On Mon, 25 Aug 2003 21:57:00 -0500, "Jeff" my last name @fidnet.com
wrote:

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. Polyurethane should not be hot wire cut since it
emits cyanide gas when burned, but it is impervious to fuel. Generally
speaking, polystyrene foam comes in big blocks for hot wire cutting wings
and the like. Polyurethane foam normally comes in sheets or varying
thicknesses (1/4" to about 1"). The foams will also come in various
densities in weight per cubic feet.

When you talk about blue foam or polystyrene foam there is the construction
insulation stuff and flotation billets. The construction insulation has a
very small cell structure and I do not think it would bond very well to the
fiberglass. The flotation billet on the other hand has a more open cell
that will bond well with the fiberglass cloth.

There are several kinds of polystyrene insulation board. Usually
referred to as Styrofoam and Styrofoam SM in the construction trades
up here in Canada. Styrofoam is almost always white, and has a beady
texture. It is low density and rough. It is also available in big
blocks. Cheap foam coolers are made of this stuff.
Pink and Blue Styrofoam SM is often used as sheathing. It is higher
density and smooth. Usually comes in 2 foot widths, and with lap
edges. Occaisionally found in large blocks. This stuff has some
strength to it, where the white bead board is relatively low strength.

Hope this helps.

Jeff

"Corrie" wrote in message
. com...
What's the difference? I see references to blue foam all the time - why?