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Message:: [QUOTE="lrbguy, post: 2871964, member: 88829"]According to you the difference between verdigris and bronze disease is that the first is stable and the second "spreads."  That is a good informal way to distinguish them.  What you are not observing, however, and what I was pointing out, is that copper chloride tends to be soft and "spreads" while the acetates and carbonates tend to be stable.  So the chlorides are in a different class of danger to a coin than the acetates and carbonates.  Chloride ions are the essence of bronze disease, and that powdery green requires attention.  Acetates and carbonates tend not to be so invasive, and do not require extreme treatment, even though they are hard and green.  But to remove them requires different chemicals than the neutralization of chlorides.  There's not much more to it than that. BTW the questions I posed earlier were rhetorical.  I have used sesquicarbonate for years and am very familiar with what it does to the patina on a bronze coin.  You don't use it to remove verdigris unless you want to strip the coin.  But it is indeed the treatment of choice for bronze disease.  That tells you right there that these problems are not all one kind.  At this point that's all I intend to say on the subject.[/QUOTE]