Time to close out this thread for the time being. I can say that I have completely failed to sub cellulose diacetate. I've been through every formula that I could find here on APUG and patents and ... I've tried acetic acid based, ascorbic acid based, formulas dissolving CD in acetone to make resin to dissolve in the subbing, two step formulas, drying, not drying, whatever.
I can get the subbing to adhere to the base, soak it in water and it stays put. Coat same with gelatin and the gelatin binds to the subbing and pulls it off in water. Or the gelatin will just not adhere to the subbing. There have been various outcomes, but none have worked. Actually, my most successful test was just plain undiluted nail polish remover. That lasted for about two minutes before the gelatin started lifting.
I can successfully sub cellulose triacetate and soak it in water for over 10 minutes, but not diacetate. Only trouble is finding triacetate, other than dissolving emulsion off of junk film with bleach - which is my current source. If anyone knows of a source for triacetate, I'd like to know about it.
So unless anyone has some new ideas, I'm putting this to bed for awhile. Denise was gracious enough to send me some Melinex 535 and a 3M product, so I'm off in that direction with my DIY film making.
Interested in suggestions anyone might have but I am here to tell you all this is not easy. Or I've just missed the boat!
Have fun, that's what it's all about!