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the Bronze disease thread


Nerosmyfavorite68
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The dreaded bronze disease...  Back when I had an outbreak in c. 1999 (and subsequently am very reluctant to handle my coins) the best advice I had was to bake the coins.  While this seemed to have stopped it, it's not the best solution.

I avoid bd coins, but I got some 'uncleaned' coins, which were mostly stripped pick-bin type coins. Some of the pick-binners have the beginnings of BD.  What to do?  Said coins are all decrepit, but I'd like to attempt to stop it.  All are stripped coins, with no patina, other than some darkening.

I would like to especially treat a large provincial, an Elagabalus? Byblos? (unsure of both ruler and mint, the obverse is worn beyond easy ID) with an arch reverse. 

I plopped the bd ones in a separate bag.

What's the gentlest way to treat bd?  I've heard plonk it in distilled water, change daily? and brush with toothbrush?  Repeat with new water changes.  How does one dry them properly?

The smaller ones would make good bd removal practice coins.  One's a ho-hum Constantine campgate, another a Byzantine tetarteron or half with a monogram (Manuel, I think?), and said coin also has a hole in the middle.

I'm assuming it's bd and not the beginnings of repatination.  It's not the classic neon green type or raised splotches, but mostly a greenish or whitish matte fuzz, for the lack of a better term.

The large one has a more pronounced case.  The fuzz type, not the raised splotches type.

The actual uncleaneds of the lot range from decrepit to nice.

 

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a: Remove the BD manually. This is not a big problem as BD is usually powdery.

b: wash it with distilled water

b: Put the coin into a ethanolic 2% solution of BTA. (Benzotriazol)

Ethanol 99.9%  is better than water, since the Ethanol removes traces of water. 

Remove the coin and let it dry.

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Mechanically removing the green bits then putting them in distilled water and changing daily definitely works. It neutralises the chloride compounds that cause bronze disease. But you have to do it for weeks. Afterwards they need to be completely dry before they go back in a holder - ethanol, in an oven or even air dry. You have to check them for a long time after to make sure it doesn’t return.

Even then, they will deteriorate a little further before it’s gone, as the bronze disease might flare up a couple of times during treatment.

Edited by John Conduitt
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The following is a slightly edited version of a post I made some time ago in another forum, worth repeating I hope.

Bronze disease can't be cured but it can be interrupted and prevented from recurring. Bronze disease behaves in the manner it does because it is not a single chemical reaction but a repeating series of reactions where one feeds on the byproduct of another in an endless cycle. The basic reactants are copper, oxygen and chlorine. Put simply, a coin with bronze disease is slowly eaten away by hydrochloric acid. The object will eventually be completely consumed if not treated. Treatment involves breaking the cycle and then depriving the reaction of one of its essential ingredients - water. Even the small amount of water in the air on a humid day is enough to start the reaction again. This wikipedia article covers the basics, including treatment. One method commonly used by collectors involves sodium sesquicarbonate which will neutralize any remaining acid and convert reactive cuprous chloride to relatively inert cuprous oxide. Sodium bicarbonate (baking soda) will similarly neutralize the acid but does not do everything that the sesquicarbonate does. The baking soda bath can have unpredictable results on the patina if left too long and/or not completely dissolved. Maintenance involves regular inspection and keeping the object as dry as possible.

Edited by DLTcoins
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Thanks for the replies. I looked on youtube, but no good illustrated step-by-steps came up.

8 hours ago, shanxi said:

a: Remove the BD manually. This is not a big problem as BD is usually powdery.

b: wash it with distilled water

b: Put the coin into a ethanolic 2% solution of BTA. (Benzotriazol)

Ethanol 99.9%  is better than water, since the Ethanol removes traces of water. 

Remove the coin and let it dry.

Does this ethanolic solution of BTA come pre-mixed?  How long do I let it soak?

I haven't baked a coin in the longest time.  How long and what temperature?

Does only one coin go in b and c, or can more than one go in at once?

Is A) done while dry?  What kind of tool?

How do I tell the difference between BD (other than the super-obvious type) and the beginnings of patination? 

Is it just me, or are stripped coins more prone to BD?

Yeah, I'm going to avoid the 'uncleaned holy land' section if I order again.  That's more trouble than it's worth.  To be fair, one doesn't expect much for $3, and a couple of the 7 buck provincials weren't bad.

Nerocoins are mentioned in some uncleaned videos.  Are they good?

I also need to get new cotton gloves. Mine were on their last legs,a nd I handled these.  I don't want to get it on a good coin.  Too bad more dealers don't carry these.  Hmm, since my next order's probably from Savoca, I doubt they'd have gloves. Time to look.  I've been doing the Michael Jackson one glove thing for a while, as the other one disappeared.

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I would do them separately in fresh water.

You can take the green off wet or dry as it is loose and powdery. That’s how you know it’s not just stable verdigris, as well as the fact that it grows. I think people use toothpicks and tooth brushes.

Stripped coins would be more prone as the patina is what protects the copper from the dangerous particles in the air and on your fingers.

Edited by John Conduitt
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2 hours ago, Nerosmyfavorite68 said:

Does this ethanolic solution of BTA come pre-mixed?  How long do I let it soak?

You can buy it as solid, and mix it yourself. In the end this is cheaper.

BTA is not a cleaning agent. It forms a complex with the metal surface and protects it from further corrosion. It is not only used for coins and other metals, but e.g. also for airplanes. 

Therefore a long soaking time is not necessary but it is important to remove BD as much as possible before.

As I wrote, you should use a solution in ethanol. This has advantages over water. On the one hand because ethanol removes water residues, but it also has a much lower surface tension than water. This means that it can also penetrate into small cracks.

 

Edited by shanxi
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Can't I find it pre-mixed?  Do I really need BTA?  Where does one get it? These are junk coins; I don't want to spend a lot. I'm doing this mainly as practice in case something happens to a coin which I care about.  Is this stuff super-toxic? Are there fumes?  I should wear rubber/latex gloves, correct?

I think many would benefit if there were  permanent how-to threads on important things; basic cleaning, preservation, etc.  There's many people out there who have no clue what to do.  There are what look to be acceptable youtube tutorials on cleaning uncleaneds, but none for BD, preservation,etc.

I have a can of renaissance Wax, but have never used it.  The can just got shoved in the closet and has stayed there.  

There does seem to be a youtube tutorial, but wouldn't using a bare finger defeat the purpose?

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As much as I, too, would like to see a "how to" for crabby coppers and bronzes, I cannot see anyone committing to writing one. Anything that can have an adverse effect on the coin surface is not something anyone is going to want their name associated to. The thread would need more disclaimers than help text. The only really helpful excercise is to practice on your worst coins and keep a written journal or word document on coin metal composition, what steps have been taken, using what brushes and picks, with what agents, for how long and with photos of each step.

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2 hours ago, Nerosmyfavorite68 said:

Can't I find it pre-mixed?  Do I really need BTA?  Where does one get it? These are junk coins; I don't want to spend a lot. I'm doing this mainly as practice in case something happens to a coin which I care about.  Is this stuff super-toxic? Are there fumes?  I should wear rubber/latex gloves, correct?

I think many would benefit if there were  permanent how-to threads on important things; basic cleaning, preservation, etc.  There's many people out there who have no clue what to do.  There are what look to be acceptable youtube tutorials on cleaning uncleaneds, but none for BD, preservation,etc.

I have a can of renaissance Wax, but have never used it.  The can just got shoved in the closet and has stayed there.  

There does seem to be a youtube tutorial, but wouldn't using a bare finger defeat the purpose?

I have ordered a 200ml Box of them - will be here at next week. I will try it with some provincial bronze coins and some silver denarius and tetradrachms. I want make a YouTube video for my channel to show the handling and the before / after look. 

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1 hour ago, expat said:

As much as I, too, would like to see a "how to" for crabby coppers and bronzes, I cannot see anyone committing to writing one. Anything that can have an adverse effect on the coin surface is not something anyone is going to want their name associated to. The thread would need more disclaimers than help text. The only really helpful excercise is to practice on your worst coins and keep a written journal or word document on coin metal composition, what steps have been taken, using what brushes and picks, with what agents, for how long and with photos of each step.

I see. I didn't realize that.  Well, the coins in question certainly are crappy, so it couldn't be any worse, although I'd always try the conservative route.  I'm too much of a conservator to take undue risks with even the most awful old object.

 

1 hour ago, Prieure de Sion said:

I have ordered a 200ml Box of them - will be here at next week. I will try it with some provincial bronze coins and some silver denarius and tetradrachms. I want make a YouTube video for my channel to show the handling and the before / after look. 

That would be most halpful.  Thank you!

By the way, does anyone know if any AE4's had three standing figureson the reverse?  One non-bd ones is a teensy weensy thing.  So teensy that it spurted out of my hand and I had to get a flashlight to find it.  I found it, on a reel to reel box.  I haven't bought AE4's in a long time, but I don't remember them being that thin.  I thought it was a curved E at first, like a pentanummia, but I think it's three figures.

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  • Benefactor

Benzotriazol is extremely toxic. Read the material safety data sheet on it if you are interested. I would not mess with it unless you're working in a fume hood you're wearing goggles and you have gloves on. And then how much fun you going to have handling your coin after that? Using simple bases is a much safer way to treat bronze disease.

John

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Ok, thanks!  Wow, yeah, I think I'll skip the toxic stuff.  I'm glad I asked.  That's not worth it, for coins with a total retail value of $16.  It especially wouldn't be safe, for someone who is not well-versed in working with chemicals.

I'll check out the thread, many thanks.  I could try a couple of the lesser coins, to start out with.  If I have success, then perhaps the Byblos? arch provincial.

A more fun first project might be non-invasively cleaning the two uncleaned trachea.

I'm going to start a safe chemical reaction now, by heating up my chili and beans for dinner.

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  • Benefactor

Here is a follow up thread I did about the connection between humidity and bronze disease. Humidity is probably the biggest factor in whether untreated bronze disease is going to move on and destroy your coin or go into remission.

https://www.cointalk.com/threads/controlling-humidity-through-holiday-baking.372553/

John

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8 hours ago, Theodosius said:

Benzotriazol is extremely toxic... I would not mess with it unless you're working in a fume hood 

Sorry, this is nonsense. You should not swallow it, of course, gloves are OK (also because of the alcohol) but there is no need for panic. Benzotriazole, for example, is used in dishwasher tablets, and at least I don't use my dishwasher in a fume hood. :classic_smile:

 

 

Edited by shanxi
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This one's interesting..I purchased this Nabetaean coin about 5 years ago...Here's the original photo.

1053444150_ARETAS_WHITE(1).jpg.8bce4a7707b392d2eb1607ee7cfb0209.jpg

On the obverse you can see two areas that looked like bd?....The green colouring hasn't grown...With a wooden cocktail stick I scraped off the green and yes it was slightly powdery..I have now soaked the coin in distilled water for 3 weeks and here's the result after another 3 weeks in my cabinet.

20221009_115009.jpg.73bdb8b6383693158db30c5f6ffaab49.jpg

The dark green in the two crevices is hard there doesn't seem to be any green powdery formation...Was it bd? . I'll keep my eye on it and post any changes.

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1 minute ago, Spaniard said:

Was it bd? . I'll keep my eye on it and post any changes.

Powdery and light green is often a bad sign, on the other hand I have some coins with sand patina where the sand was discolored. After removing the sand nothing happens, the coins are stable. If you are lucky it is something like that.

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4 minutes ago, shanxi said:

Powdery and light green is often a bad sign, on the other hand I have some coins with sand patina where the sand was discolored. After removing the sand nothing happens, the coins are stable. If you are lucky it is something like that.

Thanks..Maybe I'm wrong but doesn't BD come out from the core of the coin? Or can it form purely on the surface? ..I do have a cheap coin microscope so later this afternoon I'll see if I can take some decent detailed photos of what's happening at the bottom of the crevices..

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7 minutes ago, Spaniard said:

Maybe I'm wrong but doesn't BD come out from the core of the coin?

It always starts on the surface where the surface is exposed to the environment, but it can progress into the core, forming deep holes.

 

Edited by shanxi
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Thanks @John Conduitt & @shanxi....I think I'm probably lucky as I live in a very dry climate and as I said from the original photo of 5 years ago it hadn't spread...

Off for a good old Indian now and a couple of beers, later, depending on the "couple", I'll post some microscope photos.

Edited by Spaniard
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  • Benefactor

The fact that some commercial companies put a (probably very small) amount of benzotriazole in their products does not mean it is safe to handle the pure form.

To treat bronze disease with benzotriazole you dissolve the solid in reagent grade ethyl alcohol. Using watered down alcohol defeats the purpose of the treatment to a large degree.  Let's look at how safe pure benzotriazole is from the Material Safety Data Sheet:

The MSDS for benzotriazole:

https://www.fishersci.com/store/msds?partNumber=AAA1542318&productDescription=BENZOTRIAZOLE%2C+99%+(ASSAY)+50G&vendorId=VN00024248&countryCode=US&language=en

Here are hazards they list:

2. Hazard(s) identification
Classification
This chemical is considered hazardous by the 2012 OSHA Hazard Communication Standard (29 CFR 1910.1200)
Label Elements
Signal Word
Warning
Hazard Statements
Harmful if swallowed
Causes serious eye irritation
Company 
Alfa Aesar
Thermo Fisher Scientific Chemicals, Inc. 30 Bond Street
Ward Hill, MA 01835-8099
Tel: 800-343-0660
Fax: 800-322-4757
Email: tech@alfa.com
www.alfa.com
Acute oral toxicity Category 4
Serious Eye Damage/Eye Irritation Category 2
Precautionary Statements
Prevention
Wash face, hands and any exposed skin thoroughly after handling
Do not eat, drink or smoke when using this product
Wear eye/face protection
Eyes
IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing
If eye irritation persists: Get medical advice/attention
Ingestion
IF SWALLOWED: Call a POISON CENTER or doctor/physician if you feel unwell
Rinse mouth
Disposal
Dispose of contents/container to an approved waste disposal plant
Hazards not otherwise classified (HNOC)
Toxic to aquatic life with long lasting effects
3. Composition/Information on Ingredients
Component CAS-No Weight %
1,2,3-Benzotriazole 95-14-7 98+
4. First-aid measures
General Advice If symptoms persist, call a physician. Eye Contact Rinse immediately with plenty of water, also under the eyelids, for at least 15 minutes. Get
medical attention. Skin Contact Wash off immediately with plenty of water for at least 15 minutes. Get medical attention.
Inhalation Remove to fresh air. If breathing is difficult, give oxygen. Get medical attention.
Ingestion Clean mouth with water and drink afterwards plenty of water. Get medical attention if
symptoms occur.
Most important symptoms and
effects
None reasonably foreseeable.
Notes to Physician Treat symptomatically

 

How about reagent grade Ethyl Alcohol?  It evaporates very quickly so the fumes are hard to avoid without a fume hood. The vapor is toxic. It is also extremely flammable and is absorbed through the skin.

The MSDS for Ethyl Alcohol:

https://fscimage.fishersci.com/msds/95414.htm

Section 3 - Hazards Identification

EMERGENCY OVERVIEW
Appearance: Not available. Flash Point: 18.3 deg C.
Danger! Poison! Causes severe eye irritation. Causes respiratory tract irritation. Flammable liquid and vapor. May be fatal or cause blindness if swallowed. Vapor harmful. This substance has caused adverse reproductive and fetal effects in humans. May be absorbed through intact skin. May form explosive peroxides. May cause central nervous system depression. May cause liver, kidney and heart damage. Cannot be made non-poisonous. Causes moderate skin irritation.
Target Organs: Kidneys, heart, central nervous system, liver, gastrointestinal system, cardiovascular system, eyes.

Potential Health Effects
Eye: Causes severe eye irritation. May cause painful sensitization to light. May cause chemical conjunctivitis and corneal damage.
Skin: Causes moderate skin irritation. May be absorbed through the skin. May cause cyanosis of the extremities.
Ingestion: May be fatal or cause blindness if swallowed. May cause gastrointestinal irritation with nausea, vomiting and diarrhea. May cause systemic toxicity with acidosis. May cause central nervous system depression, characterized by excitement, followed by headache, dizziness, drowsiness, and nausea. Advanced stages may cause collapse, unconsciousness, coma and possible death due to respiratory failure.
Inhalation: Inhalation of high concentrations may cause central nervous system effects characterized by nausea, headache, dizziness, unconsciousness and coma. Causes respiratory tract irritation. May cause visual impairment and possible permanent blindness. May cause narcotic effects in high concentration. Vapors may cause dizziness or suffocation.
Chronic: Prolonged or repeated skin contact may cause defatting and dermatitis. May cause reproductive and fetal effects. Laboratory experiments have resulted in mutagenic effects. Animal studies have reported the development of tumors. Prolonged exposure may cause liver, kidney, and heart damage.

 

So now let's take these two chemicals and mix them together, then soak some of our coins in them.  Do it outside at least with proper protection.

I think I will pass because there are safe alternatives available.

John

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I've got a coin coming which looks like it has some active bronze disease. 

Has anyone tried using an ultrasonic cleaner? Would it be able to clean out the BD more effectively or would it damage the coin?

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