Term: Binder

A binder, commonly referred to as a vehicle in paint, is the agent that makes paint stick to the support. It is the component in paint that forms a solid film. The binder holds the pigments together and influences the visual properties of the paint (such as, gloss, durability, flexibility, and so forth).

Binders can be categorized according to how they cure or dry. For example, the binder used in watercolor and gouache is gum arabic which dries by evaporation. Oil paints use some sort of drying oil, usually linseed or a modified oil called an alkyd. Oil paints cure using a oxidative crosslinking process.