Any tips on cleaning vintage glass negs?

I bought 7 whole plate size glass negatives. Looks like they were shot around 100 years ago. They were stored with glassine type sheets as separators however over the decades these sheets have stuck to the emulsion side of the plates. I would like to clean this paper off so i can have a go at contact printing the negs. I put one plate in a sink of lukewarm water & left it for 15 minutes approx. The paper came off easily but also took the emulsion with it from the parts of the plate where it had become fused.

Does anyone know of a way to remove the paper without lifting off the emulsion? I would think that conservators might have some technique or fluids for this.

You might want to ask Blackmelas as he works in Greece at an excavation company and he deals with glass plate negatives. He might know how to clean that kind of negative.

I think his name is normally not capitolized.