Author Topic: Green event happening on Bronze (Read 4669 times)

John K · « **on:** April 16, 2009, 09:29:12 pm »

It is green...
It is solid...
What it is?
Should I treat it in any way or leave it?

Joe Sermarini · « **Reply #1 on:** April 17, 2009, 09:56:03 am »

Looks like bronze disease. Is it really solid? If so, it might not be bronze disease, but it sure does look like it.

slokind · « **Reply #2 on:** April 17, 2009, 02:19:49 pm »

I was wondering whether it could be a lime encrustation colored by copper oxide (of BD or not). Pat L.

John K · « **Reply #3 on:** April 17, 2009, 03:37:44 pm »

Hmmm as I look at the photo it LOOKS that the green appears more fragile looking than it is... This is misleading!

I have now looked at it under a microscope.

It is solid green, solid a smooth AND with two shades of green. One is dark green and the other is a aquamarine green. Now I also see "pot holes" with a brick red color in them. In fact I did not notice them until the photo and now under the microscope there are quite a few but they are very small.

If it is BD then I read about baking soda/washing soda. However if it is encrustration I will go in search of a treatment method for that and will treat it when it becomes clearer what I am dealing with.

Thanks!

slokind · « **Reply #4 on:** April 17, 2009, 06:19:04 pm »

My instinct, if my old eyes were still up to it (they focus, but make small things look smaller, so I'd need a binocular microscope at my age), would be to take a very fine, very sharp scalpel and very gently, without pressure, take off some flakes where the stuff is thickest, to see. . . what will you see? If you see more of that red, then the chances are very great that you're dealing with BD, whatever the chemistry of the hard stuff may be. In that case, I'd see how much of the thick and hard could safely be removed by continuing with the scalpel--or small XActo knife, new blade so you don't have to press. Then I'd proceed as for BD. Sodium sesquicarbonate solution, that is 50% washing soda and 50% bicarbonate of soda, if you want to make your own, in distilled water. Gently simmer (ideally in pyrex glass container, or stainless if you have to use an electric stove) for a half hour, or so, watching. I find that a teaspoon of sodium sesquicarbonate in a pint of water is plenty strong enough (it is safer to rinse and repeat than to boil too long and too strong),
Rinse in distilled water, brushing with a soft toothbrush. If it looks clean, rinse again, very thoroughly, and dry very thoroughly. Examine under magnification to make sure that no more BD remains. If any does, repeat.
Work very slowly. There are no second chances.
When others see that I've chimed in, they probably will check up on what I said and add to it.
Pat L.

bruce61813 · « **Reply #5 on:** May 10, 2009, 04:37:14 pm »

It is Bronze Disease, the orange you see around some of the green is raw copper, and you can also see the pitting. Treat it now and you will have a coin with some damage, but not too bad looking, wait 4 months and you will have a slug. If you don't know how to treat it contact me, and also read the paper in the Numiswiki . Time is important.

Bruce

John K · « **Reply #6 on:** May 10, 2009, 08:34:38 pm »

Clearly I now understand there is a need to act quickly. I will look for the two recommended products and distilled water tomorrow and start the process. This should be interesting and most likley I will have to be in contact for some advice along the way.

Thanks
John

bruce61813 · « **Reply #7 on:** May 14, 2009, 11:20:14 pm »

John, don't worry if the water turns green, it should if the green is BD. The copper chloride will be disloved. I would us at least 1 cup or 350 ml of the mix fo the coin, as youwant to be able to leach as much of the salts out od the coin as possible. also this may be a slow process, give the coin at least 3 to 5 days, with daily light scrubbing , then change the solution and let it sit for another 3 day. You can dry it after that , but Iwould just let it sit in the air and see if the green re-appears, if it does [after about a month] repeat the process, if not you should be safe.

Bruce

mwilson603 · « **Reply #8 on:** May 17, 2009, 02:58:53 pm »

I don't want to disagree with Bruce but I don't think it is Bronze Disease, I have had green encrustations that look very similar on bronzes before, and John's description of the two-coloured green reminds me of hard, malachite like crusts that can be "popped" off with the right pressure.
Mark
(Although I have been wrong before)

bruce61813 · « **Reply #9 on:** May 24, 2009, 11:51:50 pm »

There is a problem with Forum right now and noone seems to be able to post pictures. But the coin does have BD, the scaring is unmistakable, the raw copper with the active BD is also a give-away. One major difference between malachite [copper carbonate] and BD [tinchloride] is that BD does disolve in the soda/water solution, malachite is uneffected. I will try to post examples later.

Bruce

mwilson603 · « **Reply #10 on:** May 25, 2009, 08:50:21 am »

Hi Bruce, I can't disagree with what you are saying, but at no point in the thread has the owner mentioned the green dissolving in any solution, just that it is solid.
BD that I have come across is powdery and not solid, however I have cleaned coins that have had a REALLY hard green layer of what looks like malachite under a lens. Where I had a small group of coins stuck together, I have seen copper remnants of a second coin stuck to the green of a first coin, if that makes sense.
It just doesn't like pits and scarring to me, it looks like a surface crust, but maybe that it one of those picture things where one sees an indentation and another sees a raised device.
I would be interested to see how the soaking works for the owner.
regards
Mark

John K · « **Reply #11 on:** May 25, 2009, 02:59:06 pm »

When I first began to read over the posts here it became clear that I may have BD and as I read more about BD I saw that it could pass onto other coins. I immediately removed the coin from my collection for safety reasons. Brilliant move, but I did this on the run and cannot now find the coin. I have purchased all the chemicals needed but cannot give you any results yet to help this discussion until I find the coin. Currently I am on the road for meetings and will not return until after June 1st. Then my search for my coin's hiding place will continue and then the first series of treatments will begin and I will then share with you all the results! Thanks for your comments... and also thanks for your patience!!

bruce61813 · « **Reply #12 on:** May 25, 2009, 08:26:53 pm »

When BD first starts it is a green powder onthe surface, but with high enough humidity it begins to faor a solid. But the solid is about the consistancy of chalk, tha tis often seen as a coating onthe coin and looks like a very pale green patina shell. the problen is that by this time the coin's surface has been eaten away and there is nothing left of it. I am goining to attach some old photo's of BD.

Bruce

John K · « **Reply #13 on:** June 15, 2009, 02:44:39 pm »

The coin has been found! I really did a great job hiding it!

Treatment #1 has begun with Baking Soda and Washing Soda mixture. When this mixture begins to boil it suddenly expands with a white foam rapidly!!! But it settled down when I turned to low heat for 5 minutes. It is now soaking. Initial observation is that the water is crystal clear after the boil.

mwilson603 · « **Reply #14 on:** June 15, 2009, 03:03:50 pm »

Thanks John. And is the green still on the coin?

regards

Mark

John K · « **Reply #15 on:** June 15, 2009, 07:52:49 pm »

Mark,

There is still green but it does seem less in some areas. The water is still clear and I wipedthe coin on a white cloth to see if there would be a green mark but none appeared. I will let it soak the night and make a new mixture tomorrow.

Thanks for keeping on eye on this and any insights are most appreciated!
John

mwilson603 · « **Reply #16 on:** June 16, 2009, 04:10:32 am »

Hi John,

I am not a chemist, that would be Bruce, however it definitely doesn't sound like bronze disease to me if the green is still there. I am still of the opinion that the substance is malachite or similar.

Bruce, do you still believe BD?

regards

Mark

bruce61813 · « **Reply #17 on:** June 17, 2009, 09:16:55 pm »

Yes, i think it is BD. If it were malachite, it would remain, the soda mix will not remove that, but but copper chloride will dissolve. It may not be apparent, depending on volume of solution. But do no cut the soak short, embedded chlorides need time to dissolve. You will probably see raw copper patches, that is another tell tale sign of BD, it leave raw rough scars on the surface where it has been working. Don't forget to scrub the coins at least once a day, and change the soak after three days.

It would be good to see a new scan after a weeks soaking and scrubbing.

Bruce

mwilson603 · « **Reply #18 on:** June 18, 2009, 05:04:06 am »

So to recap,
The green is solid and not powdery or chalky, the boiled mix didn't cause the green to be removed, the mix also didn't turn green with dissolved green substance, and the green didn't streak a cloth when rubbed after the boil.
If Bruce is right this is surely the toughest BD I have ever seen!
regards
Mark

bruce61813 · « **Reply #19 on:** June 18, 2009, 08:48:57 pm »

But you do have to scrub the coin with a brush. The layer of the BD ,if it is advanced does not dissolve easily. In some instructions that were posted here long ago, it was recommended to use a fine needle to remove so of the BD first, to allow the soda solution to get to the coins surface. Otherwise it is like working with oil, it takes ages to penetrate the first fraction of a mm. Soaking alone will not get rid of all of it, it does take some work. Soaking will deal with the new 'fuzzy' BD, but old established BD needs some mechanical help to remove it.

Bruce

John K · « **Reply #20 on:** June 19, 2009, 03:17:49 pm »

Update: Coin after 3 - 5 minute boils in distilled water with Bakingsoda/Washing soda solution. I also scrubbed with a toothbrush each day. 36+ hours between each boiling. No green noticable in water or on toothbrush.

To me the coin looks greener the lower left area. Maybe it is leeching out and I had not noticed it before?

mwilson603 · « **Reply #21 on:** June 19, 2009, 04:26:41 pm »

John,

As I am still convinced that this is not BD, why don't I find out if I am talking bull, or if I am correct.
So my offer.........private message me and I will send you my address. Then send me the coin and I will discover if it is encrustation or BD. If BD, I will cure the coin and remove all of the BD. If encrustation, I have cleaned coins with encrustations like this before, and with your permission I will clean the coin for you.
As I say, just an offer, and I will not be offended if you say no, but it seems that constantly repeating the same thing, and expecting a different result is a sure sign of madness

regards
Mark
P.S. Bruce, if it is BD, I will humbly beg your forgiveness for ever doubting you. (I use Gringotts and usually swear that you are a genius!)

bruce61813 · « **Reply #22 on:** June 21, 2009, 02:27:39 pm »

Mark, how are you going to determine if it is BD? The only way you can tell [BD does produce it's own encrustations] is by chemical analysis. You need to establish the presence of Cl- and after the soaking , that may be neutralized or leached out. That is the object of the soaking and initial boiling. I the chloride bearing salts are not leached out of the fabric of the flan, the BD cycle will keep re-occurring.

The coin will not become 'magically' free of encrustations without mechanical work. With my original instructions, people were told to use a magnifier and a needle to remove as much of the external encrustations as possible, then do the soaking and boil. the boiling was to force the solution deep into the crevasses of the flan.

The presence of raw copper, the red areas, surrounds by the green is one of the sure signs of what would be called second stage BD. The first stage is the surface green "fuzz", that is that easiest to treat. the second stage is deeper into the the actual coins flan, the acids have gone blow the surface and tend to follow areas that are stratified, hard and soft. The tin will be attacked, leaving raw copper. In your cleaning of coins have you seen the 'red blisters" ? Red colored bumps, but if you open one, it is hollow, some times with wat looks like tiny copper grains inside. that would the last stage of BD. The acids have been either diluted or neutralized over time, leaving just the pits behind.

Bruce

mwilson603 · « **Reply #23 on:** June 21, 2009, 02:55:05 pm »

Bruce, let me see the coin in hand. The green still looks more on the surface to me than through the surface. Therefore I will carefully scrape it with a scalpel, and once I am happy that I have done all I can for the coin, I will treat it anyway for BD with your amazing Gringotts No.1 mix. If it is BD then great, I will have cured it for now, and if isn't then I will have done no harm with the GG, and cleaned John's coin for him.
Whilst they don't show it in this picture, a bunch of coins I cleaned from a small hoard had similar encrustations and some even seemed to show the traces of what you are saying is copper. As you can see from the thread here, there was no BD despite the green appearing to look like it was.
https://www.forumancientcoins.com/board/index.php?topic=42699.msg269473#msg269473
I do not have the ability to chemically analyse the green myself, but I will show the after pics to show what the coin looks like under the crust.
regards
Mark

mwilson603 · « **Reply #24 on:** June 27, 2009, 08:20:46 pm »

Just got the coin today and thought that I would give a quick update after 30 minutes or so.

First few "bits" of green I attacked with a scalpel popped right off, and left normal surface behind. So far so good I thought. Then the next bit scraped away leaving red beneath and an obvious pit. This pattern continued for a little nit and then I had to leave it for family commitments. I will get back to it later/next week.

So in short, whilst I feel vindicated slightly that some of the encrustation did appear to be what I thought, I also have to be honest and say that more of it is definitely BD as Bruce thought.

So John, I will do what I can with the coin and mail it back to you once finished,

regards

Mark

John K · « **Reply #25 on:** June 27, 2009, 10:08:41 pm »

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Author Topic: Green event happening on Bronze (Read 4669 times)