This paint was a colloid because bits of color or pigment were suspended in egg yolk, the emulsifier, which was suspended in water. This type of paint was called egg tempera. Leonardo Da Vinci was one of the first painters to make oil paints. He made them by mixing colored powders into linseed oil and then mixing the linseed oil with water. Oil paint is a colloid because tiny bits of pigment are suspended in the oil that is then suspended in the water.
Acrylic paints are also a colloid.
In acrylic paints, pigment is suspended in a liquid plastic called acrylic, the emulsifier, which is then suspended in water. Using the hammer, break the chalk into a fine powder. You want to make the powder as smooth as possible. It will be harder to break up the small chunks once you have taken the chalk out of the baggie. Your paint will end up lumpy if you do not break up the chalk fine enough.