DISTEMPERS

 Function of Distempers

Distempers are water paints consisting of whitening (i.e., powdered chalk), glue or casein as a binder and suitable colouring pigments. Distempers are used on plastered, cement concrete and on various wallboard surfaces. They are cheap, durable and are pleasing in appearance. They also safeguard the surfaces from adverse weather conditions.

Constituents of Distempers

Distemper comprises a base, a binder, a thinner and a pigment. Whitening or chalk forms the base, glue forms the binder, water forms the carrier or thinner and a colouring pigment.

Distempers are available in a powder form or a paste form. They are to be mixed with hot water before use. This is more or less used as a water paint. Here, whitening or chalk serves as the base instead of white lead and the water is used as a carrier instead of linseed oil.

12.4.3 Properties of Distempers

General properties of distempers are given below:

1. On drying the distemper shrinks which may lead to cracking and flaking. This is predominant if the surface is weak.
2. In general distemper coating is thicker and hence they are more brittle than other types of water paints.
3. They are less durable than oil paints.
4. The distemper layer is porous in nature and allows water vapour to pass through it.
5. They provide less workability.
6. It is not suitable in places where there is dampness.
7. They are available in light shades.

12.4.4 Types of Distempers

Different forms of distempers are discussed below:

1. White Distempers

This type of distemper is prepared by mixing only whitening (i.e., powdered chalk) and glue.

2. Coloured Distempers

In this type of distemper, the required colour pigment is added to the whitening before mixing with glue.

3. Oil Bound Distempers

A variety of oil paints are available in which drying oil is so treated that it mixes with water. Whenever required, such distempers are diluted or thinned with water. These distempers after allowing drying form a washable and durable surface.

4. Casein Paints

Casein is extracted from milk curds and acts as a binder. These paints are prepared by mixing a finely ground casein with a white base, normally slaked lime. This has high opacity. Thus, it is preferred for use on plastered surfaces, stuccos, fibre boards, cement blocks, etc.