General Theory Paint Technology1. Name four other paint constituents besides pigment, binder and solvent.Answer.----Anti skinning, anti settling , driers & plasticisers .

2. Solvent/water based paints and liquid solvent free paints are two paint types; name a third.Answer.----Powder paints.

3. What is meant by the term opaque????.Answer.----Hiding power .

4. What is meant by the term vehicle.?Answer.----Is the liquid component of the paint that contains the pigment , resin driers curing agent etc etc.

5. Give another name for an unpigmented paint.Answer.----Varnish

6. What are the functions of a paint binder.?Answer.----A paint binder holds the pigment particles of the paint together and allows them to bond together during the drying process , resulting in the formation of a film .

7. How is the word Alkyd derived ?Answer. ----Alcohol/Acid8. Which solvent would be used with an alkyd resin?Answer.----Aliphatic

9. Which solvent would be used with chlorinated rubber?Answer.---- Xylene

10. Which solvent would be used with an epoxy?Answer.--- Acetone

11. Which solvent would be used with a phenolic resin?Answer.---Aliphatic.12. Indicate which would be acceptable practice :a. Alkyd applied over chlorinated rubber.---- Acceptable.

b. Chlorinated rubber applied over a phenolic.----Not acceptable.c. Chlorinated rubber applied over an alkyd.------Not acceptable.

d. Phenolic applied over chlorinated rubber.-----Acceptable.

e. Epoxy applied over linseed oil based.------Not acceptable.

f. Chlorinated rubber applied over epoxy.-----Acceptable.

g. Epoxy applied over alkyd.------Not acceptable.

13. List the advantages and disadvantages of a water based paint.Answer.----Advantages :-Environmentally friendly ,cheaper than solvent based, easier applied , non toxic ,non flammable & odourless.

Disadvantages:-Cannot be overcoated with strong solvent based paints , less durable , needs inhibitors , environmental issues affect times it can be applied & needs very clean substrate.14. Name four advantages of a chlorinated rubber paint system.Answer.----Non flammable, non toxic , easily maintained & low water permeability .15. Name three disadvantages of a chlorinated rubber paint system.Answer.----Cobwebs when sprayed , breaks down when in contact with strong solvents & may pinhole at high temperatures .16. What is polymerisation ?Answer.----The linking together of the particles in a paint film to form linear, branched & complex structures , they can have single( saturated ) bonds and others can have two or three (unsaturated)

bonds the results of the polymerisation is to produce a finished paint , with the desired qualities that are required for any particular environment .

17. What is meant by the terms linear polymer, branched polymer and complex polymer ?Answer.----Linear, may be single or multi bonded , common in water & non drying oil based paints and usually produces a paint that is reversable.

Branched , like above may be single or multi bonded , usually reversable.

Complex, polymerisation takes place primarily in paints drying by

oxidation , and produces non reversable ( thermosetting )coatings . 18. What are the basic units of a polymer called?Answer.----Monomers.

19. Name two natural resins.Answer.----Coppall & shellac.

20. What is meant by oleoresinous ?Answer.----Oil & resin mixtures .21. Explain the difference between saturated and unsaturated polymers.Answer.----Saturated polymers are single bonded polymers , unsaturated are multi bonded ,saturated polymers are usually linear or branched and result in reversible (thermoplastic) coating types , where as unsaturated polymers tend to be complex and result in non reversable(thermosetting) paints !!.

22. What is the use of driers in paint formulation.?Answer.----They are used to accelerate the drying / curing times of oil based paints .

23. Name two unsaturated drying oils.Answer.Tung & linseed oils .

24. What is meant by the term long oil paint. ?Answer.----A paint that has more oil than resin in the mixture so that it takes longer to cure and results in an elastic coating, pleasing to the eye usually used for cosmetic purposes.

25. What properties would a short oil paint possess ?Answer.----Fast drying and brittle , usually used on structural steelwork

26. What is the difference between a dye and a pigment ?Answer. ----A dye is soluble, a pigment is insoluble27. From what sources are pigments derived ?Answer.----Animal , mineral ,vegetable and as a result of chemical reactions (synthetic).

28. Name four ways in which a pigment can effect the properties of a binder.Answer.----Strength, opacity,durability & permeability .29. What is a typical pigment particle size. ?Answer----Typically less than 1 micron for opacifying pigments.

30. What is an opaque pigment ?Answer. ----A pigment that adds hiding power to the paint .

31. If carbon was used a as pigment in paint, what would be the resulting colour ?.Answer. ----Black.

32. If titanium dioxide was used as a pigment in paint, what would be the resulting colour ?Answer ----White.

33. If chromium was used as pigment in paint, what would be the resulting colour.Answer. ----Yellow,orange & green.

34. Which are the most commonly used rust inhibitive pigment ?Answer.----Aluminium or zinc

35. Name three toxic rust inhibitive pigments ?Answer.----Red lead , zinc chromate & coal tar .

36. How do rust inhibitive pigments work ?Answer.----They are applied to a properly prepared substrate , and are less noble than the material that they are to protect , in the event that an electrolyte comes into contact with the component an electrochemical reaction will occur and the corrosion will take place at the rust inhibitive coating and

not on the substrate.

37. Name two metallic pigments used in galvanic paint systems.Answer. ----Zinc chromate and Zinc phosphate.

38. What is the purpose of using extenders in a paint formulation.Answer. ----Lowers cost , by adding bulk to the paint with relatively cheap materials , they can also have a bearing on the colour of paints produced.

39. Name four popular extenders.Answer.----Chalk, talc, slate dust, kaolin.

40. Which common extender could not be used in white paint formulation. ?Answer. ------Slate dust.

41. Name three laminar pigments.Answer.----- MIO,aluminium flake & glass flake .

42. What is meant by the abbreviation C.P.V.C.?Answer. ----Critical Pigment Volume Concentration.43. What would be the result of adding Pigment over the CPVC ?Answer.----Poor gloss ,high moisture impermeability & less likely to blister .

44. What would be the result of adding pigment well below the CPVC.Answer.----High gloss ,poor moisture impermeability & susceptible to blistering.

45. Name three important properties of a solvent in addition to the flash point.Answer.----Toxicity, evaporation rates & solvent strength .

46. Name two types of occupational exposure limits.Answer. ---- MEL/OES.

47. What is a Drager Tube ?Answer. ----A device for measuring toxicity of solvents present in the working environment , which determines if the OES/MEL levels are being exceeded .

48. What unit are inscribed on a Drager Tube. ?Answer. -----PPM

49. What is the function of a plasticiser. ?Answer.----It allows the coating to dry in a controlled manner and allows the pigment particles to find & link up with each other so that coatings of a high standard are achieved

50. Name two plasticisers.Answer.----Castor oil & coconut oil .

51. What is the function of a drier in an oil based paint. ?Answer.----It accelerates the drying process

52. What is the function of an anti skinning agent in an oil based paint. ?Answer.----It retards the formation of a skin on the surface of a paint still in its container, which forms as a result of storage , or oxidation if tin is incorrectly sealed , or as a result of driers in the paint .

53. What is meant by the term thixotrope ?Answer.----Jelly like paint that needs to be worked to flow , when working out its viscosity it would need to be done with a rotary viscometer .54. What is a solution. ? Give an example.Answer.----A solution is where one component is completely dissolved in another eg ; sugar in water & salt in water etc.

55. What is a dispersion ?Answer.----A liquid containing free particles of another component , usually completely wetting them (although 100% wetting is almost impossible due to particles sticking to each other, forming aggregates, resulting in some edges not being wetted )but there is no dissolving of one component into the other .

56.What are the two types of dispersion. ?Answer.----Emulsion & suspension .

57. In paint technology what is meant by an aggregate ?Answer.----A group of pigment particles.

58. What is another name for degree of dispersion.Answer. ---- Fineness of grind.

59. What is the term relating to paint drying at normal temperatures. ?Answer.----Air Drying

60. What is the term used if drying is carried out by the application of heat up to 65deg.Answer.----Forced drying .

61. What is the term used if drying is carried out by the application of heat over 65deg.Answer. ----Stoving .62 What is meant by the term dust dry.Answer . ----When no dust will stick to the surface of the recently applied coating .

63. What is meant by the term surface dry or sand dry. ?Answer.----When the application of sand to a coating results in no sand sticking to , or marking the coating .

64. What is meant by the term touch dry.Answer.----When you touch the coating with your thumb nail ,pencil tip or other objects with an edge and no marks are left or stickiness present.

65. What is another popular term for touch dry. ?Answer.----Free from residual tack66. What is meant by the term tack free. ?Answer.----Free from tack , even under pressure.67 What is meant by the term hard dry.Answer.----When the surface hardness of the paint can be measured by specific methods , without leaving a mark and can be overcoated if required .

68. What is meant by the term dry to handle ?Answer.----When the painted component can be moved without fear of damaging the coating.

69.What are the four drying mechanisms ?Answer. ----Solvent evaporation, chemical cure, oxidation and coalescence.

70. What type of polymerisation occurs in a paint solely by solvent evaporation ?Answer.----Linear or branched polymers & they are reversible paints .

71 What is meant by a non-convertible paint

Answer.----A paint that when cured , if subjected to its original solvent or stronger type will revert back to a liquid .

72. What is meant by a reversible paint.?Answer.----Same as above

73. Name a paint that dries solely by solvent evaporation.Answer.----Chlorinated rubber.

74. Which generic type of paint dries by oxidation after solvent evaporation.Answer.----Acrylic & vinyl emulsions.

75. What type of polymerisation takes place in a paint film which dries by oxidation.Answer.----Complex.

76. What is meant by chemical curing ?Answer.----It is when a curing agent is added to the paint either at the manufacturing stage in which , when the paint components are mixed reacts to produce curing , or it can be activated by the application of heat, ultra violet light, infra red light & electron beam.

77. Are chemically curing paints convertible or non-convertible. ?Answer.----Convertible.

78. Are chemically curing paints reversible or non-reversible ?Answer. ----Non-reversible.79. Which type of polymerisation occurs in a chemical curing paint ?Answer.Complex

80. Are two-pack paints convertible or non-convertible ?Answer.Convertible

81. What is meant by pot-life ?Answer.----The amount of time that the mixture in an MCL can be used from the paint can after mixing, once this time has been expired, paint is to be disposed of in a controlled manner ,due to the environmental considerations of chemicals within the the painting industry.

82. What is meant by induction period. ?Answer----The amount of time that MCL paint needs to stand after mixing before it can be used .

83. Name two other terms for induction period.Answer----Stand time & lead time .

84. Does an Alkyd resin paint have an induction period ?Answer.----No ?????

85. What would be a typical induction period for a chlorinated rubber paint ?Answer.----There wouldn't be one as it is a single pack paint ????.

86. What is an exothermic reaction ?Answer----.One which gives off heat .87. What type of reaction is opposite to an exothermic reaction.Answer ----Endothermic.

88. What is a thermic reaction ?Answer.----A reaction that occurs when iron filings & aluminium powder are brought together at around 200 degrees C , a reaction resulting in temperatures in excess of 2000 degrees takes place .

89. What is meant by coalescence ?Answer.----The evaporation into the atmosphere of the water in a water based paint , which allows the components of the paint to dry by oxidation 90. Which of the following paints are reversible :a. Phenolic

b. Alkyd

c. Vinyl

d. Epoxy

e. Urethane

f. Chlorinated rubber

Answer----C & F.????

91. Which of the above paints are convertible ?Answer.A , B , D & E .????

92. Name three epoxy curing agents.Answer.----Heat , ultra violet & infra red light .

93. Describe the difference between paints which are thermosetting and paints which are thermosplastic.Answer.----Thermosetting paints are non reversible , whereas thermoplastic will return to their liquid state if subjected to their original solvents or solvent of greater strength.

94 Is epoxy powder thermosetting or thermoplastic?.Answer.----Thermosetting .95. Explain the abbreviations : OES, MEL and PPM.Answer. ----OES :_ Occupation exposure standard is a figure based on long term exposure (8 hours) & short term exposure (10 minutes) to toxic substances and is a measure of the amount of a toxic substance that can be in the atmosphere in a working environment.

The long term exposure can be exceeded ,so long as a reason can be given for the excessive limit & steps have been taken to reduce the level of toxicity to below the maximum .

The short term exposure is normally in the region of four times the long term exposure limit.

MEL :-Maximum exposure limit "this level of exosure should never be exceeded "

Parts per million :-this is the unit of measurement for the levels of toxicity in the atmosphere , it can be measured using a Draeger tube or you can have permenant digital monitoring devices .

96 Explain the different functions of the primer, the mid-coat(s) and the finish coat.Answer.----The primer is the first layer of paint which is applied on top of a suitably prepared substrate , its function is to give complete coverage of the substrate, strong adhesion , form a rust inhibitive,passivation barrier,and to provide a key for the subsequent paint layers .

Mid coat(s) are to give a barrier to stop any moisture that gets through the finish coat fom reaching the substrate and causing corrosion .

Finish coat is to give a pleasing look to the eye ,strong coating that can resist abrasion , mechanical damage ultra violet ligt & environmental conditions . 97. What is cross-linking ? Name two paints which cross link.Answer.----Cross linking is when the particles in the paint join together , by grabbing hold / sharing free electrons in the outer level of the molecules. This results in a very strong coating resistant to chemical attack , severe weathering etc, very good adhesion can also be achieved , due to molecular interference. ????

98. Is a paint a solution or a dispersion ?Answer.---- A dispersion.

99. What is meant by the permeability of a coating ?Answer.----A coats permeability is its strength of barrier against moisture attack the more impermeable the less water that will get through the coating .100. How does an epoxy ester paint dry. ?Answer. ----Single pack air curing, temperature dependant.

Paint Theory

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