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<p>[QUOTE=&quot;Colonialjohn, post: 2127812, member: 57741&quot;]I did develop my own coin cleaner for high end copper based on chemicals in the lab and based on what worked with the original Coin Care which is now ban because of the Freon TF it contained and its implications to ozone. My product has no metal effects to copper but (YES) when you take 200 years of soil from a surface AWAY there is a visual change. Normally if the coin has not green (Cu2O) issues I leave it alone. Most people like leading EAC people I talked to use the old standby - Xylol. An inert solvent is fine but I find a cleaner if properly done with trace synthetic detergents and the proper fluorocarbon mix works very well.</p><p>Recently on a Mexican coin of some value it was purchased cheap but had SEVERE black oxide coatings on both the obverse and reverse. Interestingly after SEM/EDS it indicated this was due to due to probably salt water corrosion. The Red Rose CC patron here (BTW - how is Byron Weston doing - BTW?) mentioned thiourea. I did not use the citric acid (mild organic acid) additive but it worked. It did create a grayish overtone but most if not all of the black gook was removed which I thought was inert and non-removable. I made $300 on the piece after this cleaning. To me this was not robbery but just improving the surface of a coin.</p><p>When I have to tone a coin after cleaning it my cleaner (fluorocarbon-based ingredients - proprietary) I sometimes will wrap the coin in aluminum foil and put it into a an electric oven at 400*F checking it at 15 minute cycles and expediting the 5% Cu do its work naturally on the toning of the silver alloy coin. To me for sure is AT but I do this on coins that normally have corrosive or oxidative residues which should be removed. Only on silver issues.</p><p>The danger I have in cleaning is hairline scratches so I am normally very careful with UNC specimens and in most cases will not touch these coins at this level if RAW - of course.</p><p><br /></p><p>John Lorenzo</p><p>Numismatist</p><p>United States</p><p>Author - Counterfeit 8 Reales &amp; their metallurgy - Amazon Books[/QUOTE]</p><p><br /></p>

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