Fresco

Fresco (Italian “fresh”), method, or art, of painting with watercolours on plaster, while the plaster is still wet, or fresh. The term is also applied to the painting executed in this manner. In the Renaissance this process was termed true fresco, or buon fresco, to differentiate it from fresco secco, the process of painting on dry plaster. The term fresco is also sometimes used, improperly, for tempera painting, or distemper, in which watercolour is mixed with egg or other glutinous substances and applied directly to masonry.

In true fresco, pigment is applied to the top layer of several layers of plaster. To the penultimate layer of plaster, the painter usually applies a sketch, or cartoon, of the painting. The outlines of the various figures and forms of the cartoon are then reinforced with dark watercolour. Plaster is laid over the drawing in small sections, and colour is applied to the wet plaster, the painter often also working from a separate sketch of the colour scheme. As the plaster dries, the lime in the plaster reacts chemically with carbon dioxide in the air to form calcium carbonate; this compound forms a film over the colours, which binds them to the plaster, making them part of the wall's surface and giving the colours an unusual clarity. The colours of a fresco are usually thin, translucent, and light, often with a chalky look. In the Renaissance, methods were found to give the colours somewhat greater opacity.

In true fresco, the painting must be done quickly and confined to essentials. The artist must know precisely how much watercolour the plaster will absorb. Too much paint causes the surface to become “rotten”. Cutting away the defective portion, laying on fresh plaster, and repainting is then necessary.

In fresco secco, the dry plaster is rubbed with pumice stone to remove the crust, then washed with a thin mixture of water and lime. The colours are applied to this surface. The effect of fresco secco is inferior to true fresco; the colours are not as clear, and the painting is less durable.

Fresco painting was known to the ancient Egyptians, Cretans, and Greeks. The Romans also practised fresco painting; fine examples have been found in Herculaneum and Pompeii. In early Christian times (2nd century ad) frescoes were used to decorate the walls of catacombs, or underground burial chambers. The art of fresco underwent a great revival in Italy during the 13th and 14th centuries, begun by the Florentine painters Cimabue and Giotto, who painted numerous fine examples in churches in Assisi, Florence, and Pisa. In the 15th century the art flourished in Florence, notably in the work of Masaccio, Benozzo Gozzoli, and Ghirlandaio. Fresco painting reached its peak in the 16th century, with the supreme achievements of Raphael in the Vatican Palace and with The Last Judgement and Genesis frescoes by Michelangelo in the Vatican's Sistine Chapel.

Fresco painting was widely practised in Europe in the 18th century, with nobility of style replaced by elegance and illusionistic effects. One outstanding fresco painter in this period was Giovanni Battista Tiepolo in Italy. In the 19th century the art was revived, largely for the embellishment of public buildings. The most important centre for fresco painting in the 20th century has been Mexico. Two Mexican painters in particular, Diego Rivera and José Clemente Orozco, created outstanding frescoes in Mexican government buildings.

Fresco painting also flourished in India. Famous examples include frescoes in Ajanta Caves, painted between 200 bc and ad 650, and at Ellora, dating from the late 8th century. Painting on plaster walls was also an ancient art in China; examples dating from the 5th century onwards, and depicting scenes from the life of the Buddha, survive in the Cave of the Thousand Buddhas, at Tun-huang in north-western Kansu.