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<p>[QUOTE=&quot;-jeffB, post: 3080598, member: 27832&quot;]<a href="http://www.chemicalbook.com/ChemicalProductProperty_EN_CB7740372.htm" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://www.chemicalbook.com/ChemicalProductProperty_EN_CB7740372.htm" rel="nofollow">Here&#039;s a citation</a> for methylene chloride attacking copper and nickel when water is present (which it usually is unless you take special precautions):</p><p><br /></p><p><br /></p><p><br /></p><p>That&#039;s more reactive than acetone, which has only been shown to attack copper in the presence of water and intense light -- copper is claimed to catalyze the reaction of acetone with water to make acetic acid. (I have doubts about this claim, because copper&#039;s well-known to catalyze the <i>oxidation</i> of acetone to acetaldehyde at high temperature in the presence of air; photocatalytically oxidizing acetone to acetic acid seems a lot more plausible than metathesis from acetone and water to acetic acid and methane.)</p><p><br /></p><p>Getting acetone to act as an <i>oxidizer</i>? Good luck, unless you&#039;re pouring it onto alkali metals...?</p><p><br /></p><p>If acetone changes the color of a piece like this, it just means that there was a layer of something organic causing the color (&quot;residue&quot;). Sure, if you <i>want</i> to keep this unnatural, un-market-acceptable, and un-gradeable color, you should keep acetone away from it -- but because it will <i>dissolve</i> the colored goop, not somehow oxidize or bleach it.[/QUOTE]</p><p><br /></p>

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