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Random musing/question re. silvered bronze Roman antoninianii

Since fully-silvered bronze Roman antoninianii fetch a premium over pieces where the silvering didn't survive, what's to stop unscrupulous coin doctors from resilvering them, akin to the way that some US 1943 steel cents were "reprocessed" by replacing the zinc plating?

Has this happened? Obviously, such a person would need to choose higher-grade coins to resilver, since a replated coin with flat spots due to wear wouldn't look right. But it seems it would be a fairly simple thing to do. Or would they come out looking too white? I wonder what sort of composition the Romans used to plate the coins with originally, and how pure the silver was.

Not that I plan on silvering my own antoninianii, but I do plan on buying more silvered ones to upgrade my nonsilvered ones.

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Comments

  • Like you said they would have to start with pretty nice looking coins to begin with. So how cost affective would it be? Not that I would put anything past the counterfeters and doctors.
  • lordmarcovanlordmarcovan Posts: 43,194 ✭✭✭✭✭
    I guess that's the issue. The potential monetary gain by such a practice probably isn't worth the trouble of doing it.

    Then again, if people reprocess inexpensive US steel cents, one has to wonder? Hypothetically speaking, if you had a scarcer antoninianus coin that lacked the silvering, and you were unscrupulous enough, who's to say you wouldn't try to resilver it and make it all the more desirable?

    Hm.

    Even if it is done, I doubt it's a common practice. I was just randomly wondering.

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  • Rickc300Rickc300 Posts: 876 ✭✭


    << <i>they would have to start with pretty nice looking coins to begin with >>

    So maybe instead of 30-40 dollars for a coin you might get 80-90 dollars... Over a 50% increase for a nominal cost to wash the coins with mercury or even just to heat them up in an oven with the presence of lead... I am not sure how one would detect the alteration, especially if India die or some other washing agent were used to "dull" out the coating. This is yet another reason I have not gotten into the Roman thing even though I am facinated by the history and coinage... I guess it would be like my learning the German coins that I collect. I have handled enough that I can pick out counterfeit/cleaned or altered coins quite well. But trying to pick out a copy/altered/counterfeit of something that even specialized catalogs don't always agree on leaves me a little worried. I have seen and handled probably hundreds of thousands of German coins so I have acquired a certain "feel" for them. I probably have not even seen a thousand Roman coins total, let alone a hundred of the same coin to compare side by side. This uneasiness of not knowing, has me feeling way out of my league and capable of being ripped off without being any the wiser... This is one field that I wish had a definitive TPGS so that I may venture in, get my feet wet and learn as I go and not feel every purchase was a complete rip-off...

    PS-Welcome back Rob~!
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  • SapyxSapyx Posts: 1,977 ✭✭✭✭✭


    << <i>Since fully-silvered bronze Roman antoninianii fetch a premium over pieces where the silvering didn't survive, what's to stop unscrupulous coin doctors from resilvering them, akin to the way that some US 1943 steel cents were "reprocessed" by replacing the zinc plating?

    Has this happened? >>


    Yes, of course. More so in years gone by, when it was considered quite acceptable to re-silver a coin that was supposed to look silvery, but didn't. They tried various methods, but the end results were often less than satisfactory - the coins often looked like they were made of billon, rather than silver or silvered. Nowadays, the "old coins should look old" school is prominent, and the only folks attempting to resilver are those on the shadier side of the business.

    As Ricke300 implied, it takes an experienced eye to spot a re-silvering job. General rule of thumb: a coin that is supposed to be silvered and is quite well worn, but appears to be uniformly coloured, can be considered suspect. A silvered coin shouldn't simply look pitted, like a pure silver or pure copper coin should. If the surface isn't clean and intact, different coloured metal or corrosion should be visible through the pits or holes in the silver layer of a silvered coin.

    Cleaning a silvered coin is a tricky and delicate process. The silver layer may be the only part of the coin that has preserved the original detail, with the core having corroded quite deeply. And the silver layer is easily damaged by harsh or overzealous cleaning. So in general, a poorly cleaned silvered coin won't be in too good a shape, and won't be likely to be convincing if it was replated.

    Which leads to discussion of how a thin layer of silver was applied to ancient coins in the first place. The Romans, of course, didn't have electricity, so they couldn't electroplate silver directly onto the blanks like some folks do with zinc on '43 Lincolns.

    There are two leading theories as to how the silvering was applied. Which method was used is generally debatable, and both methods may even have been employed at different times and by different mints. They may even have used an electrochemical technique; just because they didn't know the theory behind electrochemistry, doesn't mean they couldn't have discovered it by accident. But ultimately, we don't know. Striking coins was a craft, and like all ancient crafts, they were reluctant to divulge or publish their trade secrets.

    The first theory is the "pickled blank" method. Remember, the blanks were made of very low-grade silver alloy (Aurelian's alloy of 20:1, or .048 fine silver, is an excellent example). These were then soaked for awhile in an acidic solution (like vinegar), which dissolved the copper etc out from the surface of the coin blank, leaving the silver behind in a sponge-like surface. When the coin was then struck, the sponge was smashed flat, leaving a thin layer of silver all around the coin.

    The other theory of applying a silver coat is to simply dunk the blanks (or the finished coins) into a bath of molten silver, and then fish them out. Both these theories would have added a lot of processing time to coin manufacture, right at a time when the empire needed it's mints to churn out coins as fast as possible. Either they considered the improved aesthetics worth the wait, or they had some means of speeding up the process.

    A third method, of making a "silver foil sandwich" wrapped around a copper core, doesn't seem to have been used for "official" coinage; this is what is known as a "fouree", and they are normally considered to be contemporary counterfeits.
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  • lordmarcovanlordmarcovan Posts: 43,194 ✭✭✭✭✭
    Well said as usual, Sapyx and Rick.

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  • PrethenPrethen Posts: 3,447 ✭✭✭
    I think Wayne Sayles agrees that it's the pickling method. So, in effect, there's no real "layer" per se of silver, it just sort of brought to the surface by eating away the surface copper.
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