Fresco, tempera and oil – the difference between painting techniques

Fresco is painted with pigments suspended in water directly into wet lime plaster, tempera with pigments bound in egg yolk, usually on wooden panels, and oil painting with pigments in linseed oil. The techniques partly succeeded one another: fresco and tempera dominated in the Middle Ages and early Renaissance, and oil took over from the 15th and 16th centuries.

Facts

Fresco: painted into the wall

The word fresco comes from the Italian fresco, fresh. In true fresco, buon fresco, the painter lays a thin layer of wet lime plaster and paints directly into it with pigments mixed with water. When the plaster dries, the colour is chemically bound into the wall. This makes fresco very durable, but it demands speed: only as much is plastered as can be painted the same day, a giornata, and the joins can sometimes be seen.

Giotto painted the frescoes in the Scrovegni Chapel in Padua at the beginning of the 14th century, among them The Lamentation of Christ. Michelangelo painted the ceiling of the Sistine Chapel in fresco in 1508–1512, with The Creation of Adam at its centre. Painting on dry plaster, fresco secco, is easier but flakes more readily.

Leonardo's failed experiment

The Last Supper in Milan looks like a fresco but is not one. Leonardo da Vinci wanted to work slowly, make changes and build up soft transitions, which true fresco does not allow. He therefore painted with tempera and oil on dry plaster.

The paint adhered poorly, and only a few decades after the painting was finished in the late 1490s it began to flake. It has been restored many times. The example shows why technique matters: it determines not only how a picture looks but also how long it survives.

Tempera: egg and gold

In tempera painting the pigments are bound with egg yolk, sometimes diluted with water. The paint dries quickly and cannot be blended smoothly on the surface, so the painter builds up the forms with thin layers and fine, parallel brushstrokes, known as hatching. The surface becomes matt, clear and very durable.

In the Middle Ages and early Renaissance altarpieces were painted in tempera on wooden panels first primed with chalk and glue. Backgrounds and haloes were often laid with gold leaf. Duccio and Cimabue painted this way, and Botticelli's The Birth of Venus is tempera, unusually on canvas.

Oil: depth and lustre

Oil paint, with pigments bound in linseed oil, dries slowly. That makes it possible to blend colours directly on the surface, to rework and to lay thin, transparent layers, glazes, on top of one another so that the light seems to come from within the picture. Jan van Eyck did not invent oil painting, but he refined it in Flanders in the 1430s, as in The Arnolfini Portrait of 1434.

The technique spread to Italy, where painters in Venice such as Titian began to paint on canvas instead of wood. Canvas was lighter and could be made very large. Later Rembrandt laid the paint on thickly, known as impasto, and in the 19th century tube paint made it possible to paint in oil outdoors.

How to tell them apart in practice

If the picture sits directly on a wall or ceiling and the surface is matt and slightly chalky, it is probably fresco. If it is a panel painting from the Middle Ages or early 15th century, with clear, flat colours, fine strokes in the shadows and gold in the background, it is probably tempera.

If the picture has deep, saturated colours, soft transitions, glossy dark areas and a network of fine cracks, craquelure, it is probably oil. The museum label often states the technique, and more examples can be found in the section Looking at art: techniques.

How to tell the techniques apart

Exercise

Why has Leonardo's The Last Supper been so badly damaged?