I have recently been given a few of my late grandfathers photographs, some that he exhibited and some that have been hidden for years. They are all mounted, presumably by him - but have been badly stored in an old, rusty trunk for years. The most recent is dated 1984 and I think they've been stored since around then. The photos themselves show no signs of fading or deterioration, but some are stained by the rust and there is grime on most of them (some even have surface marks from spiders that had made their home with them!). I would like to clean them if I can, so that I can frame them, but since they're all mounted I don't know how I should go about it. Would cleaning with alcohol on cotton wool damage the print (how would this effect the mount)? Does any one have any ideas how I should proceed?