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Re: Coin Chemistry / grading observations

Bob - there is no question in my mind that you do and have done an excellent job in that regard. Your eye for beauty is among the best Canadian numismatics today.

While I agree with much of what Mr White has to say, I do not agree that a piece of metal cannot improve with age (and associated color). Let's jump in our handy time machine, and go back 100 years to visit the Tiffany studios in NY. We walk in and purchase two identical signature lamps with bases. We then lock one lamp away in our great grandparents home, in a room with which we maintain the key. Now we return to our century with our new lamp - going into (now our) house and open the locked door, setting the lamps next to each other. The locked away lamp now has a lovely patina, from its 100 years in limbo. The lamps are no longer identical. The lamp which has sat 100 years in stasis is more beautiful, having developed a lovely patina to the metal base and lead between the glass pieces, compared to our new one which has only seen a few hours of "real" time.

In this example, the term patina equates with both toning and corrosion. While the example is imperfect, it does illustrate the dilemma we face as collectors. Anyone who has had the opportunity to look at beautifully toned coinage, such as Bob's collection, will likely agree that a coin's appearance can improve with age. Just as wine matures, so can a coin. Silver and copper will develop color. The small amount of copper in gold will help those pieces mature, though to a lesser extent. The color may improve or detract from the coin's appearance. In the case of unprotected copper, green results. Protected copper will eventually become brown (or perhaps irridescent brown).

Encapsulation will not only help protect the coin, it will dramatically slow down the color changes if stored in a proper environment. Here I concur completely with Mr. White. Use of a product containing Intercept Shield is a huge benefit to conservation. I have also found coins carefully wrapped in aluminum foil for 50 years ccompletely untoned. Not being a chemist I can only speculate that this is due to the absence of air and/or an air exchange.

There are no easy or even right answers. Common sense must dominate our collecting decisions. We may disagree on what factors determine a coin's grade. And/or, how much each factor should count in the overall grade - even if one side of a coin is more important than the other. So without universal agreement of all grading components, is it any wonder grades differ between services?

jmc, 3/9/2011
CCRS member since: 4/2/2003
Posts: 3219

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Postings in this thread

Coin Chemistry (jmc, 3/7/2011)
 Re: Coin Chemistry (Dave in the Grove, 3/7/2011)
 Re: Coin Chemistry (5cents, 3/7/2011)
  Re: Coin Chemistry (Dick, 3/7/2011)
   Re: Coin Chemistry (token hawk, 3/7/2011)
    [this post has been deleted by its author] (3/7/2011)
     [this post has been deleted by its author] (3/8/2011)
      Re: Coin Chemistry / grading observations (jmc, 3/9/2011)
      Re: Coin Chemistry / grading observations (AussieBob, 3/9/2011)
      Re: Coin Chemistry / grading observations (5cents, 3/9/2011)

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