2 Part Polyurethane Foam
A 2-part liquid foam, which when mixed together in equal parts can expand up to 25 times it's original volume and set rigid.
It is extremely buoyant - 1 cubic foot will support 27kg in water, and will bond well to most materials. It should always be protected by a GRP skin because, although closed cell and water-proof when set, it will absorb water when crushed.
1kg of liquid foam = 1 cubic foot when expanded under conditions of 18°C. Lower temperatures produce less foam.
See our guide to Pouring 2-Part Polyurethane Liquid Foam.