Improved pottery plaster formulations for the manufacture of plaster molds

摘要

A plaster composition for making molds for reproduction by casting is disclosed. Calcium sulfate hemihydrate, potassium sulfate and potassium sodium tartrate are mixed together. The potassium sulfate and potassium sodium tartrate are in a ratio of from about 1:1 to about 10:1. Potassium sodium tartrate is present in an amount of from about 1 to about 10 pounds per ton of dry calcium sulfate hemihydrate, and the total of the potassium sulfate and potassium sodium tartrate is from about 2 to about 35 pounds per ton of calcium sulfate hemihydrate. Methods of making and using molds of this composition are also disclosed.