NOTES

Glaze colourants
	Antimony	Oxide	Sb2O3	yellow body stain in combination with rutile or titanium
	Chrome	oxide	Cr2O3	bright to dark green
	Cobalt	carbonate	CoCO3	almost always produces blue carbonate tends to disperse better In glazes with a high magnesia content, very small amounts of cobalt can give a range from pink through blue violet with manganese and iron will yield an intense black
		oxide	CoO
	Copper	Carbonate	CuCO3	generally gives green in oxidation and red in reduction In alkaline glazes, will produce turquoise in barium high-fired glazes produce intense blue and blue-green in both oxidation and reduction in low-fire raku glazes can yield metallic copper. Over time, however, the glaze will oxidize to green.
		Oxide Black	CuO
		Oxide Red	Cu2O
		Sulphate	CuSO4.5H2O	water soluable, used in saggar & pitt firing
	Erbium	oxide	Er2O3	light baby pink color,use CMC gum. best pink color at concentrations of 8-10%, but it is difficult to get more than 8% to fully dissolve in the melt
	Ilmenite		FeTiO3	produces dark brown specks in bodies and specialized glazes used in combination with rutile to develop characteristic rutile break glazes; it seeds crystals in titania glazes.up to 2%
	Iron	chromate	FeO.Cr2O3	used in glazes to produce gray (with feldspar), brown (with zinc), red (with tin) or black depending on the base glaze and percentage and other coloring oxides present. Often used in underglazes, engobes and clay bodies. Highly toxic in absorption, inhalation, and ingestion.
	Iron	Oxide black	Fe3O4	produces warm colors ranging from light tan and straw to deep, rich browns. Iron and tin in high-fire glazes result in a mottled cream color celadon green in reduction
		Oxide red	Fe2O3
		Oxide yellow	Fe2O3.H2O
	Manganese	carbonate	MnCO3	in an alkaline glaze, manganese carbonate can produce blue-purple and plum colors fairly weak colorant, adds spotty texture
		oxide	MnO2
	Neodymium	oxide	Nd2O3	good aqua color in most glaze bases at 1-2%. At 4-7% it gives a pleasant lavender/grape color
	Nickel	oxide	Ni2O3	Normal additions are 2-5% when used by itself, gives notoriously unpredictable results. It can be used to produce quiet grays and browns, but nickel is almost always used to modify and tone-down the colors produced by other colorants
	Potassium	Dichromate	K2Cr2O7	Occasionally used as acid-green colorant in raku glazes, but is highly toxic in absorption, ingestion, and inhalation
	Praseodymium	oxide	Pr2O3	small range of vibrant lime green colors  5-8%
	rutile		TiO2	unique property of breaking up and variegating the color and texture of glazes encourages crystal growth
	tin	oxide	SnO2	As little as 4-7% can produce brilliant white, although it is more typical to use 8-10% for full opacity chrome tin pink
	Vanadium	oxide	V2O5	yellows, especially when in combination with tin oxide

opacifiers
	Alumina	calcined	Al2O3	added to glazes in the tile industry to impart matteness,hardnes and texture  generally used in the manufacture of high-grade ceramic shapes, refractories
		Hydrate	Al2O3.3H2O	promotes opacity in enamels and glazes by generating gas bubbles in the glaze melt.
	Rutile		TiO2	unique property of breaking up and variegating the color and texture of glazes encourages crystal growth
	Tin	oxide	SnO2	As little as 4-7% can produce brilliant white, although it is more typical to use 8-10% for full opacity chrome tin pink
	Titanium		TiO2	Cream colours rather than white (compared to tin) Mottling effects
	Zinc	oxide	ZnO
	Zirconium	silicate	ZrO2.SiO2	Brand names: zircopax, ultrox, superpax Produces harder glaze than Sn or Ti. Less strong opacity than tin
Flux that is also opacifier:
	Barium	Carbonate	BaCO3	If available in sufficient amount, barium oxide will promote crystallization of a melt during cooling, thus imparting a measure of opacity.
	Bone Ash	Synthetic	3CaO.P2O5	encourages strong glaze textures; however, too much can produce crazing or blistering no effective substitute
	Calcium	carbonate	CaCO3	High calcium coupled with lower alumina will favour the formation of calcium silicate crystals during cooling. This mechanism promotes opacity
	Magnesium	carbonate	MgCO3	Buttery glaze surface

Glossary of Ceramic Raw Materials

Note: AT = all temperature, LT = low temperature, HT = high temperature.

ALUMINA HYDRATE - Al(OH)3 - Alumina source, rarely used in clay bodies or glazes, because all needed alumina comes from clay and feldspar. Used primarily for shelf-wash and wadding - better adhesion and suspension than aluminium oxide (Al2O3). Small additions increase viscosity of glaze melt. Should not be used as matting agent in functional glazes - produces immature glaze.

ANTIMONY OXIDE - Sb2O3 - colorant - soluble, toxic, expensive, produces yellow with titanium. Highly toxic in ingestion and inhalation.

BALL CLAY - Al2O3.2SiO2.2H2O - fine particle-size secondary clay, extremely plastic – primary plasticizing clay in most clay bodies - in large quantities promotes high shrinkage.

BARIUM CARBONATE - BaCO3 - alkaline earth - active HT flux, but also promotes matt glaze surface. Unsafe for low-fire functional glazes. Controversial in HT functional glazes, but toxicity problems from balanced HT glaze not proven. Often used as additive in clay bodies in very small percentages to render sulphates insoluble, reducing scumming. Toxic in inhalation and ingestion.

BBR; CLAY CERAM see Kaolin clay

BENTONITE - Al2O3.5SIO2.7H2O - montmorillonitic clay formed from decomposition of airborne volcanic ash - finest particle-size of all clays - plasticizer (3-times as powerful as ball clay), suspension agent, should be used in quantities no more than 3% of dry materials weight.

BONE ASH; CALCIUM PHOSPHATE - 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).

BORAX; SODIUM TETRABORATE - Na2O.2B2O3.10H2O - a major LT alkaline flux, available in granular or powdered form. Gives smooth finish, bright colours - water soluble, so is often used in fritted form. In excessive amounts creates brittle glass, and can cause blistering and pinholing. Available in granular and powdered form. Sometimes used with salt or soda in vapour glazing to lower firing temperature and/or achieve a smoother, shinier surface.

CHROME OXIDE - Cr2O3 - standard vivid green colorant - often softened with a little iron or manganese. Very refractory. With tin produces pink. May go gray-brown in reduction. Highly toxic in inhalation and ingestion.

COBALT CARBONATE - CoCO3 - standard blue colorant for slips and glazes - very powerful - 5% will give dark blue in glaze or slip. Will cause crawling is used raw for underglaze brushwork. Toxic in inhallation and ingestion.

COBALT OXIDE - Co3O4 - calcined cobalt carbonate - twice as powerful - coarser than carbonate, and may give mottling in glaze. Works well for underglaze brushwork, with few crawling problems. Toxic in inhalation and ingestion.

COLEMANITE - see GERSTLEY BORATE.

COPPER CARBONATE - CuCO3 - a major glaze colorant to produce greens in LT and HT, copper reds in HT reduction, and greens and metallic effects in raku. Toxic in inhalation and ingestion.

COPPER OXIDE, BLACK; CUPRIC OXIDE - CuO - alternate source of copper, coarser particle size, twice as powerful as copper carbonate. Toxic in inhalation and ingestion.

COPPER OXIDE, RED; CUPROUS - Cu2O - alternate source of copper, may help promote copper reds in LT and HT glazes. Rarely used, because has no affinity for water, and floats back to surface, but a few drops of detergent will break surface tension. Toxic in inhalation and ingestion.

COPPER SULFATE - CuSO4 - colour source for saggar firing and pit firing. Soluble, and highly toxic in absorption, ingestion, and inhalation.

CORNWALL STONE; CORNISH STONE - K2O/Na2O/CaO.Al2O3.10SiO2 - HT feldspathic alkaline flux containing calcium and potassium, but more refractory than potash feldspars. Substitution: eight parts potash feldspar, two parts silica, one part kaolin. Toxic in inhalation.

CRYOLITE; SODIUM ALUMINUM FLUORIDE - Na3.AlF6 - small amounts promote crackle effects, larger amounts become very volatile with silica, and may cause blistering. Used for special effect crater glazes.

CUSTER FELDSPAR - K2O.Al2O3.6SiO2 - a common USA potash feldspar - HT alkaline flux. See FELDSPAR. Close match to G-200. Toxic in inhalation.

DOLOMITE; CALCIUM/MAGNESIUM CARBONATE - MgCO3.CaCO3 - HT alkaline earth flux, promotes hard, durable surfaces and re-crystallization/matting in glazes. Often added to clay bodies to give longer firing range, and can promote more durable low-fire bodies.

EPK; EDGAR PLASTIC KAOLIN - Al2O3.2SiO2.2H2O - pure white kaolin, frequently used in glazes.

EPSOM SALTS; MAGNESIUM SULFATE - MgSO4 - Water soluble, rarely used as magnesium source in glazes. Most often used as flocculant for slips and glazes. Often added to porcelain and porcelaineous stoneware bodies (1/2 of 1% of dry materials weight) to counteract deflocculating alkalinity released by kaolins or fluxes.

FELDSPAR - HT alkaline fluxes - insoluble aluminium 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

FIRE CLAY - very refractory clay, for sculpture and raku bodies. Tremendous variation between different brands.

FLINT - see SILICA. Highly toxic in inhalation.

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

FRIT - fluxes which have been melted to a glass, cooled and ground, in order to stabilize soluble and/or toxic components during handling of unfired 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.

GERSTLEY BORATE; COLEMANITE; CALCIUM BORATE - 2CaO.3B2O3 - major LT alkaline flux - often gives slight opalescence in glaze - for greater transparency and long-term stability substitute Ferro 3134 or other Gerstley borate substitute.

ILMENITE - an iron ore with significant titanium - most often used in granular form to produce dark specks in clay or glaze. Higher iron concentration than in rutile.

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

IRON CHROMATE - FeO.Cr2O3 - glaze colorant producing pink or red with tin, brown with zinc, grey with alkaline fluxes. Highly toxic in inhalation and ingestion.

IRON OXIDE, RED, FERRIC - 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.

IRON OXIDE, BLACK, FERROUS - FeO - reduced form of iron oxide - gives same results as red iron in the firing, dependent on oxidation/reduction.

IRON OXIDE, YELLOW - see YELLOW OCHRE

KAOLIN; CHINA CLAY - Al2O3.2SiO2.2H2O - very refractory white primary clay – essential ingredient of porcelain and whiteware - less plastic than most other clays

LEAD CARBONATE; WHITE LEAD -2(PbCO3).Pb(OH)2- Former source of lead for glazes. Highly toxic in absorption, inhalation, and ingestion. Remove from studio and dispose of in a responsible fashion.

LEAD OXIDE, RED LEAD - Pb3O4 - Former source of lead for glazes. Highly toxic in absorption, inhallation, and ingestion. Remove from studio and dispose of in a responsible fashion.

LEAD SILICATE - 3PbO.2SiO2 - fritted lead compounds - LT flux, but resulting glazes may be toxic, and should cannot be used on functional wares. Most powerful of all fluxes, promotes smooth flowing, self-healing glazes. Highly toxic in inhalation and ingestion.

LEPIDOLITE - lithium feldspar - HT alkaline flux - used for thermal shock bodies and matching glazes. Contains fluorine, with associated problems. Toxic in inhalation.

LITHIUM CARBONATE - Li2CO3 - powerful AT alkaline flux, especially with soda or potash feldspars. Promotes hardness and re-crystallization in LT glazes. Forms low-temperature eutectic with silica.

MAGNESIUM CARBONATE - MgCO3 - alkaline earth - HT flux, promotes mattness and opacity in LT glazes, smooth, hard, buttery surface in HT glazes - promotes purples or pinks with cobalt. Used to promote controlled crawl glaze effects. See also MAGNESITE

MAGNESITE - in WA it refers to the “heavy” form of magnesium Carbonate

MAGNESIUM SULFATE - see EPSOM SALTS.

MANGANESE DIOXIDE - MnO2 - flexible colorant - with alkaline fluxes gives purple and red colours - by itself gives soft yellow-brown - with cobalt gives black. Used with iron to colour basalt bodies. Concentrations of more than 5% may promote blistering. Toxic in inhalation and ingestion.

NEPHELINE SYENITE - K2O.3Na2O.4Al2O3.9SiO2 - a common feldspathic flux, high in both soda and potash, used in clay bodies and glazes. Less silica than soda feldspars, and therefore more powerful. Increases firing range of low-fire and midrange glazes. Toxic in inhalation.

NICKEL CARBONATE, GREEN - Ni2CO3 - weaker nickel colorant, reduces to GREEN NICKEL OXIDE in the firing.

NICKEL OXIDE, BLACK - Ni2O3 - reduces to GREEN NICKEL OXIDE early in firing, and produces similar effects.

NICKEL OXIDE, GREEN - NiO - colorant or modifier - can give blues, tan, browns, greens, greys, dependent on fluxes present. Often used to mute the effects of cobalt, copper, and other colorants.

PEARL ASH; POTASSIUM CARBONATE - K2CO3 - HT alkaline potash flux, but soluble. Occasionally used as AT colour modifier to soften effects of colouring oxides.

PETALITE - Li2O.Al2O3.8SiO2 - lithium feldspar - HT alkaline flux - good for reducing thermal expansion, increasing thermal-shock resistance.

PETUNTSE - feldspathic rock, similar to CORNWALL STONE, found in China . Traditional Chinese flux for HT glazes and clay bodies.

CORNWALL STONE - used in place of potash feldspar in some porcelain bodies to increase plasticity.

POTASH FELDSPAR - see G-200; CUSTER.

POTASSIUM CARBONATE - see PEARL ASH.

POTASSIUM DICHROMATE -K2Cr2O7 - Occasionally used as acid-green colorant in raku glazes, but is highly toxic in absorption, ingestion, and inhalation.

PYROPHYLLITE - Al2O3.4SiO2.H2O - used in HT clay bodies (20% or less) to reduce thermal expansion, increase thermal shock resistance, reduce shrinkage, give stronger vitreous bodies. May reduce plasticity.

RUTILE - Titanium ore, used as source of TITANIUM DIOXIDE, contains iron, other trace minerals - gives tan colour, promotes crystallization giving mottled multi-colour 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.

SILICA; SILICON DIOXIDE; FLINT ; QUARTZ - SiO2 - main glass-former - vitrification, fluidity, transparency/opacity controlled by adding fluxes and/or refractories. Highly toxic in inhalation.

SILICON CARBIDE - SiC - used in very small quantities for localized reduction of copper reds - larger amounts for frothing glazes.

SODA ASH; SODIUM CARBONATE - Na2CO3 - soluble source of soda, used as deflocculant, or to supply soda in vapour-glazing process. Source of flux in Egyptian paste recipes. Brush solution over hi-fire glaze to increase carbon trapping. Highly toxic in inhalation and ingestion. See “magic water” under SODIUM SILICATE.

SODA FELDSPAR - Na2O.Al2O3.6SiO2 - feldspars contributing sodium (and potassium), primarily as a HT flux - includes KONA F-4, NC-4 and NEPHYLINE SYENITE. Toxic in inhalation.

SODIUM CARBONATE- see SODA ASH.

SODIUM CHLORIDE; SALT - NaCl - table salt, rock salt - used in salt-firing.

SODIUM SILICATE; WATERGLASS - Na2SiO3 - comes as a liquid - used as a deflocculant in slips, as an air-setting binder for LT refractories. Used  in “magic water” for use in place of slurry for joining wet or soft-leather-hard ceramic forms. Add 1.5% sodium silicate and 1.5% soda ash by weight to a measure of water.

SPODUMENE - Li2O.Al2O3.4SiO2 - lithium feldspar - powerful HT alkaline flux – promotes copper blues - good for thermal-shock bodies and matching glazes. Toxic in inhalation.

STAINS - MASON, HARSHAW, PEMBCO, FERRO, ETC. - stable fritted ceramic colorants available in wide range of colours, suitable for colouring clays, slips, engobes, and glazes. Most are stable up to cone 5, many to cone 10. Can be mixed with 25-50% Ferro 3134 frit for Maiolica overglaze decoration. Most stains are ground glass, and are highly toxic in inhalation.

STRONTIUM CARBONATE - SrCO3 - alkaline earth, HT flux, similar to barium, slightly more powerful - gives semi-matt surfaces. Non-toxic in balanced glaze. Substitute .75 parts strontium to one part barium..

TALC; MAGNESIUM SILICATE; STEATITE; SOAPSTONE - 3MgO.4SiO2.H2O – HT alkaline earth flux in glaze, promotes smooth buttery surfaces, partial opacity - similar composition to clay, but in LT clay bodies gives low shrinkage and high thermal-shock resistance, as in standard 50/50 talc/ball clay whiteware body. Highly toxic in inhalation and ingestion.

TIN OXIDE - SnO2 - most powerful opacifier, but expensive - inert dispersoid in glaze melt - 5-7% will produce opaque white in a clear glaze.

TITANIUM DIOXIDE - TiO2 - matting/opacifying agent. Promotes crystal growth, visual texture in glazes.

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

WHITING; CALCIUM CARBONATE; LIMESTONE; MARBLE; CHALK - 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 clay bodies to extend firing range and give greater fired strength.

WOLLASTONITE; CALCIUM SILICATE - CaSiO3 - used in partial replacement of silica and whiting in HT bodies, improves thermal-shock resistance. In some cases, it is used in place of whiting to eliminate L.O.I. Toxic in inhalation.

YELLOW OCHRE - high-iron yellow clay mineral, used as colorant in glazes and slips, converts to red iron oxide in oxidation or black iron oxide in reduction and/or high-fire.

ZINC OXIDE - ZnO - HT flux which promotes brilliant glossy surfaces. In some glazes can encourage opacity. With titanium in low-alumina glaze can encourage macrocrystalline growth (crystalline glazes). Volatizes in high-fire reduction. Toxic in inhalation.

ZIRCONIUM SILICATE - ZrSiO4 - zircon opacifier - inert dispersoid in glaze melt - low-cost substitute for tin oxide - use double the recipe weight of tin. Includes ZIRCOPAX, OPAX, SUPERPAX, ULTROX. All are toxic in inhalation.

ZIRCOPAX - zircon opacifier, no longer being manufactured. See ZIRCONIUM SILICATE. Toxic in inhalation.

1200 Glazes:	%		5kg (in grams)	10kg (in grams)
dark green satin (111)
Frit 4108	30.0		1 500	3 000
Silica	30.0		1 500	3 000
Dolomite	20.0		1 000	2 000
Kaolin	20.0		1 000	2 000
Chrome oxide	2.5		125	250
Cobalt oxide	0.3		15	30
Sarah’s mauve (23)
frit 3134		26.4	1 320	2 640
p. feldspar		31.4	1 570	3 140
whiting		13.6	680	1 360
kaolin		14.5	725	1 450
silica		24.0	1 200	2 400
cobalt ox		0.5	25	50
tin ox.		5.0	250	500
Sarah’s maroon (45)
frit 3134		26.4	1 320	2 640
p. feldspar		31.4	1 570	3 140
whiting		13.6	680	1 360
kaolin		14.5	725	1 450
silica		24.00	1 200	2 400
chrome		0.25	12.5	25
tin ox.		5.0	250	500
Phila green (410)
Nepheline syenite		57.0	2 850	5 700
strontium  carb		25.5	1 275	2 550
Ball clay		9.9	495	990
magnesium carb		2.8	140	280
silica		4.9	245	490
copper carb		4.0	200	400
rutile		4.0	200	400
Bright Sky Blue
Frit 3134		26.0	1 300	2 600
Potash feldspar		22.0	1 100	2 200
Talc		5.0	250	500
Whiting		4.0	200	400
Kaolin		17.0	850	1 700
Silica		26.0	1 300	2 600
Cobalt carb		1.0	50	100
Rutile		6.0	300	600
Iron oxide		0.5	25	50