Wet-on-wet (also wet-in-wet) is a term used to describe the practice of applying one color of paint either beside or on top of another before the first layer is dry. Because both paints are wet, some mingling of colors occurs. See also: alla prima.

Screen Shot 2020-12-08 at 5.58.46 PMRembrandt van Rijn. Self-Portrait (det.). Oil on canvas. 1659. National Gallery of Art, Washington, D.C.