Hi

 I have an original OEM part that is made from EPP, and I need to finish it so that I can use it as a master to pull some composite molds from (ie. fiberglass and CF) is it possible to use just epoxy resin to finish the surface of the EPP or will it react with the EPP and melt it?

Thanks

No reaction between PP and epoxy. Although you might still need to seal it so that it can release, depending on how dense the foam is. Probably best to wrap it with the lightest glass cloth you can get and wet it with epoxy. After it cures, sand it smooth.

Thanks carbon cactus,

you could do that too, it would be weaker. It depends on the geometry of the foam, it might be rigid enough.