How to Make a Non-Toxic Plaster Mold
Make a custom non-toxic plaster mold to use in your clay, soap making or wax crafts. You can use nearly any solid object or a dry clay sculpture to form your mold using plaster of Paris, which is available from most craft stores. Plaster of Paris is generally considered non-toxic, according to the National Oceanic and Atmospheric Administration, although the dry powdered plaster could cause eye irritation or respiratory problems if inhaled.
Things You'll Need
- Modeling clay
- Object to mold
- Plaster of Paris
- Water
- Bucket
- Vaseline
- Newspaper
- Paintbrush
- Spoon
- Chisel
- Hammer
Instructions
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1
Roll out a 1-inch-thick rope of modeling clay slightly larger than the circumference of the object you wish to mold.
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2
Press the clay rope onto the object to divide the object into two halves with a clay barrier. This allows you to create a three-dimensional plaster mold of your object.
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3
Mix two parts plaster of Paris and one part water in a plastic bucket or large plastic bowl.
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4
Smooth a thin coat of petroleum jelly onto one half of your mold object. The petroleum jelly will help prevent the plaster from adhering to the object and make the mold easier to remove.
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5
Place the object with the petroleum-jelly-covered side facing up on a newspaper-covered work surface.
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6
Brush the plaster onto the petroleum-jelly-covered half of the object with a paintbrush. Continue to add the plaster until you have built up a 1-inch-thick layer of plaster on the object. Pour some plaster onto the object with a spoon or ladle to speed up the process. Do not spread any plaster beyond the clay barrier you created in Step 2.
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7
Wait for the plaster of Paris to become hard and dry, which could take 30 minutes or several hours.
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8
Peel away the clay barrier gently.
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9
Smooth a thin layer of petroleum jelly over the exposed side of the object and a thick layer over the edge of the hard plaster around the object. This will prevent the second half of the mold from sticking to the object and the first half of the mold.
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10
Repeat Step 6 to coat the other half of the object with plaster of Paris. Allow the plaster to dry overnight to make sure the mold is completely dry.
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11
Place a chisel at the top of the plaster mold where the two halves of the mold meet. You should see an obvious seam in the plaster.
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12
Tap the chisel gently with a hammer to carefully separate the two halves of the mold and loosen them from your original object. Work slowly and gently to avoid breaking the mold.
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13
Pry the plaster molds gently away from the object with your hands. Use the chisel as necessary to loosen the plaster mold but try to remove the mold by hand to avoid cracking the mold.
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