What is Egg Tempera?

Egg tempera paint consists of three ingredients: pigment, egg yolk and water. Powdered pigments are dispersed in water to form a paste, and then mixed with yolk. The egg oil and proteins in the yolk cure and bind the pigments to a surface. The surface most often used is a wood-based panel coated with traditional gesso (collagen glue and chalk or gypsum) sanded to a smooth finish. (part of description by Koi Schadler Egg Tempera artist).