Does anyone know what kind of foam is used inside of foam-cored paddle blades? I built a couple of them with some polystyrene that I got from a surfboard shaper, but I'm not convinced it's the best type of foam to use for paddles. I also have some polyisocyanurate. It's stiffer than the polystyrene, but I'm not sure how well it'll bond with glue or epoxy.

Thanks in advance for any insight.

Pedro Almeida