Glossary Terms (Simple)

Heatwork

Work done by effective heat transfer to wares, resulting from ramp rate, temperature and duration of firing. 

Source: Clay: A Studio Handbook

Hardbrick

Hard, dense firebrick generally used only in high-stress areas of kiln (floor, burner ports, flues, bag wall) and for corrosive firing processes (salt, soda, wood). 

Source: Clay: A Studio Handbook

Gum Additives

CMC Gum, Veegum Cer—water soluble organic thickeners often added to glazes or slips as a suspension and/or brushing agent. Also used to allow glaze adhesion to vitrified or previously glaze-fired surfaces. Most commercial low-fire glazes and underglazes contain gum additives. 

Source: Clay: A Studio Handbook

Groundhog Kiln

A long, low horizontal sprung-arch or barrel-arch wood-fired kiln, often banked with earth, traditionally used by potters on the eastern slope of the Appalachian Mountains. 

Source: Clay: A Studio Handbook

Grolleg Kaolin

Al2O3×2SiO2×2H2O—English kaolin, more costly than other choices in the United States, but gives whiter porcelain. Less plastic than TILE-6. Best kaolin for translucent bone china. 

Source: Clay: A Studio Handbook

Grog

Crushed high-fired clay graded in sizes from 15-mesh (very coarse) to 150M (extra fine) added as a source of filler or tempering grit to clay bodies to reduce shrinkage and give structure for throwing or handbuilding. Does not shrink in firing, so in medium and coarse grades will show texture through thin to medium glaze. Toxic in inhalation. 

Source: Clay: A Studio Handbook

Goldart

Buff stoneware clay, produced by Cedar Heights Clay Company. 

Source: Clay: A Studio Handbook

Glomax
Calcined kaolin.

Source: Clay: A Studio Handbook

Glaze Resist

Decorating technique where resist materials are applied to prevent glaze from adhering to certain areas. 

Source: Clay: A Studio Handbook

Glaze Melt

The chemically active state of the melted glaze. 

Source: Clay: A Studio Handbook

Glaze Fit
The matching of glaze to clay body in terms of composition and coefficient of expansion so that it will adhere permanently.

Source: Clay: A Studio Handbook

Glaze Firing

Kiln firing in which glazes are melted to form a smooth glassy surface. 

Source: Clay: A Studio Handbook

Glaze Compression

In high-fired wares, ideal state when clay body shrinks slightly more than glaze, putting glaze under slight compression, giving greater strength, resiliency. See crazing and shivering. 

Source: Clay: A Studio Handbook

Glass Former

The primary material that, in combination with fluxes, forms the glass essential to all fired ceramics. Primary glass-former at all temperatures is silica. 

Source: Clay: A Studio Handbook

G 200

K2O×Al2O3×6SiO2—common potash feldspar, HT alkaline flux—close match to Custer. Toxic in inhalation. 

Source: Clay: A Studio Handbook

Fuming

Process of introducing metallic salts into kiln or onto wares at about cone 018, producing thin layer of metallic surface iridescence. 

Source: Clay: A Studio Handbook

Forced Air

Firing system in a fuel-burning kiln that uses power-driven blowers or other pressurized air source to entrain primary air. 

Source: Clay: A Studio Handbook

Foot

Base of a ceramic piece. 

Source: Clay: A Studio Handbook

Fly Ash

Airborne ash in a wood-kiln. 

Source: Clay: A Studio Handbook

Fluting

Decorating technique involving carving or forming vertical flutes or grooves in surface of a piece. 

Source: Clay: A Studio Handbook