fresco

fresco. A method of wall painting in which powdered pigments mixed only in water are applied to wet plaster freshly laid on the wall (the word ‘fresco’ is Italian for ‘fresh’). As the wall dries an irreversible chemical reaction occurs that binds the pigment with the plaster, making the picture an integral part of the wall (the lime (calcium hydroxide) of the plaster combines with carbon dioxide in the atmosphere to form a crust of calcium carbonate). This technique is also called buon fresco or fresco buono (true fresco) to distinguish it from painting on dry plaster, which is called by analogy fresco secco or simply secco. Buon fresco is exceptionally permanent in dry climates, but if damp penetrates the wall, the plaster is liable to crumble and the paint with it. Consequently the art has been practised chiefly in dry countries, particularly in Italy (though less often in watery Venice), and seldom in northern Europe. The technique is of great antiquity. Minoan and Greek wall paintings were probably in fresco; those at Pompeii certainly are and the Roman writer Vitruvius describes a method much like that in use during the Renaissance. Fresco painting is also found outside Europe, for example in China and India.

The Italian practice was described in detail by Cennini in the early 15th century. The wall was first given a coating of plaster, prepared from lime and sand in water. When this rough surface (the arricciato) had dried, any horizontal, vertical, or diagonal guidelines needed were produced by ‘snapping’ a stained cord or string between appropriate points on the wall, and the basic design was drawn in charcoal. Over the charcoal the design was indicated in more detail in a red chalk called sinopia. A layer of finer plaster, called the intonaco, was now applied over one section of the rougher arricciato. This was the actual painting ground and was made very smooth. Because the sinopia was covered by it, the essential lines of the buried drawing had to be quickly indicated again on the intonaco. At any one time, only as much plaster was applied as could be painted in one day, before it had time to dry. This might be a fairly large area if little detail were involved, for example in the sky, but a much smaller area might be given a day to itself if it required special care, for example the head of an important figure. On close examination joins can be discerned between areas of plaster that correspond to each day's work (giornato in Italian), so it is possible to calculate reasonably accurately the number of days' work that have gone into a fresco. In Giotto's Arena Chapel, for example, 852 giornate have been counted, so even allowing for the fact that assistants would almost certainly have painted repetitive areas such as decorative borders, the work probably took a minimum of two years. Cennini's account of fresco technique was written before the use of cartoons, which generally supplanted sinopie around the middle of the 15th century. Cartoons had the advantage not only of transferring the design accurately but also of transferring it directly onto the final painting surface (intonaco) rather than onto the arricciato.

The fresco painter had to work rapidly, before the plaster could dry; corrections were almost impossible to make without chipping away the plaster and applying a fresh surface, so the technique demanded a sure hand and purpose. The colours available were limited (they had to be chemically compatible with the process), and as they were apt to become lighter in drying, depth of tone was hard to attain. Blending, too, was difficult, so much use was made of hatching to produce tonal effects. Finishing touches were sometimes added after the plaster was dry (al secco), but this had to be done with egg tempera or size paint instead of pure pigment and water. Vasari called it a ‘vile practice’ and the parts done al secco were liable to flake off, but many of the greatest exponents of the art resorted to it. The difficulties and limitations of the technique encouraged the artist to design the subject broadly and treat it boldly, and did much to foster the purity, strength, and monumentality of Italian Renaissance painting.

Giotto stands at the head of the glorious Italian tradition of fresco painting, and from his time many of the leading Italian masters produced their most famous works in the medium: Masaccio, in the Brancacci Chapel, Florence; Piero della Francesca in S. Francesco, Arezzo; Michelangelo in the Sistine Chapel; Raphael in the Stanze at the Vatican; Correggio in his church domes at Parma; Annibale Carracci in the Farnese Gallery. It became less common in the 18th century and Giambattista Tiepolo was the last in the line of great Italian painters who used it. The medium was revived in the 19th century, notably by German painters such as the Nazarenes and Cornelius, but some notable decorators of the time, such as Delacroix and Puvis de Chavannes, preferred to use the method of marouflage. In the 20th century the greatest exponents of fresco were the Mexican muralists Orozco, Rivera, and Siqueiros.