Sculptors use clay as a material for working out ideas; for preliminary models that are subsequently cast in such materials as plaster, metal, and concrete or carved in stone; and for pottery sculpture.
Depending on the nature of the clay body itself and the temperature at which it is fired, a finished pottery product is said to be earthenware, which is opaque, relatively soft, and porous; stoneware, which is hard, nonporous, and more or less vitrified; or porcelain, which is fine-textured, vitrified, and translucent. All three types of pottery are used for sculpture. Sculpture made in low-fired clays, particularly buff and red clays, is known as terra-cotta (baked earth). This term is used inconsistently, however, and is often extended to cover all forms of pottery sculpture.
Unglazed clay bodies can be smooth or coarse in texture and may be coloured white, gray, buff, brown, pink, or red. Pottery sculpture can be decorated with any of the techniques invented by potters and coated with a variety of beautiful glazes.
Paleolithic sculptors produced relief and in-the-round work in unfired clay. The ancient Chinese, particularly during the Tang (618–907) and Song (960–1279) dynasties, made superb pottery sculpture, including large-scale human figures. The best-known Greek works are the intimate small-scale figures and groups from Tanagra. Mexican and Maya sculptor-potters produced vigorous, directly modeled figures. During the Renaissance, pottery was used in Italy for major sculptural projects, including the large-scale glazed and coloured sculptures of Luca della Robbia and his family, which are among the finest works in the medium. One of the most popular uses of the pottery medium has been for the manufacture of figurines—at Staffordshire, Meissen, and Sèvres, for example.
Jaina pottery figurine, Late Classic Maya style, from Campeche, Mexico; in the collection of Dumbarton Oaks, Washington, D.C. Height 15.5 cm.Dumbarton Oaks/Trustees for Harvard University, Washington, D.C.
The main source of ivory is elephant tusks; but walrus, hippopotamus, narwhal (an Arctic aquatic animal), and, in Paleolithic times, mammoth tusks also were used for sculpture. Ivory is dense, hard, and difficult to work. Its colour is creamy white, which usually yellows with age; and it will take a high polish. A tusk may be sawed into panels for relief carving or into blocks for carving in the round; or the shape of the tusk itself may be used. The physical properties of the material invite the most delicate, detailed carving, and displays of virtuosity are common.
Ivory was used extensively in antiquity in the Middle and Far East and the Mediterranean. An almost unbroken Christian tradition of ivory carving reaches from Rome and Byzantium to the end of the Middle Ages. Throughout this time, ivory was used mainly in relief, often in conjunction with precious metals, enamels, and precious stones to produce the most splendid effects. Some of its main sculptural uses were for devotional diptychs, portable altars, book covers, retables (raised shelves above altars), caskets, and crucifixes. The Baroque period, too, is rich in ivories, especially in Germany. A fine tradition of ivory carving also existed in Benin, a former kingdom of West Africa.
Related to ivory, horn and bone have been used since Paleolithic times for small-scale sculpture. Reindeer horn and walrus tusks were two of the Eskimo carver’s most important materials. One of the finest of all medieval “ivories” is a carving in whalebone, The Adoration of the Magi (Victoria and Albert Museum, London).
Plaster of paris (sulfate of lime) is especially useful for the production of molds, casts, and preliminary models. It was used by Egyptian and Greek sculptors as a casting medium and is today the most versatile material in the sculptor’s workshop.
When mixed with water, plaster will in a short time recrystallize, or set—that is, become hard and inert—and its volume will increase slightly. When set, it is relatively fragile and lacking in character and is therefore of limited use for finished work. Plaster can be poured as a liquid, modeled directly when of a suitable consistency, or easily carved after it has set. Other materials can be added to it to retard its setting, to increase its hardness or resistance to heat, to change its colour, or to reinforce it.
The main sculptural use of plaster in the past was for molding and casting clay models as a stage in the production of cast metal sculpture. Many sculptors today omit the clay-modeling stage and model directly in plaster. As a mold material in the casting of concrete and fibreglass sculpture, plaster is widely used. It has great value as a material for reproducing existing sculpture; many museums, for example, use such casts for study purposes. Secondary
Basically, concrete is a mixture of an aggregate (usually sand and small pieces of stone) bound together by cement. A variety of stones, such as crushed marble, granite chips, and gravel, can be used, each giving a different effect of colour and texture. Commercial cement is gray, white, or black; but it can be coloured by additives. The cement most widely used by sculptors is ciment fondu, which is extremely hard and quick setting. A recent invention—at least, in appropriate forms for sculpture—concrete is rapidly replacing stone for certain types of work. Because it is cheap, hard, tough, and durable, it is particularly suitable for large outdoor projects, especially decorative wall surfaces. With proper reinforcement it permits great freedom of design. And by using techniques similar to those of the building industry, sculptors are able to create works in concrete on a gigantic scale.
When synthetic resins, especially polyesters, are reinforced with laminations of glass fibre, the result is a lightweight shell that is extremely strong, hard, and durable. It is usually known simply as fibreglass. After having been successfully used for car bodies, boat hulls, and the like, it has developed recently into an important material for sculpture. Because the material is visually unattractive in itself, it is usually coloured by means of fillers and pigments. It was first used in sculpture in conjunction with powdered metal fillers in order to produce cheap “cold-cast” substitutes for bronze and aluminum, but with the recent tendency to use bright colours in sculpture it is now often coloured either by pigmenting the material itself or by painting.
It is possible to model fibreglass, but more usually it is cast as a laminated shell. Its possibilities for sculpture have not yet been fully exploited.
Various formulas for modeling wax have been used in the past, but these have been generally replaced by synthetic waxes. The main uses of wax in sculpture have been as a preliminary modeling material for metal casting by the lost-wax, or cire-perdue, process (see Methods and techniques, below) and for making sketches. It is not durable enough for use as a material in its own right, although it has been used for small works, such as wax fruit, that can be kept under a glass dome.
Papier-mâché (pulped paper bonded with glue) has been used for sculpture, especially in the Far East. Mainly used for decorative work, especially masks, it can have considerable strength; the Japanese, for example, made armour from it. Sculpture made of sheet paper is a limited art form used only for ephemeral and usually trivial work.
Numerous other permanent materials—such as shells, amber, and brick—and ephemeral ones—such as feathers, baker’s dough, sugar, bird seed, foliage, ice and snow, and cake icing—have been used for fashioning three-dimensional images. In view of late 20th-century trends in sculpture it is no longer possible to speak of “the materials of sculpture.” Modern sculpture has no special materials. Any material, natural or man-made, is likely to be used, including inflated polyethylene, foam rubber, expanded polystyrene, fabrics, and neon tubes; the materials for a sculpture by Claes Oldenburg, for example, are listed as canvas, cloth, Dacron, metal, foam rubber, and Plexiglas. Real objects, too, may be incorporated in sculpture, as in the mixed-medium compositions of Edward Kienholz; even junk has its devotees, who fashion “junk” sculpture. Methods and techniques