Pigments give paints their
colours. Paint usually
contain solvent, binding
medium and pigment.
The binding medium is a liquid that carries the
pigment particles and holds them together.
When the binding medium goes solid, it sticks
the pigments to the surface you have painted.
The solvent thins the paint.
Paints are colloids. A colloid
consists of tiny particles of
one kind of stuff dispersed in
another kind of stuff. They are
mixed in but not dissolved.
The particles can be either
solid, droplets of liquid or
bubbles of fas. Colloids don't
separate out because the
particles are so small. They do
not settle out at the bottom.
A paint is a colloid where particles of a pigment
are dispersed through a liquid.
Some paints are water-based and some are oil-based. When
you paint, you usually apply a thin layer and the paint will dry
as the solvent evaporates. Oil paints dry in two stages. 1.
Solvent evaporates. 2. The oil is oxidised by oxygen in the air
before it turns solid. Oil paints take longer to dry than
water-based paints, are glossy, waterproof and hard-wearing,
but the solvents used to make them often produce harmful
fumes.
Emulsion paints are
water-based. The solvent
used is water, and the
binding medium is usually an
acrylic or vinyl acetate
polymer. A water based
emulsion dries when the
solvent evaporates, leaving
behind the binder nad
pigment as a thin solid film.
Emulsion paints are
fast-drying and don't
produce harmful fumes.