These are the most traditional and common blanks available in the world. Polyurethane blanks were the type of foam Clark Foam manufactured before they went out of business December 5th 2005. Here you will find all sizes and shapes of Surfboard blanks made from Polyurethane foam manufactured by US Blanks. All of the polyurethane blanks are molded to a crude form of a surfboard and need some shaping.