How to Create a Cast Using Plaster
Plaster of Paris is an inexpensive, easy-to-use sculpting material that you can use to create a variety of decorative projects. Flexible molds for plaster casting are commercially available at most craft stores, but you can make your own customized mold using modeling clay. Once you have an impression in the clay, you can create a cast of the design using Plaster of Paris. Always wait at least 24 hours after the plaster has dried before embellishing your design with paint.
Things You'll Need
- Modeling clay
- Rolling pin
- Fresh leaf
- Non-stick cooking spray
- Cardboard
- Craft knife
- Tape
- Plaster of Paris
- Mixing bowl
- Spoon
Instructions
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1
Roll out a sheet of modeling clay onto a flat surface with a rolling pin. Adjust the thickness of the clay sheet to the desired thickness of the plaster cast.
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2
Press a fresh leaf into the center of the modeling clay sheet. A leaf is only one of the many objects you can use to create a mold for casting plaster. Make sure that you apply enough pressure to create an outline of the leaf (or other object) without leaving finger marks in the clay. Remove the leaf carefully from the clay.
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3
Inspect the leaf impression left in the clay. If you are not happy, start over from Step 1 until the clay pattern suits you. The quality of the plaster cast will only look as good as the clay impression. Spray the final clay mold with non-stick cooking spray or some other release agent. This will help remove the plaster cast from the mold.
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4
Cut a four-inch-wide strip of cardboard to fit around the clay impression. Bend the strip around the clay impression and tape the ends together. Press the bottom edge of the cardboard into the clay so that it surrounds the imprint.
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5
Mix the Plaster of Paris according to the manufacturer's directions. Typically this involves slowly mixing in two cups of water into every three cups of plaster powder. Stir as you add the water to get rid of the lumps.
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6
Quickly spoon the Plaster of Paris into the clay impression. Make a thick cover of plaster over the impression. Allow the plaster to set according to the manufacturer's directions. Remove the cardboard ring carefully from the edges of the plaster cast.
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7
Allow the plaster to dry completely. Remove the plaster cast from the clay mold.
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