Duramold Pottery Plaster  A long-lasting, durable gravity slip casting mold.
Puritan® Pottery Plaster  A hard, wear-resistant plaster mold material, recommended for jiggering.
No. 1 Casting Plaster  Similar to White Art Plaster, except it mixes at a lower consistency for greater strength.
No. 1 Pottery Plaster  Used for dinnerware slip casting ceramic molds.
Moulding Plaster  A general purpose casting plaster used when expansion, hardness and strength are not important.
White Art Plaster  Similar to Moulding Plaster, features a surface hardening agent.
Pottery Plaster  A general purpose product recommended for more absorbent, slip casting pottery molds.
Hydro-Stone Gypsum Cement - One of the hardest and strongest gypsum cements. Resistant to water absorption.
Statuary Hydrocal Gypsum Cement - Harder and stronger than standard Hydrocal White gypsum cement.
Ceramical Gypsum Cement - A low-consistency, smooth-wearing, low absorption mold material, suitable for RAM processes.
Ultracal 30 Gypsum Cement - A high-density, high-strength, and low absorption gypsum cement made for close tolerance tooling.
Hydrocal White Gypsum Cement - A neutral, high-strength gypsum cement. Can be carved or added to.
Consistency is the number of pounds of water combined with 100 pounds of material.
Weigh clean, room temperature water in a clean container. Allow space for addition of material.
Weigh correct corresponding amount of plaster or gypsum cement.
Sprinkle the plaster or gypsum into the water. Allow material to sink to avoid adding lumps of material.
After adding all the plaster or gypsum, allow several minutes while the material soaks up water.
Mix using motions that do not introduce air into mixture, either manually or with an electric drill attachment at slow RPMs.
Final mix consistency should be like heavy dairy cream when poured.
Cleaning material from tools and buckets is easiest if material has not hardened. Power spray with water.
Absolutely, do not allow any material to enter plumbing drains.
Do not allow material to contaminate clay. Plaster absorbs water and can cause ware to explode during firing.
NOTE: Calculating the amount of necessary material and water on the basis of volume is tricky. Hydrocal White will yield about 50% more volume than the water after the addition of the material. I like to mix more than I will need, and typically will have an extra mould available (such as a plaster batt or plastic storage container) for the excess.
© 2003 by James Q. Jacobs. All rights reserved. Inquiries and feedback are welcomed. E-mail.