underpaint

Etymology

From under- + paint.

verb

To rough in the colors of a painted work of art, prior to painting the final version.“The underpainting should be neutral and preferably cool in color. Positive colors may be underpainted with shaded tints of the full color. This is especially true of blues and reds because the oil glazes darken or fade. Reds are best underpainted with vermillion or cadmium.”