Definition:
Gum arabic is a binder made from acacia trees. It's most commonly used in the manufacture of artist's quality watercolour and gouache paints as well as pastels.
Mature acacia trees exude the gum from incisions made in their bark. This dries into hard, transluscent balls, which are collected and ground into a fine powder. The lighter the colour of the gum arabic, the better the quality. To use it, gum arabic is dissolved in water, using two parts water to one part gum arabic.
Adding extra gum arabic to watercolour increases the body and gloss of the paint, but you must be careful not to add too much as the paint may become brittle and may flake off.
