Questions about Potential Bronze Disease

[milesofwho]

I recently acquired a diobol of one of Ptolemies. However, it appears to have some bronze disease on the edge. How can I treat it? Additionally, which Ptolemy is it? I believe the eagle has an epsilon between its legs.

[Kali]

To me, it looks like a powdery Patina, which is fairly common. Try taking a toothpick and picking at it, if it doesn't move, your OK. If not, toss it in some distilled water and pick at it some more.

There is internet searches to treating it in various ways.

[Ryro]

As you can see by the purple discoloration, pitting and that light green around the edge your coin has dealt with BD before and currently has an active case, imo.

Rub your fingernail over the light green of any of comes off on your fingernail you know that it's active. Then it's all about the distilled water bath, yadda yadda. 

If you need further help riding your coin let me know. 

[robinjojo]

If the green areas are hard, then they don't harbor bronze disease.  They're just typical hard green patches that are almost impossible to remove.

If the green is light to almost white in color, and powdery, those are indications of active bronze disease.

Looking at the photos I think your coin is okay, but you might want to leave it out for a couple of months, at least, to keep an eye on it.  If there are no changes or development of powdery residue, you might want to consider using Verdicare to seal the coin.

Was there any powder in the coin's holder when you received it?

If there is BD, then a distilled water bath, as Ryro suggests, is the first step.  Leave the coin in the bath for a day and check on it regularly.  Use a wooden toothpick to loosen the BD.  If the water turns green, change it with fresh distilled water.  Use distilled water, not tap water.

There is a more aggressive measure to take if the BD is persistent, but it is also more destructive since it will remove virtually all of the coin's patina, usually leaving rough raw surfaces.  If this step is necessary, come back to discuss. 

[milesofwho]

Thank you all for your help. I’ll ready the water and report back. It did indeed come off after some picking. Is there any issue if this does in fact not have BD and I put it in the water? I picked it up for $2 out of a large bag of various ancient coins so I suppose I’m getting what I paid for in terms of effort and care.

Edited June 7, 2022 by milesofwho

[Ryro]

I was surprised the others said that it didn't look like active bronze disease after that last picture and the obvious fact that the coin has dealt with BD before. There is no issue whatsoever putting a coin in distilled water. After it has sat in the distilled water for a few days you will want to scrub off any of the remaining BD with an old toothbrush or something to that affect. Repeat. If you have verdi care after you've done that a couple of times and then baked it on low (350) for 40 minutes you will want to treat it. if you don't have Verdi-care you will just want to keep an eye on the coin for a few months.

[Theodosius]

Change the water every day too.