Tempera (from the Latin temperare, “to mix”) is a painting technique which uses water as a thinner for colours. Pigments, the coloured substances in paint, usually come in powdered form and are made of finely-ground organic or mineral elements. A substance is therefore needed to bind them, ensuring the mixture’s consistency, and allowing it to adhere to the medium: this agent can be starch, a gum (arabic, tragacanth etc), glue, casein (a protein found in milk), or most commonly, egg yolk.
The addition of water, which characterizes this technique, gives the paint its fluidity and allows it to be applied more easily to the medium. To paint a wood panel or a wall mural in tempera, it must first be covered with numerous layers of a chalk or plaster-based preparation.
In the 15th century this technique was also used on canvas. Tempera is a technique that is clear, luminous, precise, fairly robust, yet not completely irreversible: it can dissolve if water is present. The painting must be executed quickly, as the pictorial layer dries rapidly and therefore cannot be easily redone.
Tempera is one of the most ancient pictorial techniques. Traces of it can be found in paintings of Antiquity, Egypt and Rome, but it was also the preferred method of Byzantine icon painters. Its use dominated the Middle Ages until the 15th century, when oil painting began to be favoured, as it is more resistant and allows for more varied effects.
