I have a
silvered antoninianus with some hard
red and green encrustation on both
obverse and
reverse. In perusing the
discussion board for a solution, I came across several that seem to fit the situation.
First: the diagnosis: "
Red incrustations are usually composed of Cu2O (copper (I) oxide)"
So,
bronze disease?
Remedies...
1. "People say
benzotriazole solution in ethyl alcohol is a powerful inhibitor of copper corrosion. Benzotriazole can be purchased here:
(link)"
2. "[Put] into [distilled water] with
Gringott's Bronze Disease Killer on a low boil, followed by a long soak/pick/soak/pick cycle. For cleaning, I alternate between a
dental pick and a diamond tipped Dremel tool." I've not heard of this product before, or seen it for sale.
3. "Ammonia will remove it, slowly. The household ammonia will have to be changed after a day or two, and if it seems to stop working, it is probably because there is lime mixed in, so rinse, put it in vinegar for a day or two, rinse, and then go back to the ammonia."
4. "I would imagine a brief soak in lemon juice followed by a gentle rub would clean them off."
I've opted for solution #4 as the least aggressive approach, at least to start. It was a
good start, but not a runaway
success. Here's the result in pictures:
Before and
After.
The
red encrustation is
still there, but
reduced, and the coin is shinier. I tried to chip away at the encrustation (blackening Q-tip ear buds). I am tempted to leave
as-is. Suggestions welcomed.