Term: Underbound

A condition that occurs when too much solvent is added to paint. The result is that the binder in the paint is not sufficient to hold the pigment, so the paint does not adhere to the support (or ground). It may also be said that the paint is over-pigmented, meaning that there is more pigment than can be uniformly held by the binder.

Some artists dilute the paint they use for the initial lay-in (see underpainting) to a point where it becomes an underbound wash. While this is a common practice, the artist must over-paint the wash with a more cohesive paint or glaze to bind the pigment underneath. If the wash is to be exposed as part of the final painting, a better practice would be to use a lean medium rather than a solvent to dilute the paint.