Products bearing the CL seal of the Art & Creative Materials Institute ("Caution Label") contain ingredients that are toxic or hazardous, but when used in properly supervised and controlled conditions, they can be enjoyed with complete safety.
This hard varnish turns slightly milky and produces a high-gloss finish. Old Holland Mastic Picture Varnish is made from a pure, clear mastic resin dissolved in white spirit. It should be used only after oil paints have dried, which can take up to one year. It may yellow somewhat.