STUDY ON CHEMICAL FORMS OF IRON IN PHOTOGRAPHIC GELATIN USED IN COLOR FILM MAKING

Chemical forms of iron in photographic gelatin used in color film making were studied by means of gel filtration-atomic absorption spectrum method. It is shown that most of the iron in photographic gelatin coordinate with protein to form stable large molecular compounds and a litter one is small molecular. The trace inorganic iron salt added in the gelatin exists as protein-free iron form only. The foreign iron pollution, therefore, should be paid special attention when iron content in photographic gelatin is very low. Both total iron content and iron chemical form in photographic gelatin should be considered in photographic emulsion making.