Three jobs in one tin
What Is Paint Made Of?
Every paint is the same three things: something coloured, something sticky, and something to thin it down.
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Step 1 of 5
The pigment is just coloured dust.
On its own, pigment is a powder that would blow off the wall. It supplies the colour and nothing else — the same pigment can end up in paint, ink or plastic.
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Step 2 of 5
The binder is the glue.
The binder surrounds every grain and sticks it to the wall and to its neighbours. Change the binder and everything changes — how tough the paint is, how shiny, and how long it lasts.
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Step 3 of 5
The solvent only exists to leave.
Paint has to be runny enough to spread and solid once it is up. The solvent — water in most house paint — does the thinning and then evaporates, which is what drying actually is.
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Step 4 of 5
Gloss and matt are about the surface.
More binder gives a smooth surface that reflects light in one direction, so it looks glossy. More pigment leaves it microscopically rough, scattering light every way — that is matt.
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Step 5 of 5
Some paints dry and some set.
Water-based paint dries: the water leaves and the film hardens. Oil paint sets: it actually reacts with oxygen from the air and changes chemically, which is why it takes so much longer.
Very old paints used whatever was to hand — egg yolk as the binder, ground rock as the pigment. Some of them are still bright after five hundred years.
The short version
Paint is coloured powder, a glue to hold it on, and a liquid that thins it and then leaves.
Try it yourself
Look at a glossy and a matt wall from an angle. The glossy one throws a reflection; the matt one scatters it away.
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