I recall that Kodak once made a Negative-Cleaner solution (which was probably only Isopropyl alcohol anyway?)
Personally, I simply sleeved my negatives as soon as they were dry; and I handled them only by the edges so they didn't get messed up.
You couldn't buy pure alcohol in the UK at that time without a prescription — possibly because someone in government thought that the populace would drink it?!
On that note, I raise my glass to everyone with all good wishes for 2022.