Tempera
Paint made by mixing pigment with egg yolk and water; it dries fast to a matt, lasting film.
Also: egg tempera
Egg tempera was the main paint for panel pictures in Europe before oil paint took over in the 15th century, and it is the traditional medium of icon painting. Pigment ground in water is mixed with egg yolk, which binds it. The paint dries within seconds, so it cannot be blended on the surface. Painters build form with many fine strokes laid side by side. The colours are clear and change little with age. More loosely, tempera is used for any paint bound with glue or gum, including cheap poster paints.