Author Topic: Bronze Disease  (Read 28387 times)

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Offline Pellinore

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Re: Bronze Disease
« Reply #30 on: September 28, 2015, 02:10:30 PM »
What would happen if you would make the soda mix stronger, I mean putting more soda mix in less water? Would the process go faster?
-- Paul

Offline THCoins

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Re: Bronze Disease
« Reply #31 on: September 28, 2015, 05:25:24 PM »
Just try on a coin you don't like.
(I did. You usually end up with a very ugly surface of rough (uitgebeten) copper)

Offline bruce61813

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Re: Bronze Disease
« Reply #32 on: September 28, 2015, 05:38:34 PM »
Beyond the recommended strength it does not speed things up. Heating the solution, I us an old coffee makers, as it keeps the solution at about 150 F. Considering the coin has has centuries to absorb the salt, it will take awhile to leach it out.  Changing the solution every three days, and scrubbing in between will speed things. Multiple coins can be done at the same time. I us an open mesh pad on the bottom of the carafe so the solution touches the maximum surface area.


Bruce

Offline Pellinore

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Re: Bronze Disease
« Reply #33 on: July 12, 2016, 12:30:06 PM »
Multiple coins can be done at the same time. I us an open mesh pad on the bottom of the carafe so the solution touches the maximum surface area.


So if you put two coins in one bottle (I'm using old plastic medicine bottles) with the sodium solution, they don't "contaminate" each other? I thought BD was contagious. How does the contamination work?
-- Paul

Offline bruce61813

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Re: Bronze Disease
« Reply #34 on: July 12, 2016, 02:38:16 PM »
n the dry powder form, BD can be passed from coin to coi, or holder they were in.  In a liquid solution it is neutralized and won't spread.  However the solution should be change,a couple time in the first 48 hours. The chemical reactions are relatively fast at first but taper off as time passes. By keeping the solution "fresh" you get the maximum reaction. Also, giving the coins a scrub every 12 hours or so and putting them in a clean solution will improve BD removal.

Bruce

Offline Pellinore

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Re: Bronze Disease
« Reply #35 on: January 23, 2017, 10:45:20 AM »
A little bit more on the contamination process. What one's naturally afraid of, is that BD spreads from coin to coin in one's coin holders. Is that possible, or does it only contaminate if coins are touching each other?

In these drawers, I'm keeping my coins. I noticed that the little Persian bronzes I like are a bit BD-prone. Is there a danger in keeping them together, but in separate boxes like my system?

-- Paul


 

Offline bruce61813

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Re: Bronze Disease
« Reply #36 on: January 23, 2017, 12:51:02 PM »
There are two factors to consider.  BD "transmits" in its powered form, the light blue-green fuzz that sometimes appears in the early stages. It is this powdered form that gets onto other surfaces and to other coins. Humidity is the other factor, if the BD is present the humidity can provide enough moisture to activate it.

Any coins that show signs of BD, especially if it seems to recur, should be isolated and soaked in the soda/soda mix. I would do it for a couple weeks. Remember that the salts have had centuries to embed themselves. After the coins have dried, I would coat them with wax, REN Wax or a high quality paste wax [used for furniture].  This has two advantages. the first is that it restricts the ability of atmospheric moisture to reach the coin. The second is that the coins may be handled and not leave finger prints. they should be re-waxed every  couple years.

Bruce

Offline jkk

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Re: Bronze Disease
« Reply #37 on: April 04, 2017, 02:42:47 PM »
I went ahead and tried the method on an ancient coin of Magnentius. It was a perfect candidate: otherwise had a lot of detail, and was a coin I would wish to conserve if possible, but it look like a smurf had sprayed spittle on it. I didn't heat the water, so it took longer, but sure enough: the proportionate mix of baking soda and washing soda in distilled water blew all the aquamarine smurf spit off it in about a month.

The process did leave rough spots, but they are better than having the rest of the coin eaten alive. I changed the solution out once a week, when the water started to turn a bluish hue. No doubt I could improve on my execution of the method, but it definitely worked for me. Thanks, Bruce, for a clear explanation of the process and the chemistry behind it.
Jonathan

Offline bruce61813

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Re: Bronze Disease
« Reply #38 on: April 04, 2017, 03:07:47 PM »
You are welcome. the rough spots can't be helped, the BD does remove some of the coins flan, so the sooner the treatment the better.

Bruce

Offline jkk

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Re: Bronze Disease
« Reply #39 on: April 04, 2017, 03:33:59 PM »
You are welcome. the rough spots can't be helped, the BD does remove some of the coins flan, so the sooner the treatment the better.

And would keep doing so. The Cu in the BD has only one possible source, absent cross-contamination, and it isn't the atmosphere. I waited for a coin that I cared enough about to desire to improve, because I figured that a throwaway coin would not motivate me sufficiently to get the best results. Kind of like how I advise spreadsheet newbies: don't start with a fake practice project. Start with a real one that you care about, so that you are motivated to work through the problems as they arise. But in the case of coins, definitely not an expensive or rare practice project...
Jonathan

Offline bruce61813

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Re: Bronze Disease
« Reply #40 on: April 04, 2017, 07:00:38 PM »
You can do coins in batches, just change out the solution more often during the first few weeks. I also recommend a light scrubbing with a nylon brush, one of the type sold for cleaning dentures works very well, between soaks. Do this between solution changes.

Bruce

Offline Pellinore

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Re: Bronze Disease
« Reply #41 on: October 09, 2017, 09:03:11 AM »
Bruce, 5 tablespoons bicarbonate and 8 tablespoons sodium. Makes about 200 ml stuff. And 3 cups of distilled water - makes 750 ml fluid, together a bit less than 1 litre? That is the idea? An American cup being 240 ml. Just want to know if I have the quantities right.
-- Paul
« Last Edit: October 09, 2017, 01:13:13 PM by Pellinore »

Offline bruce61813

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Re: Bronze Disease
« Reply #42 on: October 10, 2017, 03:10:01 PM »
Paul, you have it correct. the actual volume of water is not critical. I have used more or less, you are changing the concentration. the numbers
I gave are optimal, but not critical. Four cups [American] are about 10% short of a liter.

Bruce

Offline Pellinore

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Re: Bronze Disease
« Reply #43 on: October 10, 2017, 11:32:52 PM »
Great, thanks! So I did do it right all these years. Here are the plastic pots on my window sill, filled with old Romans, Elymaeans (particularly prone) and other Persian bronzes. When the sun shines the water temp can get to 50 Celsius in the afternoon. The deepest blue water (second from right) contains coins I have given up, Im afraid.
-- Paul


Offline bruce61813

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Re: Bronze Disease
« Reply #44 on: October 11, 2017, 03:11:21 AM »
change their soak solution every three or four days, and give them a scrub with a nylon brush.  It takes about 4 weeks of this to remove most embedded salts , and the BD goes away.






bruce