Art Spectrum Retouch Varnish is a temporary picture varnish. A thin coat restores luminosity to dull areas to aid colour matching. Sealer for painting grounds if the surface is too porous. Art Spectrum Retouch Varnish must be applied to a completely dry surface. While further layers of oil paint and varnish can be applied over Retouch Varnish, best practice is to remove the Retouch Varnish when the oil is completely dry (with Art Spectrum Artists’ Turpentine or Art Spectrum Odourless Solvent). Depending on your environment, Art Spectrum Retouch Varnish will be touch dry after 24 hours, although in colder climates it can take up to 4-5 days to dry completely.