Photographic support material heavy metal impurity determn. - by coating with hydrophobic polyvinyl alcohol bonding agent, wetting with chemical indicator soln. and drying

摘要

Heavy metal impurities are detected on surfaces e.g. paper, coated, varnished or laminated paper, cardboard or resinous films or foil by coating the surface with a hydrophilic bonding agent, wetting the dried bonding agent surface with a chemical indicator soln. and allowing the indicator soln. to dry at room temp.. The bonding agent is pref. a soln. of gelatin, starch, sodium alginate, carboxymethyl cellulose, PVA or polyacrylate, together with a hardening or crosslinking agent. ADVANTAGE - Photographic support material contg. microscopic amts. of heavy metal impurites can be treated and the impurities detected with the naked eye due to diffusion of the indicator colour in the bonding layer.