Due to poor handling on my part ( I so need to get some proper storage for them ) I have dirt on some of my negs. I was thinking of cleaning it with some lens cleaner but wasn't sure if this was a good or bad idea.
Don't use lens cleaner, there are cleaners specifically for film, I use PEC-12 made by Photographic Solutions. Film cleaners are solvent based and have no water.
I have bathed negatives in a 50 / 50 solution of distilled water and the purest rubbing alcohol I can get (Isopropyl 90+%) to remove fungus, and other junk after some preservers became damp from long term storage.
After this bath, I hung them up as if they had just been washed with no problems.
There is a thread a month or two ago, that I started, with a lot of helpful posts here: (there was a url link here which no longer exists)
Don't use lens cleaner, there are cleaners specifically for film, I use PEC-12 made by Photographic Solutions. Film cleaners are solvent based and have no water.
PEC-12 or other film cleaner, again, because they contain no water. Water will soften the emulsion making it really easy to scratch. Which is a bad thing.
When you use PEC-12, wipe it off with a scanner wipe -- clean, soft, non-scratching, and won't leave any fibers behind. Wipe with a rolling motion -- to lift stuff up off the film as you go. Do not, under any circumstances, scrub film. That almost guarantees scratches.