A water-based paint medium that, upon drying, produces an opaque surface with a soft sheen. The most common types are egg tempera, which is made primarily from egg yolk (although egg white can be added), and glue tempera (sometimes called distemper or, if painted on very fine linen, tüchlein), which is made from animal glue.

Egg tempera techniques were fully developed during the early Italian Renaissance. Although egg was eventually replaced by oil as the predominant painting medium, interest in the use of egg tempera revived during the nineteenth century and has continued to this day. The medium produces a hard, durable, and somewhat lustrous surface. Egg tempera dries very quickly and cannot be brushed uniformly over broad areas; as a result, egg-tempera pictures are painted with repeated brushstrokes, visible as many small hatches on the finished surface.

Source: Looking at Paintings: A Guide to Technical Terms / eds. Tiarna Doherty and Anne T Woollett. (Los Angeles: J. Paul Getty Museum, 2009), pp. 74-75.