Sculpture (Latin sculpere,"to carve"), three-dimensional art concerned with the organization of masses and volumes. The two principal types have traditionally been freestanding sculpture in the round and relief sculpture.
MATERIALS AND TECHNIQUES
Sculpture can be made from almost any organic or inorganic substance. The processes specific to making sculpture date from antiquity and, up to the 20th century, underwent only minor variations. These processes can be classified according to materials - stone, metal, clay, and wood; the methods used are carving, modeling, and casting. In the 20th century the field of sculpture was enormously broadened and enriched by new techniques, such as welding and assemblage, and by new materials resulting from technology, such as neon tubing.
Carving: A procedure dating from prehistoric times, carving is a time-consuming and painstaking process in which the artist subtracts, or cuts away, superfluous material until the desired form is reached. The material is usually hard and frequently weighty; generally, the design is compact and is governed by the nature of the material. For example, the narrow dimensions of the marble block used by Michelangelo to carve his David (1501-1504, Accademia, Florence, Italy) strongly affected the pose and restricted the figure's outward movement into space.
Various tools are used, depending on the material to be carved and the state to which the work has progressed. In the case of stone, the rough first cutting to achieve the general shape may be performed by an artisan assistant using sharp tools; then the sculptor continues the work of cutting and chiseling. As work progresses, less penetrating tools are used, such as a bow drill and a rasp; finishing touches are carried out with fine rasps; then by rubbing with pumice or sand, and - if a great degree of smoothness is desired - by adding a transparent patina, made with an oil or wax base.
Modeling: Modeling consists of addition to, or building up of, form. The materials used are soft and yielding and can be easily shaped, enabling rapid execution. Thus, a sculptor can capture and record fleeting impressions much the way a painter does in a quick sketch. Clay or claylike substances, baked to achieve increased durability, have been used for modeling since ancient times.
Casting: The only means of obtaining permanence for a modeled work is to cast it in bronze or some other durable substance. Two methods of casting are used: the cire perdue, or lost-wax process, and sand-casting. Both methods have been used since antiquity, although the lost-wax process is more widely employed. Casting is accomplished in two stages: First, an impression or negative mold is formed from the original - a clay model, for instance - and second, a positive cast or reproduction is made of the original work from the negative impression. The term negative refers to the hollow form or mold into which the liquefied casting material is poured. The term positive means the copy or reproduction resulting from filling the negative mold with the substances selected for the specific cast, which are then allowed to harden. Plaster is frequently used for the negative mold, and bronze for the positive or final work.
Construction and Assemblage: Although traditional techniques are still employed, much 20th-century sculpture was created by construction and assemblage. These methods have their origin in collage, a painting technique devised by Pablo Picasso and the French artist Georges Braque in 1912, in which paper and foreign materials are pasted to a picture surface. Picasso also made three-dimensional objects such as musical instruments out of paper and scraps of diverse materials, which were termed constructions. Examples of modern constructivist sculpture range from the surrealistic boxes of Joseph Cornell to the junk-car and machine-part works of John Chamberlain, both Americans. The term assemblage, which is now sometimes used interchangeably with construction, was coined by the French painter Jean Dubuffet to refer to his own work, which grew out of collage.