The surface properties of a material can be improved by means of highly resistant protective coatings, such as those obtained by photocrosslinking. Various types of materials are currently protected with UV varnishes, including wood, plastics, optical fibres, paper, leather, textiles, metals... The films from 20 to 100 μm thick increase the durability of these materials by slowing down the phenomena of degradation, oxidation, corrosion, aging and wear during their use. The introduction of photostabilizers in the resin formulation gives the coating a UV filter role and thus increases the photoaging resistance of polymer materials tenfold.

Although photopolymerization is mainly used to insolubilize thin photosensitive films, typically between 1 and 100μm, this technology allows much thicker samples to be crosslinked. For this, it is necessary to operate at low concentrations of photoinitiators, choosing a compound that undergoes rapid photolysis, without creating absorbent photoproducts in the near UV. This allows light radiation to gradually penetrate into the sample and initiate polymerization of the deep layers. Various types of acrylate and epoxy resins have been crosslinked by this frontal photopolymerisation to thicknesses of up to several centimetres.

By using solar radiation, this liquid/solid phase change can be achieved in a few minutes at room temperature and large panels can be processed at zero energy cost.