An examination of the influence of photon flux and flux duration on the photoinitiated polymerization of UV curing acrylates. Initial experiments with medium pressure mercury lamps showed that increasing photon flux density by the use of focusing elliptical reflectors gave an improvement in cure. The work was extended by using the very high photon fluxes available from xenon flash lamps. Single and multiple flashes of light were used to cure a variety of formulations. The influence on cure, as measured by infrared spectroscopy, of photon flux density and pulse duration, is interpreted in terms of the elementary processes involved in free radical polymerization.