Tempera

Tempera (also known as egg tempera) is a type of artist's paint and associated art techniques that were known from the classical world, where it appears to have taken over from encaustic and was the main medium used for panel painting and illuminated manuscript in the Byzantine world and the Middle Ages in Europe, until it was replaced by oil painting in Europe. It has remained the required medium for Orthodox icons. It is paint made by binding pigment in an egg medium. However, the term... full article at wikipedia