Urethane foam, also referred to as polyfoam, is a synthetic version of foam rubber. It is flexible, shock-resistant and is a good insulator. Urethane foam is a malleable material that can be formed or cut into just about any shape. Urethane foam may be used to give soft, flexible support to costumes, make seat cushions or pillow forms, insulate hand-made lunch bags, or even to insulate seedlings in a garden cold-frame. Urethane foam is available in sheets or blocks and may be purchased at fabric, craft and upholstery supply stores. Cutting a thin sheet of urethane foam may be done with heavy-duty scissors. Accurately cutting thick sheets or blocks of foam, however, is best done with a reciprocating electric (turkey-carving) knife.
Instructions
1. Cut the outline of the paper pattern for the costume piece, seat cushion, pillow form, etc. with scissors. Position the paper pattern on the block of urethane foam. Push several thumb tacks through the pattern into the foam. Use a marker to outline the pattern and to draw dots on the edge of the pattern at corners, curves and every 3 or 4 inches on straight parts of the pattern. Make sure the dots are both on the edge of the pattern and on the outline on the foam. Remove the pattern and thumb tacks.
2. Place the foam block on a flat surface that has been covered with several layers of newspaper. Holding an ice pick vertically, position it on a dot on the edge of the pattern. Push down until you feel the resistance of the work surface. Carefully lift the foam block and ice pick and, using a marker, make a dot on the other side of the foam block where the ice pick is protruding. Repeat to transfer the entire pattern dots to the other side of the foam.
3. Turn the foam block over and position the paper pattern (also turned face-down) on the back of the foam block. Use the reference marks to properly position the pattern on the foam and apply thumb tacks to hold it in place. Trace around the pattern.
4. Place the foam block on a flat work surface, with about 1/3 of the block sticking out over the edge. The work surface will support the foam block while you are cutting the portion protruding over the edge of the work surface. Holding the knife vertically, begin cutting along the pattern line on top. Frequently look at the bottom surface of the foam to make sure your cutting lines are correct. Make corrections as needed.
