Low-fired ware, usually still porous after firing—must be sealed with vitreous glaze to be functional.
Source:
Clay: A Studio Handbook
Dunting
Traditional term referring to serious cracking occurring in cooling, resulting from drawing too soon, from extreme excessive glaze-compression, or from low thermal shock-resistance in overvitrified wares resulting from overfluxing and/or over-firing.
Source:
Clay: A Studio Handbook
Drill Mixer
Electric-drill-mounted impeller-mixer excellent for mixing glazes, slips, and slurries and for blunging casting-slip.
Source:
Clay: A Studio Handbook
Draft
The flow of exhaust gases out of a fuel kiln, affecting intake of flames and secondary air.
Source:
Clay: A Studio Handbook
Downdraft Kiln
Kiln where exhaust gases exit through flue at floor level.
Source:
Clay: A Studio Handbook
Dissolution
Action of a solvent material on a solid, bringing it into liquid solution.
Source:
Clay: A Studio Handbook
Dispersion
Natural tendency of materials in liquid solution to go from area of high concentration to area of lower concentration, resulting in even distribution of materials throughout the glaze melt.
Source:
Clay: A Studio Handbook
Devitrification
The phenomenon that occurs early in the glaze cooling cycle, when certain materials crystallize out of the vitrified (fused) mass.
Source:
Clay: A Studio Handbook
Darvan
Common deflocculant for casting slips. Product of R.T. Vanderbilt Company.
Source:
Clay: A Studio Handbook
Damper
In fuel-burning kilns, adjustable refractory plate located in exhaust flue, allowing control of back-pressure and secondary air, regulating kiln atmosphere.
Source:
Clay: A Studio Handbook
Custer Feldspar
K2O×Al2O3×6SiO2—a common potash feldspar—HT alkaline flux. See feldspar. Close match to G-200. Toxic in inhalation.
Source:
Clay: A Studio Handbook
Cullet
Crushed window or bottle glass, occasionally used as a glaze material.
Source:
Clay: A Studio Handbook
Cuerda Seca
Technique where a design is outlined in oxide-tinted wax resist, and the intervening spaces coated with glazes. Finished results show areas of glaze divided by dark unglazed lines.
Source:
Clay: A Studio Handbook
Crystalline Glaze
Glazes in which significant macrocrystalline structure forms in surface of low-alumina glaze seeded with zinc or titanium. Crystalline glazes feature large, visible crystal development, vs. microcrystalline effects, as in matt glazes and saturated-iron glazes.
Source:
Clay: A Studio Handbook
Crystalline
Solid material characterized by regular repeating geometric molecular structure or lattice, with specific melting point, as compared to glass, an amorphous, non-crystalline material that softens over broad temperature range.
Source:
Clay: A Studio Handbook
Cross Draft
Fuel-burning kiln, usually downdraft, where heat enters at floor level at one side of ware chamber and exits at floor level at opposite side of chamber.
Source:
Clay: A Studio Handbook
Cristobalite
Crystalline form of silica, which can form in clay and glaze above 2200°F; has very high coefficient of expansion, producing low thermal shock resistance. Promoted by excessive free silica in clay and/or glaze, by repeated firing, and/or by excessive soaking or slow firing/cooling at high temperatures.
Source:
Clay: A Studio Handbook
Crazing (Crackle)
Very fine surface cracks in fired glaze surface—technically a fault in glazed wares, but often sought after, especially in raku.
Source:
Clay: A Studio Handbook
Crawling
Glaze fault where glaze recedes away from an area in the firing, leaving bare clay. Usually caused by dusty, dirty, or oily surface beneath glaze or by excessively powdery glaze. In some cases results from very high L.O.I. in glaze materials, causing high glaze-shrinkage and resulting cracking during firing. Used intentionally in controlled crawl and beading glazes.
Source:
Clay: A Studio Handbook
Cottles
Adjustable wooden forms used in casting plaster molds.
Low-fired ware, usually still porous after firing—must be sealed with vitreous glaze to be functional.
Source: Clay: A Studio Handbook
Traditional term referring to serious cracking occurring in cooling, resulting from drawing too soon, from extreme excessive glaze-compression, or from low thermal shock-resistance in overvitrified wares resulting from overfluxing and/or over-firing.
Source: Clay: A Studio Handbook
Electric-drill-mounted impeller-mixer excellent for mixing glazes, slips, and slurries and for blunging casting-slip.
Source: Clay: A Studio Handbook
The flow of exhaust gases out of a fuel kiln, affecting intake of flames and secondary air.
Source: Clay: A Studio Handbook
Kiln where exhaust gases exit through flue at floor level.
Source: Clay: A Studio Handbook
Action of a solvent material on a solid, bringing it into liquid solution.
Source: Clay: A Studio Handbook
Natural tendency of materials in liquid solution to go from area of high concentration to area of lower concentration, resulting in even distribution of materials throughout the glaze melt.
Source: Clay: A Studio Handbook
The phenomenon that occurs early in the glaze cooling cycle, when certain materials crystallize out of the vitrified (fused) mass.
Source: Clay: A Studio Handbook
Common deflocculant for casting slips. Product of R.T. Vanderbilt Company.
Source: Clay: A Studio Handbook
In fuel-burning kilns, adjustable refractory plate located in exhaust flue, allowing control of back-pressure and secondary air, regulating kiln atmosphere.
Source: Clay: A Studio Handbook
K2O×Al2O3×6SiO2—a common potash feldspar—HT alkaline flux. See feldspar. Close match to G-200. Toxic in inhalation.
Source: Clay: A Studio Handbook
Crushed window or bottle glass, occasionally used as a glaze material.
Source: Clay: A Studio Handbook
Technique where a design is outlined in oxide-tinted wax resist, and the intervening spaces coated with glazes. Finished results show areas of glaze divided by dark unglazed lines.
Source: Clay: A Studio Handbook
Glazes in which significant macrocrystalline structure forms in surface of low-alumina glaze seeded with zinc or titanium. Crystalline glazes feature large, visible crystal development, vs. microcrystalline effects, as in matt glazes and saturated-iron glazes.
Source: Clay: A Studio Handbook
Solid material characterized by regular repeating geometric molecular structure or lattice, with specific melting point, as compared to glass, an amorphous, non-crystalline material that softens over broad temperature range.
Source: Clay: A Studio Handbook
Fuel-burning kiln, usually downdraft, where heat enters at floor level at one side of ware chamber and exits at floor level at opposite side of chamber.
Source: Clay: A Studio Handbook
Crystalline form of silica, which can form in clay and glaze above 2200°F; has very high coefficient of expansion, producing low thermal shock resistance. Promoted by excessive free silica in clay and/or glaze, by repeated firing, and/or by excessive soaking or slow firing/cooling at high temperatures.
Source: Clay: A Studio Handbook
Very fine surface cracks in fired glaze surface—technically a fault in glazed wares, but often sought after, especially in raku.
Source: Clay: A Studio Handbook
Glaze fault where glaze recedes away from an area in the firing, leaving bare clay. Usually caused by dusty, dirty, or oily surface beneath glaze or by excessively powdery glaze. In some cases results from very high L.O.I. in glaze materials, causing high glaze-shrinkage and resulting cracking during firing. Used intentionally in controlled crawl and beading glazes.
Source: Clay: A Studio Handbook
Adjustable wooden forms used in casting plaster molds.
Source: Clay: A Studio Handbook