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<p>[QUOTE=&quot;7Jags, post: 8361410, member: 78719&quot;]Fortunately it is not as difficult as chemistry class with regards to precision and so the quantities are not all that important but will give what I use; it works REALLY well on gold with the red copper oxidation spots like on the centennial 2016 gold coins but also does on silver a bit. I posted this some while ago on here.</p><p>It is actually an electrolytic action.</p><p><br /></p><p>- I just use the porcelain bowl because of the non-reactive surfaces.</p><p><br /></p><p>- Then I pour in about 4 oz. of the white vinegar from grocery store</p><p>then I microwave it up for about 1 minute, fifty seconds (this heating increases rate of reaction). I always have my microwave on &quot;10&quot; setting, but no matter.</p><p><br /></p><p>- Then I put in a rough square or rectangle of aluminum foil about 3 inches each dimension (enough to be greater than diameter of coin); be careful vinegar is HOT at this stage</p><p><br /></p><p>- Then I pour in about 1-2 teaspoons of baking soda (NOT powder), kind of spreading even over surface of aluminum</p><p><br /></p><p>- Then I carefully set coin on top of this (don&#039;t forget it is HOT liquid) for about 30-40 seconds</p><p><br /></p><p>- probably not necessary but I pull aluminum and coin up by edge of aluminum (you can use gloves if you like) and flip coin over and put back in solution for another 30-40 seconds</p><p><br /></p><p>- Then I pull out aluminum, hold coin by edge and thoroughly irrigate with cold water. </p><p><br /></p><p>- Then I tamp dry with a clean dry white high nap cotton towel (DO NOT RUB ACROSS SURFACE OF COIN)</p><p><br /></p><p>- Let dry further for about 1/2 hour or more on dry part of this same towel</p><p><br /></p><p>- Put in holder</p><p><br /></p><p>I remembered this from chemistry class but I believe Weimar (sp?) White has a book on coin conservation that covers a bit of this type of thing. I think it is called &quot;Coin Chemistry&quot; and is a good read even if you never plan on using it as IMHO it is good science.[/QUOTE]</p><p><br /></p>

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