In fuel-burning kilns, adjustable refractory plate located in exhaust flue, allowing control of back-pressure and secondary air, regulating kiln atmosphere.

Common deflocculant for casting slips. Product of R.T. Vanderbilt Company.

The process of removing the air from a plastic clay mass, usually accomplished through wedging, or far more effectively with a vacuum de airing pug mill.

Process of adding an alkaline (usually) material (deflocculant) to a suspension, which introduces like electrical charges to all particles, causing them repel one another and remain in suspension. A deflocculated suspension gives flowing consistency with less water content, meaning lower drying shrinkage especially important in slip-casting. Extremely low percentage of deflocculant additive is needed 1/4 of 1% (of dry-batch weight) soda ash and/or sodium silicate. See flocculation.

Clays that have been transported away from their point of geologic origins by wind or water. Finer particle-size gives greater plasticity ball clays, stoneware clays, fireclays, etc.

The phenomenon that occurs early in the glaze cooling cycle, when certain materials crystallize out of the vitrified (fused) mass.

Natural tendency of materials in liquid solution to go from area of high concentration to area of lower concentration, resulting in even distribution of materials throughout the glaze melt.

In glaze-melt, inclusions that disperse throughout the melt without actually dissolving into the glassy-phase. Examples are titanium or zirconium particles, colloidal copper, or minute air bubbles.

Action of a solvent material on a solid, bringing it into liquid solution. During glaze firing, the point at which the glassy-phase dissolves the sintered structure of the glaze, producing a true glass.

MgCO₃—CaCO₃ HT alkaline earth flux, promotes hard, durable surfaces and re crystallization matting in glazes. Often added to clay bodies to give longer firing range and can promote more durable low-fire bodies.

Kiln where exhaust gases exit through flue at floor level. Requires chimney to develop convection currents needed to draw off exhaust gases. Best system for reduction firing.

The flow of exhaust gases out of a fuel kiln, affecting intake of flames and secondary air.

In vapor-glaze firing, small rings of clay, formed to stand vertically, which are placed inside a peephole and may be removed with an iron rod during the firing, quenched in water, and examined to determine the degree of glaze deposition.

The removing of wares from a kiln.

Electric-drill-mounted impeller-mixer excellent for mixing glazes, slips, and slurries and for blunging casting-slip.

Traditional term referring to serious cracking occurring in cooling, resulting from drawing too soon, from extreme excessive glaze-compression, or from low thermal shock-resistance in over vitrified wares resulting from over fluxing and/or over-firing.