B.D. Treatment leaves coin worse off.

Discussion in 'Ancient Coins' started by Topcat7, Dec 7, 2019.

  1. Topcat7

    Topcat7 Still Learning

    I had this Sestertius of Commodus which I noticed was showing signs of B.D. (A couple of specks on the 'reverse'.)
    Commodus AD 177-192 AE Sestertius His laureate head right R Uncertain female deity.jpg

    After 'scratching at it with a toothpick, I soaked it in a solution of 5gm of (Mixture - 5x parts Bicarb of soda, and 8x parts Sodium Carbonate), with 95Ml of de-mineralized water, for 5x days, brushed it with a toothbrush, and repeated the process 6x times.
    This (may) have treated the B.D. but it has brought out the 'patina' (verdigris?) to the point that it detracts from the appearance of the coin.
    Magical Snap - 2019.12.07 17.42 - 004.png

    I don't want ti hit the coin with "Verdi-Care" or 'Renwax' if I should be applying a different process first.
    Does anyone have a remedy for this that they can offer me, please?
    (Note: The colors in the photographs are true to life.)
     
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  3. TypeCoin971793

    TypeCoin971793 Just a random nobody...

    You simply took off a layer that was hiding the green
     
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  4. gsimonel

    gsimonel Supporter! Supporter

    Despite the fact that your BD treatment left the coin looking, in your opinion, worse, leaving it untreated was not an option, so you should have no regrets. It's still better than letting the coin commit suicide.

    Before you put any kind of treatment or sealer over the coin, let it sit out for a month or two to make sure the BD does not return. If it does, you will need to treat the coin a second time.

    Next time you treat a coin, though, try using just pure distilled water without any additional chemicals. Soak the coin in about 6- 8 oz. of DW, changing it every 2 or 3 days, for at least a month; 6 weeks is better. The process may take a little longer, but pure DW will eventually leach all the BD out from your coin, and it won't change its appearance.

    Good luck with your coin.
     
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  5. ancient coin hunter

    ancient coin hunter Cogito Ergo Sum

    Yes, good luck.
     
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  6. Topcat7

    Topcat7 Still Learning

    @gsimonel (et. al.)
    Thank you for your comments.
    (As advised) I will wait for a month to see if the B.D. returns, and if not I will hit it with 'Renwax' and hopefully the Verdigris will 'darken'.
     
  7. Silverlock

    Silverlock Well-Known Member

    Generally speaking, copper oxides like cuprite (red patina minerals) won’t naturally form on copper carbonates like malachite (green patina minerals). It’s usually the other way around.

    Given how easily it dissolved in a dilute base solution, I question whether the red layer was natural. Fragile surfaces like that don’t survive long in the ground. By exposing the green, you may have recovered the natural patina.
     
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