This coin presents a
bit of a bind.
It is clearly susceptible to BD. It has several small BD spots showing and the
pitting throughout shows that it has
had problems in the distant past too.
On the other hand it looks about as nice now as it ever will. If it was cleaned of all the dirt, but
still retained all the
patina, you would lose that nice contrast and be faced with a much less attractive and clearly
pitted coin. Losing the
patina will make it look much worse.
Full BD treatment with
Gringotts BD killer or Benzotraizol-in-ether will remove the dirt and quite possiblly damage the
patina.
Personally I would look at two options.
1) Mechanicaly clean out the BD and put
Gringott's BD killer only on those spots. The challenge is that they are small spots and this needs to be done with pin and microscope for the cleaning and with toothpick or shaved q-tip for the
Gringott's application.
Or, the one I would actually start with:
2) Clean out as much of the BD as you can using sharpened toothpick and small soft brush (those small gum-cleaning tooth brushes that have just a tuft of brush
work well). (Maybe clean out the BD with a
sharp steel pin if you feel comfortable, but if not just the sharpened toothpick.) Then place the coin in the oven at about 150 F for about 30 minutes to remove any microscopic water traces. This method is not/not a BD treatment but may arrest the spread and if you then keep the coin dry and monitor it it might last for quite a long time with no more BD. If more BD does appear then you would have to move to another option.
Shawn
Shawn
