"Jeff" my last name @fidnet.com wrote in message ...
Here is the quick down and dirty on foam....

When you are talking about building airplanes there are 2 basic types of
foam, polystyrene (blue, pink) and polyurethane (tan, white, yellow). What
you really need to know is that polystyrene foam can be hot wire cut and is
very susceptible to fuel.

I wasn't going to mention this, but since you started talking about construction
materials later, I'll go ahead anyhow. Polystyrene also comes in white.