C1H - Paints & Pigments Flashcards
What gives the paint it’s colour ?
Pigment
What does a solvent do in paints ?
Thins it and makes it easier to spread
What’s a binding medium ?
A liquid that carries the pigments and holds them together. When it turns solid it sticks the pigments to the surface you’ve painted.
Paints are what ?
Colloids
What do colloids consist of ?
Really tiny particles of one thing dispersed in another thing. But they are NOT dissolved. Just mixed in.
What can the particles be in a colloid ?
Bits of solid
Droplets of liquid
Bubbles of gas
Why don’t colloids separate out ?
Because the particles are so small they don’t settle at the bottom
Are the particles in a colloid heavy ?
No light so they can stay dispersed
Describe an emulsion paint ?
They are water based. Their solvent is water and the binding medium is usually an acrylic or vinyl acetate polymer
Describe an Oil paint ?
They are oil based. The solvent is an organic compound that dissolves oil and the binding medium is oil.
How does an emulsion paint dry ?
The solvent which is water evaporates leaving behind the binding medium and the pigment as a thin solid film.
How does an oil paint dry ?
The solvent evaporates. Then the oil which is the binding medium is oxidised by oxygen in the air. Then it turns solid.
Lily is painting her room. Her dad tells her to use oil paints. Why would this be a bad idea ?
It takes longer to dry and the solvent can produce harmful fumes
Why would someone paint their bike ?
In order to stop it from rusting
What kind of pigments change colour when heated ?
Thermochromic
