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Glossary
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May 29, 2009
Titanium ore, used as source of titanium dioxide, contains iron, other trace minerals—gives tan color, promotes crystallization giving mottled multicolor effects in some HT glazes, or in overglaze stain (very refractory, use sparingly). Gives rich mottled medium blue in some HT glazes. Dark rutile contains higher percentage of iron.May 29, 2009
Small stamp wheel with raised pattern around the rim, which when rolled along a plastic clay surface leaves a band of relief pattern. Usually formed with damp or dry clay and bisque-fired.May 29, 2009
Beveled edge obtained by rolling the outer edge of the foot of a soft leather-hard pot at an angle against a hard flat surface.May 29, 2009
Variable electric switch often found on forced-air burners to control blower speed. Small inexpensive rheostats used on most power burners are imprecise, and adjustments should always be made on basis of flame at burner tip, preferably with an air- shutter on the blower-intake for fine adjustments.May 29, 2009
In a well-used salt/soda kiln, the light salt/soda effect that may be obtained by firing wares in the kiln without introducing any additional salt or soda, due to the revolatization of salt/soda from the walls of the kiln.May 29, 2009
In a wood kiln, the surface effects created by fly-ash settling upon the wares. Effect is maximized by turbulence in firebox, considerable draft through kiln, and/or active stirring of the coal bed. In short wood firings ash doesn't have time to melt, and leaves a rough, crusty surface.May 29, 2009
In a reduction firing, oxidation that occurs after fuel is shut off at end of firing.May 29, 2009
In plaster slip-casting molds, small rounded depressions carved in each parting face of a mold segment, so that when adjacent segments are cast a corresponding bump will form. In use, the keys allow the mold segments to be aligned and assembled securely after the original prototype is removed.May 29, 2009
Any materials highly resistant to the effects of heat. In kiln construction, high-temperature insulating materials, such as firebrick, ceramic fiber, etc. In clay and glaze chemistry, the neutrals or stabilizers that are resistant to melting and that combine with the fluxes (bases) and glass-formers (acids). Primary refractory material in ceramics is alumina, most often introduced in the form of clay (aluminum silicate).May 29, 2009
In fuel-burning kilns, firing atmosphere with insufficient oxygen to completely combust fuel, introducing abundance of unoxidized carbon and hydrogen, which extract oxygen molecules from surface of wares, altering appearance of clay and glaze. See climbing reduction.May 29, 2009
In a fuel kiln, maintaining slight reduction atmosphere during cooling cycle, from maturing temperature down to approximately 1400° F, in order to minimize reoxidation of clay and/or glazes. See reoxidation.May 29, 2009
Fe2O3—powdered rust—refractory red in oxidation, converts to black iron (flux) in reduction and/or high-fire. Low quantities in clear glaze produces celadon-green—high quantities produce temmoku black or saturated iron red—powerful flux. More than 5% in a glaze significantly increases fluxing in reduction.May 29, 2009
FeO—reduced form of iron oxide—gives same results as red iron in the firing, dependent on oxidation/reduction.May 29, 2009
Material such as silicon carbide used in clay or glaze to create localized reducing conditions in an oxidation firing.May 29, 2009
FeO×Cr2O3—glaze colorant producing pink or red with tin, brown with zinc, gray with alkaline fluxes. Highly toxic in absorption, inhalation, and ingestion.
