: Actually, these days many do. Clarkfoam ran into trouble with the EPA so the
: traditional surfboard foam is rare now.

: Windsurf boards definitely use eps. It comes in a multitude of densities -
: The variety used as a substrate for plaster finishes on buildings is quite
: dense (check your local plaster supplies dealer). I can step on it with
: all my weight on one foot (80kgish) and not leave an impression. If I
: jump, I can dent it.

: There's also xps - extruded polystyrene. Commonly used as an insulating layer
: under the concrete in multilevel carparking buildings. It's a bit more
: expensive, but doesn't have the gaps between the beads to worry about
: filling before glassing.

: You probably already know that you can use only epoxy resins with styrene
: foam of any description.. unless you want a really gooey mess!

Btw, never really got into surfbords but learned of they construction in many seminars I've attended on composite construction over the years. Still I suspect there are better substitutes for Clark Foam than building insulation foam, that stuff has some interesting uses but for projects requiring damage resistance it's not the ideal.

Bill H.