2-part, high-density liquid polyurethane expanding pour foam cures very hard and rigid, with high compressive strength ideal for structural support, architectural castings, art-related applications, and flotation. 6 lb. density formula is great for plug making, filling buoys, creating sculptures, and more. Cures to a rigid, 94% closed-cell foam, where each individual cell traps air and prevents liquids like water, gas, and oil from penetrating.