A series of thermosetting polymers based on the chemical reactivity of an epoxide group. Epoxies, first developed in Switzerland in the 1930s, they became commercially viable in 1939, were further developed in the 1940's and 50's. They are composed of a liquid that, when mixed with a catalyst, crosslinks to form a hard, strongly bound solid. The most commonly used epoxies are made with epichlorohydrin reacted with bisphenol A. Epoxies are typically dense, insoluble structures that are dimensionally stable and wear resistant. They are used as protective coatings, as very strong adhesives, and with glass fibre to make fibreglass. Synonyms: epoxide resin; Ablebond; Araldite [Ciba-Geigy]; CM Bond; Epon® [Shell Chemical]; Epotek; Hxtal; Phillyseal R (formerly Pliacre) [Philadelphia Resins]; UHU Trench (2000); Museum of Fine Arts, Boston (2000). [J. Cassar, R. de Angelis]