Glossary Terms (Simple)

Cordierite

2MgO×2Al 2O3×5SiO2—magnesium/aluminum silicate clay mineral, used to make grog for refractory products—promotes formation of mullite. 

Source: Clay: A Studio Handbook

Copper Sulfate

CuSO4—color source for saggar firing and pit-firing. Soluble, and highly toxic in absorption, ingestion, and inhalation. 

Source: Clay: A Studio Handbook

Copper Carbonate

CuCO3—a major glaze colorant to produce greens in LT and HT, copper reds in HT reduction, and greens and metallic effects in raku. Toxic in inhalation and ingestion. 

Source: Clay: A Studio Handbook

Convection Currents

Upwards rise of warm air currents due to the transference of heat. 

Source: Clay: A Studio Handbook

Compression

In wheel throwing, the act of hand or finger pressure on the clay, resulting in lower moisture content and a denser structure. Lack of compression in bottoms of pots can result in S-cracks. 

Source: Clay: A Studio Handbook

Combustion

Reaction initiated when fuel reaches kindling temperature, at which point oxidation of hydrocarbon gases releases heat, sustaining and accelerating reaction. 

Source: Clay: A Studio Handbook

Combing

Decoration where a toothed instrument is dragged over a soft clay surface, sometimes through a layer of slip. 

Source: Clay: A Studio Handbook

Coil Construction

Ceramic forming method utilizing ropelike coils of plastic clay, assembled in successive courses to build up wall of vessel or sculpture. 

Source: Clay: A Studio Handbook

Cobalt Oxide

Co3O4—calcined cobalt carbonate—twice as powerful—coarser than carbonate, and may give mottling in glaze. Works well for underglaze brushwork, with few crawling problems. Toxic in inhalation and ingestion. 

Source: Clay: A Studio Handbook

CMC Gum

Carboxymethylcellulose (CMC) — an organic gum used as a suspension/adhesion agent in glazes. Normally, a small amount of gum is added to a quart or so of warm water and left overnight. Once dissolved, this solution may be added in small doses to glazes, slips, and engobes to improve application performance. 

Source: Clay: A Studio Handbook

Closed Form

Wheel-thrown form that is closed off completely and then altered to form a vessel or sculptural component. 

Source: Clay: A Studio Handbook

Climbing Kiln

Any one of a variety of East Asian kiln designs featuring single or multiple chambers that climb up a slope, creating adequate draft often with little or no chimney. 

Source: Clay: A Studio Handbook

Clay Body

Clay mixture formulated of clays and other ceramic raw materials to give desired working characteristics. 

Source: Clay: A Studio Handbook

Clay Earthenware

Natural low-fire secondary clay—fluxed with iron, fires porous. Often called “common” clay, found almost everywhere, matures below 2000°F. 

Source: Clay: A Studio Handbook

Clay

Widely occurring aluminum silicate mineral resulting from natural decomposition of feldspar and granite. Composed of microscopic disk-shaped platelates that give clay its slippery, plastic quality. 

Source: Clay: A Studio Handbook

Chun Glazes

A pale gray-blue feldspathic stoneware glaze featuring opalescence due to inclusions of phosphorous and/or other materials. 

Source: Clay: A Studio Handbook

Chuck

On the wheel, a temporary wet-clay form or reusable bisque-fired form upon which wares may be inverted for trimming. 

Source: Clay: A Studio Handbook

Chrome Oxide

Cr2O3—standard vivid green colorant—often softened with a little iron or manganese. Very refractory. With tin produces pink. May go gray-brown in reduction. Highly toxic in inhalation and ingestion. 

Source: Clay: A Studio Handbook

Chinoiserie

European pottery, eighteenth century and later, featuring decoration inspired by imported Chinese Ming Dynasty wares. 

Source: Clay: A Studio Handbook

China Paints Enamels

Very low temperature (cone 018) glaze colors applied over a previously fired higher-temperature glaze. Allow greater detail, brighter colors than other ceramic glaze effects, but are vulnerable to surface abrasion. 

Learn all about using China paints in this in-depth video!

Source: Clay: A Studio Handbook