Reply to Thread

Message:: [QUOTE="SuperDave, post: 2396017, member: 1892"]Yours is a coin which does not justify the micro-level work Insider hinted at; it needs to be at least MS67 to have any kind of significant value. So, dipping copper. I'm just going to offer one single link which can be the basis for anything you want to do to any coin, and a lengthy commentary after with a little less meat than previously planned. Go here, read everything, and use it as the basis for further research: <a href="http://www.metaldetectingworld.com/cleaning_preservation_coin.shtml" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://www.metaldetectingworld.com/cleaning_preservation_coin.shtml" rel="nofollow">http://www.metaldetectingworld.com/cleaning_preservation_coin.shtml</a> I'm hoping that a site designed to help those whose concentration is in coins which are heavily-corroded by nature will engender the proper perspective regarding what you should and shouldn't do with coins that aren't. You will learn just about all you need to know about cleaning coins, and how you apply that knowledge is up to you. There is no altruistic reason to reduce an oxidized copper coin from Brown to Red (which is what we're frankly talking about here, unless you're unsophisticated-enough to consider dipping as a "cleaning" operation for crud on a copper coin), only self-centered ones. The process does not help the coin, and whether you like it or not the coins are not here for your selfish purposes. Whatever you do to the coin, unless you melt it into a puddle it will survive you and be owned by another. And another, and another after that. Anyone who's ever owned a patinated Ancient knows that Nature always wins. Eventually, unless you encase a Red copper in impermeable material of some sort, it will oxidize. You can personally preserve it during its' time in your ownership, but down the road someone will care less and oxygen will have its' way. Slabs help, but one has to wonder why, given that the technology is so readily available, TPG's haven't chosen to hermetically seal them....even plastic is porous to one extent or another. We can start contemplating Red copper as something with lasting value when we swing back to approving of permanent coin coatings which prevent oxidation. For the moment, Red copper is a form of Russian Roulette, which is why I don't like the market for Red copper. _________________________________________________________________ Check this out: [ATTACH=full]492868[/ATTACH](Credit for this image is offered both to the original shown copyright holder and KaiserScience, a wonderful website which anyone interested in science for the non-scientist ought to know about) That's the Reactivity Series, a scale of the general reactivity of metals. For our general purposes, metals lower on the scale oxidize less-readily than those above, and those above are useful in stealing the oxygen which has caused what we want to remove from where it's currently living on a metal below. Note Aluminum's position on the scale; it's why you use it in electrolysis. Aluminum is quite willing to grab random stuff from other metals. It's also why copper can be reduced with relative ease; it takes quite a while for that copper roof to turn green, and chances are the Cent you're looking at is only currently involved with oxygen as a corrosive agent. We've talked about reducing copper before, methods involving both hydrogen and carbon, and if you're paying attention you should already know that reducing it isn't a problem. Keeping it reduced, however, is kind of a different animal. <img src="styles/default/xenforo/clear.png" class="mceSmilieSprite mceSmilie1" alt=":)" unselectable="on" unselectable="on" /> [ATTACH=full]492869[/ATTACH] When you expose the heated copper sheet to hydrogen gas, it is immediately reduced (the oxygen combined with the copper is removed because the hydrogen wants it more). But the moment you remove the hydrogen, the still-hot copper goes right back to copper oxide because copper oxidizes far faster when hot. And unfortunately, it has to be hot to be reduced. That's the "devil in the details" for turning Brown copper Red. Or, um, one of them. Another devil in the details is, your copper Cent isn't pure copper. It's brass, alloyed with tin and zinc. An alloy, by nature, isn't a chemical combination; it's a cake mix well-beaten in the bowl. But how well-beaten is it, actually? Not always that well.... [ATTACH=full]492870[/ATTACH] And zinc and tin do different things when oxidized than copper does. Further, they're not so easy to reduce as copper (note their positions on the Reactivity Scale), and are difficult to reduce by more than atoms at a time. That kinda interferes with keeping your Cent whole, when the only way to reduce part of it is to remove atoms and redeposit them onto the cathode.... Speaking of interference, I think that's why copper tones into nice colors sometimes - thin-film interference involving the tin and zinc components. It has nothing to do with the copper itself, and I suspect poorer alloy compositions tone more nicely than better ones. All of this would be pretty easy if the coin were pure copper. Reduce it, quench it quickly in something unlikely to offer it oxygen during the process (Google "Therminol" and learn from there), and there's your Red cent. There's still a lot of devils in those details, and I'm unwilling to share them.... But all the same, the zinc and tin involved are as likely to screw the process up as not, no two Cents have perfectly similar compositions, you won't know if it works until afterward, and sometimes the finest of technique not only fails but further damages the coin. In summation: Yeah, you can turn a Brown Cent into a Red Cent. It probably won't stay that way, and you don't get to decide if it works or not.[/QUOTE]

Create my FREE Account!

Log in or Sign up

Reply to Thread

Useful Searches