Rick Pennywhistle

I once did some research involving pure nicotine, and noticed that it had very much the same odor as cigarette butts in the department lounge ashtrays. So that suggests (a) one way to test methods without endangering your concertina (practice by de-odorizing used cigarette filters**, or store cigar butts for awhile in old soft- leather shoes) ; and (b) a molecular model for your chemist pals to use when suggesting approaches. Nicotine alone dissolves well in pure water at low pH (acid), and in oils at high pH (alkaline, typical of soaps). Lingering cig-smoke smell involves (nicotine + tars & oils). Totally untested suggestions* based on the above (warning: I know practically nothing about leather care) I'd first try a high-pH soap like a (diluted with some water, not straight from bottle) saddle soap or Murphy's Oil soap, then a quick water-rinse, dry & apply some leather cream or leather conditioner. Or you could try a mechanic's citrus-based hand cleaner withOUT pumice (permatex brand has neutral pH of 7), which might still remove oils while adding that happy orange-y aroma (but nicotine +citrus=ick). Be aware that some leather dyes can be affected by pH changes, so test on an inconspicuous part, maybe with coton swabs. Also avoid soaking the leather for long periods. *Your mileage may vary. Not responsible, yadda^2. **acquiring these will be left as an exercise for the reader. Or get unflavored vape oil. Richard (pennywhistle, but a concertina ally)