Factice
Factice is vulcanized unsaturated vegetable or animal oil, used as a processing aid and property modifier in rubber.
Longer chain fatty-acid containing oils such as rapeseed or meadowfoam produce a harder, more desirable factice. Soybean oil produces lower quality factice, though it can be mixed with longer-chain oils to yield factice nearly as good as that made from long chain oils alone. Oil-resistant factice is made with castor oil.