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Words beginning with K
Kaki
Kaki (persimmon) glazes are high fired reduction transparents with a generous supply of iron oxide (12% or more) which forms a microcrystalline surface. If cooled correctly they exhibit "red" coloration. The atmosphere during cooling should be reduction. The iron content of the body and level of reduction affect the fired results. Tenmoku glazes are closely related, however they have less iron oxide (around 10%) so that crystallization occurs on the edges of pieces.Kiln fumes
Fume results when a clay or glaze decomposes during heat-up in the kiln and forms a vapor. These vapors can deposit as very tiny particles on walls and other surfaces. The individual particles are so small that they can be inhaled deep into the alveoli (air sacs) of your lungs.
The most common fumes associated with kiln firing are sulfur and it is easy to identify from the odor. Many clays contain it as do fuels. Some metal oxides volatilize and form fumes (notably copper, zinc, manganese) that can lead to metal fume fevers of different types. Manganese in particular can be quite toxic.Kiln venting system
Kilns vents are hoods with an exhaust fan that are suspended above an electric kiln. They suck air from around the kiln and expel it through a hose to the outside. Some vents also suck air through a hole in the bottom of a kiln. Vents are intended to remove all harmful kiln fumes from the room.
Kiln vents also have other benefits. They help make for better temperature uniformity at low temperatures giving firings an even start. Below red heat the only way to get heat to move around in the kiln is to move the air (above red heat, the dominant way heat moves is by radiation). They also give better atmospheric uniformity. Continuously bringing in fresh air and expelling products of decomposition makes for more consistency from firing to firing.Kiln wash
A refractory powder that can be mixed with water and painted on kiln shelves to prevent ware and accidental glaze drips from sticking. Porcelain clays, for example, melt enough during firing that they tend to stick onto the kiln shelf. Certain clays contain soluble salts which fire to a glaze-like sheen, these also tend to stick ware to shelves.
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