TotalBoat Liquid Urethane Foam Kit 6 Lb Density, Closed Cell for Flotation & Reinforcement (2 Gallon Kit) 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. Fast-setting, pourable polyurethane foam has a simple 1:1 mix ratio that makes it very easy to use. Mixed foam expands rapidly, and hardens in place in about 5 minutes at 70-80F. To fill larger areas, pour foam in separate batches, building up multiple layers. Sizes: Available in 2-Quart and 2-Gallon Kit sizes; Yield: 2-Quart Kit  3/4 cubic ft., 2-Gallon Kit  3 cubic ft.; Flotation Range (admixed): 23 lbs./qt. and 92 lbs./gal.; PROPER TEMPERATURE, TIMING, MIXING, and VENTING ARE CRITICAL TO ACHIEVING PROPER EXPANSION - Application Temperature: 75-80F; Mixing Time: 25 seconds (mix thoroughly; there should be no visible swirls in the material); Pouring Time Before Foaming Starts: 65 seconds; Full Expansion: Approximately 5 minutes.