Glossary Terms (Simple)

Keramos

Greek term meaning earthenware from which the word ceramics is derived. 

Source: Clay: A Studio Handbook

Kaolinite

Crystalline clay mineral forming the basis of most clays we use in ceramics. 

Source: Clay: A Studio Handbook

Kanna

Japanese trimming tool, formed of a steel strap bent and sharpened on the ends. 

Source: Clay: A Studio Handbook

Kaki

High-fired Japanese saturated iron glaze usually containing at least 10% (of dry-batch weight) iron oxide, which produces iridescent microcrystalline rust red.

Source: Clay: A Studio Handbook

Iron Oxide Black Ferrous

FeO—reduced form of iron oxide—gives same results as red iron in the firing, dependent on oxidation/reduction. 

Source: Clay: A Studio Handbook

Iron Chromate

FeO×Cr2O3—glaze colorant producing pink or red with tin, brown with zinc, gray with alkaline fluxes. Highly toxic in absorption, inhalation, and ingestion. 

Source: Clay: A Studio Handbook

Iron

Most abundant coloring material on earth, responsible for brown and sometimes black color in natural rock and fired clays. In oxidation firings, the red ferric oxide remains very refractory, but in reduction firing and or at high-fire temperatures it transforms to the black ferrous oxide, a powerful flux. 

Source: Clay: A Studio Handbook

Interface

Contact face between clay and glaze. On low-fired wares, primarily just a physical interlocking of glaze into pores in clay. In high-fired wares, an intimate interaction of clay and glaze, reinforced by mullite crystals, creating very strong bond. 

Source: Clay: A Studio Handbook

Inclusions

Any particles or bubbles of material that remain suspended within the glaze-melt, affecting the glaze appearance. 

Source: Clay: A Studio Handbook

Incising

Decorating technique where design is formed by cutting or carving shallow lines in clay surface. 

Source: Clay: A Studio Handbook

Impressing

Decorating technique where textured or patterned material or object is pressed into clay surface. 

Source: Clay: A Studio Handbook

Ilmenite

An iron ore with significant titanium—most often used in granular form to produce dark specks in clay or glaze. Higher iron concentration than in rutile. 

Source: Clay: A Studio Handbook

Hydrometer

Laboratory device for measuring specific gravity in slips and glazes. Does not give absolute measurement, and should be used only for comparing and reproducing results. Must be an appropriate glaze hydrometer for measuring suspensions heavier than water. Does not work well in thick glazes. 

Source: Clay: A Studio Handbook

Hydrocarbons

Combustible gases containing hydrogen and carbon, present in fuel gases and produced when carbon-based liquid or solid fuels are heated above kindling temperature. 

Source: Clay: A Studio Handbook

Hot Face

The interior refractory surface of a kiln. 

Source: Clay: A Studio Handbook

Hobs

Steps constructed in walls of wood-kiln firebox in place of grates. Wood cut to proper length catches on hobs and remains suspended above coal bed, insuring quick and complete combustion. 

Source: Clay: A Studio Handbook

Hispano Moresque

Decorative style originating in Moorish Spain, characterized by extremely elaborate patterning and curvilinear plant motifs; major influence on Italian maiolica. 

Source: Clay: A Studio Handbook

High Fire

High-temperature firing range usually including cone 8 to cone 12, for firing stoneware or porcelain. 

Source: Clay: A Studio Handbook

HEPA (High Efficiency Particulate Arrestor)
Industrial designation that indicates that a filter or dust mask is capable of blocking microscopic particulates such as silica dust.

Source: Clay: A Studio Handbook

Helmer Kaolin

Al2O3×2SiO2×2H2O—Kaolin that works especially well as flashing slip for salt, soda, and wood firing, especially since Avery kaolin is no longer being mined. 

Source: Clay: A Studio Handbook