Hi my chemistry is pretty dire but have vague idea that an electrochemical cell could be used to remove soft solder (lead/tin probably) from a piece of sterling silver in need of a repair.
The correct electro cell arrangement could be a good method of removing contaminants without damaging the silver / copper of the piece since lead and tin are less noble...
Opt 1 (reverse electroplating): Cell with something like a weak sulphuric acid solution as electrolyte, the contaminated silver as cathode, and possibly a stainless/carbon anode. Current should cause oxidation of the soft solder to lead/tin sulphate in solution. I'm guessing lead/tin may build up on the anode where would also be a release of... er, oxygen???
Opt 2 (Conversion to lead/tin chloride): Cell with something like H2O / NaCl solution as electrolyte, the contaminated silver as the anode and carbon / stainless cathode. Current should cause Cl to liberate at the anode and bond with lead / tin which hopefully will dissolve in the solution or can be scraped off easily. (not sure this is any better than just pouring HCl onto piece though!)
Opt 3 (conversion to lead/tin oxide): Cell with pure water or weak NaOH solution as electrolyte, the contaminated silver as the anode, and a carbon/stainless cathode. Current should generate oxygen at anode which might also cause lead/tin to convert to oxides which can hopefully be scraped off easily.
Are any of these methods viable/preferable? Opt 1 seems to be best as i dont think the electrolyte will react with the silver/copper if not too strong. Not sure if the sulphates will go into solution though or just build up / precipitate out from cathode.
Are any of these methods likely to be preferable to just pickling the piece in acid such as HCl?