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<p>[QUOTE=&quot;rasielsuarez, post: 25439993, member: 148921&quot;]Some bad advice and incorrect notions here :-(</p><p><br /></p><p>The problem with bronze disease is that this particular type of corrosion acts somewhat like a zipper: the offending molecules disrupt the metal surface then free themselves to latch onto the next, disrupting the atomic lattice like a cue ball blasting through a rows of balls. Many types of corrosion can be halted once you cut off the supply lines of the corrosive agent or you introduce a neutralizing chemical. With BD though the reaction is self-propagating because all it needs to continue is a fresh supply of copper and water vapor. This is why immersion in water is ineffective.</p><p><br /></p><p>In practical terms water vapor is nearly impossible to get rid of. Short of hermetically sealing the coin in an impermeable container it&#039;s hopeless to attempt to arrest the damage. The only effective method is to dig <i>under </i>the chlorides by exposing the copper core and only then applying something like benzotriazole or RenWax or whatever.</p><p><br /></p><p>For BD to begin you generally need three things to occur: salt, humidity and prolonged contact time. It is not true that merely handling your AEs with sweaty fingers will spell doom. While sweat does have dissolved salt, and obviously plenty of moisture, you&#039;re still missing the third factor of extended time. This is because, if you remember from your chemistry class, NaCl is a very stable molecule given the intense bonds created from these two elements. You would need a very rare set of conditions under which those two atoms would 1) momentarily let go of each other and, 2) for the sodium ion to preferentially attach to some other atom and not immediately retake the chlorine one. Only then would that Cl be free to attack copper and begin the destructive process. It&#039;s far likelier that the instances of BD happen as a result of halogenated compounds degrading as these provide a more plausible route for the release of those highly reactive atoms.</p><p><br /></p><p>Summary: if you&#039;re unlucky enough to get a coin with BD</p><p>1) scrape the lesion down to bare metal</p><p>2) clean the area with something like 35% concentrated hydrogen peroxide</p><p>3) optionally apply a protective barrier-forming film. Or just let it tone naturally. If the cleaning job was successful the chances of it reoccurring in normal conditions are very low.</p><p><br /></p><p>Rasiel[/QUOTE]</p><p><br /></p>

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