Ceramic materials and glaze ingredients

Materials for ceramic artists

Quick reference

Read about materials and health here:

I use this safety color-system to organize materials in my studio:

I consider this materials as low health threat for studio use.
I consider this materials as increased health threat.
I consider this materials to be potensially dangerous.
I consider this materials to be too dangerous to use in my studio.

Note that this list is incomplete, may contain errors and inaccurate information.

• Celadon

  Blue Celadon Glazes

• Sodium | Na

  Low health threat for studio use (Non toxic).
  Alkaline and can cause irritation to eyes, skin, and by inhaling.

  Melting point 97.7 °C

  Alkaline and can cause irritation to eyes, skin, and by inhaling.
  Sodium is a soft, silvery-white, alkali, highly reactive metal with a low melting point.

• Sodium Chloride / Household salt / Table salt | NaCl

  Low health threat for studio use (Non toxic).

  Melting point 801 °C

  Used as glaze. Salt is aprox 40% sodium and 60% chloride. The active component in a saltglaze is Sodium. Sodium Chlorid ordenary table salt, and sodium carbonat (soda ash) is another soda glace used in low temperatures

• Sodium Carbonate / Soda Ash / Soda / Washing Soda | Na₂CO₃

  Low health threat for studio use (Non toxic).
  Alkaline and can cause irritation to eyes, skin, and by inhaling.

  Melting point 851 °C

  Used in clay, slip and glazes, can be added directly into the burning kiln, or as an ingridience in a glaze. Soda Ash Is a low fire flux and common in low fired ceramics. Is an environment friendly alternativ to saltglazes, and produses only water and carbon dioxide. Sodium carbonate is most often used in industries, less in households. A widely used chemical substances, produced all over the world.

• Sodium Bicarbonat / Baking soda | NaHCO₃

  Low health threat for studio use (Non toxic).

  Melting point: Decomposes to Sodium Carbonate, starts at 80 °C

  Used in clay, slip and glazes. A low fire flux and common in low fired ceramics. Makes a lot of bubbles in contact with water, need 30 minuts before the reaction stops. From 80 °C Sodium Bicarbonate starts to decomposes into Sodium Carbonate, water, and carbon dioxide. Sodium bicarbonate is one of the most common house items for baking and cleaning. Buy as bakingpowder in eveyday-stores. Widely used chemical substances, produced all over the world.

• Sodium Diphosphate / Disodium Diphosphate | Na₃PO₄

  Low health threat for studio use (Non toxic).

  Melting point 988 °C

  A deflocculant, a component in bakingpowder (see Soda Ash / Baking Powder).

• Sodium Silicate / Water Glass | Na₂SiO₃

  Low health threat for studio use (Non toxic).
  Alkaline and can cause irritation to eyes, skin, and by inhaling.
  

  Melting point 1.088 °C

  Used in ceramics as a deflocculant, prevent lumping, used in slip to neutralize the charges of particles. Sticky when wet, and hard when dry. It improves the green strength of glazes and clay. It also reduces viscosity in water.The material is often called “water glass”.

• Sodium Tetraborate / Borax | Na₂[B₄O₅(OH)₄]·8H₂O

  Medium health threat; avoid consumtation, inhaling, and skin contact.

  Melting point 740 °C

  Borax is a natural ocuring salt, and it’s a combination of boron and sodium. Borax has a pH of 9.5, and baking soda has a pH of 8.0. This makes borax considerably more alkaline than Sodium Bicarbonat (baking soda). Both soda ash and borax can be used as flux in glazes (see Soda Ash / baking powder).

• Sodium Borate / Boric Acid | H₃BO₃

  Medium health threat; avoid consumtation, inhaling, and skin contact.

  Melting point 170 °C

  Is a strong melting agent. Where borax is a mineral (salt) taken from the ground, boric acid is its extracted, processed and refined form. Borax and boric acid are two different formulations of the same compound (see also Gersley Borate).

• Boron | B

  Low health threat for studio use (Non toxic).
  In it self not considered harmful in foods and beverages, but is alkaline.

  Melting point 2.076 °C

  Almost all low-temperature glazes owe there existanse to boron-sourcing materials. Exept for Lead, no other flux melts in this low temperatures. Boric acid is a refined form of Boron.

• Gersley Borate (source of Borax)

  Low health threat for studio use (Non toxic).

  Melting point 740 °C

  Used in the clay, slip and glazes – A low temperature Akaline flux, an strong melting agent, and an opacifier. Gerstley Borate is very plastic like a clay, hardens glazes when dry. And make low-fired ceramics stronger. Often used in low fire glaze and fritts.
  Gerstley borate is a calcium borate ore containing Ulexite, and other minerals like Bentonite, Colemanite, and Probertite.

• Gillespie Borate

  Gillespie Borate is a synthetic blend to replace the natural form of Gerstley Borate. Gillespie Borate is produced by Hammil and Gilispie. Gillespie Borate reduces crawling and pinholes, and with less impurities.

• Laguna Borate

  Laguna Borate is an artifisial blend and an Gerstley Borate Alternative

• Colemanite | CaB3O4(OH)3·H2O

  Low health threat for studio use.

  Melting point 950 °C

  Is both a flux and glass-former. Colemanite is a low-fire glaze ingidiens, a popular source of Boron, similaritys with Gerstley Borate, often used to replace Gerstley Borate.

• Calcium | Ca

  Alkaline earth metal, Calcium is a reactive metal

• Calsium Borate

  Low health threat for studio use (Non toxic).

  Melting point 740 °C

  Gersley Borate and Colemanite is sorces of Calsium Borate, Calsium Borate is a sodium-calcium-borate compound. Used as a low-fire glaze fluxes.

• Calcium Carbonate / Whiting / Chalk / Limestone | CaCO3

  Low health threat for studio use.

  Melting point 825 °C

  A melting agent at high temperatures, improves the strength of the glass body. Is an economical source of calcium oxide, is a main component in the production of ceramics. Eggshell contains 95% Calcium Carbonate

• Calcium Oxide | CaO

  See Calsium Carbonate.

• Lithium Carbonate | Li2CO3

  Medium health threat, can be a helth issue.

  Melting point 720 °C

  Used in clay and glazes. Lithium is a very strong alkaline low-temperature flux and a powerful melter. Lithium is used in small amounts (up to 5%) and makes fluid glazes and a glossy surface, often used in combination with other fluxes. Lithium is a colorless salt, used in glazes to reduces thermal expansion of the glaze and increases a glaze’s firing range. It also increases strength of ceramic bodies.

• Quarts | SiO2

  Low health threat for studio use.
  Inhaled crystalline silica can be carcinogenic

  Melting point 1.650 °C ±

  “Silica”, “Flint” and “Quartz” are different names for the same mineral.

  Used in clay, slip and glazes. See also Silica and Flint. Is the primary glas-former in glazes. Quartz is the mineral form of Silica, and is used to reduce shrinkage when drying and firing. resent in many different ceramic materials from feldspars to bentonite to sand.

• Silica / Silica Sand | SiO2

  Low health threat for studio use.
  Inhaled crystalline silica can be carcinogenic

  Melting point 1.650 °C ±

  “Silica”, “Flint” and “Quartz” are different names for the same mineral, see Quarts.

• Flint / Flintstone | SiO2

  Low health threat for studio use.
  Inhaled crystalline silica can be carcinogenic

  Melting point 1.650 °C ±

  “Silica”, “Flint” and “Quartz” are different names for the same mineral, see Quarts.

• Powder Glass / Glass Frit / Glass Flux / Low temperature Powder Glass

  Low health threat for studio use.

  Melting point 580 – 700 °C ±

  “Powder glass” / “Low temperature Powder Glass” is a white powder glass milled down to very small particles, the variable melting points indicates several commersial products with different caracteristics and types of Flux.

• Feldspar | KAlSi3O8

  Low health threat for studio use.

  Melting point 1.150 °C

  The Feldspar group is a large groupe of minerals consisting of Alumina and Silica. Its a rock-forming mineral that make up 60% of the Earth’s crust. Feldspar often occurring as colourless crystals.
  
  Feldspar used in clay, slip and glazes. Feldspar is not a single mineral but a group of minerals. Feldspar is a natural resource, containing (among others): Calcium Oxide, Potassium Oxide, and Sodium Oxide, all 3 described in this list as fluxing agents. This makes Feldspar a significant flux. The two most common feldspars for Potter’s are “Potash Feldspar”, and “Soda Feldspar” (Albite). Feldspare affects the viscosity and fluidity of the melt. Feldspar is a glaze on its own, in fact; In Feldspar, Potassium (potash) and Sodium (soda) are insoluble, making Feldspar a naturally occurring Frit.

• Feldspar Custer / Custer Feldspar / Custer Potash|

  Low health threat for studio use.

  One of the main Feldspars used in the ceramic industry in North America

• Kona F-4 Feldspar |

  Low health threat for studio use.

  Once a popular Feldspar, no longer available

• Mahavir / Mahavir Feldspar |

  Mahavir Potash Feldspar, potassium feldspar imported from India

• Albite | Na2O·Al2O3·6SiO2

  Low health threat for studio use. Practically a non-toxic compounds.

  Melting point 1.100 °C

  See Alkali Feldspar. Albite is a very common mineral and a pure Sodium Feldspar. Albite use longer time to crystallize than other Feldspars.

• Microcline | K2O·Al2O3·6SiO2

  Low health threat for studio use. Practically a non-toxic compounds.

  See Alkali Feldspars. Microcline is a Potassium rich Alkali Feldspar. The most important use of Microcline is for manufacture of porcelain, ceramics and glass.

• Custer Feldspar

  Feldspar minded in Custer.

• Plastic Vitrox / Plastic Vitrox Clay / PVC

  Is a plastic, high-potash feldspar. Often used in low-fire clay bodies because it’s low melting point

• Petalite | LiAlSi4O10

  Melting point 1.350 °C

  Petalite is a Lithium Feldspar and a strong alkaline flux. Petalite gives unique color response to copper and cobalt. Its extreme thermal shock resistance, and a valuable additive to increases the clay body resistance to direct flame and rapid cooling. Petalite is an important ore of lithium, an higly refractory material but also quite expensiv.

• Cornwall stone |

  Low health threat for studio use (non-toxic).

  Melting point 1150-1300 °C

  A mid to high range flux for clay and glazes. Is a low iron feldspar material, there are 5 or more different types. Used in “Cornish Stone glazes”.

• Nepheline Syenite | Al2KNaO8Si2

  Low health threat for studio use.

  Melting point 1.200 – 1.450 °C

  Used in clay, slip and glaze. A hight temperature flux, used in the claybody or matte white glazes in low fire ceramics. Improves the vitrification process. Extremely stable up to 1.070 °C.

• Alumina Hydrate | Al(OH)3

  Low health threat for studio use.

  Melting point – very high melting temperature

  Commonly used in kiln wash, is the hydrated oxide of aluminium.

• Dolomite | CaMg(CO3)2

  Low health threat for studio use.

  Melting point 2.800 °C

  Used in clay, slip and glaze. A refractory material with a low thermal expansion that fits almost any claybody. Dolomite glazes is both hard and pleasant to the touch. The “Dolomite matte glaze” is a mid-range temperature glaze.

• Wollastonite | CaSiO3

  Low health threat for studio use.

  Melting point 1.450 °C

  Used in clay, slip and glaze. In low-fired ceramics it reduces shrinkage and firing warpage. Increases greenware and fired strength.

• Talc | Mg3Si4O10(OH)2

  Low health threat for studio use.

  Melting point 1.500 °C

  Used in clay, slip and glaze. Make matteness and opacity in low-fire glazes. Improves the vitrification process, lower the melt temperature. Talc is a refractory powder, above 1.050 °C talc re-crystallises.

• Zink Oxide | ZnO

  Low health threat for studio use.

  Even considered safe to used in cosmetics, but inhalation of Zinc Oxide can cause metal fume fever, and Zink will vaporize in a kiln reduction atmosphere at high temperatures, resulting in highly dangerous fumes.

  Melting point 1.970 °C

  Is a low expansion, secondary flux. Improves the elasticity of glazes. Zinc oxide is an important ceramic raw material. The industry widely use zinc oxide in glazes for bricks and tiles. Used in krystallinske glazes.

• Iron Oxide / Ferric oxide | Fe₂O₃

  Low health threat for studio use.

  Considered safe for use in cosmetics and personal care products. Exposure to Iron Oxide fumes can cause metal fume fever.

  Melting point 1.565 °C

  Iron oxide is primarily a colorant for glaze or slip. Is a chemical compounds composed of iron and oxygen. Available in several colors, where red iron oxide is the most common colorant used in glazes. Iron is the second most abundant metal on the earth’s crust.

• Spanish Red Iron Oxide | Fe₂O₃

  See also Iron Oxide

  Spanish red is a brown red natural earth based deposits in Spain containing 85% iron oxide.

• Iron Chloride | Fe₂O₃

  Is corrosive and can damage skin, eyes, and lungs if Inhalated.

  Melting point °C

  Colorant. Act as a high temperature flux in reducing atmosphere (iron in different form do so).

• Iron Chromate | Fe2(CrO4)3

  Low health threat for studio use.
  Repeated skin contact may cause slight to moderate irritation, overexposure of airborne particulate may irritating nose, throat, and respiratory tract, excessive levels of dust may be harmful.

  Melting point 1.760 °C

  very refractory in oxidation. To make brown underglaze colors, should not be used at temperatures above 900°C

• Iron Chromite | FeCr2O4

  See Iron

• Copper Carbonate | CuCO3

  Causes eye and skin irritation, harmful if swallowed/inhaled.
  Toxic to aquatic life. Is not a heavy metal, and not as toxic as other coluring agents for ceramics.
  

  Melting point 200 °C

  Primarily a colorant for glaze or slip. Has the potential to produce shades of green, turquoise, and reds.

• Copper Oxide / Black Copper Oxide / Red Copper Oxide | CuO

  Causes eye and skin irritation, harmful if swallowed/inhaled.
  Toxic to aquatic life. Is not a heavy metal, and not as toxic than other coluring agents in ceramics.
  

  Melting point 1.326 °C

  Used as colorant in glaze or slip. Normally produces green colors in small amounts toward black. Reduction firing can give vibrant red hues. Copper Oxider can give speckles in a glazes whereas the carbonate form will give a more even effect. Can potentialy produce shades of green, turquoise or reds.

• Sillimanite

  Is fine milled zirconium silicate.

• Ultramarine

  Not for pottery

  “Ultramarine” is a colour for paintings made of the stone lapus lazuli, artifisial made by heating soda, clay, and sulfur. “Ultramarine” for pottery, is comersial stains or glazes that imitate the famous blue colour

• Trona

  Trona is a raw material, a Sodium Carbonate compound. Then refined into soda ash, or Soda Bicarbonate. Wyoming in USA has the world’s largest deposit of Trona. The ore gets calcined, dissolved, and re-crystallized

• Shale

  Shale is a fine grained sedimentary rock that is formed by the compression of mud. Shale is used to make pottery, bricks, tiles and cement.

• Mica

  Low health threat for studio use (non-toxic).

  Mica flake is used in low fire clay bodies to add small sparkling particles, if burned to high the particles will melt and the efect is gone. Mica is typical used with low fire and Terracotta clays. Mica gives the clay an luster and subtle sheen. Mica is a natural stone with a pearly luster look formed in distinct layers. The most common form of Mica is Muscovite.

• Muscovite / Common Mica / Potash Mica / Isinglass | KAl2(Si3Al)O10(OH,F)2

  Low health threat for studio use (non-toxic).

  Melting point 1.300 °C

  Muscovite is a silicate mineral, it comes out of the ground as large shimmering, iridescent flakes. Mica flakes are prosessed into fine powder. Muscovite is the most common member of the mica group. See Mica.

• Ilmenite | Fe2+Ti4+O3

  Melting point 1.050 °C

  Ilmenite is a Titanium-iron Oxide mineral, and the most abundant titanium minerals on Earth, Ilmenite is the main source of Titanium Dioxide.

• Magnesium Carbonate | MgCO3

  Low health threat for studio use (non-toxic). High doses can be a health treat. Magnesium Carbonate is also sold as health supplements for humans.

  Melting point 990 °C

  Gives a matt, opaque surface in glazes, also used in low fired glazes. Magnesium carbonate is very refractory, but quite expensiv.

• Trisodium Phosphate | Na₃PO₄

  Low health threat for studio use (non-toxic).
  May not be harmful in small doses, large amounts can cause acute and long-term health effects

  Melting point 1.583 °C

  Lower the viscosity of slurryes to improve the fluidity of the mass.

• Pyrophyllite / Pyrax | Prl

  Low health threat for studio use (non-toxic).
  

  Melting point 1.580 °C

  Pyrophyllite-Talc mineral group. Talc and pyrophyllite are two monoclinic minerals with similar physical properties.

• Pyrotol

  Pyrotol is a commersial blend(?), based on the mineral Pyrophyllite. Used as a clay body ingredient in the same way as pyrophyllite. After World War I it was also an explosive with the product name “Pyrotol”.

• Metal salts / Metallic Salts

  Metal salts are chemical compounds produced in an Acid Bath mixing metal, acid, and (alkali) Potash. Every type of metal produces its own salt. Salts can be used to give colors to glazes. Examples of salts:
  Aluminum Chloride, Aluminum Nitrate, Aluminum Sulphate.

• Strontium Carbonate | SrCO3

  Naturally occurring strontium is not radioactive. Chronic exposure can result in serious health issues. However not considered hazardous to the environment.

  Melting point 1100 – 1494 °C

  Strontium Carbonate is a flux, producing matte, scratch resistant glaze surfaces. Is a recommended substitute for Barium Carbonate.

• Nickel Oxide | NiO

  Toxic by skin contact. May be irritating to eyes, respiratory tract and skin.

  Melting point 1.955 °C

  A colorant that produces grey, blue, and yellow. More concentrated than Nickel Carbonate. Not normally used in low fire glazes

• Nickel Carbonate | NiCO3

  Toxic by skin contact. May be irritating to eyes and respiratory tract.

  See Nickel Oxide

• Cristobalite | SiO2

  Inhaled crystalline silica in the form of cristobalite can be carcinogenic

  Melting point 1.713 °C

  Forms in clay. Cristobalite formes at very high temperatures, it has the same chemical formula as quartz but a distinct crystal structure.

• Hectorite | Na0.3(Mg,Li)3Si4O10(OH)2

  Low health threat for studio use (non-toxic). Considered safe for use in cosmetics and personal care products

  Melting point 300 °C

  An uncommon, highly plastic clay mineral related to bentonite, Hectorite is a rare magnesium lithium clay mineral.

• Tin Oxide |

  Low health threat for studio use.

  Melting point 1.630 °C.

  Valued in glazes for it’s white colour, is an opacifying agent and also a glossy glaze.

• Cryolite | Na3AlF6

  Medium health threat; avoid consumtation, inhaling, and skin contact. Classified as toxic.

  Melting point 1010 °C

  Is a valuable source of insoluble Sodium, lower melting point of Alumina to around 900 – 950 °C Cryolite is a fluoride of Aluminum and Sodium associated with Granite. Used in frits and glazes, mostly used for effect glazes and produce crackled and shrinking glazes.

• Titanium Dioxide | TiO2

  Low health threat for studio use (Non toxic). Also used for consumption by the food industry.

  Melting temperature 1.843 °C

  Used in glace and slip. Occurs naturally. The strongest white pigment used as pigment in everything from paint to icecream. 2% or more Titanium Dioxide develops crystals in glazes. Rutile works in similar manners, 6% or more i the glaze recipe producing a dry, visualy rich texture, but also an unstabile glace surface. In small amounts it make strong melts and strong surfaces.

• Titanium Oxide | TiO2

  melting point 1.843 °C

  Seams like Titanium Dioxide is used for ceramics, not Titanium Oxide

• Rutile / Dark Rutil | TiO2

  Low health threat for studio use (Non toxic).

  melting point 1.843 °C

  Rutil makes beautiful and attractive effects in glazes, it is not a strong colorant but can produce colors ranging from light, dark blue, tan, gold, yellow, and purpleeen. Highly prized additive by potters. Rutile is used for produsing titanium dioxide. Dark uncalcined Rutil contains some iron this gives it the red to brown colour.

• Light Rutile / Calcined Rutile |

  Low health threat for studio use (Non toxic).

  melting point 1.843 °C

  Light Rutile is Calcined Rutile, the calcining process clean out materials that can cause problems in a glazes. Rutile is as a blend of (mostly) Titanium Dioxide and Iron, Light Rutile has less iron than Dark Rutile.

• Bismuth / Bismuth Subnitrate | Bi

  Industrially it is considered one of the less toxic of the heavy metals. May cause diarrhea, skin reactions, headache, fever and more. The long-term use of bismuth can be harmfull to humans.

  Melting point 500 °C

  Bismuth is an important component in very low temperature frits and colors.

• Cerium Oxide | CeO2

  mildly to moderately toxic. Harmful if swallowed, irritating to eyes, respiratory system and skin.

  Melting point 795 °C

  A rarely used flux / opacifier / colorant. Used in glazes as a powerful flux. In combination with high temperature and titanium give a yellow colour.

• Cerium Carbonate

  See Cerium Oxide

• Cerium Chloride

  See Cerium Oxide

• Earth pigments: Yellow ochre / Limonite |

  Low health threat for studio use (non-toxic).

  Melting point 1.000 °C

  Earth pigments are naturally occurring minerals, mostly iron oxides, silica and clay, it is found throughout the world in many shades from yellow to brown. Yellow ochre is a yellow form of the mineral Limonite, contain about 50% iron. Makes an brown / black colour in a claze or as a slurry.

• Earth pigments: Sienna |

  Low health threat for studio use (non-toxic).

  Melting point °C

  Earth pigments are naturally occurring minerals, mostly iron oxides, silica and clay, it is found throughout the world in many shades from yellow to brown. Sienna is a form of limonite clay. Used from prehistoric times. The unique color is derived from ferric oxides.

• Earth pigments: Burnt Umbers |

  Low health threat for studio use (non-toxic).

  Melting point °C

  Earth pigments are naturally occurring minerals, mostly iron oxides, silica and clay, it is found throughout the world in many shades from yellow to brown. A clay pigment, contains iron and manganese oxides.

• Granite

  Low health threat for studio use.

  Powdered granite. Not a common material in glazes but can be used. Maybe buy from the local headstone-makers?
  Granite contains Silica, Alumina, Potash, Soda (Na2O), small amount of Iron and other materials.

• Rhyolite

  Low health threat for studio use.

  Rhyolite is the most silica-rich of volcanic rocks.

• Monzonite

  Low health threat for studio use.

  Monzonite contains less quartz than granite.

• Veegum T

  Glaze addetive, burns away in the fire. A surface hardener, improve the green-strigth of the glaze. It can also be spray-on the surface and harden, before hand-decorating.

• CMC gum

  Glaze addetive, burns away in the fire. Is a glaze thickener, make the glaze to dry slower (for painting), it also improve the green-strigth of the glaze.

• Epsom Salts

  Glaze addetive, a flocculating medium, dissolved in warwr, alternative to vinegar

• vinegar

  Glaze and clay body addetive to improve plasticity. The acid neutralize sodium ions that deflocculate the clay. The effect can also be to gel a slurry.

• Starch

  Glaze addetive, improves plastisity. From rice-water or potato-flour, wheat-flour, mais-flour, or other sources with much starch. Boil wheat-flour to a thickend soup, let it cool down and add dry clay. Will start to smell rotn in a few days so work fast

• Nylon fibers

  Nylon fibers burns away, awoids cracks whe drying

• Plaster of Paris / Plaster / Gypsum

  Gypsum, plaster is a fine white powder (calcium sulfate hemihydrate), can not be used as a glaze ingredience. plaster of paris gots it name due to abundant gypsum found near Paris. Known since ancient times.

• Organic ash |

  Low health threat for studio use (Non toxic).
  

  Melting point varies

  Ash for ceramics can be collected from a wide range of organic sources like: Trees, plants, scrubs, grass, seaweed, and countless different sources. Tje ash contain a wide range of oxides and minerals the plant has taken from the ground. Ash from each species can have there own signature cbination of stored minerals and nutrient

• Wood Ash |

  Low health threat for studio use (Non toxic).

  Melting point 1.000 – 1450 °C (depending on what type of ash)

  Wood ash contain lots of fluxing oxides like; Calcium, Potassium, Magnesium, Manganese, Phosphorus, Sodium. But ash needs hige temperatures to melt the ash into a glaze. This is why earthenware pottery often do not use Ash Glazes. Wood Ash has been used in glazes since primitive times.

• Volcanic Ash / Pumice

  Low health threat for studio use (Non toxic).
  Use respiratory protection when working with fine particle powder.

  Melting point 1.100 °C approx

  Volcanic Ash, also known as Pumice, consists of extremely fine particles of volcanic glass. Is is fragments of rocks and minerals. It add unique melting properties to glace recipes. Geologically it’s a type of feldspar. Volcanic ash varies a lot throughout the world, and can be used as a glaze.

• Bone China / Bone Ash | Ca5(OH)(PO4)3

  Low health threat for studio use (Non toxic).
  Not for human consumption.

  Melting point 1.670 °C

  Bone ash or bone china, is a white material and used in both clay body and the glaze where it adds translucency. Used to give texture in low fire glazes and act as a opacifier. Real Bone Ash is obtained by heating cattle bone up to 1100 °C, then milling into fine powder. After this it’s free for organic material. It also exist a syntetic Bone Ash.

• Bentonite | Al2H2O12Si4

  Low health threat for studio use.

  Melting point 1.200 °C

  In clay and glaze. Bentonite is a high plastisitet secondary clay, used to give more plasticity to clay bodys and higher green-stregth for glazes. Use max 5% in any glaze or clay.

• White Bentonite |

  Low health threat for studio use.

  Super white bentonite, or Calcium Bentonite Clay. Some cat litter are made of white bentonite clay

• Macaloid |

  Low health threat for studio use.

  Very clean white type of Bentonite. Also used as a plasticizer in fine porcelain.

• Kaolin / EPK kaolin / China clay | Al2H4O9Si2

  Low health threat for studio use.

  melting point 1.750 °C

  Used in clay, slip and glazes. Is a stabilizer, a white refractory clay with high shrinkage.

• Calcined Kaolin

  Low health threat for studio use.

  Calcined Kaolin is heated to high temperatures. Naturally occurring Kaolin contains water within its crystal lattice, calcining causes the Kaolin to loose its water and the structure to collapse, making the kaolin particles harder, denser, sharper, but also more porous.

• Grolleg Kaolin

  A blended English china clay: 81% kaolinite, 15% mica, 4% feldspar.

• Georgian Kaolin

  Mined in Georgia.

• Helmer Kaolin / Helmer clay

  Mined in a deposit near Helmer, Idaho.

• Molochite

  Addon to the clay body. Molochite is a high fired granular material made by Kaolin. The granules are hard and refractory.

• Ball Clay |

  Low health threat for studio use.

  Melting point 1.250 °C

  Used in clay, slip and glazes. A higly plastics secondary clay, consist of: 20-80% Kaolinite – 10-25% Mica – 6-65% Quartz.

• OM-4 / Old Mine #4 |

  Low health threat for studio use.

  OM-4 or Old Mine #4 is a ball clay

• Kentucky Stone

  Low health threat for studio use.

  A Ball Clay known for its high strength and plasticity. Contains 48% kaolinite, 39% quartz, 10% feldspar, and 1% organic matter.

• Albany Slip

  Albany Slip was a low plastic clay with silt particles, the clay melts down to a glossy brown glaze. Mined in Albany

• Terracotta clay

  Low health threat for studio use (non-toxic).

  Melting point 1.100 °C

  secondary lowfired clay, also used as a component in slip and glazes.

• Redart

  Low health threat for studio use (non-toxic).

  Melting point 1.100 °C

  Red-firing earthenware clay

• Porcelain

  Low health threat for studio use (non-toxic).

  Melting point 1.927°C

  White stoneware.

• Carbonedale Clay

  High iron refractory clay.

• Lizella Clay

  Red burning clay from Lizella, Georgia.

• Sagger XX Ball Clay

  Fine grained secondary clay which fires to a light colour.

• Cedar Highlights Redart

  Red firing earthware with low plasticity and low shrinkage

• Earthware / Earthenware

  Many different low-fired clays like terracotta and blueclay.

• Stoneware

  Stoneware clay / high-fire clay, A typical white high temperature stoneware is often about 25% each of kaolin, ball clay, feldspar and silica.

• Silicon Carbide / Carborundum | SiC

  Not used in crafts or ceramics workshops.

  Highly refractory. One of the most corrosion-resistant materials, used in a wide range of products that must withstand high heat and temperature shock, Like ceramic plates.

• Olivine | (Mg2+,Fe2+)2SiO4

  Contains small amounts of crystalline silica which can causes silicosis.

  Melting point 1.780 °C Approx

  Olivin sand is highly refractory.

• Titanium carbid | TiC

  Not used in pottery, see also: Titanium Oxide and Titanium dioxide

  melting point 3.160 °C

  Extreme strong and heat resistant ceramics, colour black.

• Aluminium Oxide | Al2O3

  Low health threat for studio use.

  Melting point 2.070 °C

  Used in clay, slip and glaze. Is a stabilizer, also higly refractory. Aluminium is the third most abundant element found in the earth’s crust.

• Mullite | Mul

  Low health threat for studio use. Not classified as dangerous according to transport regulations.

  Melting point 1.828 °C

  Mullite is valued for its refractory properties. An important ceramic material for structural applications due to its high temperature stability, high melting point, and low thermal expansion. Sintered Mullite and fused Mullite are primarily used for the production of refractories. Mullite is produced artificially, and rarity found in nature. Mullite is Kaolin or clay, mixed with Alumina and Silica.

• Andalusite | Al2SiO5

  Low health threat for studio use. No serious health risks have been found from exposure to andalusite

  Between 1.200 °C and 1.550 °C Andalusite transforms into Mullite

  Adding small amounts can increase material density, and improve the bending strength of ceramic plate materials. Is a promising material for manufacturing high-quality refractories

• Kyanite | Ky

  Low health threat for studio use. Harmful if swallowed or inhaled

  Over 1.100 °C Kyanite decomposes into Mullite and vitreous silica

  Kyanite is a refractory material with high resistance to thermal shock. Used as a grog in porcelain, tile clay, and casting slip. Reduces shrinkage and increases strength in the clay body.

• Chrome Oxide / Chromium | Cr2O3

  High health threat (toxic). Both states is toxic to animals, humans and plants.

  Melting point 2435 °C

  Used in slips, washes and glazes. Is a very powerful colorant, produces a wide range of greens. Chrome is the seventh most abundant element on earth.

• Cobalt Oxide | CoO

  High health threat.

  Harmful to swallow, inhaled and skin contact. Cobalt may cause an asthma-like allergy and respiratory reaction. The level of harm depends upon the dose and duration.

  Melting point 1.326 °C

  Used in slips, washes and glazes. A metallic coloring oxide, and a strong ceramic colorant, stabile at all temperatures where it produces blue / blue-violet blue colours in glazes (high amount make black color). Can make purples when manganese is present.

• Cobalt Carbonate | CoCO3

  High health threat

  See Cobalt Oxide.

  Melting point 427 °C

• Barium Carbonate | BaCO3

  High health threat when inhaled. Glazes containing Barium carbonate should not be used on surfaces in contact with food.

  Melting point 811 °C

  Acts as a flux. Widely used in the ceramics industry as an glaze ingredient, where it is matting and crystallizing. combines with certain colouring oxides it produce unique and exiting colours. Can make a glossy surfaces together with Boron. Red clays can contain soluble salts that will form a white scum on the ceramic surface after firing. In firing barium carbonate will form barium sulfates, and render the salts insoluble, 5% addition is enough.

• Potassium / Potash |

  High health threat (toxic). Skin contact with solid Potassium can cause severe burns. Toxic if swallowed. Potassium It is chemical known as a caustic (caustic soda is higly corrosive). Potassium is a flammable and reactive chemical, Potassium is a fire and explotion hazard (Potassium cyanide can releases hydrogen cyanide gas).

  Melting point 63,2 °C

  Many forms of Potassium: P. chromate, P. carbonate, P. hydroxide, P. Cyanide, P. arsenate, P. bromide, P. dichromate.
  Potassium is a soft silvery-white metal, can easily be cut with a knife. Potassium has a very low melting point, even a candle can melt it.

• Potassium Carbonate / Potash |

  Melting point 891 °C

  High health threat (toxic).

  Potassium carbonate is used in pottery and glaze. Are classified as either Potash or Soda (Sodium). It is a strong flux and can be used as a color modifier in glazes.

• Zirconium Silicate / Zircopax / zircon | ZrSiO4

  Low health threat; but avoide inhalation, skin contact, and chronic exposure. Considered to be non-toxic. As opposed to Zirconium Dioxide is not classified as flammable

  Melting point 2.550 °C

  Act as an opacifier, widely used in ceramic because of its good chemical stability. Can improve the binding performance of ceramic glaze and improve the hardness. Zirconium Silicate is not affected by the burning atmosphere in the kiln.

• Zirconium Dioxide / Opax | ZrO2

  Some sorces say Zirconium Oxide is highly flammable and can explode spontaneously in air. Some sorces say it is not a flammable material. Some sorces say it can emit toxic fumes if involved in a fire.

  Melting point 2.715 °C

• Silver nitrate | AgNO3

  High health threat (toxic). Poison and corrosive.

  Melting point 212 °C

  Used in metallic and lustre glazes. Gives a metalic shine when reduction fired.

• Gold luster | Au

  Over-glaze, on top of the burned and glazed clay.

• Platinum Lustre | Pt

  Platinum Lustre

• Praseodymium | Pr

  Rarely used colouring agent.

• Neodymium | Nd

  Rarely used colouring agent.

• Erbium | Er

  Rarely used colouring agent.

• Samarium | Sm

  Rarely used oxides.

• Europium | Eu

  Rarely used oxides.

• Terbium | Tb

  Rarely used oxides.

• Dysprosium | Dy

  Rarely used oxides.

• Thulium | Tm

  Rarely used oxides.

• Lanthanides | Ln

  A rare metal

• Scandium | Sc

  A rare metal.

• Yttrium | Y

  A rare, soft, and silver metallic. It’s highly crystalline.

• Gallium | Ga

  A rare, soft metal that melts in your hand. The abundance of gallium in the Earth’s crust is small, Gallium is not found in free form, or in any substantial amount in any mineral.

• Anorthite |

  See Alkali Feldspars

• Celsian |

  See Alkali Feldspars

• Anorthoclase |

  See Alkali Feldspars

• Oligoclase |

  See Alkali Feldspars

• Sanidine |

  See Alkali Feldspars

• Ulexite |

  See Gerstley Borate

• Titanium Dioxide |

  See Ilmenite

• Diaspore |

  An aluminium hydroxide oxide mineral

• Cadmium | Cd

  High health threat (toxic). Highly toxic and carcinogenic. Is the seventh most toxic heavy metal

  Melting point 321 °C

  Cadmium is used primarily to create bright orange and red colors.

• Spodumene | LiAl(SiO3)2

  High health threat.

  May cause cancer, damage to lungs, kidneys, and autoimmune system through repeated exposure by inhalation. Causes skin irritation and serious eye irritation.

  Melting point 950 °C

  Used in high-fire glazes and in some clay bodies. Small amounts of spodumene are frequently added to glaze recipes to lower glaze expansion and strengthen the resistance against thermal shock.

• Antimony oxide | Sb2O3

  High health threat. Inhalation are highly toxic.

  Melting point 656 °C

  Used as an opacifier for low fire glazes, also used as a substetutt for Tin oxide. Zink oxide and Antimony Trioxide together is used as substetutt for tin.

• Mercury | Hg

  High health threat (toxic).

  Melting point -39 °C

  Mercury is a naturally occurring metal.

• Manganese Dioxide / Manganese Oxide / Black Manganese | Mn

  High health threat when inhaled, not use in glaze for food.

  Melting point 535 °C

  Manganese is used as a colorant producing blacks, browns, and purples. Large amounts can produce metallic effects. Manganesein is also used to make a speckling decorative effect.

• Sulfur / Sulphur | S

  Sulfur is low in toxicity to people. But when heated it will release Sulphur Dioxide gas, which is highly toxic and can be fatal if inhaled.

  Melting point 444.6 °C

  Pure Sulfur is a odourless yellow solid. Sulfur is an impurity in many types of clay. Sulfur is released naturally by volcanic activity.

• Pyrite / Iron Pyrite / Fool’s Gold | FeS2

  High health threat (toxic) when heated to high temperatures.

  pyrite is not considered a hazardous material, but when heated the Sulphur in Pyrite will release Sulphur Dioxide gas, which is highly toxic. Pyrite is an Iron Sulfid.

• Asbestos | Mg3Si2O5(OH)4

  High health threat (carcinogenic), not used in ceramics any more.

  Historicly, asbestos has been embedded to clay pots to strengthen them with asbestos-fibers and to make the ceramics flame resistant.

• Lead | Pb

  High health threat (toxic). A highly toxic metal who has caused extensive environmental contamination and health problems.

• Arsenic Oxide | As2O3

  High health threat (toxic). Highly toxic and carcinogenic.

  Melting point 312 °C

• Thallium Sulfate | Tl2SO4

  High health threat (toxic). Not used in ceramics or glaze.

• Uranium | U

  High health threat. Not used in ceramics. Among the 118 elements present in the periodic table, Plutonium is the most dangerous. Uran is always radioactive.

  Nevertheless; Uranium oxide have been used in glazes, described in the book: “The Encyclopedia of pottery technicues”

• Tellurium | Te

  High health threat (toxic).

  Melting point 450 °C

  Tellurium is used as a coloring agent in ceramics, produce blue and brown colour

• Vanadinite | Pb5(VO4)3Cl

  High health threat (toxic), contains Lead, Lead is very harmful.

  Melting point 1.910 °C

  vanadinite is the main industrial ores of Vanadium. Vanadinite can also be used as a source of lead.

• Vanadium | V

  High health threat (toxic). Inhalation is highly toxic.

  Melting point 1.910 °C

  A colorant used to produce yellow, greenish, reddish to brown.

• Vanadium Pentoxide | V2O5

  High health threat (toxic). Inhalation is highly toxic.

  Melting point 690 °C

  Water soluble and bleed into surrounding glaze giveing interesting results.