Abstract: A foam form sheet material having a first large surface comprising substantially only closed cells and an opposite large surface and an interior comprising substantially only open cells. This material comprises a cross linked olefin thermoplastic polymer or copolymer. The foam is made by mixing the polymer with a blowing agent and a cross linking agent. The mixture is maintained in a two roll mill means for a time sufficient to initiate cross linking and to initiate foaming to form closed cells. The sheet material is then disposed in a second two roll mill means having a nip that is larger than the thickness of the foamed sheet material and maintained under elevated temperature and pressure sufficient to initiate further cross linking and foaming. The fully cross linked cell foam is then compressed to rupture the closed cells that are disposed in the interior to form open cells.