacterial sampling may be carried out at the 24-hour assessment and occasionally also at the 6-hour assessment. Odour assessment is performed by at least three assessors, since even experienced judges have anosmias to particular elements. Selection of assessor panels is based on ability to rank graded dilutions of odiferous materials such as isovaleric or butyric acids. Sniffing is carried out with the nose less than 10 cm from the axilla and scores are assigned on a scale of 0 - 10, according to the strength of the perceived odour. The distribution of odour scores is usually skewed, so that nonparametric statistical methods, such as the Wilcoxon matched pairs signed rank test, are used to analyse the results. Direct panellist-judge interaction does have certain disadvantages in evaluating underarm deodorants. For example, there is the risk of contamination of odour by the smell of clothing or other body odours. In addition, the judge may be influenced by visual effects such as product residue in the axilla or recognition of the subject. As an alternative to direct axilla sniffing by the judges, odour may be collected on cotton pads or on some other suitable vehicle. The method discussed below uses the rounded end of 20 x 150 mm borosilicate glass test tubes which are placed in the axillary vault. Panellists are pre-screened to ensure an ability to develop moderate axillary odour in both axillae when deodorants are not used. Conditions operating during and prior to testing are as follows. Panellists should: – abstain from use of all deodorants, antiperspirants, medicated or perfumed products for seven days prior to testing and during the test period, with the exception of those products issued – abstain from smoking, chewing gum and drinking alcohol for at least 15 minutes before each visit to the test location – use control soap for all bathing and washing during pre-treatment and test periods. During the test period only, only, all underarm washing is performed at the test location under supervision – refrain from washing for a full 24 hours before assessment on the first day of the test period – wear a clean shirt or blouse after each daily washing and application of product during the test period. Judges are selected as described above on the basis of their ability to rank correctly increasing concentrations of isovaleric acid from 0 - 600 ppm. They are requested not to smoke or eat within 15 minutes of evaluations and to refrain from the use of fragrances throughout the study. study. Evaluations are made on a 10-point odour intensity scale, disregarding fragrance. For evaluation a 20 x 150 mm borosilicate glass test tube is placed in each axillary vault and held in place by the subject keeping his arms by his sides. When directed, the subject vigorous vigorously ly rotates the bottom portion of the tube in the axilla. The tube is then given to an operator who covers the bottom of each tube with a plastic closure. The two tubes from each pair of axillae are quickly passed to two judges who independently evaluate them for odour intensity. Judges evaluate pairs of samples from test subjects at intervals of approximately 1.0 - 1.5 minutes. Each evaluation is entered on a separate score sheet which does not record details of product assignment scores.



A typical test design is as follows. On day 1, the final selection of subjects is made. Individuals achieving a pre-wash score of at least 4 in both axillae, as judged by at least half the assessors, are selected. This is the baseline score and is recorded. The axillae are washed, rinsed, dried and the designated product is applied to each axilla. Subjects return for evaluations, usually at intervals of 3, 6 and 24 hours. On day 2, the first 24-hour post-treatment assessment is made and the day 1 procedur procedure e is repeated. On day 3, the second 24-hour post-treatment assessment is made and the test is then complete. The first day scores, used to screen out subjects with low odour levels, are also examined to ascertain whether right/left side differences are sufficient to warrant using the day 1 scores as a covariate in the analysis of post-treatment data to adjust for left or right lateral bias. The data are analysed using a repeated measures design. Odour scores for the two test materials are compared at each time period. Factors used in the analysis are panellists, treatment, test days, and judges. The number of subjects experiencing superior performance with each treatment are tabulated and treatment differences tested using the W ilcoxon signed rank test. Advantages of the indirect sniffing method over the direct sniffing method may be summarised as follows: – subjects do not come into recognition proximity proximity with judges, thus minimising the effects of revulsion, embarrassment and bias – judges can perform their task in a relaxed position and may therefore concentrate more effectively on scoring – the interference of extraneous smells from a subject’s subject’s skin, hair or clothing is effectively eliminated – the odour samples can be stored for several hours under refrigeration without quantitatively or qualitatively affecting the odour perceived. This can be most useful if one of the judges is temporarily incapacitated. While these indirect methods of deodorant evaluation are admittedly less ‘true to life’ than the direct sniffing of axillary odour, which accurately mimics how we evaluate our own body odour, it would seem that the experimental practicalities are strongly in their favour. favour. The testing of antiperspirants The most widely used procedure for efficacy testing of antiperspirants is a gravimetric method which involves the collections and weighing of axillary sweat under controlled conditions. conditions. A variety of different test methods have been cited in the literature. An example of the so-called ratio method involves panels of at least 20 volunteers who abstain from use of antiperspirants for a period of at least two weeks prior to testing, although the use of alcoholic deodorants is normally permitted. On 3 - 4 days following this pre-treatment phase, they enter a controlled environment environm ent chamber maintained at approxim approximately ately 100°F and 35% R.H., the ‘hotroom’ with absorbent pads (the ‘A’ pads) strapped to both axillae. After 40 minutes, these pads are removed and discarded as sweating rates are highly variable over this initial period. A fresh pair of weighed pads (the ‘B’ pads) are substituted and remain in place for 20 minutes before being removed and reweighed. A second set of weighed pads (the ‘C’ pads) are placed in the axillae for a further 20 minutes. Then these in turn are removed and reweighed. This completes the control phase of the study. Applications of product are made under supervision at least once a day over 5 days, such that half the panel receive the test product on the right axilla and the left is untreated or treated with the control product. The other half of the panel receive the opposite pattern of application. Repeated applications are necessary to build up the maximum antiperspirant effect. On the fifth day and at least an hour after the final applications of product, panellists re-enter the hot-room and the series of A, B, and C pads is repeated.

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The percentage reduction in sweating is calculated according to the following formula: ( Post-treatment treated/untreated treated/untreated sweat ratio )

1 – ---------------------------------------------------------------------------------------------------------------------------×- 100

Corresponding mean control sweat ratio

A product cross-over may be employed to validate the reproducibility reproducibility of the test result. Panellists are selected on the criterion that they consistently yield at least 100 mg sweat from each axilla during control collections, which is reported to exclude only about 1% of a normal population.. The only other reason for exclusion is a lack of reasonable uniformity in control population sweating ratios. This appears to be largely due to poor compliance with test conditions and occurs infrequently. Most individuals produce slightly more sweat from the dominant axilla depending on right- or lefthandedness. Certain individuals exhibit pro-perspirancy pro-perspirancy, i.e., they fail to t o show the expected sweat reductions or actually yield increased sweat weights following treatment with known effective products. This is apparently not linked to product irritancy but is due to specific individual differences. Assuming Assuming a panel of reasonable size, such individuals would not be excluded as, in this way, it would be possible to achieve artificially much greater reduction values than those generated by nonselected random populations populations.. Finally, two entirely different techniques, hygrometry and thermography, are worthy of mention. Hygrometry involves measurement of the rate of evaporation of moisture from the surface of the skin. The cooling effect of sweating is due to evaporative water loss at or below the skin surface. Thus, as ambient air flows over the skin, its moisture content is increased. The product of (increased water content) x (air flow rate) is a measure of the rate at which sweat is evaporating. Provided that sweat droplets are not formed on the skin surface, the rate of evaporation is equal to the rate of emergence of sweat from the sweat ducts. Cylindrical cells are fixed to test and control skin sites on the back of test subjects. Ambient air is drawn from the hot-room and pumped into the cells which are held in close contact with the skin to prevent gross leakage. Outgoing air from each cell passes through t hrough a humidity sensor which records relative humidity. A modified version of the Servomed Evaporimeter equipped with dual probes is now available for this type of measuremen measurement. t. Thermography is a process of recording variations in intensity of long wavelength emissions from a surface, comparable to that of a visible wavelength television system. Hot areas emit more energy in the sensitive range of the instrument than cold areas, so are displayed on a TV screen as brighter areas in a monochrome system, or as different colours in a colour system, displaying temperature variations over the skin surface as a map. The sensitivity is such that temperature changes as small as 0.1°C appear as distinct colour changes. Localised cooling of t he skin contributes to thermoregulation. thermoregulation. It is reasonable to assume, therefore, that there is less cooling of the skin when an effective antiperspirant has been applied to that area, i.e., the skin temperature is higher. higher. Thermography requires only 1 second to map the surface temperature of the axilla. Hygrometry measurements can be made in less than 2 minutes, while gravimetric measurements measuremen ts require at least 20 minutes’ collection period to achieve acceptable reproducibility. reproducibility. In addition, both hygrometry and thermography allow antiperspirant activity measurements to be made under conditions which do not interfere with the normal operation of sweat glands or the cooling caused by sweat evaporation. From H. Butler (ed.), Poucher's perfumes, cosmetics and soaps, soaps , Volume 3, (9th edition), Chapman and Hall, 1993.

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Skin care technologies As the population ages and the standards for beauty remain, technology becomes more important in deciding the trends in the industry and the results clients see on their skin. BY SARA MASON GCI magazine, March 2002, Volume 170, No. 3, pages 36-39 Reproduced with permission.

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Module 2 Unit 16 Skin Products

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