The word tempera originally came from the verb temper, “to bring to a desired consistency.” Dry pigments are made usable by “tempering” them with a binding and adhesive vehicle. Such painting was distinguished from fresco painting, the colours for which contained no binder. Eventually, after the rise of oil painting, the word gained its present meaning.
The standard tempera vehicle is a natural emulsion, egg yolk, thinned with water. Variants of this vehicle have been developed to widen its use. Among the man-made emulsions are those prepared with whole egg and linseed oil, with gum, and with wax.
Martini, Simone: Christ Discovered in the TempleChrist Discovered in the Temple, egg tempera on panel with gold leaf by Simone Martini, 1342; in the Walker Art Gallery, Liverpool. 49.5 × 35 cm.Board of Trustees of the National Museums and Galleries in Merseyside (Walker Art Gallery Liverpool)
The special ground for tempera painting is a rigid wood or wallboard panel coated with several thin layers of gesso, a white, smooth, fully absorbent preparation made of burnt gypsum (or chalk, plaster of Paris, or whiting) and hide (or parchment) glue. A few minutes after application, tempera paint is sufficiently resistant to water to allow overpainting with more colour. Thin, transparent layers of paint produce a clear, luminous effect, and the colour tones of successive brushstrokes blend optically. Modern tempera paintings are sometimes varnished or overpainted with thin, transparent oil glazes to produce full, deep-toned results, or they are left unglazed for blond, or light, effects.
Martini, Simone: detail of The AnnunciationDetail of The Annunciation, tempera on wood by Simone Martini and Lippo Memmi, 1333; in the Uffizi Gallery, Florence.© Photos.com/Jupiterimages
The great tradition of tempera painting was developed in Italy in the 13th and 14th centuries by Duccio di Buoninsegna and Giotto and continued in the work of Giovanni Bellini, Piero della Francesca, Carlo Crivelli, Sandro Botticelli, and Vittore Carpaccio. The 20th century saw a revival of tempera by American artists Ben Shahn, Andrew Wyeth, and Jacob Lawrence and by the British painter Lucian Freud. Mid-to-late 20th-century artists such as Andy Warhol, Mark Rothko, and David Hockney might have used tempera had it not been replaced mid-century by acrylic paints.
Madonna Rucellai, tempera on wood by Duccio, 1285; in the Uffizi Gallery, Florence.Alinari/Art Resource, New York
Fresco
Fresco (Italian: “fresh”) is the traditional medium for painting directly onto a wall or ceiling. It is the oldest known painting medium, surviving in the prehistoric cave mural decorations and perfected in 16th-century Italy in the buon’ fresco method.
Cave painting of a bull and a horse; in Lascaux Grotto, near Montignac, France.Hans Hinz, Basel
Magdalenian cave painting of a bison, Altamira, SpainA. Held/J.P. Ziolo, ParisThe cave paintings are thought to date from about 20,000–15,000 bce. Their pigments probably have been preserved by a natural sinter process of rainwater seeping through the limestone rocks to produce saturated bicarbonate. The colours were rubbed across rock walls and ceilings with sharpened solid lumps of the natural earths (yellow, red, and brown ochre). Outlines were drawn with black sticks of wood charcoal. The discovery of mixing dishes suggests that liquid pigment mixed with fat was also used and smeared with the hand. The subtle tonal gradations of colour on animals painted in the Altamira and Lascaux caves appear to have been dabbed in two stages with fur pads, natural variations on the rock surface being exploited to assist in creating effects of volume. Feathers and frayed twigs may have been used in painting manes and tails.
These were not composite designs but separate scenes and individual studies that, like graffiti drawings, were added at different times, often one on top of another, by various artists. Paintings from approximately 18,000 to 11,000 years ago, during the Magdalenian period, exhibit astonishing powers of accurate observation and ability to represent movement. Women, warriors, horses, bison, bulls, boars, and ibex are depicted in scenes of ritual ceremony, battle, and hunting. Among the earliest images are imprinted and stencilled hands. Vigorous meanders, or “macaroni” linear designs, were traced with fingers dipped in liquid pigment. Fresco secco
In the fresco secco, or lime-painting, method, the plastered surface of a wall is soaked with slaked lime. Lime-resistant pigments are applied swiftly before the plaster sets. Secco colours dry lighter than their tone at the time of application, producing the pale, matte, chalky quality of a distempered wall. Although the pigments are fused with the surface, they are not completely absorbed and may flake in time, as in sections of Giotto’s 14th-century San Francesco murals at Assisi. Secco painting was the prevailing medieval and early Renaissance medium and was revived in 18th-century Europe by artists such as Giovanni Battista Tiepolo, François Boucher, and Jean-Honoré Fragonard. Buon’ fresco
Buon’, or “true,” fresco is the most-durable method of painting murals, since the pigments are completely fused with a damp plaster ground to become an integral part of the wall surface. The stone or brick wall is first prepared with a brown trullisatio scratch coat, or rough-cast plaster layer. This is then covered by the arricciato coat, on which the linear design of the preparatory cartoon is pounced or engraved by impressing the outlines into the moist, soft plaster with a bone or metal stylus. These lines were usually overworked in reddish sinopia pigment. A thin layer of fine plaster is then evenly spread, allowing the linear design to show through. Before this final intonaco ground sets, pigments thinned with water or slaked lime are applied rapidly with calf-hair and hog-bristle brushes; depth of colour is achieved by a succession of quick-drying glazes. Being prepared with slaked lime, the plaster becomes saturated with an aqueous solution of hydrate of lime, which takes up carbonic acid from the air as it soaks into the paint. Carbonate of lime is produced and acts as a permanent pigment binder. Pigment particles crystallize in the plaster, fusing it with the surface to produce the characteristic lustre of buon’ fresco colours. When dry, these are matte and lighter in tone. Colours are restricted to the range of lime-resistant earth pigments. Mineral colours such as blue, affected by lime, are applied over earth pigment when the plaster is dry.
Plato and Aristotle surrounded by philosophers, detail from School of Athens, fresco by Raphael, 1508–11; in the Stanza della Segnatura in the Vatican.Erich Lessing/Art Resource, New York
The intonaco coat is laid only across an area sufficient for painting before the plaster sets. The joins between each successive “day piece” are sometimes visible. Alterations must be made by immediate washing or scraping; minor retouching to set plaster is possible with casein or egg tempera, but major corrections necessitate breaking away the intonaco and replastering. The swift execution demanded stimulates bold designs in broad masses of colour with a calligraphic vitality of brush marks.
No ancient Greek buon’ frescoes now exist, but forms of the technique survive in the Pompeian villas of the 1st century ce and earlier, in Chinese tombs at Liaoyang, Manchuria, and in the 6th-century Indian caves at Ajanta. Among the finest buon’ fresco murals are those by Michelangelo in the Sistine Chapel and by Raphael in the Stanze of the Vatican. Other notable examples from the Italian Renaissance can be seen in Florence: painted by Andrea Orcagna in the Museo dell’Opera di Santa Croce, by Gozzoli in the chapel of the Palazzo Medici-Riccardi, and by Domenico Ghirlandaio in the church of Santa Maria Novella. Buon’ fresco painting is unsuited to the damp, cold climate of northern countries, and there is now some concern for the preservation of frescoes in the sulfurous atmosphere of even many southern cities. Buon’ fresco was successfully revived by the Mexican mural painters Diego Rivera, José Orozco, and Rufino Tamayo.