OZ, I think the term cleaning, is something that should be used to describe 'a procedure that removes something that's integral to the life-cycle of the coin,' such as age-related oxidisation for example? A lot of cleaning efforts that breach the above statement, are what we talk about in the negative. What I'm saying re cleaning is, yes, acetone may 'technically' be cleaning, but only removing the things that are NOT integral to the lifecycle of the coin, and so preventing those things that ARE great about an old coin from being diminished! When we store a coin in an ambient state, and handle them with kid gloves, are we not in a way protecting them from further contamination, maybe (technically) keeping them clean? If we are, then my argument is we should start with maintenance, namely, remove damaging contaminants! This is different to removing something that's already occurred, such as an acid print, or removing an unfortunate tone by dipping, etc.