For ComposiMold or ImPRESSive Putty Molds with Plaster of Paris. To use, add 4% Plaster Powder Additive to your Plaster of Paris. The addition of the Plaster Powder Additive is to curethe plaster to a strong solid casting in these molds. By creating cure more quickly, the water in the plaster does not react with the ComposiMold or ImPRESSive Putty to give strong, hard plaster castings.
Plaster of Paris comes as an easy-to-mix formula that mixes with water and dries to a dense, durable, and smooth and bubble free finish. Plaster of Paris is a great material to use for basic castings and molds and art projects because it is simple to mix and use. The Plaster of Paris sets in a few minutes, although it takes an hour before it is ready to be removed from the mold. It takes 24-48 hours to fully cure.
You can also use our pre-made ComposiMold plaster that has already been mixed.
3 oz. of ComposiMold Plaster Powder Additive is enough for 5 pounds of plaster powder. Mix the powder into the dry plaster mixture. Then mix the Plaster with cold water. Use 3 parts of Plaster with one part of water (by weight or volume). Let cure for 1 hour in the ComposiMold Plaster Molds before removing from the mold. Let the Plaster Casting cure for 24 to 48 hours before painting or sanding.