Fire (ceramics)

Firing is the controlled heating of clay or ceramic ware in a kiln, causing chemical and physical changes that make it durable or alter its properties.

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Clay firing stages: The successive physical and chemical changes clay undergoes as it is heated in a kiln. These stages explain how drying, burnout, sintering, and cooling contribute to a fired body's properties.
Clay mineral: A fine-grained hydrous silicate mineral that gives clay its plasticity and changes under heat. Clay minerals lose water and change structure as ceramic bodies are fired.
Bisque firing: An initial firing that turns dried clay into a porous, durable ceramic ready for glazing. Bisque firing prepares ware for glaze application without fully sealing its surface.
Low-fire pottery: Ceramic ware fired at relatively low temperatures, often retaining a porous body beneath its glaze. Its firing range contrasts with the higher temperatures used for stoneware and porcelain.
Sintering: The bonding of particles by heat, typically below their melting point, which reduces porosity and strengthens a material. Sintering bonds ceramic particles as firing makes ware denser and stronger.
Ceramic body: The formulated mixture of clays and other materials used to make a ceramic object. Body composition determines the temperature range and properties attainable in firing.
Glaze firing: A firing that melts and bonds glaze materials to a ceramic surface. This firing develops the glassy coating that gives glazed ware its surface qualities.
Stoneware: A dense, durable ceramic fired at high temperatures, typically becoming vitrified or nearly so. Stoneware illustrates the density achieved by hotter firing than low-fire bodies.
Vitrification: The formation of a glassy phase in a material through heating, which can reduce porosity and increase density. Vitrification helps explain how some clay bodies become less porous during firing.
Kiln: An insulated chamber designed to heat materials to high temperatures for processes such as ceramic firing. The kiln supplies and distributes the heat that transforms ceramic ware.