thumb|300px|Soft-paste porcelain Swan tureen, 1752-6, Chelsea.

Porcelain is a ceramic material made by heating raw materials, generally including clay in the form of kaolin, in a kiln to temperatures between and . The toughness, strength, and translucence of porcelain arise mainly from the formation of glass and the mineral mullite within the fired body at these high temperatures.

Porcelain derives its present name from old Italian porcellana (cowrie shell) because of its resemblance to the translucent surface of the shell. Porcelain can informally be referred to as "china" in some English-speaking countries, as China was the birth place of porcelain making. Properties associated with porcelain include low permeability and elasticity; considerable strength, hardness, glassiness, brittleness, whiteness, translucence, and resonance; and a high resistance to chemical attack and thermal shock.

For the purposes of trade, the Combined Nomenclature of the European Communities defines porcelain as being "completely vitrified, hard, impermeable (even before glazing), white or artificially coloured, translucent (except when of considerable thickness) and resonant." However, the term porcelain lacks a universal definition and has "been applied in a very unsystematic fashion to substances of diverse kinds which have only certain surface-qualities in common" (Burton 1906).

Porcelain is used to make table, kitchen, sanitary, and decorative wares; objects of fine art; and tiles. Its high resistance to the passage of electricity makes porcelain an excellent insulator. Dental porcelain is used to make false teeth, caps and crowns.

Scope

The most common uses of porcelain are the creation of artistic objects and the production of more utilitarian wares. It is difficult to distinguish between stoneware and porcelain because this depends upon how the terms are defined. A useful working definition of porcelain might include a broad range of ceramic wares, including some that could be classified as a stoneware.

Materials

The composition of porcelain is highly variable, but the clay mineral kaolinite is often a significant component. Other materials can include feldspar, ball clay, glass, bone ash, steatite, quartz, petuntse and alabaster; further information on these formulations is given at "soft-paste porcelain".

The clays used are often described as being long or short, depending on their plasticity. Long clays are cohesive (sticky) and have high plasticity; short clays are less cohesive and have lower plasticity. In soil mechanics, plasticity is determined by measuring the increase in content of water required to change a clay from a solid state bordering on the plastic, to a plastic state bordering on the liquid, though the term is also used less formally to describe the facility with which a clay may be worked. Clays used for porcelain are generally of lower plasticity and are shorter than many other pottery clays. They wet very quickly, meaning that small changes in the content of water can produce large changes in workability. Thus, the range of water content within which these clays can be worked is very narrow and the loss or gain of water during storage and throwing or forming must be carefully controlled to keep the clay from becoming too wet or too dry to manipulate.