underpainting

underpainting.
The preliminary blocking out of a composition on the painting surface in which the main shapes and tones of the picture are established before being built up by layers of glazes, scumbles, or solid paint. Until the late 19th century, when alla prima painting became general, most paintings were built up in a series of such layers. Usually underpainting was monochromatic (see grisaille). In tempera, it was traditionally done in terre verte (green earth colour), and a greenish caste can often be seen in 14th-century paintings, especially in the shadows of the flesh. In oil painting, various neutral colours were used for the monochrome underpainting, which might be painted over a coloured imprimatura. In the 15th and 16th centuries it was common to use tempera for the underpainting of works in oil. By the 19th century the main design of the painting was usually put in a colour scheme similar to that planned for the finished work, though each colour might be more subdued and extreme darks and lights were avoided.