I am doing some experiments for molding a kayak seat and would appreciate some input.

I want to use using expanding polyurethane foam ["Great Stuff"] for the core and a thin coat of fiberglass for the skin of the seat.

The mould is made from burlap and a plaster-like material used for leveling floors.

I was thinking of saturating the mold with paraffin wax as a base and then spraying something [Teflon?] on top.

Any suggestions for a mould release agent?

Any other thoughts on keeping the polyurethane foam from gluing the mold together?

Thanks,

Hank