Paints (Short
Note)
Definition
Paints are fluids that are applied on
a surface to form a hard continuous film on it for protection or decoration.
Wooden and metallic articles are
coated with paints to decorate them as well as to protect from corrosion or
rusting.
Composition
of Paints
Paints are usually composed of three
components.
1. Pigments
2. Binders
3. Volatile Solvent
To make a paint, a suitable solvent
is used in which both the binder and the pigment are dissolved.
1. Pigments
The pigment of paint gives it colour,
it also gives hardness and bulk. Common pigments are titanium dioxide – TiO2
(white), Iron oxide – Fe2O3 (brown or red), Carbon Black – C (black), Chrome
Yellow – PbCrO4 (yellow) and organic dyes of various colours.
2. Binders
The binder or vehicle is the part of
the paint that carries the pigment particles and hold the entire film of the
paint on the surface. Generally some plant oils such as linseed oil, natural
and synthetic resin (liquid plastics) are used as binders.
3. Volatile Solvents
To make paint a suitable solvent is
selected in which both the pigment and binder are dissolved. The solvent
evaporates after the paint is applied. Solvent does not effect the quality of
dry paint. Commonly, water or turpentine is used as solvent.
Classification of Paints
On the basis of nature of solvent,
the paints are classified into the following two classes.
1. Oil Based Paints
2. Water Based Paints
1. Oil Based Paints
In these paints turpentine is used as
solvent. Turpentine is a liquid mixture of hydrocarbon that is obtained from
pine trees.
2. Water Based Paints
In these paints, water is used as
solvent. Both binders and pigments form a suspension in water.
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