Tempera
Tempera colors are paints made of pigments in a liquid binder consisting of a water and oil emulsion. Depending on the kind of emulsion used, tempera colors are designated gum tempera, egg tempera, casein tempera and wax tempera. The oils used include dry oils such as linseed oil, poppyseed oil, walnut oil and sunflower oil and resinous binders such as lacquer, alkyd resin solutions, turpentine and various waxes. Genuine tempera colors are perishable once they are mixed. Bought ready-made in tubes, they can be kept for a while because so many preservatives have been added to them (this is particularly true of casein colors). Distemper colors with size (glue) as a binder but without oil are also erroneously called tempera although the correct term for these paints is gouache [Italian: "quazzo" = puddle of water]. In the Middle Ages, tempera painting in Europe grew out of encaustic (hot wax painting) that was widespread in Greco-Roman antiquity and the Early Christian era. Tempera painting as such has been largely replaced by oil painting in the Modern Age since oils are easier to work with and keep longer. In addition, oil painting allows depth of color and the application of color in glazes or washes. At the same time, the wooden panels used for tempera painting have been replaced by canvas: canvases can be much larger and are much lighter and canvas is not a suitable support for tempera painting because it tends to crack. Tempera painting yielded to oil painting from the 15th century, at first in the Lowlands, whence it rapidly spread as far as Italy and Spain. The van Eyck brothers were among the famous painters who switched from tempera to oil and used both media either in a mixed technique or in parallel. Egg tempera has survived primarily as the medium of preference in traditional icon painting on wooden panels.
