In Tempera egg yolk and vinegar is mixed with oil colors and painted on dry plaster. It is paint made by binding pigment in an egg medium.
In the early days egg yolk and hand ground dry powdered pigments were mixed together to create tempera. Sometimes ther materials such as honey, water, milk (in the form of casein) and a variety of plant gums were added to this concoction. With the invention of oil paint in the Late Middle Ages, tempera was somewhat relegated to the shadows. However it was still used for awhile as the underpainting (base layer) with translucent or transparent oil glazes on top. Slowly but surely oil painting began to replace tempera, and by the 16 th century it was all but forgotten.
Three easy steps of making Tempera
A small amount of colour is to be placed onto a palette, dish or bowl.
Equal volume of the egg is to be added and the color and the egg yolk is o be mixed well making sure there are no lumps of pigment. Some pigments require slightly more egg medium, some require less.
Distilled water is to be added. Traditionally a tablespoon of water is added per egg yolk. Trial and error will dictate just how much water is required.
Voila, your tempera base is ready to be used.
Leonardo Da Vinci's experimentation with tempera
Novelist Dan Brown in his blockbuster novel “ The Da Vinci Code ” committed an error, he claimed that Da Vinci's' masterpiece The Last Supper was a fresco which in fact it wasn't, It was what we call a tempera.
Had it been a fresco (a technique where the painting is done when the plaster on the wall is still wet therefore the colors intermingles permanently with the plaster and is permanent.) it wouldn't have weathered and wouldn't be falling off the way it has been for all these years.
Leonardo Da Vinci chose to adopt this style, which we now know as tempera. Egg yolk and vinegar were mixed with oil colors and painted on dry plaster. That way it made it easy to be redone when necessary. However this technique proved to be disastrous, the painting almost immediately began to fall off the plaster.
The term tempera in modern times is also used by some manufacturers to refer to ordinary poster paint, which is a form of gouache that has nothing to do with real egg tempera.