Building Materials, Third Edition

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Paint is a liquid surface coating. On drying it forms a thin film (60–150
) on the painted surface.
Paints are classified as oil paints, water paints, cement paints, bituminous paints and special
paints such as fire proof paints, luminous paints, chlorinated rubber paints (for protecting
objects against acid fumes), etc.
The functions of the paints are: to protect the coated surface against possible stresses—
mechanical or chemical; deterioration—physical or environmental; decorate the structure by
giving smooth and colourful finish; check penetration of water through R.C.C; check the
formation of bacteria and fungus, which are unhygienic and give ugly look to the walls; check
the corrosion of the metal structures; check the decay of wood work and to varnish the surface
to display it to better advantage.

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f—The base, usually a metallic oxide, is the principal constituent of the paint. It makes the paint
film opaque and possesses binding properties which reduce the shrinkage cracks in the film
on drying. Some of the examples of base are white lead, red lead, zinc white, aluminium powder,
iron oxide, etc. Their detailed description is given in Table 17.1. Lead based paints are in
general affected by atmosphere and are not recommended for final coats. Zinc white is
weather resistant. For inferior works Lithophone (barium sulphate chemically combined with

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