Message:

<p>[QUOTE=&quot;-jeffB, post: 2117336, member: 27832&quot;]I&#039;m betting that, if you investigate this carefully enough, you&#039;ll find that it&#039;s NOT <i>fully</i> reversible. The sulfide ions don&#039;t attach solely to the coin&#039;s surface without disrupting the crystal structure; to get colors, you need layers many atoms thick. When you remove those sulfide ions, the silver atoms don&#039;t go back to their original positions.</p><p><br /></p><p>I&#039;ll grant that it may be possible to produce a formulation that doesn&#039;t damage pure metal, even on extended exposure; such a &quot;safety dip&quot; seems like it would be a big win. But if you let a coin tone deeply enough, or if you send it through enough toning-dipping cycles, you&#039;re going to lose the fine surface structure that produces luster.</p><p><br /></p><p>All the same, I look forward to seeing your results. I&#039;ve thought of doing such a series of experiments myself, but that&#039;s not likely to happen. (Besides, I&#039;m still miffed that I don&#039;t have an XRF gun or AFM of my very own. Yet.)[/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