kiln

High-temperature furnace used for drying timber, roasting metal ores, or for making cement, bricks, and pottery. Ceramic kilns include early kilns, such as bonfire, sawdust, and wood-fired kilns, which have their roots in primitive cultures; and modern kilns, such as electric-, gas-, and oil-fired kilns, used in both the arts and industry. Oil- or gas-fired kilns can bake ceramics at up to 1,760°C/3,200°F; electric kilns do not generally reach such high temperatures. The type of kiln used to fire a ceramic will affect the qualities and appearance of the final creation.

Early kilns The bonfire kiln, one of the oldest firing methods, involves firing pots in the open air. Various systems remain in use all over the world. One method is to lay the pots on a bed of dried grass, cover the pots with more brush, and then set fire to the entire structure; another involves piling the pots on top of one another, covering the pile in dried grass and a final layer of earth, and making a small flue through which burning coals are dropped, setting light to the pots and grass inside. The sawdust kiln is another early, yet very effective, kiln still in use today. The kiln, which may be round or square, and made from brick or steel, is filled with pots, sawdust, and paper. Once the sawdust is lit and smouldering, the kiln is covered with a lid that can be raised and lowered to regulate the flow of air. Wood-fired kilns are also rooted in primitive cultures. Kilns fuelled by wood, both large and small, are becoming increasingly popular, as they are efficient to run and can reach extremely high temperatures.

Modern kilns Oil-, gas-, and electric-fired kilns are modern interpretations of the early kilns. Oil-fired kilns have become less popular as they give off high amounts of pollution, but gas-fired kilns are increasingly common, particularly in the arts. Kilns fuelled by bottled gas come in all sizes, are easy to build, and offer artists many different firing methods. Raku (a low-fired Japanese ceramic), porcelain, and stoneware can all be fired in gas kilns. Electric kilns are probably the easiest to use of all the kilns, as they are safe, clean, and quick. Fuelled by electricity, the elements heat up the kiln chamber, like the coils in an electric oven. Most student potters and ceramicists will begin with an electric kiln.