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  • ComposiMold Plaster of Paris Additive  for strong hard plaster castings in ComposiMold
  • Plaster of Paris Casting

Plaster Powder Additive 3 oz. (Enough for 5 pounds of Plaster of Paris)


Product Description

Use this plaster additive to make a great plaster casting in ComposiMold or ImPRESSive Putty Molds. To use, add 4% Plaster Powder Additive to your Plaster of Paris or other plaster material. The addition of the Plaster Powder Additive cures the plaster  faster on the outside to make a strong solid casting. By creating a faster cure, the water in the plaster does not react with the ComposiMold or ImPRESSive Putty so the final product is a strong, hard plaster casting.

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. Also, use a mold release such as vegetable oil or mineral oil.


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Plaster Casting of a Duck Decoy 01:25

How to Make a Plaster Casting of a Duck Decoy with ComposiMold. First make the moldbox using a box of some sort. The easiest is to use a cardboard box with a trash bag liner. Spray the outside with an adhesive and press on a trash bag for a liner. Hot glue in the duck so it won’t float. You’re now ready to make your mold. We’re using used ComposiMold that we melted in a double boiler. Pour in the ComposiMold. Fill up and around the duck. Let the mold cool to solidify. We left this overnight. Pull off the mold box and pull out the original duck. You are ready to make your casting. We will be using ComposiMold’s new Plaster specifically designed for ComposiMold and Impressive Putty Molds.This duck uses 5 pounds of ComposiMold Plaster. Mix the plaster 3 parts plaster to 1 part water and pour into the duck mold. Let solidify for 1 hour, Remove the Duck Reuse the mold for more ducks or re-melt for new shapes Let’s make it. Thank you. No ducks were harmed in the making of this video. The duck bill broke and we glued it back on.

  • Plaster Castin...
    How to Make a Plaster Casting of a Duck Decoy with ComposiMold...
  • ComposiMold Pl... Molding and Casting a plaster bird ...

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