Paints and Pigments Flashcards
Paint is a colloid, what does this mean
Fine solid particles are dispersed with liquid particles but not dissolved
What purpose does the pigment have in paints
Gives paint colour
What purpose does the binding medium have in paints
(Oil) Sticks the pigment to surface being painted on
What purpose does the solvent have in paints
Dissolves binding medium, making it thinner and easier to coat the surface
What evaporates when the paint dries
The solvent
What is the solvent in emulsion paint
Water
In oil-based paints what is dispersed in oil (the binding medium)
The pigment. Often there is a solvent present that dissolves the oil
What do thermochromic pigments do
Change colour when heated or cooled (mood rings)
What do phosphorescent pigments do and how do they work
Glow in the dark. Absorb and store energy then release it as light when dark (the paint on watch dials)
What are the stages when oil-based paint dries
The solvent evaporates
Oil-binding medium reacts with oxygen to form hard layer/skin (oxidation)
This skin sticks pigment to surface
Stages when emulsion paints dry
Water (solvent) evaporates
Oil (binding medium) sticks pigment to the surface
Why must particle size in a colloid be very small
To stay scattered throughout and not settle down to bottom
