A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for millennia to turn objects made from clay into pottery, tiles and bricks. Various industries use rotary kilns for pyroprocessing and to transform many other materials.
Pottery is the process and the products of forming vessels and other objects with clay and other raw materials, which are fired at high temperatures to give them a hard and durable form. The place where such wares are made by a potter is also called a pottery. The definition of pottery, used by the ASTM International, is "all fired ceramic wares that contain clay when formed, except technical, structural, and refractory products". End applications include tableware, decorative ware, sanitaryware, and in technology and industry such as electrical insulators and laboratory ware. In art history and archaeology, especially of ancient and prehistoric periods, pottery often means vessels only, and sculpted figurines of the same material are called terracottas.
Raku ware is a type of Japanese pottery traditionally used in Japanese tea ceremonies, most often in the form of chawan tea bowls. It is traditionally characterised by being hand-shaped rather than thrown, fairly porous vessels, which result from low firing temperatures, lead glazes and the removal of pieces from the kiln while still glowing hot. In the traditional Japanese process, the fired raku piece is removed from the hot kiln and is allowed to cool in the open air.
Earthenware is glazed or unglazed nonvitreous pottery that has normally been fired below 1,200 °C (2,190 °F). Basic earthenware, often called terracotta, absorbs liquids such as water. However, earthenware can be made impervious to liquids by coating it with a ceramic glaze, and such a process is used for the great majority of modern domestic earthenware. The main other important types of pottery are porcelain, bone china, and stoneware, all fired at high enough temperatures to vitrify. End applications include tableware and decorative ware such as figurines.
Pottery and porcelain, is one of the oldest Japanese crafts and art forms, dating back to the Neolithic period. Kilns have produced earthenware, pottery, stoneware, glazed pottery, glazed stoneware, porcelain, and blue-and-white ware. Japan has an exceptionally long and successful history of ceramic production. Earthenwares were made as early as the Jōmon period, giving Japan one of the oldest ceramic traditions in the world. Japan is further distinguished by the unusual esteem that ceramics hold within its artistic tradition, owing to the enduring popularity of the tea ceremony.
Fire clay is a range of refractory clays used in the manufacture of ceramics, especially fire brick. The United States Environmental Protection Agency defines fire clay very generally as a "mineral aggregate composed of hydrous silicates of aluminium (Al2O3·2SiO2·2H2O) with or without free silica."
In materials science, a refractory is a material that is resistant to decomposition by heat or chemical attack that retains its strength and rigidity at high temperatures. They are inorganic, non-metallic compounds that may be porous or non-porous, and their crystallinity varies widely: they may be crystalline, polycrystalline, amorphous, or composite. They are typically composed of oxides, carbides or nitrides of the following elements: silicon, aluminium, magnesium, calcium, boron, chromium and zirconium. Many refractories are ceramics, but some such as graphite are not, and some ceramics such as clay pottery are not considered refractory. Refractories are distinguished from the refractory metals, which are elemental metals and their alloys that have high melting temperatures.
A fire brick, firebrick, fireclay brick, or refractory brick is a block of ceramic material used in lining furnaces, kilns, fireboxes, and fireplaces. A refractory brick is built primarily to withstand high temperature, but will also usually have a low thermal conductivity for greater energy efficiency. Usually dense fire bricks are used in applications with extreme mechanical, chemical, or thermal stresses, such as the inside of a wood-fired kiln or a furnace, which is subject to abrasion from wood, fluxing from ash or slag, and high temperatures. In other, less harsh situations, such as in an electric or natural gas fired kiln, more porous bricks, commonly known as "kiln bricks", are a better choice. They are weaker, but they are much lighter and easier to form and insulate far better than dense bricks. In any case, firebricks should not spall, and their strength should hold up well during rapid temperature changes.
Salt-glaze or salt glaze pottery is pottery, usually stoneware, with a glaze of glossy, translucent and slightly orange-peel-like texture which was formed by throwing common salt into the kiln during the higher temperature part of the firing process. Sodium from the salt reacts with silica in the clay body to form a glassy coating of sodium silicate. The glaze may be colourless or may be coloured various shades of brown, blue, or purple.
Bizen ware is a type of Japanese pottery traditionally from Bizen province, presently a part of Okayama prefecture.
The Gladstone Pottery Museum is a working museum of a medium-sized coal-fired pottery, typical of those once common in the North Staffordshire area of England from the time of the industrial revolution in the 18th century to the mid 20th century. It is a grade II* listed building.
Ceramic glaze, or simply glaze, is a glassy coating on ceramics. It is used for decoration, to ensure the item is impermeable to liquids and to minimise the adherence of pollutants.
Glaze defects are any flaws in the surface quality of a ceramic glaze, its physical structure or its interaction with the body.
This is a list of pottery and ceramic terms.
A bottle oven or bottle kiln is a type of kiln. The word 'bottle' refers to the shape of the structure and not to the kiln's products, which are usually pottery, not glass.
A potbank is a colloquial name for a pottery factory in North Staffordshire used to make bone china, earthenware and sanitaryware.
Dick Lehman is an American ceramics artist based in Indiana. Dozens of articles and photos featuring his techniques and insights have appeared in periodicals and books on ceramic art since 1985, including 34 articles in U.S.-published Ceramics Monthly, the largest circulating magazine in the field, plus articles in 11 other international periodicals.
The mantou kiln or horseshoe-shaped kiln was the most common type of pottery kiln in north China, in historical periods when the dragon kiln dominated south China; both seem to have emerged in the Warring States period of approximately 475 to 221 BC. It is named after the Chinese mantou bun or roll, whose shape it resembles; the ground plan resembles a horseshoe. The kilns are roughly round, with a low dome covering the central firing area, and are generally only 2 to 3 metres across inside. However it is capable of reaching very high temperatures, up to about 1370°C. There is a door or bricked-up opening at the front for loading and unloading, and one or two short chimneys at the rear.
Stilts are small supports used when firing glazed ceramics to stop the melting glaze from fusing them to each other or the kiln. Stilts are a form of kiln furniture. Their presence in archaeological sites, where they may be known as pernette, along with other kiln furniture such as saggars and kiln bars can be used to support a case for local production. Some potters avoid the need for stilts by not glazing the bottom of their products. This is known as dry footing.
Kiln furniture are devices and implements inside furnaces used during the heating of manufactured individual pieces, such as pottery or other ceramic or metal components. Kiln furniture is made of refractory materials, i.e., materials that withstand high temperatures without deformation. Kiln furniture can account for up to 80% of the mass of a kiln charge.
