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<p>[QUOTE=&quot;frech001, post: 2991285, member: 20616&quot;]I had a couple of otherwise nice coppers in my collection that had one or two black spots on them that bothered me enough to experiment.&nbsp; I&#039;ve done a bit of plumbing on copper pipes and had some zinc chloride solder flux.&nbsp; I used a fine tipped artist&#039;s brush to apply a tiny drop of Zinc Chloride (available as liquid solder flux at hardware stores) to the black spots.&nbsp; It quickly dissolves copper oxidation, green oxidation and black sulfur spots.&nbsp; Wash off within a minute or less with warm water and carefully dry the coin with a soft cotton cloth without rubbing, just blotting it dry.&nbsp; There may be a spot of lighter copper exposed that can be blended in with mixture of powdered sulfur and mineral oil.&nbsp; But quickly remove this as soon as the color blends with the surrounding patina.&nbsp; Rinse the coin in acetone to remove remaining oils and handle with gloves.&nbsp; Try this on some junk coins before you try it on one in your collection.&nbsp; As another poster noted, if the oxidation is deeper than the surface, the zinc chloride will leave a noticeable depression where the oxidation had been.&nbsp; It does not seem to attack the copper, just removes oxidation but it stops the progress of copper &quot;rust&quot; or bronze disease.&nbsp; I haven&#039;t tried baking soda and distilled water, but apparently that can be used also for bronze disease - green verdigris, but takes longer and the coin is soaked in the solution for an hour or more. Google search &quot;How to Remove Verdigris From Coins” (with the quotes).[/QUOTE]</p><p><br /></p>

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