Abstract: The invention relates to metal casting employing a pattern in a sand mold. A thin film of translucent thermoplastic is coated with finely divided graphite and then superimposed on the pattern with the layer of graphite sandwiched in between. Infrared radiation is applied to the film to soften the same with the radiant heat which is absorbed by the graphite serving to speed up the softening process. Then while the film is in soft drawable condition the film is vacuum-formed onto the surface of the pattern with the graphite serving as a lubricant for the plastic film as the film is drawn about irregular or deeply indented surfaces on the pattern to produce a tightly conforming barrier layer. Sand is molded about the pattern and its barrier layer to form a mold, following which the pattern is withdrawn leaving the layer in conforming and supporting contact with the sand.