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<p>[QUOTE="Oldhoopster, post: 3055959, member: 84179"]I used quite a bit of acetone over the years, primarily for removing PVC plasticizer decomposition/reaction residue, although I have very little experience with high grade Red and/or PL copper. To date, I have had no noticeable color changes.</p><p><br /></p><p>The thing that bothers me is that there are experienced numismatists that have experienced color changes and I have no reason to doubt their observations. Like [USER=27832]@-jeffB[/USER], I have a lot of reservations about the chemical reactions between acetone and copper and it would be very interesting to read the scientific literature regarding this. So far, the only paper I know of, is the SUNY Stony Brook report (the paper [USER=8959]@Eduard[/USER]. references) They reported copper acetate formation, BUT only when the acetone completely evaporates. I dip the coin or soak for no more than 5 minutes then thoroughly rinse and I’m willing to bet that those reporting the color changes are doing something similar. So, I can’t see how the Stoney Brook report is applicable to what we do.</p><p><br /></p><p>I think the comments from [USER=46237]@Jaelus[/USER] and [USER=26302]@medoraman[/USER] are interesting. Could the acetone be removing thin layers of organic residue that are influencing color. Or, could specific organic compounds combine with the acetone to form an insoluble material that redeposits on the surface? [USER=112]@GDJMSP[/USER], have you had any experience dipping “acetone colored” copper in xylene or redipping in acetone? What happened?</p><p><br /></p><p>Finally, does anyone know of any scientific literature on this subject besides the Stony Brook report? Thanks.[/QUOTE]</p><p><br /></p>
[QUOTE="Oldhoopster, post: 3055959, member: 84179"]I used quite a bit of acetone over the years, primarily for removing PVC plasticizer decomposition/reaction residue, although I have very little experience with high grade Red and/or PL copper. To date, I have had no noticeable color changes. The thing that bothers me is that there are experienced numismatists that have experienced color changes and I have no reason to doubt their observations. Like [USER=27832]@-jeffB[/USER], I have a lot of reservations about the chemical reactions between acetone and copper and it would be very interesting to read the scientific literature regarding this. So far, the only paper I know of, is the SUNY Stony Brook report (the paper [USER=8959]@Eduard[/USER]. references) They reported copper acetate formation, BUT only when the acetone completely evaporates. I dip the coin or soak for no more than 5 minutes then thoroughly rinse and I’m willing to bet that those reporting the color changes are doing something similar. So, I can’t see how the Stoney Brook report is applicable to what we do. I think the comments from [USER=46237]@Jaelus[/USER] and [USER=26302]@medoraman[/USER] are interesting. Could the acetone be removing thin layers of organic residue that are influencing color. Or, could specific organic compounds combine with the acetone to form an insoluble material that redeposits on the surface? [USER=112]@GDJMSP[/USER], have you had any experience dipping “acetone colored” copper in xylene or redipping in acetone? What happened? Finally, does anyone know of any scientific literature on this subject besides the Stony Brook report? Thanks.[/QUOTE]
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