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<p>[QUOTE=&quot;fagaly, post: 764470, member: 22003&quot;]<b>solvents</b></p><p><br /></p><p>There are a number of organic solvents that can be used to remove surface contamination. Alcohols (methanol, ethanol, isoproponal, ...), ketones (acetone), etc. They have the advantage of not interacting with metals over reasonable time periods. This also assumes that the solvents are pure.</p><p><br /></p><p>They can not be used to remove toning, which is due to oxidation (CuO, AgO, rust if iron), sulfurization (if I can &quot;coin&quot; a term), some other chemical process which forms a chemical bond, or metal vapor deposition.</p><p><br /></p><p>Back to solvents, you should use a pure solvent. Most isoproponal (rubbing alcohol) contains 10-30% water. 100% pure ethanol will slowly absorb water from the atmosphere until it achieves a 95.5% ethanol/4.5% water equilibrium concentration. Obviously, using 100 proof vodka (50% ethanol/50% water) is not recommended, although, if you screw up the coin cleaning, you can drink what you didn&#039;t use to drown your sorrows.</p><p>When preparing surfaces for gold plating (scientific instrumentation, not racketeer nickels), I would put the metal in an ultrasonic cleaner filled with acetone, repeat the process with pure ethanol and then air dry by blowing nitrogen gas on it. Putting the sample in a dry box containing a desiccant also works.</p><p><br /></p><p>If you coin is really grungy from surface, replace your solvent. Otherwise you just move crud from one part of the coin to another.[/QUOTE]</p><p><br /></p>

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