Methods of Shaping
The potter's most basic tools are his or her hands, but many additional tools have been developed over the long history of pottery manufacture, including the potter's wheel and turntable, shaping tools (paddles, anvils, ribs), rolling tools (roulettes, slab rollers, rolling pins), cutting/piercing tools (knives, fluting tools, wires) and finishing tools (burnishing stones, rasps, chamois).
Pottery can be shaped by a range of methods that include:
Handwork or handbuilding
This is the earliest and the most individualized and direct forming method. Wares can be constructed by hand from coils of clay, from flat slabs of clay, from solid balls of clay — or some combination of these. Parts of hand-built vessels are often joined together with the aid of slurry or slip, a runny mixture of clay and water. Handbuilding is slower and more gradual than wheel-throwing, but it offers the potter a high degree of control over the size and shape of wares. While it isn't difficult for an experienced potter to make identical pieces of hand-built pottery, the speed and repetitiveness of wheel-throwing is more suitable for making precisely matched sets of wares such as table wares. Some potters find handbuilding more conducive to fully using the imagination to create one-of-a-kind works of art, while other potters find the spontaneity and immediacy of wheel-thrown pottery as their source of inspiration.
A ball of clay is placed in the center of a turntable, called the wheel-head, which the potter rotates with a stick, or with foot power (a kick wheel or treadle wheel) or with a variable speed electric motor. (Often, a disk of plastic, wood or plaster — called a bat — is first set on the wheel-head, and the ball of clay is thrown on the bat rather than the wheel-head so that the finished piece can be removed intact with its bat, without distortion.)
The potter's wheel can be used for mass production, although often it is employed to make individual pieces. Wheel-work makes great demands on the skill of the potter, but an accomplished operator can make many near to identically similar plates, vases, or bowls in the course of a day's work. Because of its inherent limitations, wheel-work can only be used to create wares with radial symmetry on a vertical axis. These can then be altered by impressing, bulging, carving, fluting, faceting, incising, and by other methods making the wares more visually interesting. Often, thrown pieces are further modified by having handles, lids, feet, spouts, and other functional aspects added using the techniques of handworking.
Granulate pressing
As the name suggests, this is the operation of shaping pottery by pressing clay in a semi-dry and granulated condition in a mould. The clay is pressed into the mould by a porous die through which water is pumped at high pressure. The granulated clay is prepared by spray-drying to produce a fine and free flowing material having a moisture content of between about five and six per cent. Granulate pressing, also known as dust pressing, is widely used in the manufacture of ceramic tiles and, increasingly, of plates.
Slipcasting
Slipcasting is often used in the mass-production of ceramics and is ideally suited to the making of wares that cannot be formed by other methods of shaping. A slip, made by mixing clay body with water, is poured into a highly absorbent plaster mould. Water from the slip is absorbed into the mould leaving a layer of clay body covering its internal surfaces and taking its internal shape. Excess slip is poured out of the mould, which is then split open and the moulded object removed. Slipcasting is widely used in the production of sanitary wares and is also used for making smaller articles, such as intricately-detailed figurines.
