Sculpture Techniques: Stone, Wood, and Ivory Carving
Stone has been almost universally employed as the chief material for monumental sculpture for a number of reasons. It is readily available in large quantities in most parts of the world. It is durable, weather resistant, homogeneous in texture, and uniform in hardness. And it has been the principal material used for the important buildings with which most monumental sculpture is associated.
The techniques used for stone carving depend on both the hardness of the stone itself and the quality of the metal tools available at the time. Gothic sculpture, mostly carved in softer stones with metal chisels, was usually cut boldly and deeply with considerable undercutting, deep shadows, and strong detail. Before the development of modern tools, harder stones, such as granite, were usually pulverized with hammers and then rubbed down with emery and similar abrasive materials, producing, for example, the smooth continuous surfaces and shallow detail of much Egyptian sculpture. All stones, however, are heavy and lacking in tensile strength and therefore encourage a massive and compact treatment without vulnerable projections or thin, easily fractured, supporting shapes. The ankles of free-standing figures, for example, are almost always given extra support.
Some sculptors have preferred to overcome rather than submit to the natural limitations of stone. A great deal of Hellenistic, Roman, and post-Renaissance European stone sculpture is very freely and openly carved out of a number of jointed blocks of stone. It often emulates the freedom of design, as seen, for example, in the outspread limbs and flying draperies of metal sculpture.
In direct stone carving, the main masses are first roughed out of the block, and the final detail is approached gradually by progressing from larger containing shapes to smaller contained ones. This systematic process imposes a characteristic order on the design of direct stone carvings. This order and other features are lost in indirect carving.
In indirect carving the design is first modeled in clay. This original model is then cast in plaster and handed over to a professional carver, who uses a pointing machine—a kind of three-dimensional tracing machine—for reproducing the design in stone. Inevitably the result has the plastic quality of modeling rather than carving.
Small-scale carvings in hard stones, such as jade, rock crystal, and agate—some of which are harder than steel—require special techniques of grinding, drilling, and abrading.
Because wood is affected by the weather and is subject to attack by insects or fungi, it does not survive the passage of time as well as stone. Nevertheless, it has been extensively used, mainly for indoor sculpture. It is the principal material of tribal sculpture in Africa, Oceania, and North America, and it has been used by every advanced civilization.
Both hardwoods and softwoods are used for sculpture. They are carved with either gouges or adzes, which are kept extremely sharp in order to cut through the bundles of wood fibers without splitting them.
Wood is a relatively light material with considerable tensile strength along its grain. It may therefore be carved openly, with more projections and thinner shapes than stone. It is also easily jointed for building up large works or for creating extensions into space, such as the arms of a crucifix. Boxwood, pear, and other close-grained woods may be carved on a small scale with a wealth of delicate detail. Open-grained woods, such as elm or pine, are better used on a large scale. Gothic wood sculpture shows the kind of complex designs that may be carved in wood, while the large elm figures of the 20th century sculptor Henry Moore show the kind of openness that may be achieved.
Ivory, obtained from elephant, mammoth, walrus, hippopotamus, and narwhal tusks, is available in only relatively small pieces. The tusks may be carved solid or sawed into panels and carved into reliefs. Because it is dense and hard, ivory may be carved with great delicacy into small, intricate designs. Tools include various saws, chisels, knives, rasps, and drills.