Sculptural Techniques and Materials

Sculpture also has - or had until the present century - two basic techniques: modelling and carving. As one depends on building up clay or other malleable material and the other on reducing a piece of stone or wood, they are called additive and subtractive processes. (Cast bronze sculpture usually derived from modelling, so too did the iron statues produced mainly in fifteenth- and sixteenth-century China; but iron is nowadays more usually forged and welded - see below. Such soft metals as gold, silver and copper may be either cast in a modelled mold or hammered into shape and chiselled by techniques akin to carving.) Carvers are restricted by the natural characteristics, shape and consistency of their materials and the efficiency of tools with which to fashion them. The cylinder of a tree-trunk, for example, is like an invisible cage enclosing a statue carved from a single piece of wood. The regularity of a block of stone hewn in the quarry similarly determines the form of a figure when a carver begins by drawing outlines on its four sides. Hardness or brittleness of stone dictates the degree of delicacy with which it can be worked. Iron chisels and drills, which came into use in the West in the first millennium BC, greatly lightened the carver's task and opened up new possibilities, especially in undercutting, though they resulted mainly in increased production. Some of the most finely worked statues ever created were carved without their aid from the hardest of stones in ancient Egypt. In wood, effects of the greatest intricacy and delicacy were often obtained with the simplest implements, such as flakes of stone and seashells in Melanesia.

So far as the history of European sculpture is concerned, by far the most important development was the invention, probably in fifth-century BC Greece, of a technique that enabled a sculptor to carve in stone an accurate version of a model in clay, plaster or some other easily manipulated substance. The model was marked at extremities with 'points' and the distances between them and a plumb line or wooden framework were measured so that holes of equivalent depth could be drilled into a marble block at corresponding points. The material between these holes was then chiselled away to reveal a rough version of the model. An ancient Greek statue, abandoned at this stage, has by chance survived (0,1). This process was carried on unchanged until the early nineteenth century, as illustrated in manuals published for sculptors (0,2). Later, instruments

were devised to measure any protuberance or cavity in the model from three fixed points and thus facilitate the finishing of the marble. By simple multiplication or division of the various measurements an enlarged or reduced scale version of the model could be carved. In nineteenth-century Europe this technique of working from points enabled many sculptors to confine themselves to modelling in clay and leave the arduous task of carving to assistants - in France called practiciens, practitioners of their craft, as distinct from creative artists.

Modellers are, however, restricted by the properties of clay, for no form extending far beyond the lump into which it naturally subsides when damp will remain standing without an interior skeleton of wood or metal. Clay figures are also impermanent unless baked hard - that is, transformed into terracotta - in an oven the heat of which must be controlled to prevent fragmentation. In the second half of the third millennium BC it was discovered in Mesopotamia (and somewhat later elsewhere) that a durable version of a clay statue could be made in bronze by a cire perdue or lost-wax process of casting. Two analogous procedures were later evolved. By one the figure modelled

in clay was covered with wax to the thickness required for the bronze and then thickly encased in more clay, leaving apertures in this outer coating through which molten bronze could be poured and many smaller holes through which the wax - which melted on contact - could escape. Alternatively, by the negative process of casting, hollow molds were made from the two sides of a model, their interior surfaces were covered with wax of appropriate thickness, they were then joined together and filled with a core, the bronze was poured in and the wax expelled. Whichever process was adopted, the outer casing was removed when the metal had cooled and hardened, the remains of the original model or core were then shaken out, leaving a shell of bronze which was finished by hammering and scraping away any blemishes. (For casting bronze vessels a different system was developed in China in the second millennium bc; see pp. 89-91.)

As hollow bronze statues are much lighter in weight than equivalent pieces of stone (especially marble and other close-grained stones favoured for their durability) and also have some resilience, the medium permits a wider range of formal effects. Stone sculptures must be columnar, cubic or pyramidal if they are to stand upright. The legs of a standing figure cannot be placed wide apart unless a third support is provided to prevent fracture at the ankles. Bronze figures, on the other hand, may be delicately, even precariously, balanced, giving an appearance of living, breathing movement rare in marble statues. The fourth-century bc Greek Boy from Antikythera is a notable example (0,3). When a Greek bronze statue was copied in marble in Roman times, the insertion of a third support, usually a tree-stump, was necessary and the figure lost much of its vitality as a result. (This is very obvious in copies of Myron's Discobolus, 4,33.)

In stone and wood, as well as clay and bronze, sculptors in many parts of the world have, nevertheless, succeeded in making images that are convincingly lifelike - more so, indeed, than casts taken from living bodies. Their production involves much more than the meticulous imitation of forms and surfaces. But this has rarely been regarded as the principal aim of sculpture, most of which has been devoted to religious and otherworldly subjects -statues of the Buddha and Hindu deities, cult figures carved in Africa and Polynesia, and masks in the American north-west. In the twentieth century verisimilitude was completely disregarded by many Western artists who conceive sculpture as the art of creating three-dimensional forms often only barely, if at all, representational in intention. Many have abandoned the long-established techniques of carving and modelling as well as such traditional materials as marble and bronze. Instead, iron has been much used as a medium, wrought by the processes of forging, hammering and welding formerly used for making weapons and utilitarian objects. It was the use of iron that made possible a great revolution in sculpture during this century: the shift away from 'closed' (solid) to 'open' (constructed) form. Gonzalez's work, and in particular his collaboration with Picasso in the 1920s and 1930s, was the catalyst for this breakthrough. Gonzalez himself was one of its great exponents (20,23). Later, new synthetic materials were taken up and three-dimensional works were made by 'assembling' pieces of the most miscellaneous materials. Some artists have extended 'sculpture' to include their own bodies (see p. 864).

Painting Techniques and Materials

The only basic practical problem confronting painters was that of fixing pigments to a ground in order to preserve them (though durability has not always been desired; many paintings were and are intended to last no more than a short time). There are normally three layers to a painting: a prepared ground between a film of pigment and the support, which may be a rock-face, a wall or some transportable material such as wood, paper, canvas or other textile. Pigments are basically of two types: stains that are absorbed into the ground and colored powders (mainly of mineral substances) mixed with some adhesive binding agent and applied on to the ground. The former have been used since very early times in many parts of the world to paint on absorbent plastered walls and ceilings. They are those adopted for fresco - a term which is often given to various types of mural paintings but should be reserved for those in which the pigment is absorbed into the wall surface, notably the technique perfected in Italy towards the end of the thirteenth century by Giotto.

For true fresco a wall or ceiling was usually covered with a fairly smooth layer of plaster which was allowed to dry before the painting was executed on another layer of plaster while it was still damp and fresh {fresco in Italian). As plaster dries quickly, no more than a section of the composition could be painted at a time, such a section being called in Italy a giornata or 'a day's work' (0,4). To avoid discontinuities between one completed section and the next - a hazard of this piecemeal manner of working -some fourteenth-century artists sketched the outlines of their compositions in a red ochre pigment (called sinopia) on to the first coat of plaster. (Some of these so-called sinopie drawings have been revealed in recent restorations.) Later the composition was sometimes drawn on paper (called a cartoon) temporarily applied to the dry plaster, which was marked through holes pricked around the main contours. (Raphael did this when painting the Stanze in the Vatican) The great advantage of fresco painting is that the pigments absorbed into the thickness of the plaster have great durability - with the corresponding disadvantage that no alterations or corrections can be

made in the course of painting. Also, the range of pigments that could be used was limited. Some colors, notably blue and a few reds and greens, could be applied only after the fresco was dry (secco in Italian). In fifteenth-century Italy artists made increasing use of pigments applied a secco. But around 1500 there was a revival of pure fresco technique, which came to be regarded by art theorists as the ideal means for painting walls and ceilings, and also as the one that revealed artistic proficiency most clearly. It required, as Giorgio Vasari later remarked, a hand 'dextrous, resolute and rapid','nimble and free'. Frescoes are large, but a somewhat similar technique was developed before the beginning of the sixteenth century for painting on small sheets of paper in watercolor. Pigments were mixed with a gum that dissolves in water and thus provides transparent stains. This, too, required rapid and free handling, for once the color had been applied and absorbed by the ground, the watercolorist, like the fresco painter, could make no changes - except by superimposing them with solid pigments or body-colors.

For painting on panels of wood, the technique generally adopted in Europe from about the twelfth century onwards was tempera: powdered pigments made workable (tempered) by egg-yolk and mixed with some form of gum. The support was covered with gesso (plaster mixed with size) on to which the composition was drawn and/or incised. If some areas were to be gilded, as they often were, they were coated with bole (a type of fine red clay) which was burnished and then covered with very thin sheets of gold leaf. Other parts were underpainted in low tones of the desired colors and finished with one layer above another of translucent tempera paint, each of which had to be completed quickly before it dried. Details could be rendered with greater delicacy than in fresco and the final work also had greater luminosity. But such effects could be more easily attained with oil paint which, in the fifteenth century, gradually superseded tempera (not to be revived until the twentieth century). Pigments had been mixed with oils for some types of painting (for example, on shields) in ancient Roman times and in the early Middle Ages. And oil painting, as the term is understood today, was not an invention, attributable to an individual at a particular moment, but a gradual, perhaps trial-and-error, development in the studios of artists some of whom mixed pigments with oils as well as egg-yolk. By the 1430s, however, Jan van Eyck and probably other painters in the Netherlands evolved mixtures that included oil (from linseed or nuts) fused with a hard resin (amber or copal) diluted with oil derived from lavender or rosemary. This was a light, fluid medium which dried easily but slowly, permitting the careful depiction of minute details. Transparent oil pigments applied in layers gave an effect of extraordinary luminosity as may be seen, for instance, in the Ghent Altarpiece (0,5). This type of oil medium was, however, suitable for painting only on panel or fine linen that was subsequently glued to a wooden support. A different mixture including a soft, rather than a hard, resin was developed in Italy for painting on canvas stretched

over a wood frame, which became the preferred type of support for all but very small oil paintings throughout Europe. It permitted much freer brushwork than tempera while also offering unlimited possibilities for shading, scumbling (applying a layer of opaque or semi-opaque pigment irregularly so that some of the color beneath remains visible), retouching and superimposing glazes (transparent films which modify underlying colors).

Painters evolved innumerable variants on the basic mixture in order to obtain not only the colors they wanted but also the consistency of the medium which might be either liquid or so thick it could be applied with a spatula if not the fingers. And in the course of time attempts were made to rediscover those found empirically - guided by experience and perhaps helped by accident - by the most famous painters, notably Titian (11,45; 46; 47; 48). Pigments that had been powdered and combined with other substances in the studios of medieval artists became, by the early sixteenth century, increasingly available ready-for-use from specialist colormen. Painters differed from one another in the pigments they used for their ground color, and still more in the mixtures they evolved to obtain the final hues. Not until the nineteenth century was the range of colors derived from natural mineral and vegetable sources expanded by the commercial production of synthetic pigments, which were similarly mixed with linseed and other oils.

Artists in the West have continued to use and exploit oil paint to the present day. There was, in fact, no other medium as satisfactory for large-scale painting on movable supports until the development in the 1960s of acrylic, a synthetic emulsion (a kind of plastic) which can be applied in the same way. Acrylic has often been adopted by artists in reaction against the mystique of oil paint (21,19) - the exaggerated prestige accorded to the medium itself, especially by connoisseurs with their admiration for bravura brushwork and their relish for the consistency of the pigments themselves, called matiere in French with a suggestion of their luscious, juicy and other sensuously delectable qualities. (The only competitor for portraiture was pastel: painting with opaque dry chalks mixed with a little adhesive, perfected in the eighteenth century [14,18] and, after falling from favour, revived in the late nineteenth.)

The framed picture on canvas is a Western phenomenon (not imitated elsewhere before the nineteenth century) and its popularity in the West accounts for the prestige acquired by the art of painting from the sixteenth century onwards. To it is also due the distinction made between painting and the crafts. In the Middle Ages paintings on precious metals in enamel (a kind of colored glass which required great skill in handling) had been more highly prized than those in tempera which, with their gilding, were often made in emulation of them. Similarly, mosaics composed of little cubes of variously colored stones and glass, embroidered panels and woven tapestries were all more highly regarded and more costly than fresco paintings for covering walls and ceilings - not only because they required greater expenditure of time and materials. Later the relationship was reversed and oil paintings set the standard. Although tapestries remained the most expensive form of wall decoration until the late eighteenth century they were usually designed by artists distinguished as painters, and their skilful weavers ranked as subservient craftsmen. Embroidery, very often the work of women and less dependent than tapestries'bn models by painters, was also downgraded.

Print-making

In the production of prints there has also been, mainly in the West and since the sixteenth century, a division of labour between designers and executants. The purpose of print-making is to produce a number of copies of a single design on sheets of paper, silk or any other material that will absorb ink. The earliest technique was that of the woodcut by which the design was drawn on a smooth block of wood, the parts that were to be white on the print were cut away, those that were to be black were left standing up in relief and covered with ink so that when the block was pressed on to paper or a textile it left an impression of the design in reverse. (This is known as a relief print.) It was first used in China in the seventh century AD for printing images of the Buddha and in Europe in the fourteenth century for Christian images. By alternative processes developed in Europe from the mid-fifteenth century, intaglio prints were made from metal plates in which the parts that are to be black and carry ink are incised by tools (engravings) or eaten away by acid (etchings). From the sixteenth century the drawing of designs and the cutting of woodblocks or the engraving of metal plates were usually separate activities. Copper-plate engravings with their fine firm lines soon superseded woodcuts for scientific illustration, anatomical, zoological, botanical and so on. For imaginative work, artists sometimes engraved copper plates but generally preferred etchings which they executed themselves, drawing with a needle on wax-coated copper plate sub-sequently immersed in acid which ate into the parts exposed by the needle (see p. 608). From the early nineteenth century artists also made prints by the process of lithography - drawing with an oily crayon on stone (15,18).

Woodcuts, engravings, etchings and lithographs both designed and executed by the same hand are termed 'original prints', as distinct from 'reproductive prints' executed by specialist print-makers, who copied the works of painters or draftsmen using a variety of techniques, often with the greatest skill. In the nineteenth century it was discovered that prints of very high technical quality could be made from engravings on steel-coated plates, which yielded a far greater number of copies than easily damaged copper. But artists took little interest in this process which was used mainly for illustrations - in books and periodicals - until it was superseded by photography. In the meantime Japanese artists had developed a woodcut process for making color prints which were imported into Europe and America from the 1850s and enthusiastically received by many artists who welcomed an escape from the European tradition of oil painting. In the West these prints were sometimes copied, and their effects emulated, in oil paint, as well as influencing etching and lithography (see p. 662). Early in the twentieth century several European artists reverted to print-making with woodblocks, emphasizing obviously hand-cut irregularities for expressive effect.

Photography

Photography, from the time of its invention in the 1830s, was closely allied with both painting and print-making. It had for long been known that light, if passed through a very small aperture, would project an image (in reverse) on to the side of a dark chamber - the camera obscura occasionally used by artists as an aid for painting townscapes and interiors in perspective. The initial purpose of photography was to fix such images, and two processes were devised simultaneously. That discovered by the French painter Louis-Jacques-Mande Daguerre by 1837 fixed the image on a sensitized copper plate called a daguerreotype. This was a unique object, like a painting or drawing, and was much used for portraits. In England, William Henry Fox Talbot succeeded before 1839 in fixing negative images on sheets of translucent paper which could then be placed over sheets of opaque sensitized paper and exposed to light to make positive prints. The advantage was that many identical prints could be made from a single negative. They were, however, slightly fuzzy on account of the uneven texture of the translucent paper (15,31). The introduction of glass plates for negatives in the 1850s facilitated the production of prints as sharply defined as daguerreotypes, which they soon superseded.

Subsequent developments were mainly technical improvements, notably those that reduced the time needed for an exposure and by the 1870s made possible split-second photographs of figures in motion (15,58). Meanwhile there had been much controversy as to whether photography should or could be considered an art (see p. 674). Until the mid-century photographs were occasionally hung among lithographs in official exhibitions of art. After that they were excluded and shown only in specialized exhibitions. At about the same time, selfconsciously artistic photographers began to select subjects similar to those of painters, concentrating on softly focused images of motionless figures and scenes. Sometimes the results might almost be mistaken for photographs of paintings. Blessed Art Thou Among Women (0,6) by the American photographer Gertrude Kasebier (1851-1934), for example, ranks with several notable paintings among the most compelling images of its period. Developments in the science of photography were exploited mainly by documentary photographers whose shots of street scenes (15,59) are considered nowadays to be among the finest photographs ever taken but were regarded at the time simply as photo-records, certainly not as works of art.

The cult of the unique art object led some photographers to reject the possibility of making innumerable prints from a single negative and to issue limited editions, each print being numbered and signed and slightly different from the others as a result of manipulation in the dark room. Although the process of color photography was perfected in the 1940s most of them continued, as some still do, to prefer monochrome. There is no more striking instance of unsynchronized and often contradictory developments in technology and art than that presented by the century-and-a-half history of photography. Despite the great achievements of so many photographers, it has only recently won widespread acceptance as a vehicle for artistic expression, with unique potentialities even when the very simplest equipment is used.

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