Casting Plaster


You will need: Plaster, your hand or a spoon and a container for the plaster to set in.
You can buy plaster at most hardware stores and some supercenters like wal-mart.


For carving plaster
Find a container that is a little larger than the sculpture you want to make. You can use a plastic milk carton after slicing off the top half for easier mixing and removal. You can use plastic tupperware but be aware that sometimes the container breaks when removing the hardened plaster.

Mix approx. 1 quart of water for every 2 pounds of plaster in your chosen container. Mix one gallon of water into every 10 pounds of plaster, and so on.

Pour the water in the container first, then add the plaster. Try not to drop clumps of plaster in; break it up well before dropping it in. Using the spoon or your hand, stir the mixture around. Make sure that any plaster at the bottom of the container is well mixed into the water on top. Stir the mix for about 10 minutes. The mixture will get warm and thick after about 10 minutes. When you can draw on the surface of the mix and it leaves an impression, it is time to pull your hand or spoon out and let it dry on its own.


For molds:
Use 2 3/4 pounds of plaster to each Quart of water. Add the plaster to the water by dropping it in slowly; allow it to stand for about 5 minutes; then stir vigorously with a spoon or hand until it is uniformly even. Use immediately.


For casting:
Add slightly less plaster to the water to make a more fluid mix. This is essential to obtain a sharp, smooth cast. After pouring  the mix into a mold, tap the mold to bring air bubbles to the surface. Do not pour too rapidly.


For retouching:
Add 1 part plaster to 2 parts water and stir vigorously. Wet the surface to be retouched thoroughly. Apply it to desired areas with a brush. When the plaster thickens, continue application with a spatula.


For mending and joining:
Mix in same proportion as for casting. Parts to be joined should be water soaked.


For bone hard castings:
Add a small amount of Jolly King Bone Emulsion to the mix and it will make a bone hard plaster casting.


To hasten the setting of plaster:
Add a few pinches of common salt to the water. Plaster casts can be made waterproof by adding boiled linseed oil; boiling a mixture of beeswax and parafin or adding plastics. Sculp metal adds a strong and waterproof finished surface.



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