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Define paints. Explain the different constituents of paints with their functions.
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Paints: Mechanical dispersion of one or more pigment in a vehicle. The vehicle is liquid consisting of nonvolatile film forming material.

Pigment: Solid substance which is essential constituent of paint. It provides capacity, strength & desired color to paint. It also gives pleasing look. It gives protection to the surface by reflecting UV rays It increases resistance towards moisture.

E.g. White –Zn & Ti oxide

Red- Iron oxide

Green –chromium oxide

Pigment should be opaque, nontoxic, chemically inert & freely mixable with oil.

Vehicle: It is called as drying oil. It is film forming constituent of paint. These are esters of fatty acids generally present in animal & vegetable oil like linseed & soyabin oil

Functions: It supplies film -

  1. It gives toughness
  2. It increases adhesion
  3. It plays important role in water proofing

Thinners:

  1. Reduce viscosity
  2. To dissolve vehicle & additive
  3. Suspend pigment
  4. Increases penetration power
  5. Increases elasticity of painted film
  6. Due to the evaporation process film dries fast

Driers: Driers are oxygen carrier catalyst. It accelerates drying by oxidation, polymerization & condensation. Main function is to improve drying quality of film e.g. linolate & tungstate of Co & Mn.

Filler: Low refractive index material. It decreases cost & cracking with increasing durability.

Plasticizer: It increases elasticity & plasticity. E.g. Trycresyl phosphate

Antiskining agent: it prevents skinning & gelling

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