Underpainting

Underpainting is the first working layer of a painting, applied to establish the composition's basic tonal structure and values, and sometimes its color temperature, before the final layers of color are painted on top. Typically rendered in a limited, often monochrome palette, such as grisaille in grays or a warm earth tone, an underpainting lets an artist resolve the placement of light and shadow across the whole composition early, working out how the finished picture will read as a pattern of dark and light before committing to detailed color, and, in oil painting, it provides a stable, already-dry foundation over which subsequent layers and glazes can be built. The technique was widely used by painters from the Renaissance through the nineteenth century as a disciplined way of separating the problem of value and structure from the problem of color.