1. A process for the production of a protective layer on a substrate which comprises thermally transferring, by the application of pressure and heat at a temperature of up to 150.degree. C., a radiation-sensitive layer from support to the substrate, which layer consists essentially of (a) a solid film-forming epoxy resin, (b) 0.1 to 15% by weight, based on the epoxy resin, of a cationic photoinitiator; and (c) 0 to 10% by weight, based on the epoxy resin, of a photo sensitizer, exposing directly said layer to radiation by an electron beam or actinic light, and then heating the layer after irradiation to harden said layer.