In the engraved roller industry known as a ‘light-sensitive varnish’. It is usually made of a branded PVA (polyvinyl alcohol) emulsion added to a solution of ammonium bichromate. One way, using Stensol (a proprietary brand which is sold unsensitized), is to make a stock solution with 6 per cent sodium bichromate and mix one part stock solution to five parts Stensol.