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<p>[QUOTE=&quot;Sunbird, post: 7603656, member: 116324&quot;]Are you meaning to say that cotton is harder than gold and silver? I don&#039;t understand how that can possibly be true.</p><p><br /></p><p>Mohs is typically used for &quot;scratch hardness&quot;, but there are lots of other more popular scales for hardness generally. I&#039;m not sure what you meant with the &quot;extrapolated&quot; 5 value for cotton. It can&#039;t be 5 if it&#039;s on the same scale as the metals.</p><p><br /></p><p>We need a clear and accurate model of what&#039;s happening when coins get scratched from contact with cotton swabs, cloths, etc. If it&#039;s always a case of contamination, where it&#039;s sand or other hard particles that are actually scratching the coin, that&#039;s one thing. But if we&#039;re thinking that the cotton itself is scratching the coin, well we really need to figure out how that works. This all should have been locked down scientifically decades ago, but I guess it&#039;s a small market.[/QUOTE]</p><p><br /></p>

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