"Protection coating" on old slides and negatives

Sorry, I am still trying to find the right place to post this question, so please forgive me if this is not it, or if you have already read this...

The thing is: I have hundreds af old colour slides to scann. Most of them, specially the older ones, have a sort of coat on both sides. It is, I guess, a kind of protection bath that they used to give the slides after development to protect them from scratchs and somehow from fading too much as well. Now I realized that this coat is what is scratched and fade! It is costing me a lot to produce nice images from those once beautiful originals, and I discovered that by taking this coat off I can have a much improved result without hours fo PS. But the only way I could remove it was "mechanically" which certainly is not the best way to do it, considering how fragile the emulsion can be and the number of slides I have to work with.

Now the question, quite simple and straight: what can I use to chemically dissolve this coating without damaging the emulsion?

If anyone can help me with this one, it would be great!
Thanks a lot,
Ucha Aratangy