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Seattle Pottery Supply/Northwest Ceramic Supply, offers one of the most complete selectiions of chemicals and raw materials for the entire ceramic spectrum, including pottery, ceramics, glass and enameling. Descriptions are provided for some, but certainly not all of the chemicals on our price list. If you need something and can't find it on our lists or on our price lists, call us. Chances are we have the material or can find it for you.

Many ceramic materials are TOXIC. We at SPS feel that the safest course is to consider all materials worked with as toxic. Before you use any raw material, read up on it. Remember that combining two different items that are perfectly safe may result in an extremely toxic product. Use good common sense and be safe. A good industrial grade respirator and rubber gloves MUST be used. Do not eat or smoke with working with chemicals! Good habits of cleanliness, including frequent changes of contaminated clothing, can keep your studio a safer place.

The companies that supply us with our raw materials are the best in their fields. However, many of the materials we supply are natural products and may vary. We urge you to test each material when purchased. We can't make any warranty concerning these materials since the control of them is out of our hands. Again, test each raw material to make sure it will do what you expect before committing to a large batch.SPS is dedicated to ongoing safety research and awareness.

Raw Materials A-C
Albany Slip Clay
Acted as a glaze when used as an engobe. No longer minded. See Seattle Slip for substitute.
Borax Na2O:B2O3:1O2O
Low fire flux. Replaces lead in some glazes.
Alumina Hydrate Al(OH)2
Increases hardness and stability in glazes. Gives a matt finish. Adds craze resistance.
Boric Acid B2O3:2H2O
Reduces crazing in medium fire glazes; promotes gloss. Can be used to replace lead in low fire glazes.
Alumina Oxide Al2O3
Allows adjustment of glaze from matt to rough. Adds strength. Also used as a kiln wash. Does not dissolve in water.
Calcium Carbonate (Whiting) CaCO3
A source of lime in glazes. Used as a high temperature flux and low-fire matting agent.
Antimony Oxide Sb2O3
An opacifier for low fire glazes. Also used as colorant producing yellow with lead oxide.
Chrome Oxide Cr2O3
A glaze colorant. Produces greens or, when used with zinc, browns, tans and pinks.
Ball Clay Al2O3:2SiO2:2H2O
Adds strength and plasticity to clays. A suspending agent in glazes. Fine particle size, moderate organic material. Fires white.
CMC (Carboxyl Methyl Cellulose)
An organic cellulose gum used as a glaze thickener, binder and suspending agent. Use about 1/2% for brushing glazes.
Barium Carbonate BaCO3
Ties up sulfate in casting slips. Reduces salt leaching in red bodies.
Cobalt Carbonate CaCO3
A glaze colorant. Produces various shades of blue and, if manganese is present, purple.
Barium Sulfate BaSO4
Functions in a glaze similar to barium carbonate.
Cobalt Oxide CoO
A glaze colorant that produces reliable strong blue hues. Used in brushed oxide decoration. Stronger and grainier than cobalt carbonate.
Barnard Slip Clay
Used as a slip glaze. Maturation range is between cone 4 and 10.
Cobalt Sulfate CoSO4
A water-soluble cobalt used in lustrous blue raku glazes. Neutralizes yellow color of white slips.
Aids in plasticity and strength in clays. A suspending agent in glazes. Fine particle size.
(See Gertstley Borate)
Bentonite GK 129
White bentonite (See Bentonite)
Copper Carbonate CuCO3
Produces green to red in glazes.
Bone Ash
(See Tricalcium Phosphate)
Copper Oxide (black) CuO
A glaze colorant similar to copper carbonate, producing greens and blues; may yield copper reds in reduction. An extremely power flux.
Copper Oxide (Red) Cu2O
Used in the same manner as black. In oxidation it reverts chemically to black copper oxide. Stronger than black copper oxide.
Copper Sulfate CuSO45H2O
A water-soluble form of copper used in raku. A colorant producing copper ruby glass.
Cornwall Stone K20
A feldspar. Has a high calcium/silica content. Increases strength during the firing process.
Cryolite (Kryolite) Na3F6
A good source of sodium-alumina. A strong fluxing agent. Produces brilliant colors.
CAUTION: Many ceramic materials are toxic and should be handled with care. Inhalation and ingestion should be avoided. User should be familiar with proper safety precautions before using. M.S.D.S. are available upon request.

Raw Materials A-C
Code Name Image Price    

Prices are subject to change, and items may not be in stock.

WARNING: Some of our products can expose you to chemicals including Quartz, which are known to the State of California to cause cancer, and Lithium Carbonate, which is known to the State of California to cause birth defects or other reproductive harm. For more information, go to