|
Styrene foams such as styrofoam can be hotwired, with excellent results, as is common for wings, etc in homebuilt airplanes. But, polyester resin dissolves that foam, so you must use more expensive epoxy. In stage props, the basic shape is often done with styrofoam, and then a layer of plaster of paris or similar is applied, for final surfacing.
Urethane foam is said to gum and clog the hotwire, and some say the process generates toxic fumes. I don't know about this, as if it were so, surely urethane foam would not be allowed as common house insulation. However, the sanding and workability of urethane foam is excellent, but makes a dusty mess and the fine granules go everywhere. Urethane foam is fine with inexpensive polyester resin. It is also chemically the same stuff as Gorilla Glue.
I've read that those who've used both styrofoam and urethane foam for one-off projects such as car body panels or mods, much prefer the urethane. RMax insulation at Home Depot or Lowes is polyisocyanurate foam, essentially urethane, so may be an option for car body mods, if the skin is pealed off.
|