At the bottom of my wine decanter (which due to its shape is fantastically hard to clean mechanically) a layer of reddish brown precipitate forms. I believe this is probably potassium bitartrate crystals, which are coloured reddish brown by the presence of tannins, which in essence is a polyphenol.
I would like to know whether there is a chemical that I could use to clean the decanter with minimum mechanical action. I have tried water (with and without soap), alcohol (in the form of vodka), isopropanol without success. I have yet to try acetone. Preferably the solvent should not be greatly toxic (at least I'd like to be able to wash it out with water and reuse the decanter), and not react with high lead-content glass (which is what decanters are made out of) - hydrofluoric acid is thus to be avoided (as usual). It is unsurprising alcohol doesn't work as the reason tartrates precipitate is apparently because they are not soluble in alcohol. It would also be useful if I could purchase the solvent outside a lab environment.
My understanding is that potassium bitartrate is more soluble in acid solutions. I've tried citric acid (made up from powder) and vinegar, but the effect if any is modest.
I don't much care if the method used is to react with (rather than dissolve) the precipitate.
(Note this question is in part a thought experiment. I realise that in fact the best way to clean decanters is generally mechanical despite the difficulties, and I'm familiar with the copper beads method and the egg-shell method, as well as no end of sponges on bendy sticks. However, I'd like to know whether there is a chemical way. Also note that I added an 'equipment' tag as it's possible that some know-how from cleaning chemistry glassware might be useful here)