All addition curing silicone elastomers are susceptible to inhibition of crosslinking when in contact with certain materials and chemicals. Inhibition occurs when the elastomer is only partially cross-linked after 24 hours or when the contact surface with another material is tacky. Materials containing amines or sulfur compounds and non-ferrous metals have a particularly strong inhibiting effect, as do organotin compounds in condensation-curing silicone rubbers. It is advisable to examine mixing containers, molding boxes, originals and release agents for inhibiting effects before processing.