Following on from another thread I am on the search for a suitable foam core for a compsand board. Locally all i can get is 0.9lb EPS as it is so rarely used nowadays here.
Nearly all insulation here in the uk is PIR boards. I had assumed these were extruded polystyrene but it seems they are not? The wikipedia entry from it seems to imply its similar to PU
Can anyone shed any light on this? Would it make a suitable core? Will epoxy glassing adhere to it?
Here is the blurb from wikipedia
Polyisocyanurate, also referred to as PIR, polyiso, or ISO, is a thermoset plastic[1] typically produced as a foam and used as rigid thermal insulation. Its chemistry is similar to polyurethane (PUR) except that the proportion of methylene diphenyl diisocyanate (MDI) is higher and a polyester-derived polyol is used in the reaction instead of a polyetherpolyol. Catalysts and additives used in PIR formulations also differ from those used in PUR.
1.6# or 2# closed cell foam would work even better for a compsand than EPS. I’ve done several veneers over PU foam (also closed cell) and that’s a great strength/weight combo.
With EPS if you get a ding out in the water the core will soak it in like sponge by the time you paddle the board in. But with closed cell foam the water intrusion is localized around the leak, and is way easier to completely replace/repair.