Message:

<p>[QUOTE=&quot;Rob Woodside, post: 3115279, member: 96187&quot;]Thanks so much. I doubt that people are using aqua regia to clean their coins. The idea should be to leach off crud and leave the coin alone. So any acid that would attack the crud would do, but something seems to be destroying the mint lustre. I was wondering if a strong mineral acid, say like nitric, might attack and leach out some of the alloying metal? Perhaps that might kill the mint lustre?</p><p><br /></p><p>What&#039;s in this putty? The carrier just evaporates and leaves a coating? Yes a coating would really change the lustre and leave no scratches. Presumably a bath in acetone or rubbing alcohol would remove such a coating and restore any mint bloom, if there was any left in the first place.</p><p><br /></p><p>Approached from another direction: Are there high magnification photos of coin surfaces? I&#039;m not sure what exactly would cause the specular reflection that i&#039;m seeing and calling mint lustre. On the coin&#039;s surface could there be local &quot;mountains&quot; with a height of around light&#039;s wavelength or so? They might produce the mint lustre I&#039;m seeing by reflecting light off many &quot;mountain&quot; sides at once as the coin is played in the light. Such &quot;mountains&quot; would be worn down with very little wear. This could explain &quot;AU Details, Cleaned&quot; on the slabs where the mint lustre is visible between the letters in the legend but not in the main field. The raised letters might protect the adjacent areas from the rubbing that would erode the &quot;mountains&quot;. If that&#039;s true there should be scratches in the surface from the rubbing. I don&#039;t see that. Are the scratches too tiny for me to see on a &quot;lightly cleaned&quot; coin? Thanks again for your help.[/QUOTE]</p><p><br /></p>

Your name or email address:

Do you already have an account?

• No, create an account now.
• Yes, my password is:
• Forgot your password?

Stay logged in