Ceramic - Pottery Dictionary

by Susan Mussi

KILN - Types

ca: FORN - Tipus

es: HORNO - Tipos

Anagama kiln – the Asian anagama kiln has been used since medieval times and is the oldest style of kiln in Japan. This kiln usually consists of one long firing chamber, pierced with smaller stacking ports on one side, with a firebox at one end and a flue at the other. Firing time can vary from one day to several weeks. Traditional anagama kilns are also built on a slope to allow for a better draft.

Bottle kiln – a type of intermittent kiln, usually coal-fired, formerly used in the firing of pottery; such a kiln was surrounded by a tall brick hovel or cone, of typical bottle shape.

Electric kilns – kilns operated by electricity were developed in the 20th century, primarily for smaller scale use such as in schools, universities, and hobby centers. As these electrical appliances improved in dependability, they became a valuable tool for artists as well. The atmosphere in most designs of electric kiln is rich in oxygen, as there is no open flame to consume oxygen molecules, however reducing conditions can be created with appropriate gas input.

Microwave Assisted Firing – this technique combine microwave energy with more conventional energy sources such as radiant gas or electric heating in order to process ceramic materials to the required high temperatures. Microwave-assisted firing offers significant economic benefits

Modern kilns – with the advent of the industrial age, kilns were designed to utilize electricity and more refined fuels, including natural gas and propane. The majority of large, industrial pottery kilns now use natural gas, as it is generally clean, efficient and easy to control. Modern kilns can be fitted with computerized controls, allowing for refined adjustments during the firing cycle. A user may choose to control the rate of temperature climb or ramp, hold or soak the temperature at any given point, or control the rate of cooling. Both electric and gas kilns are common for smaller scale production in industry and craft, handmade and sculptural work.

Top-hat Kiln – an intermittent kiln of a type sometimes used in the firing of pottery. The ware is set on a refractory hearth, or plinth, over which a box-shaped cover is then lowered.

Arab Kilns: In Spain the kilns used for firing were known as Arab kilns, they were brought to Spain by the Arabs and used in their kingdom of Granada. They created the heat by wood-firing and were large brick square structures, with two floors. The bottom floor of the kiln was for the wood-fire and the top for the objects going to be fired. The firing time depended on the size of the kiln and could take up to 24 hours. It started with a low fire, gradually heating up until it reached the required temperature. This point was judged by looking through the pin-holes to see the color of the heat and slipping out test pieces to see the evolution of a colored glaze. The timing with clay was not as important as slightly over firing does not affect it but with colors over firing can completely destroy all the work in the kiln. The firing process demanded men to work non-stop, filling the kiln with wood, checking that the temperature was continuously increasing at the same degree throughout the kiln and checking when the kiln reached the correct temperature, after which it was left to cool.
Link to Kilns Robert Compton Pottery