kiln

A kiln is a thermally insulated chamber or furnace in which a controlled high-temperature environment is maintained to process materials. Kilns are used to harden, dry, or chemically alter substances such as ceramics, lime, bricks, metals, and glass.

Kilns can be batch or continuous, fixed in place or mobile, and may operate with electric, gas, oil, coal, or wood fuels. Heat is produced by combustion or electrical resistance, and the atmosphere inside may be oxidizing, reducing, or neutral depending on fuel supply and venting. This allows different material changes, such as vitrification of glaze in ceramics or calcination of lime.

Ceramic kilns are designed to reach high temperatures needed for firing pottery and ceramic ware. Common ranges for pottery are approximately 900 to 1300 degrees Celsius, with higher temperatures for stoneware and porcelain. They include electric kilns, gas-fired kilns, and wood-fired kilns, as well as specialized designs such as downdraft or updraft configurations.

Other kilns include lime kilns, which calcine limestone to lime by heating to about 900 degrees Celsius; brick kilns, used to harden clay bricks; and metal treatment kilns such as annealing furnaces that alter metal properties. Industrial kilns may operate at higher temperatures and for continuous processing.

History and development: Kilns date back to ancient times, evolving from simple clay ovens to sophisticated industrial furnaces. Modern kilns emphasize energy efficiency, automation, environmental controls, and precise temperature and atmosphere management to support a wide range of materials and processes.