Can BD penetrate plastic?

[Andrew McCabe]

I'm learning a lot from this thread, and I appreciate that Meepzorp has guided us through with such a level of detail, and with such patience. I suspect many might not wish to share such nitty gritty descriptions of their coin cleaning adventures, or might have become disheartened. The thread has reinforced my general wish to avoid buying coins with BD in the first place, and to keep my coins in a dry airy environment so that none develop. If BD did develop, I'm not sure from this saga that I'd ever have the courage to try wet-treatment. With a couple of exceptions, all I've ever done with suspect coins is to dry them, and in general that has sufficed. The exceptions are described above in this thread and both were tragic disasters. Luckily for me I live in a dry climate.

[Meepzorp]

I'm learning a lot from this thread, and I appreciate that Meepzorp has guided us through with such a level of detail, and with such patience. I suspect many might not wish to share such nitty gritty descriptions of their coin cleaning adventures, or might have become disheartened.

Hi Andrew,

Thanks for the compliment. It has been my intention all along to make this an educational thread. I'm glad to see that it is fulfilling at least one of its objectives.

Fortunately, I am disabled, and I have much more free time on my hands than other people. I spend literally 1 - 1 1/2 hours, on average, during each new soaking cycle just "reloading" my diseased coins (washing them, inspecting them, picking at them with my sharp neelde, re-soaking them, etc.). I probably have about 30-50 hours of my time invested in all of this already, and I'm nowhere near done yet. And then, of course, there is the financial end of it too. Plus, I still need to buy the re-patinating chemicals and do all of that.

One of my biggest regrets is that I don't have easy and ready/immediate access to either a digital camera or a cell phone camera. I am relying on my niece's cell phone camera to take photos whenever she is around. I would have liked to document this thread more fully with more photos (to go along with my progress reports, etc.), but I didn't have that option. Another thing that all of this has taught me is how to take better photos with a cell phone camera and post them online.

Meepzorp

[Meepzorp]

Luckily for me I live in a dry climate.

Hi Andrew,

Unfortunately, I don't have that luxury.

Meepzorp

[Meepzorp]

Hi folks,

Here is another progress report.

Yesterday, I started my 27th soaking (day 53).

In my previous progress report, I described how I wiped off the rust colored film on 3 of my coins. After the last soaking, a little bit returned. I wiped it off again.

On one of my Augustus AE As coins (one of the coins where I wiped off the rust colored film after the last soaking), 2 new medium-sized spots of orange/rust colored stuff (approximately 8-10 millimeters long by 2-3 millimeters wide) appeared on the surface, directly above where the BD was active. It was rather thick, considering that it appeared only within the past 2 days. This is the coin in the photos on page 1 of this thread that had the really bad case of BD. It had the worst case of BD out of my 3 diseased Augustus AE As coins. Using my Dremel brass tool and wet paper towels, I scrubbed and wiped off the 2 new areas. I assume that this means that the BD is still active in this particular coin. And I've been continuously soaking it in sodium sesquicarbonate for almost 2 months.

My large, thick sestertius-sized AE Spain, Emerita, Augustus/city gate coin (I don't think I've posted a photo of it yet) has been completely stripped of the minimal patina it had. It now has an ugly splotchy/mottled look, similar to my AE Egypt, Alexandria, Augustus, 80 Nummia coin, but even uglier in many ways. After my last soaking, it still had 2 new spots of light green powdery BD (which weren't there a few days ago). I used my sharp needle to dig and scrape it out. So, it appears that I am still actively "drawing out" (via sodium sesquicarbonate soakings) chlorides from that particular coin, even after all these days of soakings.

Additionally, with regard to the Emerita coin mentioned in the previous paragraph, after my last soaking, I scrubbed it with my brass Dremel tool. I was the first time I used it on that particular coin. I hadn't done it in the past because I didn't want to damage it. I scrubbed off the red/rust colored stuff that had formed directly above the green BD. On some areas, under that, there was still light green stuff (active BD?). Also, a few tiny-to-small-sized "flakes of metal" (each approximately 1-4 millimeters in diameter) came off the surface of the coin on the reverse. This appears to have primarily happened in the areas where the red/rust colored stuff was covering the previously green BD. 

Meepzorp

[daverino]

Hi Meep

   I am glad to see someone getting the most out of his coins!! Just a couple of observations about the old BD question.

   1) Believe those who say that protecting the coin from humidity is the best preventative. A good wash to remove chlorides and acidity (hours not days) is good followed by drying. I would use low(200 F) oven heat followed by a waxing up to seal the surfaces. Keep the coin in a low humidity environment as you are doing and check on it occasionally.

  2) BD is a condition built up over centuries underground in a particular chemical environment (low oxygen, high acidity and chloride). It is often concealed by a normal looking crust. When brought to the surface moisture and air penetrate the crust and kick off the chemical reaction that ruins the coin. BD cannot travel through the air but the green 'fluff' it creates is often moist and acidic and if it gets on a similar coin it might initiate the spread of BD by eating through that crust. But it cannot create BD in a normal coin anymore than putting a piece of rust on a car will cause it to start to rust.

   3) The little PVC or mylar flips are often traps for moisture. They fill up with warm and humid air on such a day and then the temperature drops faster than the air can equilibrate with the outside, the dew point is reached, and water condenses inside the flip, typically collecting on the edges of the coin where it contacts the plastic. Over time a lot of corrosion will develop. This is bad for any coin but particularly one with underlying BD.

    4) Don't get too paranoid about BD. Only a small percentage of the greenery you see on ancient bronze is likely to be something you have to worry about. And be careful about soaking or boiling coins in strong chemicals unless you know the risks.

                                                                                                            Regards, Dave

[JBF]

I can't help but think that BD is a good argument for collecting silver or even gold or electrum.
The "noble" metals.

[daverino]

I can't help but think that BD is a good argument for collecting silver or even gold or electrum.
The "noble" metals.

I don't agree with that sentiment. The chemistry of bronze is, to me, fascinating while gold doesn't have any to speak of.  But perhaps that is because I am a chemist. For those not so interested it mostly boils down to one thing - keep your coins dry!

[Andrew McCabe]

I can't help but think that BD is a good argument for collecting silver or even gold or electrum.
The "noble" metals.

I don't agree with that sentiment. The chemistry of bronze is, to me, fascinating while gold doesn't have any to speak of.  But perhaps that is because I am a chemist. For those not so interested it mostly boils down to one thing - keep your coins dry!

As is well known, I collect bronzes as well as silver, gold and cast coins. I've about 600 bronzes, of which about 500 are high quality (major auction quality). As said I've simply passed on coins with suspect BD. Of these coins, perhaps 2 or 3 have green spots that I'm keeping an eye on but that don't appear to be doing anything. A few dozen other coins have hard green or red encrustations that I don't intend to clean but might at some point solicit expert cleaning for. I store coins in open trays in a dry environment, air conditioned in summer. My silver coins have similarly low proportions of coins with issues. Crystallisation is my main concern on silver, followed by hard encrustations. Some of my rarsest silver types are broken through crystallisation, and I have , in general, to be careful not to drop silver coins.

All in all I would say that my bronzes present me with no significant issues and anyway no greater issues than my silver coins, though that may be partly due to the very high quality of the coins to begin with, symptomatic of benign conditions over the last 2200 years.

[JBF]

well, never say never.
I do have some bronzes, but with one exception I have always bought them in person.
If one is collecting a region of Greek mints, it would be hard to completely avoid them, since minor
mints often just do (a few types for) bronze coins.  A handsome bronze is very nice, as long as
it is problem free.

[daverino]

Hi Andrew and JBF

      Sometimes appreciating the causes for the imperfections in ancient coins is a way of reconciling myself to the fact that I really cannot afford the very top quality stuff. My collection is a mixed bag of 'eBay quality' coins that I have had a good time collecting over the years. I hear what you say  about crystallization, Andrew. I once bought a Tribute Penny that was shipped to me in a flip that the seller had simply chucked into an ordinary envelope and sent through the mails. It arrived in about twenty pieces. I had been unaware of crystallization until this happened. Right now I have one coin which is partly crystallized, a Republican denarius, that I have to handle carefully.
       Crystallization is an interesting topic that even modern science does not completely understand. It is a tendency of the metal to lose its malleability and fracture. Ordinary construction metals can become embrittled due to constant stresses and strains but the properties of silver change over time without any actual mechanical stress. Silver coins are certainly in this category. It would be interesting to be able to identify these brittle coins before you accidentally drop one! My limited observation is that these coins lose some of their silvery lustre and also suffer a decrease in electrical conductivity. Metallic lustre and conductivity are related to one another.

                                                                                                                                Regards, Dave

[Meepzorp]

Hi folks,

Here is another progress report.

Today, I started my 29th soaking (day 57).

There are no new developments to report.

Meepzorp

[Meepzorp]

   1) Believe those who say that protecting the coin from humidity is the best preventative. A good wash to remove chlorides and acidity (hours not days) is good followed by drying. I would use low(200 F) oven heat followed by a waxing up to seal the surfaces.

Hi Dave (hello from a physicist to a chemist ),

Thanks for the advice. Are you saying that the soaking(s) should be for only a total of a few hours? I've been soaking my diseased coins for almost 2 months now.

I'm getting so much conflicting advice from people.

Some people have advised me not to seal my diseased coins with wax.

Meepzorp

[Meepzorp]

    4) Don't get too paranoid about BD. Only a small percentage of the greenery you see on ancient bronze is likely to be something you have to worry about.

Hi Dave,

Therein lies the problem. Sometimes, when you see "green stuff" on a bronze coin (especially one with a history of known BD), it is difficult to tell the difference between "active BD" and "previously active BD".

It reminds me of my illness. Many times, it is extremely difficult (for both doctors and patients) to tell the difference between "active Lyme Disease" and "previously active Lyme Disease". This is the old "chronic, persistent infection with the Lyme organism" theory (which I believe in) versus the "post-Lyme syndrome" theory (which I think is a load of horse manure).

Meepzorp

[daverino]

Hi Meep

   I am sorry to hear you had a case of Lyme disease. There were a lot of deer (and deer ticks) on Long Island where I worked. People I knew who contracted it were bothered by arthritis-like symptoms for years afterwards.

All that a water soak does for coins is remove soluble chloride and other salts or acids that may have accumulated on the coin's surface. No big deal really - it just cleans the coin off. The real problem with BD is an insoluble under-layer of cuprous chloride (CuCl) that has accumulated over centuries. It will not be removed by soaking on any reasonable time scale. On the other hand it is inert unless it is exposed to prolonged humidity as well as air. The purpose of mild oven heat is to drive the moisture out of the coin. Once  that is done it makes sense to seal the surfaces as much as practicable. Personally I use clear shoe wax. Also keep the humidity low. I think that 70% humidity is the point where CuCl begins to absorb water from the air and makes the coin vulnerable.

The upshot is that there is no actual 'cure' for BD that I know of. You are just preventing an outbreak that damages the coin. Fortunately coins are small and easily managed so that preventing BD spread should not be too difficult.

This is not the case with large statues and other museum pieces. Their practice of using lengthy soaks that can go on for years to stabilize them is outside my experience and, frankly, I think entirely unnecessary for coins. On the other hand there are others who actively promote sesquicarbonate and other nostrums. Are they effective? Who knows since a lot of the time I suspect that many coins are "cured" that never had BD in the first place.  

                                                                                                                              Regards, Dave

One practice that I hesitate to recommend is the taste test. Real BD generates acid. If you place a BD infested coin (unwashed) against the tip of your tongue you are likely to sense a distinct tartness from the surface acids


  

[Meepzorp]

I am sorry to hear you had a case of Lyme disease. There were a lot of deer (and deer ticks) on Long Island where I worked. People I knew who contracted it were bothered by arthritis-like symptoms for years afterwards.

Hi Dave,

I wish that arthritis was the only symptom I had. That's about 5% of my symptoms. Since being stricken with my illness in 1990, my most disabling symptoms have been my neurological symptoms (encephalitis, meningitis, etc.), followed by lung inflammation (which causes severe difficulty breathing) and cardiac symptoms (inflammation, abnormal heartbeat, etc.).

Fortunately, after taking massive doses (elephant doses) of antibiotics every single day for 8 years, I've experienced a partial resolution of my symptoms. But I am by no means "cured".

Yes, I know that Long Island is absolutely infested with Lyme Disease. In fact, I may have gotten it there. I have no history of a known tick bite. To my knowledge, I've never been bitten by a tick in my life. So, I can't say for certain. But I went away to college in Long Island. I lived there for 4 years.

I don't know how I got it, but I got a REALLY bad case of it. I have one of the worst documented cases of Lyme Disease in a human being.

Meepzorp

[Meepzorp]

This is not the case with large statues and other museum pieces. Their practice of using lengthy soaks that can go on for years to stabilize them is outside my experience and, frankly, I think entirely unnecessary for coins. On the other hand there are others who actively promote sesquicarbonate and other nostrums. Are they effective? Who knows since a lot of the time I suspect that many coins are "cured" that never had BD in the first place.

Hi Dave,

I am reasonably certain that at least 2/3 of my coins that I am treating for BD actually have it. And that is a conservative estimate. By the way, you can make that statement about Lyme Disease also. Most "experts" feel that Lyme Disease is "over-diagnosed but under-treated". And the "under-treated" part of that phrase obviously applies to people who really and truly have it. And that creates all kinds of problems. There are many parallels between BD and Lyme Disease.

In your opinion, how long is "long enough" (to soak diseased coins in sodium sesquicarbonate)?

Meepzorp

[daverino]

This is not the case with large statues and other museum pieces. Their practice of using lengthy soaks that can go on for years to stabilize them is outside my experience and, frankly, I think entirely unnecessary for coins. On the other hand there are others who actively promote sesquicarbonate and other nostrums. Are they effective? Who knows since a lot of the time I suspect that many coins are "cured" that never had BD in the first place.

In your opinion, how long is "long enough" (to soak diseased coins in sodium sesquicarbonate)?

Meepzorp

It doesn't hurt to soak them longer but I suspect that it is a case of diminishing returns. Soaking removes acids and mineral salts. It is perhaps 90% done in a day and 100% done after 5 years but that is, of course, a guess. A month seems plenty long. I think you should begin the process of drying and sealing up your coins.

[Meepzorp]

Hi folks,

Here is another progress report.

Yesterday, I started my 31st soaking (day 61).

There are no new developments to report.

Meepzorp

[Meepzorp]

This is not the case with large statues and other museum pieces. Their practice of using lengthy soaks that can go on for years to stabilize them is outside my experience and, frankly, I think entirely unnecessary for coins. On the other hand there are others who actively promote sesquicarbonate and other nostrums. Are they effective? Who knows since a lot of the time I suspect that many coins are "cured" that never had BD in the first place.

In your opinion, how long is "long enough" (to soak diseased coins in sodium sesquicarbonate)?

Meepzorp

It doesn't hurt to soak them longer but I suspect that it is a case of diminishing returns. Soaking removes acids and mineral salts. It is perhaps 90% done in a day and 100% done after 5 years but that is, of course, a guess. A month seems plenty long. I think you should begin the process of drying and sealing up your coins.

Hi Dave,

You must have read my mind. I was thinking the very same thing.

Generally speaking, I agree with your third sentence. But I think that you may have exaggerated a little. I seriously doubt if it is "90% done in a day". But I get your point.

In your first sentence, your "diminishing returns" phrase hit the nail on the head. That is exactly what I was going to write when I logged in to this forum, before I even read your post. That's why I stated that you must have read my mind. For the past several soaking cycles (at least 10 days or so), there have been no new developments to report. Additional soakings seem to be producing no new results in my coins. I was seriously thinking of winding this all down before I even read your post.

I started my soakings on 5/23. So, it is actually longer than the 61 days that I posted above. The reason for the discrepancy is my crazy sleep cycle. My body is basically on a 26 hour cycle. On average, I "jump" 1 1/2 to 2 hours per day. In other words, every day, on average, I wake up 1 1/2 to 2 hours later than I woke up the day before. Every 2 weeks, I lose a day. For me, 2 weeks consists of 13 26-hour days. I don't know why my body does this, but it has been this way for at least 10-15 years now. I certainly didn't consciously choose to do this. Things just sort of evolved into this cycle. When I was younger (high school, college, etc.), I was nocturnal. Now, I am on a 26 hour cycle. I can't figure it out.

Anyway, that explains the discrepancy. If I started my soakings on 5/23, it has actually been over 2 months. It's been 66 days of soakings, to be exact. But not all of my coins were soaking for the full 66 days. I did them in 3 batches, starting some later than others. And, for some coins, I stopped soaking them because I thought that they were "cured". But I had to start re-soaking them again because they relapsed. So, the number of days of soakings has pretty much been different for all of my 21 diseased coins.

Meepzorp

[daverino]

     I sometimes wonder what people expect to achieve by soaking their coins in the first place. Does this perform some kind of magic? Unfortunately there is no little plastic thingy that pops up and says "done" when whatever the soak is supposed to accomplish has been accomplished.

     Using an alkaline buffer like carbonate/bicarbonate ( aka "sesquicarbonate") does suppress the progress of BD since the acid which causes damage to the coin is neutralized by it. But you can't keep the coin under water forever. The idea is to protect the coin while at the same time leaching out water-attracting salts that can stimulate BD acid production once the coin has been re-introduced to the air. 

     Everyone knows that table salt (sodium chloride)clogs up when the air becomes humid - but if that salt were free of impurities it would run freely in any kind of weather since pure sodium chloride has no affinity for water.. On the other hand, you might have used the non-corrosive snow remover, calcium chloride. If you leave a few grains of it exposed to the air it will quickly turn into a puddle because it has such a strong water affinity. Just a trace of this in ordinary table salt will cause it to clog in humid weather.

   Trace contamination of the coin's patina  with water-absorbing salts like this will make it vulnerable to corrosion. Removing them as much as possible is the object of the water soak. Obviously they are easily washed away from the surface but if they are embedded in or under the patina there is no way to ensure that they are removed even by very long water soaks.

[Meepzorp]

Hi folks,

Here is another progress report.

Today, I started my 32nd soaking.

There are no new developments to report. I think this is going to be my last soaking. It's time to "wrap it up". If it is my last soaking, then I'll be done on Thursday 7/31. I started my soakings on 5/23. That means that my total duration of soakings will be 69 days.

Meepzorp

[Meepzorp]

Unfortunately there is no little plastic thingy that pops up and says "done" when whatever the soak is supposed to accomplish has been accomplished.

Hi Dave,

Therein lies the problem. And I've received so much conflicting advice from people.

Meepzorp

[Meepzorp]

I sometimes wonder what people expect to achieve by soaking their coins in the first place.

Hi Dave,

The idea is to take significant steps toward stopping the progression of BD. No?

Are you implying that there is something else (beside soaking in sodium sesquicarbonate and/or limiting humidity in the coin storage environment) that people should be doing to stop the progression of BD? If yes, what?

Meepzorp

[Meepzorp]

Trace contamination of the coin's patina  with water-absorbing salts like this will make it vulnerable to corrosion. Removing them as much as possible is the object of the water soak. Obviously they are easily washed away from the surface but if they are embedded in or under the patina there is no way to ensure that they are removed even by very long water soaks.

Hi Dave,

Are you implying that it is necessary to strip a coin's patina in order to more fully stop the spread of BD?

Is it possible to fully treat a coin without stripping the patina?

With regard to my diseased coins, it is a moot point (and question). After just 2-3 soakings, the patinas were all pretty much 80-100% stripped anyway. But, then again, is that the intended idea? By stripping the patina, you are ensuring better treatment.

Meepzorp

[areich]

I think the main problem is a lack of pictures. Without decent pictures and with your admission that you don't even know that all the coins you are treating actually have BD, you can't expect many useful opinions.