n (1611) (1) Any substance used in small proportion which increases the speed of a chemical reaction. In the paint industry, the term usually indicates materials that hasten the curing or crosslinking of a resin system. In the polyester resin field, it covers more specifically an additive which accelerates the action of the catalyst (Odian GC (2004) Principles of polymerization. Wiley, New York. (2) An organic or inorganic chemical which hastens the vulcanization of rubber, natural, or synthetic, causing it to take place in a shorter time or at a lower temperature. Accelerators, particularly organic, are not mere catalysts of vulcanization, however, because they produce different and generally beneficial states of cure and different degrees of stability or resistance to chemical attack in the vulcanization (Carley JF (ed) (1993) Whittington's dictionary of plastics. Technomic Publishing, Lancaster, Pennsylvania, USA). See Catalyst and Crosslinking Agent.