Clay body

Shaping

• Hand-building: This is the earliest forming method. Wares can be constructed by hand from coils of clay, combining flat slabs of clay, or pinching solid balls of clay, or some combination of these. Parts of hand-built vessels are often joined with the aid of slip. Some studio potters find hand-building more conducive for one-of-a-kind works of art.

• The potter's wheel: In a process called "throwing" (coming from the Old English word thrawan which means to twist or turn) a ball of clay is placed in the centre of a turntable, called the wheel-head, which the potter rotates with a stick, with foot power, or with a variable-speed electric motor. During throwing, the wheel rotates while the solid ball of soft clay is pressed, squeezed, and gently pulled upwards and outwards into a hollow shape. Skill and experience are required to throw pots to an acceptable standard, and while the ware may have high artistic merit, the method's reproducibility is poor. Because of its inherent limitations, throwing can only be used to create wares with radial symmetry on a vertical axis.
• Press moulding: a simple technique of shaping by manually pressing a lump of clay body into a porous mould.
• Granulate pressing: a highly automated technique of shaping by pressing clay body in a semi-dry and granulated form in a mould. The body is pressed into the mould by a porous die through which water is pumped at high pressure. The fine, free-flowing granulated body is prepared by spray drying a high-solids content slip. Granulate pressing, also known as dust pressing, is widely used in the manufacture of ceramic tiles and, increasingly, of plates.

• Jiggering and jolleying: These operations are carried out on the potter's wheel and allow the time taken to bring wares to a standardized form to be reduced. Jiggering is the operation of bringing a shaped tool into contact with the plastic clay of a piece under construction, the piece itself being set on a rotating plaster mould on the wheel. The jigger tool shapes one face while the mould shapes the other. Jiggering is used only in the production of flatware, such as plates, but a similar operation, jolleying, is used in the production of hollowware, such as cups. Jiggering and jolleying have been used in pottery production since at least the 18th century. In large-scale factory production, jiggering and jolleying are usually automated, allowing these operations to be carried out by semi-skilled labour.
• Roller-head machine: This machine is for shaping wares on a rotating mould, as in jiggering and jolleying, but with a rotary shaping tool replacing the fixed profile. The rotary shaping tool is a shallow cone with the same diameter as the ware being formed, shaped to the desired form of the back of the article being made. Wares may in this way be shaped, using relatively unskilled labour, in one operation at a rate of about twelve pieces per minute, though this varies with the size of the articles being produced. Developed in the UK just after World War II by the company Service Engineers, the roller-head method was quickly adopted by manufacturers worldwide; it remains the dominant method for producing both flatware and hollowware, such as plates and mugs.
• Pressure casting: Is a development of traditional slipcasting. Specially developed polymeric materials allow a mould to be subject to external pressures of up to 4.0 MPa, so much higher than slip casting in plaster moulds, where the capillary forces correspond to a pressure of around 0.1–0.2 MPa. The high pressure leads to much faster casting rates and, hence, faster production cycles. Furthermore, applying high-pressure air through the polymeric moulds upon demoulding the cast enables a new casting cycle to begin immediately in the same mould, unlike plaster moulds, which require lengthy drying times. Polymeric materials have much greater durability than plaster; therefore, it is possible to achieve shaped products with better dimensional tolerances and much longer mould life. Pressure casting was developed in the 1970s for the production of sanitaryware, although, more recently, it has been applied to tableware.
• RAM pressing: This is used to shape ware by pressing a bat of prepared clay body into a required shape between two porous moulding plates. After pressing, compressed air is blown through the porous mould plates to release the shaped wares.

• Slip casting: This is suited to the making of shapes that other methods cannot form. A liquid 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 that covers its internal surfaces and takes its internal shape. Excess slip is poured out of the mould, which is then split open, and the moulded object removed. Slip casting is widely used in the production of sanitaryware and for making other complex-shaped ware, such as teapots and figurines.
• Injection moulding: This is a shape-forming process adapted for the tableware industry from the method long established for the forming of thermoplastic and some metal components. It has been called Porcelain Injection Moulding, or PIM. Suited to the mass production of complex-shaped articles, one significant advantage of the technique is that it allows the production of a cup, including the handle, in a single process, and thereby eliminates the handle-fixing operation and produces a stronger bond between cup and handle. The feed to the mould die is a mix of approximately 50 to 60 per cent unfired body in powder form, together with 40 to 50 per cent organic additives composed of binders, lubricants and plasticisers. The technique is not as widely used as other shaping methods. Injection moulding of ceramic tableware has been developed, though it has yet to be fully commercialised.
• 3D printing: There are two methods. One involves the layered deposition of soft clay body similar to fused deposition modelling (FDM), and the other uses powder binding techniques where clay body in dry powder form is fused layer upon layer with a liquid.