2 part floatation foam, is there a material that it doesn't stick to??

I would like to form it in place before laying in the deck, and need a material for a temp form.

 

Never come across anything it didn't stick to that was cheap, My solution was to line the area with a plastic bag if small, plastic taped together with duct tape if large.

 

Plastic packaging tape works, as do most of the polyethylene and polystyrene materials. The foam does stick, but not well, so it's easily removed. Wax and other mold release agents, such as PVA's also work.

 

Thank you.

 

Packing tape works well, I have made a number of molds using it to release, also pva sprayed over melamine plywood.