The process of direct carving imposes a characteristic order on the forms of sculpture. The faces of the original block, slab, or cylinder of material can usually still be sensed, existing around the finished work as a kind of implied spatial envelope limiting the extension of the forms in space and connecting their highest points across space. In a similar way, throughout the whole carving, smaller forms and planes can be seen as contained within implied larger ones. Thus, an ordered sequence of containing forms and planes, from the largest to the smallest, gives unity to the work. Indirect carving
All of the great sculptural traditions of the past used the direct method of carving, but in Western civilization during the 19th and early 20th centuries it became customary for stone and, to a lesser extent, wood sculpture to be produced by the indirect method. This required the production of a finished clay model that was subsequently cast in plaster and then reproduced in stone or wood in a more or less mechanical way by means of a pointing machine (see Pointing below). Usually the carving was not done by the sculptor himself. At its worst, this procedure results in a carved copy of a design that was conceived in terms of clay modeling. Although indirect carving does not achieve aesthetic qualities that are typical of carved sculpture, it does not necessarily result in bad sculpture. Rodin’s marble sculptures, for example, are generally considered great works of art even by those who object to the indirect methods by which they were produced. The indirect method has been steadily losing ground since the revival of direct carving in the early 20th century, and today it is in general disrepute among carvers. Carving tools and techniques
The tools used for carving differ with the material to be carved. Stone is carved mostly with steel tools that resemble cold chisels. To knock off the corners and angles of a block, a tool called a pitcher is driven into the surface with a heavy iron hammer. The pitcher is a thick, chisel-like tool with a wide beveled edge that breaks rather than cuts the stone. The heavy point then does the main roughing out, followed by the fine point, which may be used to within a short distance of the final surface. These pointed tools are hammered into the surface at an angle that causes the stone to break off in chips of varying sizes. Claw chisels, which have toothed edges, may then be worked in all directions over the surface, removing the stone in granule form and thus refining the surface forms. Flat chisels are used for finishing the surface carving and for cutting sharp detail. There are many other special tools, including stone gouges, drills, toothed hammers (known as bushhammers or bouchardes), and, often used today, power-driven pneumatic tools, for pounding away the surface of the stone. The surface can be polished with a variety of processes and materials.
Wood turning at a craft studio, County Meath, Leinster, Ire.Brian Morrison/Tourism Ireland
Because medieval carvers worked mostly in softer stones and made great use of flat chisels, their work tends to have an edgy, cut quality and to be freely and deeply carved. In contrast is the work done in hard stones by people who lacked metal tools hard enough to cut the stone. Egyptian granite sculpture, for example, was produced mainly by abrasion; that is, by pounding the surface and rubbing it down with abrasive materials. The result is a compact sculpture, not deeply hollowed out, with softened edges and flowing surfaces. It usually has a high degree of tactile appeal.
Although the process of carving is fundamentally the same for wood or stone, the physical structure of wood demands tools of a different type. For the first blocking out of a wood carving a sculptor may use saws and axes, but his principal tools are a wide range of wood-carver’s gouges. The sharp, curved edge of a gouge cuts easily through the bundles of fibre and when used properly will not split the wood. Flat chisels are also used, especially for carving sharp details. Wood rasps, or coarse files, and sandpaper can be used to give the surface a smooth finish, or, if preferred, it can be left with a faceted, chiseled appearance. Wood-carving tools have hardwood handles and are struck with round, wooden mallets. African wood sculptors use a variety of adzes rather than gouges and mallets. Ivory is carved with an assortment of saws, knives, rasps, files, chisels, drills, and scrapers. Modeling
In contrast to the reductive process of carving, modeling is essentially a building-up process in which the sculpture grows organically from the inside. Numerous plastic materials are used for modeling. The main ones are clay, plaster, and wax; but concrete, synthetic resins, plastic wood, stucco, and even molten metal can also be modeled. A design modeled in plastic materials may be intended for reproduction by casting in more permanent and rigid materials, such as metal, plaster, concrete, and fibreglass, or it may itself be made rigid and more permanent through the self-setting properties of its materials (for example, plaster) or by firing. Modeling for casting
The material most widely used for making positive models for casting is clay. A small, compact design or a low relief can be modeled solidly in clay without any internal support; but a large clay model must be formed over a strong armature made of wood and metal. Since the armature may be very elaborate and can only be altered slightly, if at all, once work has started, the modeler must have a fairly clear idea from his drawings and maquettes of the arrangement of the main shapes of the finished model. The underlying main masses of the sculpture are built up firmly over the armature, and then the smaller forms, surface modeling, and details are modeled over them. The modeler’s chief tools are his fingers, but for fine work he may use a variety of wooden modeling tools to apply the clay and wire loop tools to cut it away. Reliefs are modeled on a vertical or nearly vertical board. The clay is keyed, or secured, onto the board with galvanized nails or wood laths. The amount of armature required depends on the height of the relief and the weight of clay involved.
To make a cast in metal, a foundry requires from the sculptor a model made of a rigid material, usually plaster. The sculptor can produce this either by modeling in clay and then casting in plaster from the clay model or by modeling directly in plaster. For direct plaster modeling, a strong armature is required because the material is brittle. The main forms may be built up roughly over the armature in expanded wire and then covered in plaster-soaked scrim (a loosely woven sacking). This provides a hollow base for the final modeling, which is done by applying plaster with metal spatulas and by scraping and cutting down with rasps and chisels.
Fibreglass and concrete sculptures are cast in plaster molds taken from the sculptor’s original model. The model is usually clay rather than plaster because if the forms of the sculpture are at all complex it is easier to remove a plaster mold from a soft clay model than from a model in a rigid material, such as plaster.
A great deal of the metal sculpture of the past, including Nigerian, Indian, and many Renaissance bronzes, was produced by the direct lost-wax process, which involves a special modeling technique (see Casting and molding below). The design is first modeled in some refractory material to within a fraction of an inch of the final surface, and then the final modeling is done in a layer of wax, using the fingers and also metal tools, which can be heated to make the wax more pliable. Medallions are often produced from wax originals, but because of their small size they can be solid-cast and therefore do not require a core. Modeling for pottery sculpture