Constantine II - Verdigris or Bronze Disease - Leave it alone or Clean ?

[paps]

I recently bought this coin marked as Constantius II but I believed it to beConstantine II.  In any case, should I try to clean off the green? I picked with a toothpick and some flaked off. I don't want to ruin this coin, I think it's a fine example of this type. But if I'm able to get the green completely removed without damaging the coin, that would be great. I've had some say leave in acetone or ammonia  for awhile and then brush.  But that seems harsh.

[v-drome]

Hi, Paps.  I can't tell from the photo if it is Verdigris or bronze disease.  If it is not powdery it might be ok.  I just wanted to say that I agree with you that brushing could be too harsh.  Brushes tend to remove material from the high spots while missing the low spots, thus reducing the relief in the coin.  Might be best to just observe it for a while, and maybe work on individual spots with a microscope, if needed.  Good luck! Neat coin!

[SC]

If the green is hard it can be left.  But if powdery it is a sign of bronze disease and should be removed.  The fact some came off with a toothpick is a bad sign.

I would work with toothpicks, bamboo BBQ skewers and a toothbrush - with bristles cut-down to close to 1/8 " to make it stiff.

None of those things would damage the coin.

SC

[Joe Sermarini]

See the following articles on NumisWiki for more information:

Bronze Disease
Bronze Disease Treatment