I don't try to clean most coins as a general rule, but on some that were out of the valuable range due to corrosion, I have done with just plain white distilled vinegar and salt. Just a few hours soaking with no electronics have produced great results. This method leaves a true color but frosty appearance from the acid etching (I guess). I'm sure that this is an old method that most have left behind for some reason or the other. Does the electrolysis method leave a frosty looking surface?