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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 M-R
Suspending agent. Similar in working properties to bentonite
Magnesium Carbonate MgCO2
Provides color and strength to glazes. Imparts opacity and can give a matt finish.
Magnesium Zirconium Silicate
Strong opacifier. Produces soft matt finishes.
Magnetite Fe3O4
A glaze specking agent. An oxide of iron.
Manganese Carbonate MnCO2
A flux and colorant. Produces purple to purplish brown.
Manganese Dioxide MnO2
Clay nad glaze colorant. Ranges from red to black depending on other materials present.
Mullite 3Al2O3SiO2
Reduces thermal expansion in clay bodies. Adds to fired strength.
Nepheline Syenite
Used as a soda feldspar. Helps to reduce crazing when added to clay bodies.
Nickel Carbonate NiCO3
Coloring agent producing browns, blues, grays, greens and yellows.
Nickel Oxide NiO
Useds as a colorant similar to nickel carbonate.
Nickel Sulfate NiSO4
Similar to Nickel Carbonate.
Provides yellows and browns in manner similar to iron.
A strong Zirconium based opacifier, no longer available. See Ultrox.
Used for mold-making, batts, wedging boards and press molds:

#1 POTTERY: High grade "porous" plaster for quality slip casting molds and general casting.

DRYSTONE: Can be used for solid of hollow applications. This plaster is a fast-casting gypsum cement that provides strong casts without the use of dryers.

DURAMOLD: Compare to No. ! Pottery Plaster! 10% longer life, 28% higher whet compressive strength, 66% stronger dry compressive strength! Much more durable!

GARDENCAST: A white gypsum cement that is perfect for freestanding, solid-cast, outdoor statuary, and takes paint well.

HYDROSTONE: One of the hardest plasters used for finished sculpture, castings, press molds (high compressive strength).

HYDROCAL: A very durable gypsum cement that works best for sculpture and architectual details.

HYDROPERM: A high-temperature gypsum used for non-ferrous casting.

ULTRACAL 30: A very strong plaster used primarily for ram-press type molds.

Petalite Li2OAL2O2:8SiO3
A lithium feldspar. Reduces thermal expansion in clay and glazes.
Potassium Carbonate (Pearl Ash)
A glaze flux and color modifier.
(See Volcanic Ash)
PV Clay
A feldspar clay.
Reduces thermal expansion in clay bodies.
Rutile TiO2
Glaze and clay colorant and specking agent.
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 M-R
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