A type of ink that is cured by exposure to UV light. The vehicle in these inks contains mostly monomers and initiators. The ink is applied to a substrate and then exposed to UV light; the initiators release highly reactive atoms, which cause the rapid polymerisation of the monomers and the ink sets into a hard film. These inks produce a very high quality of print; they dry so quickly that none of the ink soaks into the substrate and so, as UV curing doesn’t involve parts of the ink evaporating or being removed, almost 100% of the ink is available to form the film.