Hi Sue. This is a tricky one. On a photo forum that I use called retouchpro (
http://www.retouchpro.com/forums/his...uck-glass.html) I found this thread. Below is one of the messages from a guy named mike
Done a bunch of this!
I have found that just plain water is a good place to start with any photograph that is say 1930 or newer. Depending on what the customer says and what I see, we usually make a copy of the photo before we start the process, just in case we run into something bad.
Soaking in plain water will work pretty well if the print has not been on the glass for a long time. Sometimes we get photos in where they have been on the glass for what appears to be decades or something and those can be a real problem. For those I add photoflo to the water. Photoflo is a thick liquid you add to the final rinse when developing film. It breaks the waters surface tension on the film, and seems to help the water penetrate into the paper emulsion that is stuck to the glass.
One would not want to use a hair dryer on one of these. It seems that getting a print wet, then having it stick to the glass and then dry is about the worst thing that can happen.
These are much easier to do if the prints are still damp when you get them.
Very often I let the print soak for hours and sometimes days. However you really have to watch them so they just don't dissolve on you (remember the copy made before you started?)
Great care, gentle handling and patience are needed. If you really want to tackle something hard, I had a customer bring me a stack of prints about an inch thick, they had gotten wet (really soaked) and so she put them in the oven and baked them dry. We did not do to well with those
Hope this helps..