3MgO—4SiO₂—H₂O HT alkaline earth flux in glaze, promotes smooth buttery surfaces, partial opacity similar composition to clay, but in LT clay bodies gives low shrinkage and high thermal shock resistance, as in standard 50/50 talc/ball clay white ware body. Highly toxic in inhalation and ingestion.

Classic East Asian high-iron gloss glaze giving black where thick, breaking to brown or red-brown where thin.

Gritty materials like sand, grog, volcanic ash, crushed seashells, etc., added to clay to open up body, give physical structure in wet-working and increase thermal shock resistance.

Gritty materials like sand, grog, volcanic ash, crushed seashells, etc., added to clay to open up body, give physical structure in wet-working and increase thermal shock resistance.

Ultra refined clay slip that can give a soft sheen when applied to bone-dry wares and if polished or burnished while still damp may give a high gloss. All ancient Greek red-black pottery and Roman red wares were finished with this technique, without the use of glaze.

Low temperature, porous earthenware clay body, fires red-brown due to high iron content, which also fluxes clay, making it the most durable low-fired clay after firing.

A Japanese glaze similar to kaki, in which reoxidation and crystallization of iron in the glaze results in significant areas of purplish-red, often with some black or brown surface showing.

The physical expansion and contraction that accompanies the heating and cooling of most materials. See coefficient of expansion.

Effect of sudden temperature changes during firing or during subsequent heating and cooling in daily use.

Temperature probe that produces minute variable electrical current dependent on degree of heat exposure used in pyrometers and Baso valves.

See pyroplastic.

Wooden tool used by Japanese potters as an extension of the hand for raising the inside of pots, especially tall narrow forms.

Al₂O₃—2SiO₂—2H₂O air-floated secondary kaolin broader particle distribution than primary kaolins, greater plasticity, green strength.

Soluble metallic salt fuming agent to create mother-of-pearl luster on glazed surfaces. Introduced in cooling ramp at dull red heat, it will affect everything in kiln. Highly toxic in inhalation and ingestion. Fumes are especially toxic.

SnO₂ most powerful opacifier, but expensive inert dispersoid in glaze melt ”5“7% will produce opaque white in a clear glaze. Toxic in inhalation and ingestion.

TiO₂ matting opacifying agent. Promotes crystal growth, visual texture in glazes.

A t-shaped Japanese throwing gauge, used to measure the depth and rim diameter of a vessel, usually when throwing off the hump.

Method for testing three-way combinations of glaze materials, where proportional amounts vary through a series of samples between three limits. May involve change in glaze materials, or addition of colorants or modifiers. See line blend.

At the leather-hard stage, removal of excess clay from a piece, using any of a variety of sharp cutting tools.

A simple atmospheric burner with no venturi effect present.

Sequential-firing Korean kiln design evolving from Chinese bank kiln, with long sloping tubular firing chamber. See anagama.