Which substance(s) can solve gelatin (on film stock)? I want to loosen the exposed layer on film stock which is made up of gelatin. Anything which would make gelatin dissolve that's not overly toxic? Thanks
Hot water, about 100 C, should do the trick. Also, this article has some information on the properties of gelatin layers in photographic films.

Properties and Stability of Gelatin Layers in Photographic Materials