PAINT TECHNOLOGY (2)
(Wednesday)
Q01-
By what name would you call the basic unit of a polymer?
Ans-
Poly means many and Mers means single units, can be single atom or molecule.
Q02-
What is polymerisation?
Ans-
Joining together of a string structure of repeated units.
Q03-
Name three types of polymers.
Ans-
Linear polymer, branched polymer and cross linked polymer.
Q04-
What would be the characteristics of a short oil paint?
Ans-
Fast drying, brittle Less than 45% oil to resin.
Q05-
What would be the characteristics of a long oil paint?
Ans-
Slow drying properties, elastic, More than 60% oil to resin.
Q06-
What is meant by the term “opaque pigment”?
Ans-
Inert particle with excellent scattering properties in order to give covering power, opacity and colour,( Coloring pigment)
Q07-
What is the typical size of a pigment partical?
Ans-
1/10 micron. 0.1 Micron.
Q08-
Briefly describe the difference between “saturated” and “unsaturated” when referring to
th
oils or polymers. Ans-
Saturated oil will not solidify by polymerisation to form a film and unsaturated oil will combine with oxygen.
Q09-
Name two drying oils, which are unsaturated.
Ans-
Linseed oil, tung oil. Semi drying oil and Non drying oil.
Q10-
What is the main difference between a dye and a pigment?
Ans-
Dye can easily dissolve but pigment cannot.
Q11-
What are the sources of pigments?
Ans-
Animal, vegetable, mineral and synthetically syntheticall y produce.
Q12-
If Titanium Dioxide was used in paint, what would be the colour?
Ans-
White colour.
Q13-
Name three rust inhibitive pigment considered to be toxic.
Ans-
Red Lead, calcium plumbate, Coal tar and zinc chromate.
Q14-
Name four commonly occurring minerals used as extender pigments.
Ans-
Kaolin, china clay, calcium plumbhate, magnesium silicate and aluminium silicate. (4.12)
Q15-
Name three laminar pigments.
Ans-
Micacous iron oxide, Glass flake, Graphite and Aluminium flake.
Q16-
If pigment was added way below the CPVC, how would it affect the film?
Ans-
A film have a good gloss properties but poor covering power and have tendency to blister or low cohesive strength.
Q17-
The abbreviation CPVC means what?
Ans-
Critical Pigment Volume Concentration.
Q18-
why are thixotropes added to a paint formulation?
Ans-
To give more shelf life and higher film thickness.
Q19-
If carbon was used as a pigment what would be the paint colour?
Ans-
A black colour.
Q20
Name four properties that a binder contributes to a paint film?
Ans-
Ease of application, adhesion to substrate, abrasion resistance, chemical resistance and cohesive strength.
Q21-
Describe how a basic inhibiter works?
Ans-
Added into primer to protect the steel substrate by passivation.
Q22-
which of the common extenders could not be used in white and pestle?
Ans-
Slate flavor.
Q23-
How could the film be affected if pigment was added above the CPVC?
Ans-
All particle are not wetted, the paint film would be porous, low in cohesive strength and adhesion.
Q24-
Which of the rust inhibitive pigment is the most common?
Ans-
Zinc phosphate.
Q25-
Why are the extenders used in paint formulation
Ans-
Provide adhesion, cohesion, films strength and durability.
Q26-
If chromium was used as a pigment, what colour would the paint be?
Ans-
Green, yellow and oranges.
Q27-
Why are plasticisers added to paint?
Ans-
To give paint flexibility and reduce brittleness.
Q28-
Two metals are commonly used as galvanic pigmentation, name them.
Ans-
Zinc and Aluminium.
Q29-
Why are driers added to oil based paint?
Ans-
For oxidizing oil and resin which are added during paint manufacturing.
Q30-
What is meant by the term „thixotropic‟?
Ans-
It is a thickener which also allow a higher film thickness.
Q31-
What is meant by the term „aggregate‟ when referring paint?
Ans-
Process of milling or grinding a paint ingredient to a suitable size.
Q32-
If an antioxidant was added to paint, what would it do?
Ans-
Its will retard the formation of skin on the paint surface.
Q33-
Give the names of two plasticisers.
Ans-
Castor oil and coconut oil. Alkyd resins and non drying oil.
Q34-
What is meant by the term solution?
Ans-
The resulting liquids I.e. salts mix with water will result salty water. Water and sugar are solution.
Q35-
Give two example of a solution.
Ans-
Binder and solvent, water and salt, water and sugar.
Q36-
What is meant by the term dispersion?
Ans-
No solubility between two materials e.g. Paint.
Q37-
There are two types of dispersion, what are they?
Ans-
Suspension and Emulsion.
Q38-
If paint cures by chemical reaction is it reversible or convertible?
Ans-
Convertible/Non Reversible.
Q39-
what types of polymerization occurs in chemically curing paint?
Ans-
Cross linked Polymer.
Q40-
Name a paint which dries solely by solvent evaporation.
Ans-
Chlorinated Rubber, Vinyl, Acrylic, cellulous material and lacquer.
Q41-
What is meant by „non convertible‟?
Ans-
Allowing the polymer in a paint structure back into solution.
Q42-
What is meant by „non reversible‟?
Ans-
Not allowing the polymer in a paint structure back into solution.
Q43-
Name four drying mechanisms.
Ans-
Solvent Evaporation, Oxidation, Chemical Curing and Coalescence.
Q44-
In a coating, which dries by solvent evaporation, what type of polymerization occurs.
Ans-
Chlorinated Rubber, Vinyl‟s, Acrylic and fall into Linear Polymer categories.
Q45-
What is another term for Fineness off Grind?
Ans-
The Hegman Grind Gauge which used to measure degree of dispersion of paint.
Q46-
Which generic type of paint dry by solvent evaporation followed by oxidation.
Ans-
Alkyd, Phenolic and neutral oil and resin.
Q47-
What types of polymer forms during oxidation?
Ans-
Cross linking Polymer.
Q48-
What term applies to paint drying at ambient temperature?
Ans-
Air Drying. Reversible or non convertible and linear polymer.
Q49-
What is meant by the term „co-alescence‟?
Ans-
Physically joint together.
Q50-
What is meant by the term‟ Pot-life‟
Ans-
The periods of time after mixing which paint must be used.
Q51-
Name three curing agents used in epoxies?
Ans-
Amides, Amines and Isocycnate.
Q52-
Is paint a solution or dispersion, qualify?
Ans-
Dispersion.
Q53-
What is exothermic reaction?
Ans-
Giving off heat, the container will warm up.
Q54-
What is meant by the term ‟Induction period‟?
Ans-
The length of time after mixing which the paint should stand before used to allow polymerization/ wetting of paint.
Q55-
What is the difference between „thermoplastic‟ and thermosetting‟?
Ans-
Thermosetting means the material will cure with the application of heat. And Thermoplastic means materials soften with the application of heat.
Q56-
With a chemically curing paint, what type of polymerisation occurs?
Ans-
Cross Linking Polymer.
Q57-
Two other terms relate to induction period, what are they?
Ans-
Stand Time and Lead Time.
Q58-
Does a Phenolic resin have an induction period?
Ans-
Yes, the time depends on Paint Manufacturer recommendation.
Q59-
Which of the following binders are reversible?
Ans-
a)Epoxy Rubber,
b) Phenolic e) Alkyd
c) Vinyl
f) Cellulose
d) Chlorinated
g) Urethane
h) Silicon
Q60-
Is an epoxy powder paint thermoplastic or thermosetting?
Ans-
Thermosetting, the powder will cure with the application of heat.
Q61-
If a coating is permeable, what does it mean?
Ans-
It‟s a Barrier coat.
Q62-
What is meant by cross-linking, give two binders as an example?
Ans-
????????
Q63-
What is opposite to exothermic?
Ans-
Endothermic reaction, taking in heat, the paint container will cold and forming
condensation. Q64-
What is the term used for paints needing temperatures in excess of 65°c to cure?
Ans-
Stoving, using oven or infra red.
Q65-
What would be a typical induction period for Chlorinated rubber paint?
Ans-
Depends on Technical Data Sheet recommendation from paint manufacture.
Q66-
Name a material used as a dryer in paint formulation.
Ans-
Heavy metal salts, Octoates or naphtanes of cobalt, manganese and zirconium.
Q67-
Why would bentonite or wax be used in paint formulation?
Ans-
To keep solid particulated constituents in depression within the paints.
Q68-
Name two materials used as plasticisers.
Ans-
Coconut oil And Caster oil / Alkyd and Non drying oil.
Q69-
What generic type of paints would use anti-oxidant?
AnsQ70-
How does a single pack? Epoxy Easter paint dry.
Ans-
By oxidizing.
Q71-
How is Dew-point defined?
Ans-
The temperature at which water vapor in the air will condense.
Q72-
How is relative humidity defined?
Ans-
The amount of water vapor in the air expressed as a percentage of the amount of water vapor which could be in the air at that same temperature.
Q73-
When using a whirling hygrometer which bulb should be read first and why?
Ans-
Always wet bulb first and immediately, when rotation stops wet bulb start rise in
temperature. Q74-
At what speed should be thermometer bulb pass through the air?
Ans-
At a speed of 4meter/second.
Q75-
What should be used when wetting the wick on whirling hygrometer?
Ans-
Distilled water.
Q76-
By what other name can we refer to a whirling hygrometer?
Ans-
Aspirated Hygrometer and Psychrometer.
Q77-
When the air temperature rises does the air‟s capacity to hold water increase or decrease?
Ans-
Decrease.
Q78-
What is the stated criterion for accept, prior to calculation, on a whirling hygrometer?
Ans-
Must be according to BS 2482.
Q79-
Name two pieces of equipment used for taking steel temperature?
Ans-
Limpet Gauge, Digital Thermometer, Thermocouple and Touch Pyrometer.
Q80-
Is it possible for wet bulb temperature to be higher than the dry bulb?
Ans-
No, its impossible.
