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Ceramic Glossary
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Bisque-
Any fired undecorated clay object
Ceramics- A general term applying to any fired piece of clay material.
China- A translucent high fire ceramic body.
Clay- Earth that is relatively pure silica and alumina: usually a blend of different clays and minerals, combined to achieve various effects and different properties.
Clay-up- Filling in around a model to develop the parting line when making a slip cast mold.
Cone- See pyrometric cone
Cratering- Imperfections in glaze caused b rapid cooling, which "freezes" bubbled glazes before they can smooth out, leaving pits.
Crazing- A network of hairline cracks in a glazed surface which appears after firing.
Decal, Ceramic- A design or picture, usually overglaze, which is applied to and fired onto the ware.
Dry-Footing- Wiping glaze off the base of objects before firing. This is an alternative to stilting glazed ware to keep the piece from sticking to the shelf when firing.
Dry Brush- Wiping you brish so it will pick up excess material. Used in creating special effects when glazing.
Earthenware- Porous ware made of low fire clays.
Elements- Coils of wire having high electrical resistance and resistance to high temperatures which serve to convert electrical energy to heat in the kiln.
Enameling- Application of finely ground colored glass metals (usually copper or silver) resulting in a glass like finish after firing.
Firebrick- refractory blocks used in making the insulating firing chamber of the kiln.
Firing- Applying heat to ceramic materials to cause a change in the chemical composition (see maturity).
Firing Chamber- The space in the interior of the kiln where the ware is heated.
Furniture, kiln- Any of a wide assortment of shelves and posts used in loading a kiln. They are used in supporting ware to take full advantage of the firing space.
Glaze- Finely ground glass, suspended in liquid, applied to ceramic ware to give a glossy (usually) glass-like surface when melted by firing.
Greenware- Any unfired clay object.
High Fire- Firing to very high temperatures: anything over cone 4. Commonly (cone 6) used with porcelain and stoneware.
Kiln- Pronounced kiln or kil. An oven that can reach temperatures up to ~2,400 degrees Fahrenheit using either gas or electricity that heat elements within. Constructed of either insulating firebrick or with high purity, high temperature ceramic fiber.
Kiln Wash- A refractory material used as a coating to prevent sticking of ware and glazes to parts of the kiln and shelves. It is a powder which is mixed with water and applied with a brush.
Keys- Round or oval shape depressions with matching counterpart susally on flat section of parting line of a slipcast mold.
Leatherhard- Clay dried to consistency of leather.
Low Fire- Ware fired only to medium temperature as for earthenware, pottery, or terra cotta.
Luster- An overglaze giving an iridescent finish.
Maturity- The point at which bisque is completely fired and glazes reach the intended smooth, glassy state.
Nesting- Stacking one piece of greenware inside another, a technique used in leading for bisque firing.
Ohmmeter- An electrical measuring device for measuring electrical resistance. This is used to check elements for aging or an open circuit/
Overglaze- Decorative material applied on top of a glazed surface. Examples are decals, gold and other metallics, lusters, and china paints. They are always low fired (cone 018 to 014).
Parting Line- The line which divides your model when creating a mold of it.
Peephole Plug- Apiece of refractory material used to close the peephole in a kiln.
Pinholes- Imperfections in a glazed surface characterized by tiny holes.
Pins- Short pieces of high temperature wire used to anchor element in place.
Porcelain- A type of clay body which becomes vitreous and translucent when high fired.
Post- Columns of refractory material used to support shelves in the kiln. They are available with square, triangular or circular cross sections and in many different heights.
Pour Hole- Carved inlet or opening in mold to pour ceramic or porcelain slip into.
Pyrometer- A high temperature thermometer consisting of a heat sensing device (thermocouple) connected to a meter readout. Especially important in working with glass. This is an excellent device to measure the progress of a firing and temperature profile of a kiln.
Pyrometric cone- A small elongated pyramid of ceramic material which is formulated to soften and deform at a specific temperature plus time condition, indicating that the ware is mature and the firing complete
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Shelves- Slab of refractory material used in the kiln to support ware being fired (see furniture).
Silica- (Silicaflour, flint) A mineral powder used to prevent sticking of porcelain and other high fire clays during firing
Slip- Liquid clay used in casting shapes with molds.
Soaking- Heat treating objects in a kiln by keeping them at a particular temperature for a period of time.
Stilts- Small ceramic or high temperature metal prongs used to raise a piece off the kiln shelf. Used chiefly in glaze firings to prevent sticking to the kiln or shelf. Many styles are available.
Stoneware- A ceramic body which is vitreous but not translucent when high fired. It usually contains a high percentage of grog (fired clay particles) and is usually made of native clays.
Terra Cotta- A natural, low fire red clay.
Thermal Shock- The result of putting ware through sudden changes temperature.
Thermocouple- Two wires of different metals which are inserted into the kiln and comprise the temperature sensing part of the pyrometer. It produces a very small voltage in proportion to the difference in temperature between the tip (hot junction) of the thermocouple inside the hot kiln and the cold junction on the outside of the kiln.
Underglaze- Decorative material applied to greenware or bisque.
Venting- Allowing air into the kiln and vapors to escape by propping the lid slightly open and sometimes opening the peepholes. Usually done only in the early stages of firing.
Vetrify- To fully fuse ceramic material to a glass-like state so that it is nonporous and watertight without glazing.
Ware- General term for any shaped ceramic object whether or not it is in a finished state.
Warpage- Deformation of ware during firing, usually due to overfiring or to improper placement in the kiln. |
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