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<p>[QUOTE=&quot;desertgem, post: 1770488, member: 15199&quot;]<a href="http://www.cointalk.com/threads/microscopic-comparison-of-luster.126215/" class="internalLink ProxyLink" data-proxy-href="http://www.cointalk.com/threads/microscopic-comparison-of-luster.126215/">http://www.cointalk.com/threads/microscopic-comparison-of-luster.126215/</a></p><p>&nbsp;</p><p>Check out the microscopic photos of the surface of a morgan&nbsp; in the thread above . Post 1 will probably be enough to show the peaks/valleys that produce lustre and the cartwheel effect. Each occasion that a coin is dipped, the peaks are reduced by the acid. As the distance between the peak and valleys becomes less, the lustre and the cartwheel effect also lessens , until they are almost the same height, and you get a shiny coin with no lustre, no cartwheel effect, and a damaged coin.</p><p>&nbsp;</p><p>The reduction is a combination of acid strength and time of exposure.&nbsp; Commercial dips are formulated for quick action. I dilute the stock solution by a factor or 1:5 or 1:10 with distilled water so I can better control the action when a dip is absolutely needed. Since it is a physical manifestation of chemical action, you can rinse off the acid and look at the surface anytime, and do it again . A diluted dip may take several trial to get what you want, but the chances of killing the coin are much less. There is no return to original point.</p><p>&nbsp;</p><p>Jim[/QUOTE]</p><p><br /></p>

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