Paints and Pigments

Pigments give paints their colours. Paint usually contain solvent, binding medium and pigment.
1. 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.

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