You can cut versatile, high-density, or closed-cell, foam smoothly and easily for a multitude of uses. Typically found in mattresses, chair padding, gym equipment, styrofoam, insulation and roofing materials, flotation materials for ships, docks and swimming pool noodles, high-density foam also has a place in crafts as well as everyday household items, from homemade stamps to restuffed and recovered kitchen chairs. High-density foam is a durable product that can last 10 years or more. It is considered high-density if 1.30795 square yards of foam weighs more than 52.8lbs. Flame-retardant high-density foam is also available.
Place your foam on a woodworking table or work surface.
Mark your foam using a fine-tip marker, tracing pattern and/or a ruler or measuring tape, according to your project. Use a long straightedge or metal construction ruler for larger projects.
Position your foam so that the side to be cut is slightly off the edge of the table. This will allow room for your electric knife or saw blade as you work. Hold the remaining foam securely on the table with your free hand.
Saw through the foam along the marked line or pattern using an electric carving knife or a band saw with a fine-tooth blade. These power tools work best on thicker high-density foam. Spray cooking oil on the electric-knife blade to ensure a smooth cut.
Use a utility blade or scissors to cut thin layers of foam, such as foam craft-sheets. If using a blade, hold the foam in place with one hand while sliding the blade carefully along your marked line. If working through a thicker piece of foam with a blade, use shallow cuts, repeating the cuts over the same area as the foam begins to open up. Alternatively, press a ruler firmly along your line and, using the ruler as a guide, run the blade along the ruler's edge. Lay a piece of cardboard or cutting board under the foam to protect your work surface, if necessary. A utility blade will not make as nice a cut through thick foam as an electric knife or band saw.
Most foam shops offer cutting service when you buy from them, so bring your project measurements along if you going to make a purchase. If using high-density foam as chair padding, remember to also cut vent holes into the foam to allow the air to escape as someone sits down; this will avoid the embarrassing whoopee-cushion sound that most people have experienced at one time or another.
Always use your dominant hand to do any cutting and your other hand for steadying. Do not try to use scissors to cut through thick foam. You will not achieve a clean cut: The scissor blades create a messy edge as they open and close on even slightly-thick foam.