Smooth-On’s FOAM-iT!® Series are two-component water blown rigid foams that are versatile and easy to use. FOAM-iT!® products are available in 3lb., 4 lb., 5 lb., 8 lb., 10 lb.,15 lb. or 26 lb. per cubic foot densities. Parts A and B are measured and mixed in equal amounts by volume. The mixture is then poured into a mold or other form (apply release agent if necessary). The mixture will expand many times original volume (depending on which FOAM-iT!® product you are using) and develop a uniform cell structure. FOAM-IT!® 26 is tack-free in about 4 - 6.5 minutes, developing handling strength in 20 minutes and full cure in 2 hours. FOAM-iT!® 26 can be cast in blocks as a machinable prototype modeling board.