Use Fotospeed FC50. I don't know what it is based on but it works. Apply with a microfibre cloth and leave to evaporate naturally.
Does the job for me
Depends on when they were processed, and what chemistry was used.
They were processed a few days earlier, C-41 at Target. (I don't know what chemicals specifically. I think they're a Kodak shop.)
I have 91% alcohol. I wonder if I should clean them again, or just leave well enough alone.
I think you are ok, current commercial C41 processes do not have a formalin type preservative in the final rinse.
Thanks Bob. Just the same, it will be alcohol next time.
Another vote for PEC 12. Its expensive, but usually a small amount will suffice to clean the negs/slides, so the bottle may last quite a bit.
Ronsonol lighter fluid works really well for oily deposits, way less expensive than a Brand Name bottle of methanol.
I find Pec-12 smears my negatives and slides. Especially if it gets on the emulsion side. Much better results with Ronsinol lighter fluid. Works great on both sides and evaporates quickly.
I have also had good results cleaning old, sticky and dirty negatives by very gently cleaning with hand soap and fingers under running water. Followed by a soak in C-41 stabilizer and hang to dry. (this measure only to be employed when more traditional methods fail).