Like so many segments of the photonics industry, optical adhesives owe much of their early development to the military. Prior to World War II, the standard material for bonding optical elements was refined Canada balsam. But the war spurred the development of synthetic adhesives with faster cure times and greater thermal and chemical resistance. Since then, the list of commercial adhesives has grown to fill an expanding range of applications. "Optical adhesives is evolving into a custom business," said Walter Brenner, director of research and development at Master Bond Inc. in Hackensack, N.J. "Users should understand that there's no cure-all, no single product that will do everything for everyone..."