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<p>[QUOTE=&quot;John Burgess, post: 4901626, member: 105098&quot;]I&#039;ll attempt to elaborate but I&#039;m not the best with words to get a point across easily.</p><p>the capsule keeps dust and spit and fingerprints, off the coin. it protects it.</p><p><br /></p><p>However, when there is verdigris on a coin, it&#039;s actively &quot;corroding&quot; the surface of the coin and the capsule is keeping it right where it is, protected to do it&#039;s thing undisturbed.</p><p><br /></p><p>capsules or slabs are great to keep a coin from getting wear and keeping stuff of the surfaces, but it&#039;s not the best idea for a coin that has verdigris, because the slab or capsule is protecting the verdigris also. you aren&#039;t touching it, but whatever the coin came in contact with to cause the copper carbonate to form, it&#039;s likely still right there on the coin surface.</p><p><br /></p><p>It can be actively corroding the coin or not very actively corroding. Probably never totally dormant though, if it&#039;s there it&#039;s doing something, either fast or slow.</p><p><br /></p><p>To me verdigris is an active response to a contaminant, while the corrosion is kind of a past tense evidence/damage that&#039;s left behind of the activity by verdigris in response to carbon or organic contamination that leaves the corrosion/triggers the copper carbonate formation.</p><p><br /></p><p>Even slabbed copper coins by grading companies, if kept in poor conditions can get verdigris and require them to be conserved to remove it and reslabbed. if you don&#039;t the active verdigris will continue to damage the coin surface and form the green patina to protect it.</p><p><br /></p><p>Like the statue of liberty is green/blue, that green/blue is verdigris. it&#039;s copper carbonate, an ionic compound.... a salt in essence. the coppers outer layer is sacrificing itself due to a contaminant that the copper is trying to protect itself from.</p><p><br /></p><p>Like the weathering on the statue of liberty, it was copper colored in 1875, by 1900, it was turning green/blue with the copper carbonate patina forming, not as bad as it is today.&nbsp; But up close and personal now, the surface is pitted and corroded a bit under the patina.</p><p>&nbsp;this layer of copper carbonate is protecting the rest of the copper underneath sacrificing itself so to speak. it would be desirable on an item like an outdoor statue, not so much on a coin or saxophone though.[/QUOTE]</p><p><br /></p>

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