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<p>[QUOTE=&quot;wlwhittier, post: 1680827, member: 18320&quot;]<b>English Penny, after cleaning.</b></p><p><br /></p><p><br /></p><p><br /></p><p>I understand what little I do about chemistry from fifty years of practical experimentation, and a wee bit of reading.</p><p><br /></p><p>&nbsp;One of the issues you raised (<i>which <b>types</b> of contaminants</i>) is good for some serious thought; how do you determine, as in the case of the reverse of this penny, what the goop <b>is</b>?</p><p><br /></p><p>Water-clear, not yielding to a thumb-nail, apparently tough in the way that some adhesives can be once the solvent evaporates, which is to say solid, not even slightly gummy...but who knows otherwise without splashing something (hoped to prove innocuous) on the offending crud?&nbsp; I chose alcohol (denatured, ethyl) because I trust it most among all the others save perhaps mineral spirits and naphtha (Ronson lighter fluid).&nbsp; I go through maybe a quart of it a year, over half of that on the end of Q-Tips or dipped onto cotton make-up pads.&nbsp; If it fails, I move on to more aggressive aromatics; in this case such escalation was not necessary.</p><p><br /></p><p>A one hour soak in DNA reduced the offending &#039;glue&#039; to a clear jelly, which yielded to a thumbnail as easily as would ham-fat to gasoline.&nbsp; The 9.4 gram weight did not change.</p><p><br /></p><p>A neat advantage to alcohol is it&#039;s solubility in water; a simple rinse in warm tap water and a pat dry on old cotton tee-shirt, and below you have the result.</p><p><br /></p><p>Yeah, there&#039;s still stuff around some lettering on the obverse, and a few weird spots on the reverse...but the coin is otherwise in remarkably presentable condition, IMO.</p><p><br /></p><p>So: the next cruddy coin will be chosen, photographed in all it&#039;s sordid filth...and another report filed.</p><p><br /></p><p>Thanks for tuning in!</p><p><br /></p><p>[ATTACH]251671.vB[/ATTACH][ATTACH]251672.vB[/ATTACH][/QUOTE]</p><p><br /></p>

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