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
CaCO3—alkaline earth, contributing calcium oxide to glaze—powerful AT flux—major HT flux for glazes—gives strong durable glass. Sometimes used in low-fire claybodies to extend firing range and give greater fired strength. Source: Clay: A Studio Handbook
CaO×3B2O3—traditional important LT alkaline flux, but is no longer being mined. Replace with Ferro 3134 for LT glazes, commercial Gerstley borate substitutes for HT glazes. Test all substitutes. Source: Clay: A Studio Handbook
To heat a material to a temperature high enough to drive off all chemically combined water. Source: Clay: A Studio Handbook
Iron-manganese ore—good color source for basalt bodies. Source: Clay: A Studio Handbook
Method of achieving a shine by rubbing clay or slip with smooth hard object. Source: Clay: A Studio Handbook
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
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.
Na2O×2B2O3×10H2O—a major LT alkaline flux, available in granular or powdered form.
Earliest and most basic firing process, where wares are fired in an open bonfire.