Paints
Definition:
Pain is a mechanical dispersion mixture of one or more pigments in a vehicle. The ‘Vehicle’ is a liquid, consisting of non-volatile, film-forming material, drying oil, and highly volatile solvent.
Characteristics of a good paint:
1. Opaque
2. Chemically inert
3. Cheap
4. Glossy and shining on drying
5. Should be washable
6. Should not shrink after drying
7. High hiding power
Constituents of paint:
The various constituents of paint are
1. Pigment
2. Vehicle or drying oil
3. Thinners
4. Driers
5. Filters or extenders
6. Plasticizers
7. Antiskinning agents
Constituents of paint and their functions:
| Constituents | Function | Examples |
| 1. Pigment: It is a solid and colour producing substance in the paint. | a) It provide desire colour to the paint b) It gives strength to the film | Red lead, Carbon black |
| 2. Vehicle or drying oil: It is a film forming constituent of the paint | a) They form protective film b) They hold pigment particle together | Linseed oil, Tung oil |
| 3. Thinners: The Thinners are volatile substance which evaporates easily after application of paint. | a) They reduce the viscosity of the paint. b) They dissolve the film forming material. | Turpentine, petroleum spirits
|
| 4. Driers: They are oxygen carrier catalysts | a) They increase the rate of drying quality. | Tungsates and borates of Pb and Zn. |
| 5. Fillers: These are the inert materials which improve the properties of the paint. | a) They reduce the cost of the paint. b) Increase durability of the paint. | Talc, clay |
| 6. Plasticizers: A substance incorporated in the paint. | a) To give elasticity to the paint film. b) To prevent cracking of the film | Triphenyl phosphate |
| 7. Antiskinning agents: These are sometimes added to some paint. | a) They prevent the pealing of the paint | Polyhydroxyls, phenol. |