Egg tempera is a paint made from pigment and egg yolk (the yellow) as a binder. Water is added to thin the paint to the consistency desired. As eggs go off quickly, only a small quantity of paint is usually mixed at a time. It is applied in small brush strokes, in multiple glazes.
Egg tempera is best used on a rigid support such as a board, rather than a flexible one such as canvas, as it's a fairly brittle medium. This is prepared with gesso to create an absorbent surface.
Egg tempera is the second oldest painting medium, dating back to the early Egyptians. While the advent of oil paints during the Renaissance made it technologically obsolete, it enjoyed renewed popularity as a medium in the late 18th century. Given the rich, deep, slightly glossy colors the medium produces, it's no surprise egg tempera is still used today.
Most artists mix their own egg tempera, though you can buy it in tubes at specialized art stores. Egg tempera should not to be confused with the powdered tempera or poster paints you can buy.
