Glossary Terms (Simple)

Calcium Phosphate Bone Ash

Ca3(PO4)2—HT flux—opacifier in LT glazes—translucence in HT glazes (from colloidal phosphorus globules) and especially in bone china (from supercharged glassy-phase). Toxic in inhalation.  

Source: Clay: A Studio Handbook

Calcine

To heat a material to a temperature high enough to drive off all chemically combined water.  

Check out this article on calcining kaolin from the Ceramics Monthly archives!

Source: Clay: A Studio Handbook

Burnt Umber

Iron-manganese ore—good color source for basalt bodies.  

Source: Clay: A Studio Handbook

Burnishing Clay

Method of achieving a shine by rubbing clay or slip with smooth hard object.  

Here's a wonderful article on burnishing clay!

Source: Clay: A Studio Handbook

Breaking

In glazes, phenomenon where a glaze gives different colors in thick and thin areas—the color breaks from thick to thin. Effect accentuated in reduction firing when glazes reoxidize to different color in thinner areas, as in Temmoku breaking from black to brown, or copper red from red to clear.  

Source: Clay: A Studio Handbook

Bourry Box

Type of wood-kiln firebox where primary air enters at top of firebox, passes down through wood, and combustion occurs at level of grates or hobs, and is supercharged by the heat of the coal bed.

Read this great article on a community Bourry box kiln build!

Source: Clay: A Studio Handbook

Bone Dry

Completely dry (and very brittle) state clay must reach before firing.  

Source: Clay: A Studio Handbook

Bone China

Translucent porcelain containing bone ash.  

Source: Clay: A Studio Handbook

Bone Ash Calcium Phosphate

Ca3(PO4)2—HT flux—opacifier in LT glazes—translucence in HT glazes (from colloidal phosphorus globules) and especially in bone china (from supercharged glassy-phase). Toxic in inhalation.  

Source: Clay: A Studio Handbook

Body Reduction

Period of reduction atmosphere induced between cone 012 and 08 to bring out iron color and speckles in clay body, especially in high-fired stoneware.  

Source: Clay: A Studio Handbook

Blunger

A motorized impeller-mixer used in preparing casting slip.

Source: Clay: A Studio Handbook

Blunge

The process of mixing a glaze or slip with a motorized impeller-mixer.  

Source: Clay: A Studio Handbook

Bloating

Firing defect where blisters form within clay body, raising large lumps on the surface.

Get in-depth information on bloating in this article!

Source: Clay: A Studio Handbook

Blistering

Glaze defect where fired glaze surface contains bubbles, which often break open to leave sharp-edged craters in surface.

Find more information in this helpful article!

Source: Clay: A Studio Handbook

Bisque Firing

Initial kiln firing in which clay sinters without vitrifying, and though very porous, will no longer soften in water.  

Learn more about bisque firing in this post!

Source: Clay: A Studio Handbook

Bentonite

Al2O3×5SiO2×7H2O —Montmorillonitic clay formed from decomposition of airborne volcanic ash.

Taker a deeper dive into bentonite in this article!

Source: Clay: A Studio Handbook

Bases

In glaze chemistry, the fluxes or melting agents that are combined with acids (glass-formers) and neutrals (refractories).  

Source: Clay: A Studio Handbook

Barnard Clay

Slip clay with very high iron content, often used as brown colorant for clay bodies.  

Source: Clay: A Studio Handbook

Ball Mill

A mechanically revolving vessel in which ceramic materials can be placed along with water and flint pebbles or high-fired porcelain slugs. Used to grind clay and glaze materials.  

Source: Clay: A Studio Handbook

Ball Clay
diagram illustrating the formation of ball clays

Al2O3×2SiO2×2H2O —Secondary clays deposited in marshy areas. Very fine particle size, high plasticity, high in organic contaminates, and fires white or off-white. Used as the primary plasticizing clay in most clay bodies, but in large quantities promotes high shrinkage.  

Learn more about ball clays in this helpful post!

Source: Clay: A Studio Handbook