I am scanning a large number of old (back to early 20th century, and possibly earier) negs and prints of family and ancestors. Most of the prints are not mounted, and many of them are not clean - anything from tape residue to peanut butter, I suppose. I am doing well with the negs cleaning with a graphic arts cleaner called Film Kleen. When I was in the army, I saw contemporary prints cleaned occasionally with something like this. I have some prints I don't want to take a chance with, and haven't tried cleaning them yet. I also have a gallon of Isopropyl Alcohol that is 100% (or nearly so, purchased from a druggist), so I could use that too. Anyone know what is best - for the negs and the prints?