Decorating technique involving cutting or paddling flat facets in the clay surface.

Widely used (and misused) term referring to any earthenware pottery glazed with an opaque glaze (usually white) and over glaze decoration.

Decorating technique where a soft, fine pointed tool is drawn through adjacent contrasting-colored bands of liquid slip applied to a damp clay surface.

HT alkaline fluxes insoluble aluminum silicates of potassium, sodium, calcium, and/or lithium inexpensive flux for clay and glaze. Substitution of soda spar for potash spar can lower vitrification by 100 degrees. Toxic in inhalation. See Custer feldspar, G-200, Kona F-4 feldspar, Nephtline Syenite, spodumene. 

FeCl₂—6H₂O soluble metallic salt fuming agent used to produce lusters on glazed surface. Highly toxic in inhalation and ingestion.

Long tapered knife useful for trimming cast or pressed pieces, and for separating mold components.

The fundamental design relationship between foreground imagery and background or surrounding area. Foreground shapes subdivide background, creating additional important shapes.

Gritty materials like sand, grog, volcanic ash, crushed seashells, etc., added to clay to open up body, give physical structure in wet-working and increase thermal shock resistance.

Highly refractory secondary clays with minimal fluxes and usually fairly coarse particle size low shrinkage, buff-color, often non plastic.

The part of a fuel-burning kiln where fuel gases combust before contacting wares. Gas kilns need little if any firebox, whereas wood and oil kilns produce long hot flames whereas require a large firebox unless flame-flashing and ash-slagging (with wood) effects are sought.

Ultraviolet sensor used on industrial burner systems to monitor burner flame. See flame-rectification system.

Maintaining some heat input after maturation, to retard cooling, or to maintain reduction atmosphere during cooling. See reduction cooling.

The profile or schedule for temperature change in a kiln-firing, often including both the heating and cooling ramps.

Surface effects caused by direct flame contact on wares.

In burners, when speed of air/fuel mixture exiting tip of burner is greater than combustion rate flame jumps off tip of burner and often blows out.

A burner system with automated reignition feature that immediate restores flame should it become extinguished. Usually incorporates a fire-eye ultraviolet sensor to monitor burner flame.

Gas burner tip that causes turbulence in moving stream of gas and air, intermixing them, speeding combustion, holding flame at burner tip, and preventing both flame-off and back-burning.

Wares made to stand stove-top heat. Explosions from trapped moisture, and resulting lawsuits have caused studio flame ware to disappear from the domestic market.

Color change in fired clay or slip due to direct flame contact and residual ash deposition in wood firing, or due to variable currents of vapor deposition in salt and soda firing. Flashing can occur on almost any light-colored clay body, but is most dramatic on porcelain bodies and slips.

Slip that is painted or dipped onto wares in order to promote flashing effects in the firing.

SiO₂ The primary glass-former in clay and glazes vitrification, fluidity, transparency/opacity controlled by adding fluxes and/or refractories. Highly toxic in inhalation.

The process of adding an acidic (usually ) substance (flocculant) that gives particles in suspension opposite electrical charges, causing them to attract one another (to flock together) a disadvantage in a casting slip but a great advantage in a clay body or a decorating slip. Usually only clay bodies high in kaolin need to be flocculated by adding 1/2 of 1% (of dry-batch weight) Epsom salts. Flocculation also often used to thicken up a glaze to help keep it in suspension and to improve application properties. See deflocculation.

Commercial flocculant used in glazes 1/4 tsp. per gallon of glaze.

Passages in kiln for flames or exhaust gases.

CaF₂ limited use as flux. As with Cryolite, fluorine reacts w/silica at high temperatures, can cause pin holing, blisters. Useful in special-effect crater-glazes. Highly toxic in inhalation and ingestion.

Decorating technique involving carving or forming vertical flutes or grooves in surface of a piece.

Low-melting component in clay or glaze that reacts with silica to form glass.

Airborne ash in a wood-kiln.

Base of a ceramic piece.

Firing system in a fuel-burning kiln that uses power-driven blowers or other pressurized air source to entrain primary air.

Direct-connected exhaust system equipped with suction fan, used on commercial furnaces, but never on studio ceramic kilns. Term often mistakenly used to refer to forced-air system.

Fracture zone that results when clay components are pressed straight together without disrupting the surface (by scoring and adding slurry or by smearing together) to intermix the platelates. Parts hold together while wet and tacky, but will separate easily when dry or fired.

Combinations of ceramic materials that have been melted to a glass and crushed/ground back to a powder, in order to give greater chemical stability and to eliminate toxicity resulting from water solubility of raw material. All frits are ground glass and are toxic in inhalation. FERRO 3124 high-alumina calcium-borate frit, gives greater strength in LT clay bodies. FERRO 3134 calcium-borate frit often used as substitute for Gerstley borate in low-fire glazes when greater reliability and/or long-term insolubility and/or greater transparency are desired. Makes good cone 04 transparent glaze by itself. FERRO 3110 and 3195 Both very similar to 3134 run tests to determine which works best for your needs.

The process of melting particular ceramic materials to a glass and then crushing and grinding to form a frit.

Process of introducing metallic salts into kiln or onto wares at about cone 018, producing thin layer of metallic surface iridescence.

In the glaze-melt, the point where dissolution of sintered structure is complete, and all refractory particles are dissolved into the glaze melt, forming a fused material one that has melted to liquid.