V₂O₅ weak yellow colorant toxic, expensive usually fritted with tin to produce stronger yellow. Highly toxic in inhalation and ingestion.

Any glaze process where the glaze results from vapor deposited within the kiln includes salt glazing, soda glazing, and fuming.

Combination of Veegum T and carboxymethyl cellulose gum, used as a suspension and adhesion agent in glazes. Product of H.T. Vanderbilt Company.

Suspension agent/plasticizer similar to Bentonite and macaloid. Up to 2% of dry materials weight as plasticizer in high-kaolin clay bodies, and up to 1/2 of 1% of dry-materials weight as suspension agent, brushing medium in glazes and slips. Mix with water before adding other ingredients. Product of H.T. Vanderbilt Company.

Natural-draft gas burner featuring streamlined restriction in burner tube, which increases entrainment of primary air and the efficiency of gas-air mixing.

A porous expanded mica product used to introduce mica flecks in clay bodies and as filler in insulating refractory layer on kiln exterior.

Reference to a materials resistance to flowing. A viscous glaze flows less. As glass is heated it slowly becomes less viscous over a broad temperature range.

An engobe containing sufficient flux to form to a vitreous clay coating.

Fired clay that has fused together completely, so that the pores between refractory particles are filled with glass and the body is impervious to water. Vitrification is sintering in the presence of a fully developed glassy-phase.

Change from solid or liquid to gas during firing, resulting in out gassing from the clay or glaze. See out gassing, blistering.

Fine volcanic particulate expelled from surface vents in a volcanic eruption. HT alkaline flux, similar in composition to potash feldspar, but higher in silica, with at least 1% iron. May be substituted for 7 parts potash spar, 3 parts flint. Toxic in inhalation.