Constituents of Paint

The necessary constituents of paints are following:

1). Base        

2) A vehicle 

3) A pigment

4) A drier and         

5) A thinner.           

1. Bases: Base is a principal constituent of paint. It also possesses the binding properties. It forms an opaque coating. Normally used bases for paints are red lead, white lead, iron oxide, zinc oxide, aluminium powder, titanium white, and lithopone. A lead paint is appropriate for painting iron and steel works, as it sticks to them well. Though it is affected by atmosphere action and therefore should not be used as final coat. Whereas zinc forms good base but it is costly. Lithopone is a mixture of zinc sulphate and barytes, which is cheap. It gives good appearance but it is affected by day light. Therefore it is used for interior works only.

2. Vehicles: Vehicles are the liquid substances that hold the ingredients of paint in liquid suspension and permit them to be applied on the surface to be painted. Tung oil, Linseed oil, and Nut oil are utilized as vehicles in paints. Four oils, linseed oil are very commonly used vehicles of the above. Boiling makes the oil darker and thicker. By forming a thin film, Linseed oil reacts with oxygen and hardens

3. Pigment: Pigments give needed colour for paints. They are fine particles and have a reinforcing effect on thin film of the paint. The ordinary pigments for different colours are:

Black-suit , Lamp black, and charcoal black

Red-red lead , venedion red, and Indian red

Brown-raw , burned timber and burned sienna

Green-copper sulphate, chrome green,  

Blue-ultra marine, prussian blue

Yellow-chrome yellow, ochre

4. The Drier: These are the compounds of metal like, manganese, lead, cobalt. The function of a drier is to absorb oxygen from the air and supply it for hardening to the vehicle. The drier should not be added until the paint is approximate to be used. Because it destroys elasticity and causes flaking, excess drier is harmful

5. The Thinner: It is also known as solvent. It makes paint thinner and therefore increases the coverage. In spreading paint uniformly over the surface it helps Neptha and Terpentine are normally used thinners. thinner evaporates and paint dries after paint applied,.

Properties of an Ideal Paint are following:

a)     In reasonable time it should dry.

b)    It should be possible to apply freely and easily.

c)     It should not be harmful to the health of workers.

d)    It should durable surface and form hard.

e)     It should possess attractive and pleasant appearance.

f)      It should not be simply affected by atmosphere.

g)     It should possess good spreading power.

h)    It should form a thin film of uniform nature For example: it should not crack.

i)       It should be cheap.