My first case of Bronze Disease

I am posting this as it might be a help to any of you that have a similar problem, about January this year I received a coin from a vcoins dealer in the US that I have bought coins from before. The coin looked good when I got it
and for $64 US plus postage I thought was a bargain for a Vespasian 72 AD Altar coin 24mm, 10.71g, in VF condition. This coin had been on the website for a few years and in the advertisement it did mention some smoothing. Anyway I kept it out of the coin flip (cardboard type) for a couple of months. I have to mention that our summers in Victoria Australia are very hot and windy, so the ideal type of cooling is evaporative which can add extra humidity inside the house, but I have had coins sitting around in these conditions for years without a problem. Any way I finally put it in a coin flip with a couple of others, a five months ago I had a look at the coin and to my amazement it had like a little volcano of bluish-green throthing and very active just under Vespasian's nose so I quickly took it out (it had burnt through the clear window) and put it in Sodium Sesquicarbonate mixture.
After two weeks of changing the mixture, I had not lost all the patina but the dark green was breaking up to become a speckled green/light green (ugly). I have had it wrapped in paper towel for over four months now with no sign of BD, although the conditions inside the house are the exact opposite to summer as I have central ducted heating which really dries the air, anyway I will post the coin as I got it and the next one down is the ugly result of hopefully beating BD but it has a little crater under Vespasian's nose where the acid was eating into the coin. I am in two minds as to strip the rest of the patina (put it back in the mixture) or put it back in a coin flip before summer. I would appreciate your thoughts on it.

 

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The second pictures are after treatment? Needs more treatment

 

But I am pretty sure the BD has gone, so why more treatment?

 

All the light green stuff on the coin looks powdery, and there is green powder on the table. I assumed that powder was freshly shed when you were setting up for the picture.

 

No that green stuff is the patina flaking, if left longer would all be light green and the just a copper colour.

 

I'm confused. Or maybe you are. Or both of us.

The light green powdery stuff-- not the rust colored deposits/corrosion-- is the bronze disease, or evidence of bronze disease. It's on the table and widespread on your coin (in its current state).

 

Here's an assortment of articles about bronze disease and its treatment.

http://www.crescentcitycoinclub.org/seminars_and_programs/Bronze Disease.pdf

http://www.accla.org/actaaccla/bronzediseasetherapy.html

http://www.bitsofhistory.com/info/bronze_disease.html

http://www.collector-antiquities.co...estoring-and-conservation/bronze-disease.html

http://www.forumancientcoins.com/numiswiki/view.asp?key=Bronze Disease

 

If you look at the original picture you can see a sort of purple area that is where I believe the BD was (hiding) until I treated it and now those areas are a copper color, the treatment I was using was gradually breaking down the dark green patina to the result so far.

 

I don't know about that, but based on the current pictures all I can say is "needs more treatment". Perhaps the first treatment simply uncovered areas of previously hidden widespread BD.

 

No the light green is just the patina breaking down, besides the copper looking area the rest is fine. The Sodium Sesquicarbonate will eventually take all the patina if left long enough but the trick is to get the coin out in time (but still an ugly result)

 

Anyone else want to weigh in on this one?

 

I have to agree with TIF. The coin appears to be riddled with BD. The powder that fell off the coin is not patina (which was presumably stripped away earlier) but has all the hallmarks of BD residue.

You can still save it, but I wouldn't delay too long.

 

That light green is not powdery it is the patina being dilluted and fading patchily.

 

No that's what they look like after you leave them in a Sodium Sesquicarbonate for long enough the dark green patina breaks up and becomes light.

 

That's not what they looked like after I treated some BD-ridden tetradrachms with sodium sequicarbonate. After treatment, all of the light green (ie, the BD-corroded metal) was gone and the coins were very dark and rough-looking. I'll try to dig up some pictures tonight (they're on an external drive and probably not labeled or edited, so finding them will be a challenge).

Again, I suspect what happened was that your first treatment stripped the surface patina, revealing the widespread BD underneath.

 

This is why I am showing you guys the results of (repair) BD because they say that it will take all your patina but if you get it out earlier these are the results and I am not sure if you would be better of with no patina.

 

Hi there, LordM! Long time no see

Sorry about your Caligulas

 

Yes lordmarcovan it does not bother me too much as this was just an exercise in showing everyone what the results are in fighting BD
there is really no winners if you beat it you will either have no patina or a degradation of patina like I have.

 

That powder on the table is salt I just had steak before I posted LOL.