How do the specific applications (composite, plastic, rubber, etc.) affect the type of mold release agent recommended?

In general, the release agent should not be chemically compatible with the material being molded: offering a good chemical and physical barrier preventing the molded compound from chemically interacting with the mold (substrate). It is the old adage “like dissolves like”, so if the release agent and material are too compatible, the material can penetrate the release agent film and adhere to the mold surface. The composition of the material being molded, as well physical characteristics like hardness and abrasion (often influenced by fillers and reinforcing agents), influence the choice of release agent. Different metal alloys, thermosets, thermoplastics and elastomeric materials have different molding processes and conditions which demand different requirements from the release agent, affecting mold release selection.