How to Cut Styrofoam

Cutting Styrofoam (polystyrene foam) can be a challenge because the material breaks easily, resulting in uneven edges. Use these tips to cut Styrofoam into pieces with smooth, even edges.

1. Score the Styrofoam to create a clean break line.
   • Use a sharp, thin object to penetrate the foam in order to create a straight cutting line. Using even pressure, make a groove in the Styrofoam with a credit card, key, butter knife or any other sharp, thin object.
   • Break the Styrofoam along the scored cutting line. For best results, situate the foam on a table or counter top with the scored line along the edge of the surface. Press down gently along the scored line to create a clean break. If necessary, remove any excess foam with a serrated kitchen knife or craft knife.
2. Use a waxed serrated kitchen knife to cut Styrofoam.
   • Wax the knife by running the entire knife blade several times over a candle. To avoid getting colored candle wax on your foam, use a white candle.
   • Cut the polystyrene foam with the serrated knife using long, sawing motions. Keep steady, even pressure on the knife throughout the sawing motions to reduce the chances of breaking or crushing the Styrofoam.
3. Cut polystyrene foam with an electric kitchen knife. Use an electric kitchen knife, such as a carving knife or a fish fillet knife, to create clean cuts in Styrofoam.
   • Place the electric knife on the foam along the desired cutting line. Do not exert pressure on the electric knife, but allow the serrated blades to gently cut through the Styrofoam.
4. Use a craft knife to cut Styrofoam. A craft knife is ideal for cutting small, thin pieces of foam, but is not recommended for pieces with a thickness of more than 1 inch (2.54 cm). Unlike serrated blades that tear through foam, the sharp blades in craft knives tend to flatten or compress the Styrofoam. This could result in malformed or uneven cuts in thick pieces of foam.
   • Use a craft knife for small, precise cuts. Craft knives also can be used to create bevel cuts and v-cuts in foam.
   • Cut into the Styrofoam with the craft knife using small, steady movements. Create a shallow cut mark in the foam. After the initial cut, run the craft knife through the foam several times, creating deeper cuts each time until the Styrofoam is completely cut through from top to bottom.
   • Change the blades in craft knives frequently when cutting Styrofoam. Dull blades will create rough, uneven slices in the foam.
5. Use a hand saw to cut Styrofoam. Compass saws, coping saws and hacksaws create straight cuts in polystyrene foam. Avoid using a saw with a flexible blade because the blade can easily wobble in the soft foam, which may result in uneven cuts.
   • Cut the Styrofoam using long, sawing motions. Keep even pressure on the saw to reduce the chances of crushing the Styrofoam.
6. Cut Styrofoam with power saws. Jigsaws, band saws and scroll saws, which are traditionally used for cutting wood, can be used to create clean cuts in Styrofoam. Power saws are particularly effective in cutting large, bulky pieces of foam.
   • Follow the directions for the particular type of saw you are using. When using power saws to cut Styrofoam, always wear safety goggles.
7. Utilize a hot wire cutter. Hot wire cutters, which are available at home improvement or craft stores, melt through the foam with a heated wire, creating a smooth edge. Hot wire cutters are especially effective for creating shapes out of Styrofoam.
   • Apply consistent pressure with the hot wire cutter along the desired cutting line. Use extreme caution when operating a hot wire cutter because the wires are extremely hot and can cause severe burns.

• To create a variety of Styrofoam shapes, consider using cookie cutters. Press metal cookie cutters in foam sheets no more than 1/2-inch (1.27-cm) thick.
• To protect the work surface, use a cutting board or cutting mat when cutting Styrofoam.
• To smooth the rough edges of Styrofoam, rub the rough area with another piece of Styrofoam.

• Hot wire cutters are extremely hot and can cause burns. Do not allow children to use hot wire cutters.
• Use caution when cutting Styrofoam. Cutting tools are sharp and can cause injury. Seek medical attention immediately if you get cut.
• When using a power saw to cut Styrofoam, wear a dust mask. Power saws can create a "foam dust" that is similar to sawdust, but can be an irritant if inhaled.

• Sharp, thin objects like credit cards or butter knives
• Counter top or table
• Serrated kitchen knife
• Candle
• Electric kitchen knife
• Craft knife
• Hot wire cutter
• Hand saw
• Power saw
• Safety goggles
• Dust mask
• Cutting mat or cutting board