Denim Washing (thesis)

Final Year Thesis

Denim Washing

INDUS INSTITUTE OF HIGHER EDUCATION KARACHI

THE STUDY OF DENIM WASHING

A PROJECT SUBMITTED TO THE FACULITY OF TEXTILE SCIENCES

IN PARTIAL FULFILMENT OF REQUIRMENTS FOR DEGREE OF BACHELOR OF TEXTILE SCIENCE (B S TEXTILE)

SUPERVISED BY: ENGR ABDUL SALAM FACULTY MEMBER. Email: [email protected]

SUBMITTED BY: SYED ASIM NAJAM UMAIR MAJEED KHAN MAY, 2010

1 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

ACKNOWLEDGMENTS All thanks are due to Almighty “ALLAH” the most beneficial and merciful who enabled us to complete this project.

The completion of this project is perceived as the fruitful result of and incredible effort, devotion and hard work. It can be stated without any hesitation that this thesis is the outcome of the joint effort of all concerned by successfully negotiating the various tedious problems and hurdles.

We are particularly thankful of Sir Adbul Salam our project advisor for the guidance and valuable cooperation render by him at any stage regarding this project. He fully indulged himself to facilitate our job whenever approached him to seek guidance regarding this study.

Special thanks are reserved for the Head of Textile Science Department Sir Hasib-uSalam for encouraging and motivating throughout the successful completion of this project. We are very thankful to each and every person of Ragby Industries specially Sir Ejaz Shah, who make ourselves very comfortable during our whole internship program, who led us to complete this project work.


Final Year Thesis

Denim Washing

Faculty of Textile Science INDUS INSTITUTE OF HIGHER EDUCATION Karachi.

Certificate I am pleased to certify that the following students have satisfactorily carried out a thesis work, under my supervision on the topic of “Denim Washing” I further certify that his thesis is worthy of presentation to the Faculty of Textile Sciences, INDUS INSTITUTE OF HIGHER EDUCATION Karachi for the degree of Bachelor of Science in Textile.

1. Syed Asim Najam 2. Umair Majeed Khan

HOD Textile Science:

__________________

External Examiner:

__________________

Supervisor:

___________________


Final Year Thesis

Denim Washing

TABLE OF CONTENT Content

Page No.

Chapter 1 1.1 Introduction

7

1.2 Back ground

7

1.3 History of denim

7

1.3Literature Review

9

1.4 Area of study

10

1.5 Expected Results

Chapter 2 Warping 2.1 Introduction

11

2.2 Ball warping

11

2.3 Beam warping

12

2.4 Components of machine

12

2.5 Procedure of warping

13

Chapter 3 Dyeing 3.1 Introduction

14

3.2 Classification of dyes

14

3.2.1 Direct dyes

14

3.2.2 Reactive Dyes

15

3.2.3 Sulphur Dyes

15

3.2.4 Vat dyes

16

3.3 Denim dyeing

18

3.3.1 Rope dyeing

20

3.3.2 Slasher dyeing

21

3.4 Difference between rope dyeing and slasher dyeing

24

3.5 Cooking tanks and dsoing system

26 4

Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

3.6 After-washing process and drying

27

3.7 Sizing

27

3.8 Drying zone

28

3.9 Accumulator

28

3.10Leasing zone

28

3.11 Expansion comb

29

3.12 Beaming

29

3.13 Transportation of beams

29

Chapter 4 Weaving 4.1 Introduction

30

4.2 Basic weave design

30

4.3 Weaving of denim fabric

31

4.4 Typical denim construction

32

4.5 Non-conventional denim fabric

33

4.6 Shedding system

34

4.6.1 Crank shedding

34

4.6.2 Cam shedding

34

4.6.3 Dobby shedding

35

4.6.4 Jacquard shedding

35

4.7 Classification of weaving machine

36

4.7.1 Shuttle weaving

36

4.7.2 Shuttle less weaving

37

Chapter 5 Faults in production of denim 5.1 Faults of warping

41

5.1.1 Faults in machine

41

5.1.2 Faults in raw material

41

5.1.3 Faults in product

41


Final Year Thesis

Denim Washing

5.2 Faults of dyeing

42

5.2.1 Faults in machine

42

5.2.2 Faults in raw material

42

5.3 Sizing Faults

42

5.4 Weaving Faults

42

Chapter 6: Denim washing 6.1 Introduction

43

6.2 How does washing create unique look

43

6.3 Processes involve in Denim washing

43

6.3.1 Dry process

43

6.3.2 Wet process

47

6.4 Types of denim washes

48

6.4.1 Chemical wash

48

6.4.2 Mechanical wash

56

6.6 Spraying

60

6.7 Whiskering

61

6.8 Softening process

63

6.9 Machine use for denim

67

6.10 New development

69

6.11 Value edition

71

Chapter 7 7.1 Conclusion

74

7.2 Reference

75


Final Year Thesis

Denim Washing

1.1 INTRODUCTION Denim and jeans - where do the names come from? The word jeans come from a kind of material that was made in Europe. The material, called jean, was named after sailors from genoa in Italy, because they wore clothes made from it. The word 'denim' probably came from the name of a French material, serge de nimes: serge (a kind of material) from nimes (a town in France),

1.2 BACKGROUND 

We have interest in denim washing.



Denim has fewer difficulties in process as compare to other dyeing process.



Few industries work on this topic so that‟s why we decide to do the topic and we will try to optimize the process and try to invent new washes or finishes in denim.



Denim is a universal fabric, one that covers all age groups, races and social divides that‟s why we think it will have high demand in the future and this is also the point of our attraction for this topic.

1.3 HISTROY OF DENIM: In fashion history, jeans and denim history continues to baffle. No one truly knows the perfect answer to where jeans began. As so often happens fashions often emerge together in various parts of the world and are the result of the sudden availability of a new fabric, cloth, dye or technique. But we do know that the phrase denim jeans are thought to derive from several sources. No one is totally certain where the words come from. A majority of source books suggest that denim derives from the English translation of the South of France French phrase 'serge de Nîmes'. Denim fashion history is thus associated with Serge de Nimes. When talking about denim the name Levi´ s is one of the first to be mentioned. Levi´ s which stands for Levi Strauss is normally called the forefather of jeans. When tracing back the history of these trousers to its origins it is true that Levi Strauss played an important role concerning their development and distribution but he had also other inventive business partners. 7 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

Levi Strauss found out that the gold diggers´ hard work in the mines made their clothes get worn out very quickly and he produced stout working trousers out of the sail cloth he had taken with him which he called „half overalls“. When he continued producing these trousers he used cheap cotton fabrics coming from Genova. The name of the town of Genova was modified into „jeans” in the American slang. At the end of the sixties of the th

19 century he replaced the brown sail cloth by an indigo-dyed, wear resistant cotton fabric coming from France. The name of this fabric was „Serge de Nimes“. Serge is the French. Expression for a combined twill and Nimes is the French town where the fabric comes from. The fabric´s name Serge de Nimes was quickly turned into „Denim“ in American colloquial language. By applying this indigo-dyed combined twill the first jeans out of Denim was almost born or better sewn. The application of metal rivets for jeans is due to the Polish emigrant Jacob W. Davis, also called AJacob Youphes. Although the working trousers out of Denim were stout they had a tendency to get worn out where the pockets were. Jacob Youphes mended the trousers with a needle and thread. One day a customer inspired him to repair the torn off pockets with the help of rivets. Under the management of Levi Strauss the jeans were now produced in series. Since the trousers were so stout not only the gold diggers liked them but which is not surprising in America? The cowboys appreciated them very much, too. When the trousers were applied as working trousers for cowboys, however they got worn out at the crotch tip. This was no problem for Levi Strauss and Co. since they reinforced the trousers again with metal rivets at the crossing point of the four seams at the crotch tip. About 1947 denim made a break-away from work clothing image, chiefly in the area of sportswear and rainwear and an occasional appearance in high fashion collections as a "different-looking" evening dress. In 1970 American youth adopted denim as their favorite fabric. Part of a "back to nature" movement that emphasized ecology and the natural denim being a fabric created from a natural fiber was a primary factor. Since 1960 the jeans business has undergone an explosive transformation, from a source of tough, cheap clothing for cowboys, blue-collar workers and penniless youth into a fashion conscious market for a widening mass of people of almost all ages.


Final Year Thesis

Denim Washing

1.4 LITERATURE REVIEW The studies related to the denim manufacturing and processing is available to understand the process sequence and achieving various washing effects of denim. Processes for producing yarns dyed with indigo have been in use for thousands of years. The original batch methods for dyeing yarn skeins have been replaced for the most part with continuous dye ranges that can produce thousands of pounds of dyed yarns each hour. Different experiment have been done before on denim washing, denim dyeing they are done internationally as well as locally in our country in which few are discussed below. 

In past, stone (pebbles) are use for washing which is known as stone wash but now a days stone (pebbles) are replaced by rubber balls because stone damaged the fabric during the washing process.



Another experiment was done internationally and primary object of the invention is to provide a method of treating denim fabric in plain fabric form or in garment form to economically produce stonewashed denim fabric of various different shades colors without multiple steps, expensive equipment, or large inventories of fabrics and dyes. Another object of the invention is to economically provide stonewashed denim fabric of different shades and colors.



In earlier work many denim washes has been created in which some denim washed names are given below:



1

ACID WASH

2

ENZYME WASH

3

BLEACH WASH

4

STONE WASH

Companies that “finish” jeans by washing them or distressing them for a worn-in look. Most major jeans manufacturers use several different laundries that specialize in different finishes. The main techniques used include simple washing, stonewashing, which uses an abrasive-bristled Tonello machine, sandblasting, laser burning, or applying enzymes to simulate “cat‟s whisker”-wear line, and sandpapering by hand. 9 Indus Institute Of Higher Education

Final Year Thesis 

Denim Washing

Our seniour students also worked on denim washing and they also tried to developing the new techniques in denim washing but unfortunately they were not success in developing new techniques.

1.5 AREAS OF STUDY: In this project we will study denim washing along with its weaving and its dyeing process and we will try to optimize the current methods but we will focus deeply on denim washing and its finishing.

WARPING The first process in the manufacturing of denim is warping.

2.1 INTRODUCTION Warping is the process of transferring multiple yarns from individual yarn packages onto a single package assembly. Normally, yarns are collected in a sheet form where the yarns lie parallel to each other and in the same plane onto a beam, which is a cylindrical barrel with side flanges. This is known as beam warping. For ball warp denim, the yarns are brought together and condensed into a rope before being wound onto a relatively short cylindrical barrel (sometimes called the shell or log) that has no end flanges.. In both cases, the supply yarn packages are placed on spindles, which are located in a framework called a creel.

2.2 Ball Warping : In ball warping (Figure 5), 250 to 400 yarn ends are pulled from the creel. The yarns then pass through a comb-like device (sometimes called a hack or reed), which keeps each warp yarn separate and parallel to its neighboring ends. At intervals of every 1000 or 2000 yards (or meters), a lease string is placed across the sheet of warp yarns to aid yarn separation for the rebeaming operation, which will occur later. The yarns then go 10 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

through a funnel-shaped device called a trumpet or condenser, which collapses and condenses the sheet of yarn into rope form. This device is located at the base of the warper head and traverses back and forth, guiding the newly formed rope of yarn onto a log. The rope must be wound at a constant tension to keep the yarns from tangling.

2.3 Beam Warping Beam warping maintains the yarns in an open sheet form and winds the yarns parallel to each other onto a slightly wider flanged beam. These yarns will not go through the rope indigo dye range, but are left “natural” and will end up either slasher dyed or in an undyed fabric, which can later be piece dyed, garment dyed, or left natural. Another option would be to beam dye the yarns using a dye other than indigo.


Final Year Thesis

Denim Washing

2.4 COMPONENTS OF MACHINE • Creel • Rods • Chain System • Control Devices • Sensors • Head stock • Expansion Comb • Dust and fly accumulation unit Showering assembly

2.5 PROCEDURE OF WARPING: The creel stand has maximum capacity of five cones per stand. The yarn from the cones is unwounded and passes from rod by cross wound, holed by a catcher guided to the tensioning zone when cone rotates anticlockwise. There are three types of tension in warping i.e. catcher tension, rod tension, and sacker tension. Magnetic tensioner is used for yarn tension. Then the yarn comes to the winding zone or headstock. Combs straighten the yarns towards pressure drum, which supports beam, and yarns in an alignment so that each and every yarn end can wound separately. Static charges due to friction of yarns on metal surface cause static charges, which are removed through an anti static device. Then the yarn is wounded on beam in this way for a required length if beam is changed after one filling of beam then knotting of yarns is made. Similarly if cones are finished on one frame side then trolley system of cone changing is used in this way chains rotates the whole frame of empty side and new filled side of frame is forwarded again knotting is done between the new cones yarn and already winded yarn. Extra yarn is then removed through cutting. Sensors sense any type of yarn breakage and in case of yarn breakage knotting is done.


Final Year Thesis

Denim Washing

DYEING 3.1 INTRODUCTION Dyeing is a process in which we impart colour into the fabric. All commercial textile dyeing processes take place by the application of a solution or a dispersion of the dyes to the textile material followed by some type of fixation process. The dye solution or dispersion is almost always in an aqueous medium. A major objective of the fixation step is normally to ensure that the coloured textile exhibits satisfactory fastness to subsequent treatment in aqueous wash liquors. Dyeing is mainly depends on the type of fabric, structure of fabric and the properties of dyes.

3.2 CLASSIFICATION OF DYES For our convenience we make classes of dyes, due to these classes the application of dyes is much easier. The classifications of dyes are as follows: • Direct Dyes • Reactive Dyes • Sulphur Dyes • Vat Dyes

3.2.1 DIRECT DYES Direct dyes have been used to dye cellulose for over 100 years. Because of the simplicity of application and great choice of products available, direct dyes are a popular dye class. Direct dyes ranges from moderate to poor in wash fastness. Light fastness varies from poor to excellent depending on the particular dye. Direct dyes depend on secondary forces such as hydrogen bonds and vander waals forces to bond with cellulose fibres. Since secondary forces are relatively weak. Therefore, direct dye molecules have relatively high molecular weights, typically 400 to 1200. The great majority of direct dyes are azo structures.


Final Year Thesis

Denim Washing

3.2.2 REACTIVE DYES Reactive dyes contain groups that react with the hydroxyl groups in cellulose. The reaction between a reactive dye and the fibre produces a covalent bond. By their nature reactive dyes also react with water. Dye which reacts with the fibre is said to be “fixed” to the fibre. Dye which reacts with water is said to be “hydrolyzed”.

Fixation Reaction Cell – CH – OH + DYE – X Cell – CH – O – DYE + HX 2

2

Cellulose reactive dye dyed fibre acid X=reactive group

Hydrolysis reaction H – O – H + DYE – X DYE – OH + HX Dye molecules which react with the fibre and become fixed have excellent fastness to washing because of the high strength of the covalent bond. Dye molecules which are hydrolyzed may be weakly attached to the fibre and if not washed out at the end of the dye cycle have very poor wash fastness.

3.2.4 SULPHUR DYES Sulphur dyes are widely used on cotton mainly because they are economical to use. They have good to excellent wash fastness and good light fastness in dark shades. Light fastness of pale shades is poor. Sulphur dyes are usually dull in shade since the molecular structures are complex. As a class, the sulphur dyes are not resistant to chlorine containing bleaches.


Final Year Thesis

Denim Washing

Chemical nature of sulphur dyes

3.2.5 VAT DYES Vat dyes are mainly on cellulosic fibres, but some can be applied to protein fibres. They usually have outstanding colourfastness properties. Vat dyes are more expensive and difficult to apply than other classes for cellulose such as directs sulphurs, and reactive. Indigo is a special case in the vat dye class. Indigo is attractive for its pleasing blue colour and for the unique fading characteristics of garment dyed with it. Vat dyes are characterized by the presence of a keto group. Vat dyes in keto form are water insoluble pigments.

CHEMICAL CONSTITUTION OF VAT DYES


Final Year Thesis

Denim Washing

Reactions of Indigo Dye

THE SUBSTANTIVITY AND DYEING CHARACTERISTICS OF VAT DYES FOR CELLULOSIC FIBRES. BASIC STEPS IN THE DYEING PROCESS The dyeing of cellulosic materials with vat dyes follows a four-step sequence: 1. Preparation of the vat containing the leuco forms of the dyes; 2. Dyeing of the material, in which the fibers absorb the water-soluble leuco compound; 3. Oxidation of the absorbed leuco compound back to the parent pigment inside the fibers


Final Year Thesis

Denim Washing

4. Soaping of the dyed material to remove pigment loosely adhering to the fiber surfaces and to develop the true shade and fastness properties.

3.3 DENIM DYEING: The classical jeans were produced out of indigo-dyed Denim fabric. The special character of this fabric only the warp thread is dyed makes it necessary to carry out dyeing in yarn form. The yarns applied for Denim were exclusively produced on ring spinning machines in former times. The development of OE (open end) yarns by applying smaller rotors with a spinning speed of up to 200 m/min - has led to the application of OE rotor yarns both for warp and weft. The yarns applied for weaving must be of high quality: a high fiber for strength, regularity as well as a small part of short-stapled cotton fibers belong to the basic features of the denim yarn. For regular jeans qualities the warp yarns are spun in a fineness of 50 to 90 tex, for the weft yarn the fineness ranges are mainly 75 to 120 tex. If Denim is made out of Tencel or Modal especially for jeans shirts the finenesses are up to 25 tex. Indigo, sulphur and indanthrene are mainly used in the dyeing process. Two methods are applicable for continuous dyeing with indanthrene dyes: rapid dyeing and vat dyeing. While processing the basic colored denim, reactive dyes are used and fixed with hot caustic soda solution. The dyeing process is mainly influenced by the dyestuff characteristics, dyeing temperature and necessary chemicals used in the process. Indigo dye is the most popular choice as it has good depth of shade and suitable rubbing and washing fastness. When cotton yarn is dyed with indigo, it leaves a ring-dyeing effect, because of which the outer layer of warp yarn is coated with indigo, and the core of the yarn remains undyed. This gives the denim garment a unique „faded look‟ and a rich blue shade after repeated use and wash. Originally, the warp yarns or ends were put through the dye bath side by side to form a sheet of yarn, which passed continuously through several dye baths, squeeze rollers or airing sequences. However, if there were breaks in the yarn (and there would be, as each yarn had to take the tension of being pulled through these processes virtually on its own), the dyeing process had to be stopped. The yarns would be then mended, or else it would lead to very bad tangling. These stoppages would in turn cause large shade variations, and the yarn breaks would show up as bad faults in 17 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

the fabric. Now, an infinitely more efficient system has been introduced. Special attention shall be paid here to Indigo, the „king of dyestuffs” since it plays an important role in obtaining the jeans effect. Indigo belongs to the category of water-insoluble dyestuffs. It was first mentioned in a book 13 BC; at that time the name Indian blue indicated the country the color came from. It is said to have been used for dyeing in India and China 2000 years BC already. The Indigo plant is used for preparing Indigo

Nowadays, yarn dyeing with indigo is done continuously. Here the various dyeing processes with different concentrations of chemicals as well as the subsequent yarn sizing exert an influence on the quality and the appearance of the ready fabric. There are two processes in the practice for continuous dyeing: • · Rope Dyeing • · Slasher or Sheet Dyeing


Final Year Thesis

Denim Washing

3.3.1 ROPE DYEING Indigo Rope Dyeing When dyeing according to the rope dyeing or cable dyeing method.350 - 400 warp threads are bound on the ball warper to very thick cables of 10 000 - 15 000 m length. On the continuous dyeing installation, 12 to 36 cables are led side by side, wetted, dyed and dried after the dyeing process on cylinders and put into cans. Then the cables are dissolved to warps on the long chain beamer. The warps are added to the sizing machine, sized and then led together to warp depending on the total numbers of threads. In practice, this method has proven to be very good through obtaining an optimum indigo dyeing. However it is important that the cables have a constant tension in order to avoid warp stripes. The disadvantage compared to other methods is that yarn breakages do occur more often. Size of the dyeing unit is between 60 - 80 m. Normally, 6 dyeing vats are in use. There are nevertheless variations with 3 to 8 dyeing vats.


Final Year Thesis

Denim Washing

3.3.2 SLASHER DYEING Indigo Sheet or Double Sheet Dyeing (Slasher Dyeing).When dyeing according to the sheet dyeing method, instead of cables the warp threads are fed to the machine parallel next to each other. These are much smaller compared to the rope dyeing machines. Another advantage is that the cables don‟t need to be open after dyeing. Moreover, each yarn wets much faster and in this way reduces the dipping and wetting times during dyeing. All in all, each thread has a larger surface compared to a dyeing cable and this requires somewhat more hydrosulphite to prevent a premature oxidation of the indigo.


Final Year Thesis

Denim Washing

Whereas during rope and sheet dyeing the yarns are always led in succession to the dyeing baths, the fabric of the loop dye method is led several times through the same dyeing bath. The machine is then much shorter and the hydrosulphite consumption is lower. Depending on the number of dyed passages and the concentration of indigo in the dyeing vats, different dyeings of the yarn. . [3]


Final Year Thesis

Denim Washing

WORKING PRINCIPLE OF SLASHER Warp beams are brought to the dyeing and sizing section in sheet form as per requirement. The warp sheet is taken to wetting tank (like mercerize, semi mercerize and causticize tanks depends upon the dyeing methods) which swells the fiber and increases its dye uptake. It is then taken to a hot washing tank whose temperature is maintained at 0

0

85 C. It is then taken to cold washing tank whose temperature is maintained at 60 C. Warp sheet is then taken to dyeing tanks where dye is reduced to soluble leuco form by using sodium hydrosulfite, yarn is then contacted with the reduced dye, and the dye is adsorbed by the fibers. The fixed leuco indigo in the yarns of the warp sheet was oxidized to form pigment during transport of the warp sheet in the air space following the dwelling chamber, taking approximately 60 seconds. It is taken to two hot washing tanks for fixation. Following rinsing, warp sheet is dried on cylinders dryers prior to the application of sizing agent. OXIDATION REACTION

Na S O + O + 2NaOH → Na SO + Na SO + H O + C H O N Na + ½ O + H O + 2 2

4

2

2

4

2

3

2

16

10

2

2

2

2

2

Sodium Hydrosulfide C H O N + 2NaOH 16

10

2

2

Oxidized indigo During the slashing process, the sheet of yarns is passed through the size box which contains the hot water solution or mixtures of sizing agents. The yarns pick up the required quantity of size solution in the size box, excess size is squeezed off as the yarns pass through squeeze rolls. After the size box, the yarns go through the dryer section. The wet yarns are dried by using drying cylinders. Cylinder drying is done using steam heated hot rolls. The Teflon coating is done on all the cylinders to prevent sticking of yarns. Accumulator stores 150 meters of warp sheet. Due to the nature of sizing, the yarns in the sheet may be stuck together at the exit of the dryer section. They are separated into individual sheets by leasing rods and individual ends of yarns are separated by passing through comb then the yarns are wound on to a loom beam for weaving.


Final Year Thesis

Denim Washing

3.4 DIFFERERENCE BETWEEN SLASHER AND ROPE DYEING ROPE DYEING

SLASHER DYEING

Warp yarns are assembled on the ball Warp yarns are directly wound on a beam warper to form a rope.

in the form of a sheet.

Ropes are drawn through dyeing range Dyeing is done in sheet form side by side. After dyeing they are dried on a drum After dyeing the warp sheet is dried on the drier and deposited in cans. The ends are same machine in continuous process by spread out on long chain beamer Or on a drying cylinders and then sizing is done rebeamer, and the yarn sheet is wound on the same machine and after drying it is onto warp beams. These beams are then wound on a weaver beam taken to sizing. After sizing they are dried and assembled on the weaving beam. Good depth of shade is achieved

Depth of shade is not good

In rope dyeing we have very high In Slasher dyeing productivity is less but productivity but the limitation is that it is

it is feasible for short lots.

very expensive for short lots. It can only run for coarse yarn as the It can run for fine yarns too tension on rope breaks the yarn Time consuming processes are rebeaming Rebeaming is not required and sizing is and then sizing

done after dyeing.

As the dye bath is less exposed to air so Setting up or stabilization of the dye baths dye is affected less.

is affected faster.

The oxidation time is greater for fixation

The immersion and oxidation times are much shorter


Final Year Thesis

Denim Washing

The wetting time is greater and so dye is Owing to the paralleled warp threads, the applied uniformly

wetting process is shorter and a wetting trough may be adequate.

The rope dyeing machine is much The sheet dyeing machine is smaller than expensive than Slasher.

a rope dyeing machine, which means that the prime costs are lower

Rope opening is avoided



Warp sheet entanglement is a danger

Bottoming: In this case another dye is applied before dyeing with indigo. First the warp sheet is dyed with sulfur and then it is washed and then dyed with indigo.



Topping: In this case the warp sheet is dyed with indigo in start and then it is washed and then it is dyed with another dye (normally with sulfur).



Bottoming indigo Topping: In this case the warp sheet is firstly dyed with some dye and then after washing with indigo and then after washing with other dye like sulfur.

Washing is done after each bath in order to remove unfixed dye. Dyeing of indigo occurs at low temperature and that of sulfur at high temperature. Firstly the warp sheet is dipped in the dyeing liquor and then airing is done in order to do fixation as indigo and sulfur dyes are in reduced form in liquor than they are oxidized by giving air. Which is necessary because if airing is not proper than immature oxidation occurs. For this purpose an airing zone of about 40 m is provided after each bath. The airing process is also known as dwelling time.

3.5 COOKING TANKS AND DOSING SYSTEM: A color kitchen is also known as cooking tanks. Five cooking tanks are also provided with the machine which is used for the preparation of liquor for pre-treatment, dyeing and sizing. They are connected with the machine via dosing system. The computer-controlled


Final Year Thesis

Denim Washing

dosing system for dyestuff and chemicals is the heart of the machine. Indigo vat, hydrosulphite and caustic soda are continuously added according to calculated quantity indications and depending upon speed. Color UN levelness owing to fluctuations in bath concentrations does no longer occur. Owing to the high circulation rate of the dye liquor in two circuits, local bath concentration differences are avoided. The metering control stores the required adjustment parameters and guarantees a high level of process reliability and reproducibility.

The used dyes can also be preserved with the help of two storage tanks on the machine. Useless dye is drained easily from the tanks with the pipes connected at there bottom.

3.6 AFTER-WASHING PROCESS AND DRYING After dyeing of the warp sheet washing is done in order to remove the unfixed liquor from the warp sheet. The two or three hot washes are done after the dyeing. And then it is dried on the assembly having 07 drying cylinders.

3.7 SIZING Although the quality and characteristics of the warp yarns coming out of the winding, warping and dyeing processes are quite good, they are still not good enough for the weaving process for most of the yarns. The weaving process requires the warp yarns to be strong, smooth and elastic or extensible to certain degree. To achieve these properties on the warp yarns, a protective coating of polymeric film forming agent (size) is applied to the warp yarns prior to weaving; this process is called slashing or sizing. 25 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

The main purposes of slashing are as follows: • To increase the strength of the yarns • To reduce the yarn hairiness that would cause problems in weaving process • To increase the abrasion resistance of the yarn against other yarns and various machine elements • To reduce fluff and fly during the weaving process for high speed weaving machines. One sizing tank is provided after the drying zone. The capacity of the size box is about 400 liters. Sizing material is provided automatically by dosing system or it can be manually added.

3.8 Drying Zone After the size box the yarns go through the dryer section. The wet yarns are dried by using cylinder drying. Cylinder drying is done using steam heated hot rolls called the drying cylinders. The cylinders are coated with Teflon to prevent sticking of the yarns on the cylinders. The drying zone contains 14 cylinders.

3.9 ACCUMULATOR: Accumulator is also known as compensators. After drying two accumulators are provided on the machine. Whose function is to minimize chance of stoppage of machine because of the change of beam on the head stock and insertion of rods in the leasing zone they accumulate the extra warp when the speed is reduced from the headstock by moving assembly to upward direction as shown in figure below When the head stock is moved with a greater speed the excess warp is removes from the accumulator.

3.10 LEASING ZONE Due to the nature of sizing, the yarns in the sheet may be stuck together at the exit of dryer section. Therefore they are separated into individual ends using leasing rods. The individual sheets of yarns from each section beam are separated.


Final Year Thesis

Denim Washing

3.11 EXPANSION COMB Pins in the expansion comb separate the yarns within each sheet. With the expansion comb the warps are spread according to the required width of the weaver‟s beam.

3.12 BEAMING The yarns are wound on to weaver‟s beam at the headstock. Maximum beam width of 4000 mm can be used, usually 3600 mm is used. A pressing roller is pressing the warp yarn for uniform tension winding. A guide roller guides the yarns to the weaver‟s beam. A pressing roller is pressing the warp yarn for uniform tension winding. A machine speed of 100-110 m/min. is used

3.13 TRANSPORTATION OF BEAMS: After the winding of dyed warp beams the from the head stock the samples of the yarn are taken to laboratory for testing and then it is transported to the weaving department.


Final Year Thesis

Denim Washing

WEAVING 4.1 INTRODUCTION The process of producing a fabric by interlacing warp and weft threads is known as weaving. The machine used for weaving is known as weaving machine or loom. Weaving is an art that has been practiced for thousands of years. The earliest application of weaving dates back to the Egyptian civilization. Over the years, both the process as well as the machine has undergone phenomenal changes. As of today, there is a wide range of looms being used, right from the simplest handloom to the most sophisticated loom.

4.2 BASIC WEAVE DESIGNS There are three basic weaves:

• Plain weave

• Twill weave

• Satin Weave


Final Year Thesis

Denim Washing

4.3 Weaving of Denim Fabric: Denim is a fabric traditionally woven with what is known as a twill weave. This is simply a weaving pattern that produces parallel diagonal ribs. The weaving process interlaces the warp, which are the length-wise indigo dyed yarn and the filling, which are the natural-colored cross-wise yarn. The warp thread is in the form of sheet. In denim, the warp-faced twill pattern calls for passing the weft yarn over one and under two (1/2), or over one and under three warp (1/3) yarns. Because there are fewer lacings in twills than in plain weaves, the yarns are freer to move when being worn resulting in a fabric that is both flexible and resilient. The weft thread is inserted between two layers of warp sheets by means of a suitable carrier, such as Shuttle, Projectile, Rapier, Air current, Water current, etc. The selection of carrier depends upon the type of weaving machinery used. The two different technologies available for weaving machines are - Conventional Shuttle Weaving System which is done by Ordinary Looms or Automatic Looms; and the Shuttle less Weaving System which is done by Airjet, Waterjet, Rapier, or a Projectile weaving machine. The Conventional Shuttle loom results in lesser production due to slow speed and excessive wear and tear of machinery. As such, now denim is generally woven through Shuttle less Weaving System namely, Airjet looms, rapier looms or projectile looms. The most common twill used for jeans is a 3x1. A 2x1 twill is used in lighter weight denim. The yarns used in making denim have a very high twist, a process which gives the yarn much greater resistance both to tensile stress and to abrasion.

4.4 Typical Denim Constructions, Weaves, and Weights The classical construction of a bottom weight 14.5-ounce denim is 60-64 warp yarns per inch and 38-42 filling yarns per inch. The number of warp yarns per inch is sometimes referred to as the fabric sley. The weight is influenced by the size of the yarn used, the fabric weave design, and the fabric tightness. Also influencing the fabric weight is the amount of size left on the finished fabric. Other denim fabrics and denim “look-a-likes” 29 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

may vary in construction from 52 to 70 warp yarns per inch and from 36 to 52 picks per inch. As a rule, denim is woven as 3/1 twill, 2/1 twill, 3/1 broken twill, or 2/2 broken twill. The weights of these finished fabrics can vary between 3.5 and 16.5 ounces per square yard. The weight of the fabric usually determines what the final garment application will be: Numerical notations for different denim designs, such as 3/1, denote what each warp yarn is doing relative to the filling yarns that it is interlacing with. In this case, each warp yarn is going “over” three picks and then “under” one pick. This would be verbally stated as “3 by 1” twill or “3 by 1” denim. At the next end, moving to the right, the same sequence is repeated but advanced up one pick. This advancing upward sequence continues, giving the characteristic twill line. In this case, the twill line is rising to the right, and the fabric is classified as a right- hand twill weave. If the twill line is made to rise to the left, then the design is left-hand twill. Broken twills are designed by breaking up the twill line at different intervals thus keeping it from being in a straight line.

Left Hand Twill: This refers to the direction that the denim is woven. Left hand twill denim is softer to the touch than right hand twill, and was originally used by Lee denim. Left hand twill is easy to spot, as the weft threads appear to move upward and to the left as opposed to upward and to the right.

Right Hand Twill: This refers to the direction that the denim is woven. The opposite of Left Hand twill, this weave is much more common, as almost all jeans are woven with right hand twill. The weft (filler) threads will be visible in upward-right diagonal lines on right-hand twill jeans.

Broken Twill: Instead of the twill running to the right or left, broken twill jeans (traditionally considered the cowboy-preferred denim) contain no distinct direction of weave. The weave is instead 30 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

alternated right and left - the end effect resembles a random zig-zag. Broken Twill was designed to combat the twisting effect that was a characteristic regular twill (and considered a 'fault' by many at the time). By going on both directions, the tension in the yarns is balanced in Broken Twill.

4.5 Non-conventional Denim Fabric Constructions Indigo-dyed yarns have been woven in plain weaves known as chambray, oxfords, baskets, herringbones, bedford cords, and combinations of 3/1 and 1/3 twills. Jacquard designs and dobby weaves have also been incorporated into denim designs to produce new looks and textures.

Twill Weave Twill Weave is produced in a stepwise progression of the warp yarn interlacing pattern. The interlacing pattern of each warp yarn starts on a different filling yarn and follows the same formula. These results in the appearance of a diagonal line called twill line in the fabric, which is then characteristic of this design. Depending on the direction of the twill line, the twill weaves are called right-hand or left-hand twills. The sum of the digits in the formula determines the unit cell of the design, which also gives the minimum number of harnesses, requires weaving the design; at least three harnesses are required for a twill weave. Common twill, Steep twill, Reclining twill and Broken twill are the different variations of the twill weave. 31 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

4.6 SHEDDING SYSTEM: There are four shedding systems used to provide manipulation to the warp yarns: 1. Crank Shedding 2. Cam Shedding 3. Dobby Shedding 4. Jacquard Shedding

4.6.1 CRANK SHEDDING: This is the simplest shedding system. In this system, the crankshaft of the weaving machine provides the harness motion. This system is used only for plain weave and its derivatives.

4.6.2 CAM SHEDDING: A typical cam system can handle weave patterns with up to 14 different harnesses. Cam shedding mechanisms are relatively simple. A pair of cams is sufficient to weave plain fabric. A cam is a disk that transforms a rotational motion of its own to a reciprocating motion of a follower. The transfer is done by means of the cam‟s edge or a groove cut in its surface.

4.6.3 DOBBY SHEDDING: Dobby mechanisms are more complicated than cam systems. They are normally built to control up to 30 harnesses. Picks per repeat are virtually unlimited in dobby. Basically there are two separate functions in dobby mechanism: 10 power transmission, 2) connection and disconnection of the harnesses to from the power source at the proper time. Dobby mechanisms are classified as negative, positive and rotary dobby. They can be mechanical or electronic.


Final Year Thesis

Denim Washing

4.6.4 JACQUARD SHEDDING: Jacquard Shedding offers unlimited patterning possibilities. The Jacquard machines offer the highest level of warp yarn control. This versatility is due to the separate control of each warp end or groups of similarly interlacing warp ends within the pattern repeat across the fabric width. They enable the most sophisticated patterns, such as pictures, to be produced in the woven fabrics. Jacquard machines can be mechanical or electronic with single lift or double lift mechanisms; the new machines are all double lift. Most Jacquards heads generally are equipped to handle over 2000 harness cords or hooks with pattern repeating on about on about 9000 picks and multiple heads can be employed over a single weaving machine to increase the weave pattern capability. Jacquard systems are placed on top of the weaving machine.

FILLING INSERTION: After each shed change, the filling yarn is inserted through the shed. It is possible to select and insert different filling yarns one after another. Weaving machines are usually classified according to the filling insertion mechanism. The major filling insertion systems used today are rapier, projectile, air-jet, and waterjet, which are called shuttle-less weaving systems.

4.7 CLASSIFICATION OF WEAVING MACHINES: Weaving machines are classified according to their filling insertion mechanism. The classification is as follows: 1. Shuttle 2. Shuttle-less • Rapier • Projectile • Air-Jet • Water-Jet


Final Year Thesis

Denim Washing

4.7.1 Shuttle Weaving In shuttle weaving, a shuttle that traverses back and forth across the loom width, inserts the filling. Shuttles can be made of wood or plastic. Filling yarn is wound on the quill and the quill is placed in the shuttle. As the shuttle move across the loom, the filling yarn is unwound from the pirn and lay in the shed.

4.7.2 Shuttle-less Weaving:

Rapier Weaving In Rapier weaving, a flexible or rigid solid element, called rapier, is used to insert the filling yarn across the shed. The rapier head picks up the filling yarn and carries it through the shed. After reaching the destination, the rapier head returns empty to pick up the next filling yarn, which completes the cycle. A rapier performs a reciprocating motion. Rapier weaving machines can be of two types:


Final Year Thesis

Denim Washing

1. Single Rapier Machines: A single, rigid rapier is used in these machines. The rigid rapier is a metal or composite bar usually with a circular cross section. The rapier enters the shed from one side, picks up the tip of the filling yarn on the other side and passes it across the loom width while retracting. Therefore, a single rapier carries the yarn in one way only and half of the rapier movement is wasted. Also there is no yarn transfer since there is only one rapier. The single rapier‟s length is equal to the width of the loom. 2. Double Rapier Machines: Two rapiers are used in these machines: one rapier, called the giver, takes the filling yarn from the yarn accumulator on one side of the loom, brings it to the center of the machine and transfers it to the second rapier which is called the taker. The taker retards and brings the filling yarn to the other side. Similar to the single rapier machines, only half of the rapier movements is used for filling insertion

Projectile Weaving Projectile weaving machines use a projectile equipped with a gripper to insert the filling yarn across the machine. The gripper projectile draws the filling yarn into the shed. The Projectile glides through the shed in a rake- shaped guide. Braked in the receiving unit, the Projectile is then conveyed to its original position by a transport device installed under the shed.

Air-Jet Weaving Air-jet weaving is a type of weaving in which the filling yarn is inserted into the warp shed with compressed air. Air-jet system utilizes a multiple nozzle systems and a profiled reed. Yarn is drawn from a filing supply package by the filing feeder and each pick is measured for the filling insertion by means of a stopper. Upon release of the filling yarn by the stopper, the filling is fed into the reed tunnel via tandem and main nozzles, which provide the initial acceleration. The relay nozzles provide the high air velocity across the


Final Year Thesis

Denim Washing

weave shed. Profiled reed provides guidance for the air and separates the filling yarn from the warp yarn.

Water-Jet Weaving A water-jet weaving machine inserts the filling yarn by highly pressurized water. The relative velocity between the filling yarn and the water jet provides the attractive force. If there is no velocity difference, then there would be no tension on the yarn results in curling and snarling of the yarn. Water-jet weaving machine can only be used for hydrophobic fibers.

Beat-up When the filling yarn is inserted through the shed, it lies relatively far from its final position. This final position is called the fell, which is the imaginary line where the fabric starts. Beat-up is the process of pushing the last inserted filling yarn to the cloth fell by using a device called reed. The fabric is not formed until beat-up occurs. Reed is a closed comb of flat metal strips. These metal strips are uniformly spaced. The spaces between the metal strips are called dents. The reed is also used to control the warp yarn density (ends/inch) in the fabric, which affects the weight of the fabric. The reed holds one or 36 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

more warp yarns in each dent and pushes them to the cloth fell. After beating up the filing yarn, the reed is withdrawn to its original rest position before the insertion of the next filling. Reeds are identified by a “reed number‟ which is the number of dents per unit width. Specifying the number of ends per dent with a certain reed number dictates the density of warp yarns in the fabric. Reeds are of two types according to their shape; Regular reed and Profiled reed (used in air-jet weaving). Reed can be single or double. A double reed has two rows of metal strips. The rear row starts from the middle of the first dent of the front row of the metal strips. The double reed is used in terry weaving.

Fabric take-up As the fabric is woven, it should be removed from the weaving area. This is achieved by the take-up motion. The fabric take-up removes the cloth at a rate that controls filling density (picks per inch).

LOOMING Looming covers the process involved in warp preparation after sizing up to setting them to loom. The process can be shown as follows: Drawing-in → Warp Tying → Loom During slashing, the exact number of warp yarns required in fabric is wound on to the loom (or weaver's) beam. The warp ends are then passed through the drop wires of the warp stop motion, the heddles of the harness frames and the dents at the reed. This can be achieved by drawing -in or tying -in, the choice depending upon whether or not the new warp is different form the warp already on the loom.

DRAWING-IN The process of drawing every warp end through its drop wire, heddle eye and reed dent can be performed manually or by means of automatic machines. In both case, a length of warp yarn, just enough to reach to the other side of the frame, is unwound. Leasing (i.e. selecting warp) of the warp at this stage simplifies the separation of the yarns. Then they are threaded through drop wires heddle eyes and reed dents. The automatic drawing machine can handle the leasing-in and drawing -in process in one single operation. 37 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

TYING-IN When fabric of a particular type is being mass-produced, the new warp beams will be identical with the exhausted beams on the looms. Therefore, if every end on the new beam is tied to its corresponding end on the old beam, the drawing-in process can be omitted. Tying-in may be done by means of a small portable machine on the loom or as a separate operation away from the loom.

FAULTS IN DENIM PRODUCTION 5.1 FAULTS OF WARPING: 5.1.1 FALUTS IN MACHINE: • Stop motion does not work on creel and on warping drum as a result broken ends are not traceable for knotting. • Chain breakages • If frictional drum should not be kept in a polished state, then thermal damages occur due to abrasion. • Brake could be inefficient. • Sprockets are jammed. • If comb do not move properly then there is a chance of cutting of comb due to friction with yarn. • Tension supplied if varied it causes breakages or loosening in yarn. • If speed of warper increase than yarn sheet may break

5.1.2 FALUTS IN RAW MATERIAL: • Neps • Long thick places (in case of non slub yarn) • Short thick places (in case of non slub yarn) • Thin places • Weak places


Final Year Thesis

Denim Washing

• Count variation • Hairiness

5.1.3 FALUTS IN PRODUCT: • Misalignment of yarn sheet if the yarn sheet is not properly adjusted • Uneven package density • Too soft package winding • Package could not be in uniform density

5.2 FALUTS OF DYEING: 5.2.1 FALUTS IN MACHINE: • leakage of steam in drying cylinders • wear and tear of rollers if bearing is jammed • Improper working of load cell on squeezing roller. Which causes entanglement of warp sheet as pressure is not properly distributed • Faults in dosing system can cause serious problem of shade variation. • If the accumulator do not work properly than the machine is stopped. • If speed of the machine is kept greater than the yarn` s bearable strength

5.2.2 FALUTS IN RAW MATERIAL: The main causes of the dye ability variations in yarn are: • Immature fibres • Dead fibres • Vegetable matter or other foreign matter • Wrong twist • Bad splice • Neps • Count variations

5.3 SIZING FAULTS: • pressure rolls do not work properly • squeezing rollers do not work properly 39 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

5.4 WEAVING FAULTS: • dropper will not fall • sensors do not work properly • Problem in electrical panel • Problem in electronic card • wear and tear of temple • if dust comes in nozzles

DENIM WASHING 6.1 INTRODUCTION: Denim washing is the aesthetic finish given to the denim fabric to enhance the appeal and to provide strength. Much of the appeal of dry denim lies in the fact that with time the fabric will fade in a manner similar to that which artificially distressed denim attempts to replicate. With dry denim, however, such fading is affected by the body of the person who wears the jeans and the activities of their daily life. This creates what many feel to be a more natural, unique look than pre-distressed denim.

6.2 HOW DOES WAHING CREATE UNIQUE LOOK? Washing of the denim cause it to fade which result its unique look. There are at least three fundamental reason that indigo dyed denim washes down to produce lighter and more attractive shades during washing. 

the outer more heavy dyed yarn surfaces loses dyed through abrasion by stones, enzymes and chemical effect.



Indigo dye has intrinsic chemical instability to strong oxidizing agent such as chlorine bleach.



Some of the undyed fiber in the interior of the yarn migrate to the yarn surface diluting the color of the yarn.


Final Year Thesis

Denim Washing

6.3 There are two process involved in DENIM WASHING.

1. DRY PROCESS 2. WET PROCESS 6.3.1 DRY PROCESS: It is called Dry Process because all the processes which are listed below is done in dry condition, in the other says we don‟t use any chemical including water in this process.

Following process are carried out in DRY process. Which are listed below? 1. Brushing 2. Hand whisker 3. Grinding 

Hand Grinding



Wheel Grinding

4. Tagging 5. Clipping

BRUSHING or HAND SANIDING or SCRAPING:

Hand sand is step which is generally being done in rigid form of garments to get distress look. Locations can be front thigh & back seat or its can be overall / global application as per Standard. In this department dyed garment (denim) is scrabbled or brushed using Emery paper. Scraping can be done on inflated rubber balloons for better effect ( horizontal or vertical 41 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

its up to operators convenience ) , even it can done plain wooden board of garment size & hand pressure should be uniform in order to get better results. The garment is wear on the machine (horizontal or vertical machine) which have two legs is filled by air (air is directly come from the compressor).then we start brushing with the help of emery paper until our required effect is achieved. Different types of emery paper are used e.g 100,120,320,400 and 600 grain size. The selection of the emery paper is depend upon the fabric weight i.e. if fabric is light then we use emery paper of 320,400,600 grade, normally 320 grade of emery paper is used and for heavy fabric high emery paper of 100 and 120 are used. By brushing the dye is removed from the surface of the garment.

HAND WHISKER: In this process the same machine is use as used in brushing. On Denim, whiskers/Chevrons are nothing but the worn out lines / impression generated by natural wearing on hip & thigh area. There are many designs & pattern available. This is being done manually with help of sharp edge Emery paper rolled on fine wood stick or pasted on plastic material. Before starting execution placements & pattern must be marked on garments, this will help operator to execute the pattern right to match the aesthetics of garment. Hot spots are heavy/intense area on thigh or knee which is made purposely to create used look & on knee area if any whiskers line are there, called knee star.


Final Year Thesis

Denim Washing

GRINDING: Edge distressing or grinding is the process of destruction on jeans form edges of the garment. When we look at old jeans we find it destroyed from the edges of pockets, fly area, belt and bottom. This used effect can be created on jeans by grinding and is of key importance in high fashion garments. It include the following processes.

PATTERN MAKING: In grinding first the pattern is make of different designs then these pattern is mark on the grinding areas in the garment with the help of chalk. by doing all these the grinding area on the garment is become visible.

PADDING: This is the main process of grinding in which fabric is put on the plate, which have a rubber pad of same pattern or design which is already mark on the garment .then emery paper is rubbed against the garment which remove the yarn from the garment to get the desire effect. 100 grade of emery paper is use for this process.

HAND GRINDING:

This is the process in which garment is slightly damage by removing surface yarn with the help of hand grinding machine. Hand grinding is done on the small areas while padding is done on large areas. The effect of both process (padding and hand grinding) are approximately same. Grinding is done of garments by pen type of stone tools. It can be done in mid of the wash process. In many workshops it is done before any wash process as first process after 43 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

stitching. Stone tools similar to grinders used in wood and stone industry are utilized to work on garments with a few amendments to their design. Pen type tools are very affective for this art work but consistency is always a big question while dealing in production. They are not much effective in large quantity production units. Staff is to be very experienced and careful other wise it may damage the garment beyond requirement. To work on edges is very sensitive and any heavy destruction will open the edges and make the garment not to wearable. This aspect needs special care and supervision in industry.

WHEEL GRINDING:

In this process the edges of the garment like edges of the waist band, bottom hem, front pocket, back pocket and back pocket cover are grind using wheel grinding machine. In high production units it is usually done with fixed grinding machines where grinding stone wheals fixed on high speed electrical motors. Operators rub the edges to rotating stone wheal to get the effect. Again the risk of damage to extent where the edges get opend is there and to avoid it strict supervision and skilled staff is of key importance. This method is very time and cost effective and large quantities are always deal in this way.

TAGGING: Tacking or more commonly tag pinning is a very in fashion style in denim garment in these days. Usually tag pin machines are used to attach tag pins to garment. The procedure is very simple and proceeds as; garment is folded on required area and tacked 44 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

through folds. Garment is folded on specified areas and the fold is locked by tag pins. Now the garment is processed in washer and a permanent fold appears after removal of tag pin. This is important that tag pin is removed when the garment is dried completely. The inner of the fold is dark in shade due to less exposure to mechanical rubbing and chemicals.

Area of Application : This effect can be designed any where on the garment in different styles. Most favorite areas for tacking are on waistband, bottom hems, back pocket and front pocket corners etc

Tag Pin

Tagging Machine

CLIPPING: In this process the small areas of the garment is bound by using clips on the required areas (generally at the bottom hem) then garment is put in the oven and finally forward to the washing dept. for final effect.

6.3.2 WET PROCESS It is called wet process because in this we use certain chemicals to obtain a desired result. 1. Pre-Treatment 2. Washing 3. Enzyme wash


Final Year Thesis

Denim Washing

4. Bleach wash 5. Stone wash 6. Sand Blasting 7. Tinting 8. Over dyeing 9. Spraying 10. Whiskering

PRE TREATEMENT

This is very first & basic step but most important step of washing. Here the fate of denim garment is decided that it‟s going to appear good or bad. Good Pre treatments avoid streaking, stiffness & color loss. This process removes impurities, starch & stains during handling of fabric. This step is also called desizing (Removal of Size applied during denim fabric making in weft yarn). All the woven fabric contains size on them due to reasons to strengthen the yarn for weaving. There are many types of sizes available in the market but they can be divided in two major groups. 1. Water Soluble (CMC or PVA based sizes ) and 2. Dissolvable sizes in water (Starch based). Starch based sizes are most commonly used due to cheap prices & readily availability.

Methods of Removing Sizes from Denim: · Washing with High Alkaline agents ( i.e. Soda ash ) · Washing with High Acidic agents (i.e. Acetic acid ) 46 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

· Washing with Oxidative chemicals ( i.e. Hydrogen Peroxide ) · Enzymatic desizing with Alfa amylase .. This is eco friendly & convenient .

6.4 DENIM WASHES ARE OF TWO TYPES: 6.4.1. CHEMICAL WASHES: - Denim bleaching - Enzyme wash - Acid wash - Tinting - Over dyeing

DENIM BLEACH: This in one an important step in washing denim & can be done by various bleaching agents. a) Calcium hypo chlorite b) Sodium hypo chlorite c) Hydrogen peroxide d) Potassium permanganate First two chemicals are commonly being used for every medium to vintage denim but when it comes to super vintage & light shade its advisable to use potassium permanganate bleach to cut the color faster till half way & then neutralize it & go with Liquid ( Hypo ) bleach to adjust the desired shade. This process helps to get Greyer cast & also protects the lycra/spandex, retain elasticity. Hydrogen Peroxide is rarely used as bleaching agent when very less color loss required or if fabric is sulphur top. As it takes longer time to give desired effect. Potassium Permanganate is also being used on 100% sulphur black denim fabric for bleaching/reducing agent to get unique effects. As it‟s not production friendly till laundry has very expertise team to handle this program, otherwise it will result in many shades & cast. Proper Neutralizations of bleaching process is very essential in order to get rid of fabric strength, bad smell from garment, yellowing & skin irritation etc. 47 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

In this process a strong oxidative bleaching agent such as sodium hypochlorite or KMnO4 is added during the washing with or without stone addition. Discoloration produced is usually more apparent depending on strength of the bleach liquor quantity, temperature and treatment time. It is preferable to have strong bleach with short treatment time. Care should be taken for the bleached goods so that they should be adequately antichlored or after washed with peroxide to minimize yellowing. Materials should be carefully sorted before processing for color uniformity.

Process cycle


Final Year Thesis

Denim Washing

LIMITATION: 

Process is difficult to control i.e. difficult to reach the same level of bleaching in repeated runs.



When desired level of bleaching reached the time span available to stop the bleaching is very narrow. Due to harshness of chemical, it may cause damage to cellulose resulting in severe strength losses and/or breaks or pinholes at the seam, pocket, etc.



Harmful to human health and causes corrosion to stainless steel.



Required antichlor treatment.



Problem of yellowing is very frequent due to residual chlorine.



Chlorinated organic substances occur as abundant products in bleaching, and pass into the effluent where they cause severe environmental pollution.

RANDOM BLEACH: It is an uneven effect, some time also known as cloudy effect. In which denim is bleached indirectly via towel piece or cotton balls it produce more merge and cloudy effect cotton ball is more successful but cotton towel are some tome used to produce more cloudy effect.KMnO4 cannot be used with cotton balls/ribbons. It is only possible with hypochlorite. Black sulfur is not process able with hypochlorite as sulfur reacts vigorously with sulfur and pace of process cannot be controlled.


Final Year Thesis

Denim Washing

Procedure: In this process we take bleaching agent in washing machine then we put small pieces of towel or cotton (raw cotton) then we will run the machine for few minutes until the towel soaked the bleaching agent. Then we drain the bleach after that we put the garments in the machine with towel pieces and run the machine until we get a required effect. We immediately neutralize the garment to prevent bleach spots or patches.

ENZYME WASH:

It is environmentally friendly wash. It involves the Application of organic enzymes that eat away at the fabric, i.e. the cellulose. When the desired color is achieved, the enzymes can be stopped by changing the alkalinity of the bath or its temperature. Post treatment includes final rinsing and softening cycle. The effects produced by the cellulose enzyme are--1. Use of cellulase making the seams, hems, and pockets more noticeable 2. Salt pepper effect is color contrast effect. 3. Faded garment with acid cellulase enzyme provides less color contrast in proportion to garment washed with neutral cellulase enzymes.


Final Year Thesis

Denim Washing

There are four kind of Enzymes available in market for Denim Laundry business.. 

Amylase …. Desizing



Cellulase …. For Salt & pepper effect , contrast



Laccase…. … bio bleaching



Catalase …… Peroxide killer

Enzyme is kind of protein that is obtained from fermentations method from naturally existing bacteria & fungi. The structure of Enzyme is a biological polymer and it can be found in every cell. Generally called as Cellulase & it works on cotton( Cellulosic fiber ) only. Enzyme are living organisms which will attack a specific molecular group. There are mainly three kind of Cellulase being used for Denim washing , Neutral, Acid and Bio polishing Enzyme. Enzyme are very sensitive with parameters in washing cycle i.e, pH , Temperature & time. If any of these parameters are not up to the mark, result will not be accurate. The reaction of enzyme can be easily controlled, its biodegradable products, so they eco friendly. Bio Polishing Cellulase are being used to have protruded fiber removal from denim & oven fabric. This is also widely known as Anti pilling enzyme. Any Cellulase used in process must be cleaned/killed after the process completion by simply disturbing the parameters ie. By raising high temp. or raising pH to alkaline where no Cellulase withstand. Cellulase are available in 3 categories 1. Neutral 2. Acidic 3. Hybrid enzymes. Neutral enzyme gives better salt & pepper effect with very less back staining & its generally come sin powder form & also retains better strength of fabric than acidic Cellulase. Where as acidic cellulase give faster results but with too heavy back staining & cuts down the indigo color, also affects the strength of fabrics. Now a days laundry people needs faster results in less time & money hence chemical suppliers combined Neutral & acid cellulase in such way that it works faster & with better results than acid cellulase with cost effectiveness & known as Hybrid enzyme. Laccase is bio bleaching agent & alternative for conventional bleaching agents. This impart greyer cast to blue 51 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

denim & enhances salt & pepper effect. But due to high cost & low self life, laundries do not prefer it.

CLEAN UP: After finishing Enzyme wash it is must to add clean up process for better results & garments appearance & that can be done in various ways & methods. As clean up is a must process to be carried out after every chemicals steps done for any garments which allows next process to happen smoothly. All processes mentioned below kill/ deactivate the active enzymes process which is necessary in order to protect/retain garment strengt 

Hydrogen peroxide in alkaline pH clean up enhances the brightness & rich blue tone of indigo.



By using non ionic detergents in medium to high temperature



By doing two good hot water rinse etc.

Process cycle:

ACID WASH: This is the oldest of fashion washes in denim after stone wash. The name acid wash is in reference to the acids used for this wash in old recipes. In new methods it is done with 52 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

oxidation. Use of bleach/oxidative is very safe and economical in comparison to acids. Different chemicals are used and among them potassium permanganate (KMnO4) and sodium hypochlorite are mainly used. Acid wash is typically done by soaking pumice stone in hypochlorite. Some time KMnO4 is used in replace of bleach. Selection of oxidant is very important and mainly depends on the type of fabric. When it is done with pumice stone the washer and garment should not contain any water. Dry garment is much suitable for this process then a damp one. Pumice stones are soaked in bleach and left it to open for little time so they get only damp rather than wet. Then they are processed in machine with garments. The extent of effect is controlled with process time, concentration of oxidant solution and quantitative ratio of garment to stone.

Process cycle

LIMITATIONS OF ACID WASH 

Acid washed, indigo dyed denim has a tendency to yellow after wet processing.



The major cause is residual manganese due to incomplete neutralization, washing or rinsing.

OVER DYE:  Dyeing over the fabric or jeans to add another tone of color 

Most often used is a 'yellowy' over dye to create a 'dirty' look 53 Indus Institute Of Higher Education


Denim Washing

Also can be applied with spray gun or paintbrush for local coloring

There are many variations. Blue and black can be overdyed with bright contrasting colours to obtain special effects. The most current and successful forms of overdyeing consist of dyeing washed out indigo jeans with luminous colours. In this process direct dye is applied into already Indigo dyed garment. It takes 10 pieces of garment and put into the washing machine and add direct dye with all its auxiliaries and run it for 15 mins and check the shade then rinse.

TINTING: Tinting is a process where very less amount of tint is involved & mainly direct dye is being used to do this process. This is being done to change hue/cast/tone of indigo. As soon as quantity of tint color increases & it cover up indigo, reaches the level of dyeing. Tinting being used to give garments a used / vintage & muddy look. This process takes from 5 minutes to 15 minutes time for better results followed by dye fixing & cleans up of superficial dye. •

The garment has been lightly colored in order to give the final denim appearance

•

The techniques involve the addition of the colorant in the stone washing cycle.

•

Because of this it must be insured that dyes and cellulose are compatible.


Final Year Thesis

Denim Washing

PIGMENTS AND LOCAL TINT ( Staining) : Need to choose right color of pigment or tint with binder or fixer to apply locally on denim to get vintage look. This process also needs an artist to execute it nicely to merge the tint with ground indigo color & should not look too artificial. Pigments & Local tint also can be applied through spray gun or rubbing on desired area of denim garment. After application its must be cured in order to have permanent effect on jean.

6.4.2 MECHAINCAL WASHES: 1. Stone wash 2. Bio stone washing 3. Sand Blasting


Final Year Thesis

Denim Washing

STONE WASH: Stone washing is a textiles manufacturing process typically utilized by the fashion industry, in order to give a newly-assembled cloth garments a worn-out appearance. Stone-washing also helps to increase the softness and flexibility of otherwise stiff and rigid fabrics such as canvas and denim. In the process of stone washing, freshly dyed jeans are loaded into large washing machines and tumbled with pumice stones to achieve a soft hand and desirable look. Variations in composition, hardness, size shape and porosity make these stones multifunctional. The process is quite expensive and requires high capital investment. Pumice stones give the additional effect of a faded or worn look as it abrades the surface of the jeans like sandpaper, removing some dye particles from the surfaces of the yarn.

Process cycle:


Final Year Thesis

Denim Washing

SELECTION OF STONE: First pea gravel, then pumice, because they float around with the jeans, instead of lying in the bottom of the water; Turkish stones are preferred for

their

porosity

and

cleanliness

or

stones

from

Sicily,

but their supply is limited. Stone should be selected of the proper hardness, shape, and size for the particular end product. It should be noted that large, hard stones last longer and may be suited for heavy weight fabrics only. Smaller, softer stones would be used for light weight fabrics and more delicate items. Stone wt. /fabric wt. = 0.5 to 3 /1 It depends on the degree of abrasion needed to achieve the desired result. Stones can be reused until they completely disintegrate or washed down the drain.

PROBLEMS CAUSED BY STONES  For instance stones could cause wear and tear of the fabric. 

Damage to wash machineries and garment due to stone to machine and machine to stone abrasion



Increase in labor to remove dust from finished garments.



Water pollution during disposal of used liquor.



Back staining and re deposition.



Denim is required to be washed several times in order to completely get rid of the stones.



The process of stonewashing also harms the big expensive laundry machines. 57 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

BACK STAINING AND RE-DEPOSITION The dye removed from denim material after the treatment with cellulose or by a conventional washing process may cause "back staining or "redeposit ion. Re-coloration of blue threads and blue coloration of white threads, resulting in less contrast between blue and white threads.

Remedy of back staining 

Adding dispersion/suspension agent to wash cycle.



Intermediate replacement of wash liquor.



Using alkaline detergent like sodium per borate with optical brightener as after wash.

Limitations of stone washing  Quality of the abrasion process is difficult to control Outcome of a load of jeans is never uniform, little percentage always getting ruined by too much abrasion.

 The process is non-selective.  Metal buttons and rivets on the jeans in the washing machines get abraded.  This reduces quality of the products and life of equipment, and increases production costs.

 Stones may turn into powder during the process of making the garment grayish in color and rough too

 Provides rougher feel than enzyme wash  Stone may lead the harm to the machine parts.

TIE AND WASH METHOD: Tie & Wash also known as crunch wash or creaking pattern effect is very typical in high fashion articles. The process is very simple but results to marvelous looks. Garment is usually tied with white cotton strips and washed with stones. The exposed portions got faded effects and a pattern of dark to light patches appears on garment. Different patterns 58 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

can be formed by tying garment in different ways. More beauty is added when the edges made by tying get prominent in form of white lines made by mechanical rubbing offered by washer.

Procedure: First we do the dry process of garment accronding to buyer requirement then we fold or bind the garment and put it into the socks or net and tie it.then we put it into the wasing machine with enzyme, stone, back stainer because in this process we get back staining problem b/c it take a very long time. And we run the machine until we get our required effect. Then we drain it.we open the socks or net and again run the garment with stone enzyme and back stainer to get a even effect(grains) in the garment.

Additional Applications: Tumbler Run To improve the crunch effect some time it is better to run the tied / packed garments in tumbler dryers for 20 min to 40 min before running in washer. Garment should be wet but not dripping when running in tumbler.


Final Year Thesis

Denim Washing

White Cotton Ribbon Garment should always be tied with white cotton ribbons. If colored ribbons or denim strips are used for tying then their color may deposit on garment to produce stain.

Cable Tie Method In some of the industries, plastic cable tie is used to replace the cotton ribbons. It is much expensive to cotton ribbons but much effective. Due to special construction of cable tie plastic strips it is easy to keep the garment maximum tight. There is no risk of getting it loose during process even it goes hours long. It is specially recommended to Dark Washes where this effect is most difficult to get.

NET WASH: Another method used for this effect is when net pockets/bags are used instead of tying. The whole garment is packed tightly in net bag. It should not be fold in proper but a random like filling of one garment to one bag will give appropriate effects. Then it is stone washed in washer for a time ranges form 20 min to 80 min depending on the fabric and pattern required.

Procedure: First we do the dry process of garment according to buyer requirement then we fold or bind the garment and put it into the socks or net and tie it. then we put it into the washing machine with enzyme, stone, back stainer because in this process we get back staining problem b/c it take a very long time. And we run the machine until we get our required effect. Then we drain it. We open the socks or net and again run the garment with stone enzyme and back stainer to get an even effect (grains) in the garment.

General Recipe Steps 

Desizing (Tied Garment)



Stoning or/and Enzyming (Tied Garment) 60 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing



Soap Rinsing (Lose Garment)



Bleaching (if required)



Neutralization (if required)



Softener Application

BIO-STONE WASHING: Many garments are subjected to a wash treatment to give them a slightly worn look; example is the stonewashing of denim jeans. In the traditional stonewashing process, the blue denim was faded by the abrasive action of pumice stones on the garment surface. Nowadays, denim finishers are using a special cellulase. Cellulase works by loosening the indigo dye on the denim in a process know as 'Bio-Stonewashing'. A small dose of enzyme can replace several kilograms of pumice stones. The use of less pumice stones results in less damage to garment, machine and less pumice dust in the laundry environment. BioStonewashing has opened up new possibilities in denim finishing by increasing the variety of finishes available. For example, it is now possible to fade denim to a greater degree without running the risk of damaging the garment. Productivity can also be increased because laundry machines contain fewer stones or no stones and more garments. Below are some cellulases for denim finishing, each with its own special properties. These can be used either alone or in combination with pumice stones in order to obtain a specific look.

DISADVANTAGES OF CELLULASE TREATMENT There are certain disadvantages of cellulase treatment. It could leave marks of backstaining like blue threads becoming more blue or white threads becoming blue. To get rid of such unwanted re-coloration of threads, the jeans are rigorously washed adding surfactants to it. This process could result to color-fading of jeans and there is added usage of water for the washing. Thus wastage of water and certain amount of backstaining could be experienced. The primary target of stonewashing the denim with pumice stones or enzymes is to provide the garment worn out, old and aged look. Sometimes both stones and enzymes are used for the purpose.


Final Year Thesis

Denim Washing

SAND BLASTING: Sand blasting technique is based on blasting an abrasive material in granular, powdered or other form through a nozzle at very high speed and pressure onto specific areas of the garment surface to be treated to give the desired distressed/ abraded/used look. 

It is purely mechanical process, not using any chemicals



It is a water free process therefore no drying required.



Variety of distressed or abraded looks possible.



Any number of designs could be created by special techniques.

6.6 SPRAYING: PP Spray is being done on denim garments to achieve local abraded area to appear whiter than back ground indigo color shade. This can be applied by spray gun or by towel dipped in to PP Solution & rubbed on desired area followed by neutralization in wet process. This process can be done in rigid after doing hand scrape or in the middle of the wash. Doing after enzyme or bleach cycle will give more natural & white effect that doing in rigid. There are many additives can be added in order to achieve desired intensity and look.in order to use less amount of potassium permanganate we add a activater (and it is also enviromently friendly process) and we get faster result with good result. The same way bleach solution also can be spray or rubbed on the garments on desired area. But this process is very complicated & needs highly skilled operators to execute it followed by immediate neutralization.


Final Year Thesis

Denim Washing

ADVANTAGES It is water free process therefore zero effluent discharge. 1. Less time consuming 2. Different designs are possible 3. Easy to use 4. No adverse effect on fabric strength.

6.7 WHISKERING (MALAVASI): There are two types of machine in this dept. 1. Malavasi 

Maximum temperature: 250 C



Maximum pressure: 1200 kpa


Final Year Thesis

Denim Washing

2. Topper machine 

Maximum temperature: 200 C



Maximum pressure: 250 psi.

In this process two types of whisker is produce. 1. Permenant Whisker 2. Non-permenant Whisker.

PERMENANT WHISKER: These whiskers are those which are permanent and not remove either after the several washes. In permanent whisker first resin is apply on the required area on the garment then the garment is placed on the Malavasi machine. Temperature and pressure is set according to the fabric e.g. for PC fabric temperature is 180-200 and pressure is 1200 kpa while the time is 20-25 sec. These all parameters can vary according to the requirement. After doing all these garment is put in the oven (to bake the resin coated area).

Crease lines around the crotch. -

Industrially done with laser, sandblasting, machine sanding, hand sanding and abrasive rods.

-

Also used for 'knee whiskers' (whiskers on the sides of knees) and 'honeycombs' (crease marks on the back of the knee) 64 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

Resin Application: Resin ( Formaldehyde free ) being used for achieving 3D effect ( 3 Dimensional ), Rigid Look etc. This process can be done by spraying or dipping the garments in to Resin, Catalyst, Silicone & PU solution in right combination according to the fabric strength & desired effect needed. After application of resin solution in right proportion, make manual designing as needed on the thigh, hip & back knee area. After making it , it should be manually dried with hot press or hair dryer & then must be cured in oven at right temperature, time as mentioned in resin product manual.If resin not cured properly, 3 D effect will not be permanent & can cause skin irritation/rashes to the wearer. Whole garment can have crushed look by resin dip & crushed manually followed by oven curing. Silicone plays an important role in getting softer hand after oven. Special streaky effect & Crackles also being done by applying resin on desired area followed by scraping & pp spray then neutralization.

RESIN RECIPE: The purpose of resin is cross linking and the typical resin recipe are as follows: Mg (as a catalyst) ARCO Fix Water L:R

1:30

NON-PERMENANT WHISKER: These are the whisker which are non permanent and can be removed easily. In this process we spray water on the garment and put in malavasi machine.

6.8 SOFTENING PROCESS: Softening process of Denim is very critical. As denim is very heavy in compare with other fabrics hence its needs softening. During this process there is a big problem -the discoloration of denim i.e change in shade or loss of whiteness, giving a yellow tint is commonly known as yellowing. By using normal softener will lead to ozone problem. 65 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

Indigo dyed fabric are even more prone to yellowing. As it‟s a widespread problem & there in no single reason for its cause. Instead a number of condition can singly or in combination lead to the problem. Yellowing in not specific to certain fibers, finishes or washing processes. It is not specific to chemicals or chemical treatment but certainly some of the factors among these can lead to the yellowing. As cotton & all organic polymers develop yellowing in time. Light , acids, impurities, detergents & chemical contribute to yellowing problems. Temperature of drying & curing can impart yellowing due to scorching of the cotton. Therefore good control must be used to minimize this type of damage. Hence its advisable to use Antiozonate softener which prolong ozone reaction of Indigo & keep garment in good condition.

MINIMISATION OF YELLOWING RISK Its Impossible to eliminate yellowing but it is possible to prolong & reduce the conditions which causes classical yellowing. 

Ensure bleaching neutralization & rinsing is proper



Minimize back staining



Avoid use of chemicals which cause yellowing



Avoid leaving garment in open air for longer time



Control drying & curing temperatures



Using right Antiozonate softener with right pH

CHEMICALS ON DENIMS 1. Bleach fast Indigo Value addition to denim Retains indigo on certain parts Kind of resist effect Chemical applied by brush, cured at 150C Ex. Indigofix AXN

2. Anti-depositing agent Prevents back staining of fabric by loose indigo during washing 66 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

Improves contrast in denim Used in stone wash step

3. Dye stuffs with softener 

To carry dyeing and softening in one step



Soft and supple hand



Saves time, money and energy as added to final rinse



Gives used and worn out effect

4. Anti creasing agent  Provides fabric to fabric lubrication  Prevents formation of crack marks and streaks  Minimizes abrasion and gives strength 5. Wrinkle formation 

Creating smooth and permanent wrinkle



Cross linking concept Ex. DMDHEU



White pigment



Can be applied by brush, spray or screen



Then cured at 150C



Washed and treated with softener

6. White pigment  Can be applied by brush, spray or screen  Then cured at 150C  Washed and treated with softener


Final Year Thesis

Denim Washing

PROCESS RCIPE SHEET:


Final Year Thesis

Denim Washing

6.9 MACHINE USE FOR DENIM WASHING: TONELLO MACHINE: Machines suitable for all types of washing processes, such us stone washing, bleaching and other washing treatments on garments of different materials (cotton, linen, viscose, tensel treatment etc). Particularly indicated for the treatment of jeans, they are supplied with baskets provided with special beaters, speeding up the process and guaranteeing at the same time uniformity in the treatment and softness to the denim fabric. They have variable speed and are equipped with an industrial B&R PC and a PLC Mod. PP 200. The software, and in particular the “Wash program”, entirely worked out by Tonello‟s engineers, allows to manage and to control all the functions of the machine as well as the process operations. It is possible to store up to 500 recipes (with 200 steps/each).


Final Year Thesis

Denim Washing

G1 420 LS EV1 Made in Italy Patented

Technical Data

G1 420 LS EV1



Cylinder Volume



Cylinder Dimensions Ø1890x1490 mm



Variable Speed

0/110 rpm



Installed Power

17 kW

4180 l

Dimensions 

Height

2600 mm



Width

2940 mm



Depth

3100 mm



Weight

4400 kg


Final Year Thesis

Denim Washing

6.10 NEW DEVELOPMENTS TOWARDS ECONOMICAL AND ECOLOGICAL DENIM PROCESSING USE OF LASER TECHNOLOGY: It is a computer controlled process for denim fading. This technique enables patterns to be created such as lines and/or dots, images, text or even pictures. In one version of this concept, a mask is used to give the desired shape that is to be applied on the fabric. The laser projects through a lens system, which expands the beam. This beam is passed through the shaped mask that comprises an aperture of the desired shape and is then deflected by a mirror to strike the textile substrate. The duration of exposure determines the final effect on the fabric. The novelty of this system is that 

It is water free fading of denim.



It is an ecological and economical process.



It can create local abrasion and fabric breaks, used look effect, moustache with excellent reproducibility and higher productivity.



Being an automatic system, chances of human error are slim.



The design is electronically translated on the fabric, thus avoiding the need for photolites of serigraphy cleaning.



The machine is very simple and compact, therefore requires very low maintenance and cleaning, extremely safe and reliable.

The machine is very simple and compact, therefore requires very low maintenance and cleaning, extremely safe and reliable

OZONE FADING: By using this technique, the garment can be bleached. Bleaching of denim garment is done in washing machine with ozone dissolved in water. Denim garments can also be bleached or faded by using ozone gas in closed chamber. The advantages associated with this process are: 

Color removal is possible without losing strength.



Denim Washing

This method is very simple and environmentally friendly because after laundering, ozonized water can easily be deozonized by UV radiation.

WATERJET FADING: Hydro jet treatment has been developed for patterning and/or enhancing the surface finish, texture, durability, and other characteristics of denim garment. Hydro jet treatment generally involves exposing one or both surfaces of the garment through hydro jet nozzles. The degree of colour washout, clarity of patterns, and softness of the resulting fabric are related to the type of dye in the fabric and the amount and manner of fluid impact energy applied to the fabric. Particularly good results are obtained with blue indigo dyed denim. As this process is not involved with any chemical, it is pollution free. By using water recycling system, the technique can be used as economical and environmental friendly denim processing. Color washout of dye in the striped areas produces a faded effect without blurring, loss of fabric strength or durability, or excessive warp shrinkage.

SINGLE BATH STONE WASHING AND TINTING TECHNIQUE Tinting of denim garment is usually done after the stone wash process. In this, garment has been lightly coloured in order to give the final denim appearance a slight shift. This is not true over dyeing but merely gives the impression of a change in overall colour of the fabric. This process consumes large quantity of water and chemical. To make this process economical and ecologically friendly, some novel colour based enzymes have been introduced in the market. By using this new technique, tinting and stone washing effect can be achieved in a single bath. 

Less process time to achieve tinted look.



No extra chemical required therefore making process more economical.



Less water consumption.



Less energy consumption.



Less chance of patches or unevenness


Final Year Thesis

Denim Washing

Alternate of pumice stone To overcome the shortcoming of pumice stones, synthetic stones have been developed. These are made of abrasive material such as silicate, plastic, rubber or Portland cement.

The advantages of using such type of products are: 

All major problems associated with the use of volcanic grade pumice stone can be overcome.



Durability of such product is much higher and can be used repeatedly from 50300 cycle depending upon type of synthetic stone.



Reproducibility of washing is manageable.



As stone discharge of the process is very less, therefore making process is economical and ecological.



Less damage of machine and garments.

6.11 VALUE ADDITION: Globally, Denim designers are experimenting with fabric and garment details including embellishments in order to add value to its garments. New add-ons are being incorporated in the form of patches, appliqué, rhinestones and glitter. The process of adding value to this legendary outfitter enhanced from time and time by devising some new methods such as:

GETTING REVERSE EFFECT ON DENIM IN DISCHARGE PROCESS: In spray process, first apply neutralizer where you want the resist effect and thereafter, spray potassium permanganate on applied portion and its surrounding area. Then, neutralize the garment to remove potassium permanganate. It gives a halo effect to denim garments. 73 Indus Institute Of Higher Education

Final Year Thesis

Denim Washing

TINTING WITH WHITE DISCHARGE EFFECT ON DENIM GARMENTS: The standard route to blasting/discharging/tinting is quite elaborate, in the light of three effects to be imparted on the same garment. There have been short cuts, which may be right/wrong/ingenious. If tinting is done on blasted/discharged areas, it obviously remains a spray method. However, if the tinting is overall, it follows the dyeing route. The process starts on gray garment being hand blasted followed by desizing and biopolishing. After drying the garment, tint-spray is given followed by air/machine drying and finishing. For tinting by dyeing method, the biopolished garment can straight away go for tinting wet-on-wet followed by finishing and drying. In case of white discharge tinting the route would start with desizing-biopolishing on gray garment, peroxide bleaching after biopolishing being optional. After drying the garment, a potassium permanganate spray is given to areas where white discharge is aimed at. After air-drying for about 1015 minutes, a neutralization step consisting of provide-acetic acid is given which is followed by hot and cold rinses. In case of spray tinting the garment will have to be dried first, whereas for overall tinting, dyeing the method could be followed wet-on-wet. Finally the finishing and drying would complete the process.

SIGNIFICANCE OF OZONE-FASTNESS IN INDIGO GARMENTS: Oxidizing agents have a property of attacking chromophoric group of the dyestuff and destroying-discharging the color. Potassium permanganate is a well-known chemical extensively used for discharge of indigo in denim garments. However, potassium permanganate is used as and when discharge is required and the ultimate purpose is value-addition. Ozone is another strong oxidizing agent, which could discharge indigo in denim-garments. The folds in folded-denim garment otherwise have relatively greater exposure to atmospheric ozone than the rest of the garment, which is protected by virtue of garments being stacked. This results into localized discharge of indigo at the folded marks. There are inorganic as well as organic ozone-seavenger, which protect the indigo in denim garments from the attack of ozone and hence control the value-loss.


Final Year Thesis

Denim Washing

TINT DENIM-GARMENTS WITHOUT CHANGING THE TONE OF INDIGO: Tinting is achieved by application of the direct/reactive dyes. In case of direct dyes, the second application would be that of dye-fixing agent for an adequate fastness. In case of reactives, the fixing chemical goes along with the dyestuff. After the application, the treated garment is dried in the air or in a tumble drier for adequate fastness. If tinting were done by immersion method, the tint would be all over. However, if a localized area is the target, a spray method is used. In either case the tinting, as the term signifies, is done very lightly to achieve a particular cast, either overall or localized. If indigo does not change tone would look like a print with a sharp boundary. When tone changes fad gradient, the effect looks more aesthetically appealing and is considered desirable. The tone-change should be gradual and not abruptive.

APPROACHES TO MILD WASHING EFFECTS ON SULPHUR-DYED DENIM GARMENTS: Garment washing may affect the whiteness level of your garments, as they can look dull or yellow after processing. Most garment washers add whitener to the process to ensure a bright white finished product. Make sure to determine any costs involved and factor them into your product costing. There are many special effects, such as weathering, stone washing, acid washing and distressing that can be produced by garment washers. These effects being very popular have their own drawbacks. They are costly, have higher fallout rates, and are generally rougher on the fabrics. Talk to your garment washer about prices and what to expect of the process you choose to do.


Final Year Thesis

Denim Washing

CONCLUSION Our aim for making this report is to provide a new finishes and working on the parameters and processes use in denim washing. In the whole report we have highlighted denim washing processes and make our main focus on the processes and washes we had done in rugby industries while in this report we also describe the manufacturing of denim fabric. The demand of denim is increasing day by day. World-consumption of denimwears today is equivalent of about 4,500 million meters per year of denim fabrics. So to meet this huge requirement of denim new finishes techniques is developed which is economical and ecological and our textile industry follows all those processes. Companies that “finish” jeans by washing them or distressing them for a worn-in look. Most major jeans manufacturers use several different laundries that specialize in different finishes. The main techniques used include simple washing, stonewashing, which uses an abrasive-bristled Tonello machine, sandblasting, laser burning, or applying enzymes to simulate “cat‟s whisker”-wear line, and sandpapering by hand. Generally saying people who don‟t know about denim washing then after reading this report you get a sound knowledge about the whole process which are carried out in denim preparation and its washing. We include approximately all the major finishes and the process which involve different operations e.g. wet process and dry process these two are the main operation although there are also other process but they are the sub process.


Final Year Thesis

Denim Washing

REFERENCES: 1. http://en.wikipedia.org/wiki/Denim 2. http://www.fashion-incubator.com/tutorials/warping 3. Dyeing and Chemical Technology of Textile Fiber by Trotman E.R 4. http://textilepedia.blogspot.com/2009/03/dyeing-process-for-denim. 5. www.thecompanymarketing.com/.../process-for-adding-value-to-denim 6. www.denimhelp.com/denim-garment-processing


Denim Washing (thesis)

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