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<p>[QUOTE=&quot;dougsmit, post: 1110568, member: 19463&quot;]Terminologies can be a problem. &#039;Bronze Disease&#039; is a form of green corrosion that is soft and powdery but, most significantly, produces hydrocloric acid by products that greatly speed the corrosion. Unlike Patina that stays on the surface and protects the coin from further deterioration, bronze disease penetrates into the coin and eats away sections rather like termites eat wood. Bronze disease requires moisture to work so it is more a problem in humid climates and some people slow it by baking the coin in a warm oven long enought to drive water out of recesses. In general, bronze disease is a lighter green than other patina forms but the significant feature is it being powdery. It is not hard to brush it away but it returns in a short time due to the remaining traces of chemicals and moisture in the air. This site has about as much as I have seen on the matter which is less than fully understood:</p><p><a href="http://proteus.brown.edu/greekpast/4867" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://proteus.brown.edu/greekpast/4867" rel="nofollow">http://proteus.brown.edu/greekpast/4867</a></p><p>&nbsp;</p><p>I do not currently own a coin with active disease but I&#039;ll attach a coin treated well over 20 years ago that has remained free since. In effect, it is a one sided coin now but considerably better than it would have been if left as it was.&nbsp; A coin has to be very special before I will consider buying it with even a small spot of the active problem.&nbsp; It is not always obvious what lurks below the surface.&nbsp; I have never heard the term &#039;verdigris&#039; appled to this prefering that to mean any generic green rather than this specific chloride.&nbsp; Does the situation described on that link match what you call verdigris?[/QUOTE]</p><p><br /></p>

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