Cutting Styrofoam

Wanted to cut inch thick (pink/blue) styrofoam insulation sheets. Considered hot knives/wire, but they are tricky to wield, generate odor/fumes, have small chance of burns, and often generate less than straight lines (like a jigsaw in wood). Some suggest using a fine saw blade (like from a hacksaw), but that generates a foam dust mess. Some suggest scoring and snapping (with varying degrees of sucess in getting a good clean edge), but scoring and snapping only works well for straight cuts. Arcs and curves are hard to score and snap.

Read about using a serrated knife coated with wax to cut styrofoam. Was skeptical. Was very skeptical after prurchasing an old beatup knife (Goodwill) and rubbing beeswax (A.C.Moore lifetime supply one pound block) on it. Knife looked a mess, with varying thicknesses of wax gooped all over the blade. Beeswax is not very fluid/smooth at room temperature.

Seemed like wax would do more to make the styrofoam chip and gouge, than help make a clean cut, but wax-on-serrated-knife worked like a charm. The starting carving stroke generates friction, but the serrated blade makes a initial clean cut. The side friction warms up the blade and starts the wax flowing and every stroke after warm up is superb. It is almost like cutting a stick of cold butter. Would not have believed it.

Caveat is that working too fast and cutting too far (say about a metre) completely cleans the wax off the working area of the blade. One must regularly get out the wax block/candle and coat the blade again. But that is a small price to pay for a clean cut (straight or curved).