Grisaille

Grisaille is a painting technique executed entirely, or almost entirely, in shades of gray or another single neutral color, producing an image that reads as sculptural relief or monochrome. The technique was used from the medieval period onward both as a finished style in its own right, notably on the exterior wings of Netherlandish altarpieces such as Jan van Eyck's Ghent Altarpiece, where painted saints imitate stone statues in niches, and as an underpainting stage: a monochrome tonal study laid down first to establish the light and shadow of a composition before transparent colored glazes were added on top. Grisaille was also adopted for stained glass and for engraved book illustration seeking to imitate sculpture, and the technique's name, from the French gris for gray, entered English art vocabulary directly from that Netherlandish and French practice.