Increasing response rate and stability of light-sensitive film - contg spiropyran and HX donor by reducing water penetration or content

The response rate and/or stability of a radiation-sensitive recording film based on a spiropyran (I), and HX donor (II), a film former (III) and opt. a sensitiser (IV) is increased by protecting the film against penetration of moisture or reducing the moisture content so that the water concn. in the surface area is 10-3, pref. 10-5 mole/1. This can be achieved by applying a water-impermeable or slightly water-permeable supercoat, pref. of a polymer, esp. a (co)polyacrylate; or by exposing the film to an atmos. of low relative humidity (RH) before and/or during recording and/or during storage. The supercoat pref. consists of polymethyl methacrylate (PMMA) and is is not>2, pref. is not5 mum thick. In the case of the use of an atmos. of low RH, the material is kept over a desiccant, pref. P2O5 or SiO2 gel.