V2O5—weak yellow colorant—toxic, expensive—usually fritted with tin to produce stronger yellow. Highly toxic in inhalation and ingestion.
Source:
Clay: A Studio Handbook
Underglaze Engobe
Colored slips formulated to have low drying shrinkage, allowing application to bone-dry or bisque-fired surface before glazing. Commercial underglazes are available in a wide palette of colors primarily for low-fire, but many will survive high-fire.
Source:
Clay: A Studio Handbook
Underglaze Decoration
Process of applying any decoration to the bare, (usually bisque-fired) clay surface directly before glazing.
Source:
Clay: A Studio Handbook
Undercut
Common flaw in plaster or bisque molds, where the clay or casting catches and will not pull free without breaking or distorting.
Source:
Clay: A Studio Handbook
Ultrox
Zircon opacifier. Toxic in inhalation.
Source:
Clay: A Studio Handbook
Trimming
At the leather-hard stage, removal of excess clay from a piece, using any of a variety of sharp cutting tools.
Source:
Clay: A Studio Handbook
Triaxial Blend
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.
Source:
Clay: A Studio Handbook
Tombo
A T-shaped Japanese throwing gauge, used to measure the depth and rim diameter of a vessel, usually when throwing off the hump.
Source:
Clay: A Studio Handbook
Titanium Dioxide
TiO2—matting/opacifying agent. Promotes crystal growth, visual texture in glazes.
Source:
Clay: A Studio Handbook
Tin Oxide
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.
Source:
Clay: A Studio Handbook
Thermocouple
Temperature probe that produces minute variable electrical current dependent on degree of heat exposure—used in pyrometers and Baso valves.
Source:
Clay: A Studio Handbook
Thermal Shock
Effect of sudden temperature changes during firing or during subsequent heating and cooling in daily use.
Source:
Clay: A Studio Handbook
Thermal Expansion
The physical expansion and contraction that accompanies the heating and cooling of most materials. See coefficient of expansion.
Source:
Clay: A Studio Handbook
Terra Cotta Clay
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.
Source:
Clay: A Studio Handbook
Terra Sigillata
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.
Source:
Clay: A Studio Handbook
Tenmoku
Classic East Asian high-iron gloss glaze giving black where thick, breaking to brown or red-brown where thin.
Source:
Clay: A Studio Handbook
Suspension
A liquid mix where insoluble particles are distributed throughout without dissolving and may settle out from gravity, as in a glaze or slip.
Source:
Clay: A Studio Handbook
Superpax
Zircon opacifier. Toxic in inhalation.
Source:
Clay: A Studio Handbook
Strontium Carbonate
SrCO3 Alkaline earth, high-temperature flux, similar to barium, slightly more powerful.
Source:
Clay: A Studio Handbook
Stoneware
High-fired vitreous ware, literally as hard and durable as stone. Matures from 2200-2400° F. (cone 5–11).
V2O5—weak yellow colorant—toxic, expensive—usually fritted with tin to produce stronger yellow. Highly toxic in inhalation and ingestion.
Source: Clay: A Studio Handbook
Colored slips formulated to have low drying shrinkage, allowing application to bone-dry or bisque-fired surface before glazing. Commercial underglazes are available in a wide palette of colors primarily for low-fire, but many will survive high-fire.
Source: Clay: A Studio Handbook
Process of applying any decoration to the bare, (usually bisque-fired) clay surface directly before glazing.
Source: Clay: A Studio Handbook
Common flaw in plaster or bisque molds, where the clay or casting catches and will not pull free without breaking or distorting.
Source: Clay: A Studio Handbook
Zircon opacifier. Toxic in inhalation.
Source: Clay: A Studio Handbook
At the leather-hard stage, removal of excess clay from a piece, using any of a variety of sharp cutting tools.
Source: Clay: A Studio Handbook
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.
Source: Clay: A Studio Handbook
A T-shaped Japanese throwing gauge, used to measure the depth and rim diameter of a vessel, usually when throwing off the hump.
Source: Clay: A Studio Handbook
TiO2—matting/opacifying agent. Promotes crystal growth, visual texture in glazes.
Source: Clay: A Studio Handbook
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.
Source: Clay: A Studio Handbook
Source: Clay: A Studio Handbook
Effect of sudden temperature changes during firing or during subsequent heating and cooling in daily use.
Source: Clay: A Studio Handbook
The physical expansion and contraction that accompanies the heating and cooling of most materials. See coefficient of expansion.
Source: Clay: A Studio Handbook
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.
Source: Clay: A Studio Handbook
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.
Source: Clay: A Studio Handbook
Classic East Asian high-iron gloss glaze giving black where thick, breaking to brown or red-brown where thin.
Source: Clay: A Studio Handbook
A liquid mix where insoluble particles are distributed throughout without dissolving and may settle out from gravity, as in a glaze or slip.
Source: Clay: A Studio Handbook
Zircon opacifier. Toxic in inhalation.
Source: Clay: A Studio Handbook
SrCO3 Alkaline earth, high-temperature flux, similar to barium, slightly more powerful.
Source: Clay: A Studio Handbook
High-fired vitreous ware, literally as hard and durable as stone. Matures from 2200-2400° F. (cone 5–11).
Source: Clay: A Studio Handbook