Abstract: The present invention contemplates a new plastic foam material which may be used to fabricate patterns for use in the Full Mold or Lost Pattern Foundry Process. Moreover, the present invention contemplates the application of organo metallic compounds to the situs of the plastic foam patterns used in the Lost Pattern Process, whereby the plastic foam patterns are vaporized during the casting process without the formation of solid carbon decomposition products. This means the casting is made in the presence of an organo metallic compound which effectively hinders the formation of solid carbon during the vaporization of the plastic foam pattern. It was found that the addition of an organo metallic compound such as metalocene to the plastic foam is surprisingly effective in this respect.