Bronze Disease: CURED

[CPK]

Some may remember a few months ago I bought a coin that looked like it might have some active BD going on. The coin pretty clearly had been a victim of bronze disease, and while most of the stuff had been removed there were still pockets and areas of green on both the obverse and reverse. Here are the dealer photos:

The coin was from a dealer I trust and the price was right, so I took the challenge and bought the coin. As you can see, despite the corrosion the coin still retains some very nice details. I like these DIVVS AVGVSTVS coins, but a really nice example doesn't come cheap. 

When the coin arrived, I took it out of the flip and scraped the green areas with a wooden toothpick. Yep, the powdery green stuff came off. Great.

I did some research and decided to do some long-term soaking. I ordered a bag of sodium sesquicarbonate and mixed it in a covered bowl with distilled water for about a 5% solution. 

I changed the water about every week, when I could see the water getting a very slight bluish tint. In between changes, I sometimes scraped the BD with a toothpick or a small nylon brush.

I probably erred on the side of caution - letting the coin soak for a couple months - but I wanted to be sure every bit of that cursed corrosion was gone before I stopped. I could see progress as the green slowly disappeared. Finally, there was only a couple tiny dots left, which turned out to be some hard deposits. The corrosion was all gone!

Unfortunately, the long soak had adversely affected the coin's surface, resulting in a hideously flat and mottled appearance. I didn't get any pictures of the coin in this state but it was so bad I thought it might be ruined, after all. The only thing I could think of to salvage the coin and bring it back to a semi-natural appearance was to give it an artificial patina - something I'm generally not in favor of but justified in this case, I think.

I mixed some liver of sulphur in some warm water and dunked the coin for a minute or two. Parts of the coin darkened quickly, but other spots stayed a light-ish gray color. Disappointing. I took it out, rinsed it, and tried again. This time, the entire surface darkened nicely and evenly. I removed the coin, rinsed it in a baking soda solution, and then under running water I gently cleaned the surface, gradually lightening the coin's high surfaces. 

After this was accomplished to my satisfaction, I thoroughly dried the coin and applied a thin coating of Rennaissance Wax to seal the surface and protect the coin from future corrosion.

Whew! Project complete! Poor old Augustus has been through a lot, but I am very pleased (and more than a little relieved!) with how it came out in the end. I can enjoy it now! I'm a little disappointed about having to give it an artificial patina, but hey, better that than to be relegated to the junk box, right? 😉 

And here is the final result:

 Feel free to share your thoughts, good and bad!

 

[mc9]

@CPK
A great result! I myself did the same process last month on an AE, axle from Augustus and Agrippa.
A light blueish cast remains. In the meantime I have ordered verdi care, in the hope that this discoloration can be removed. 
(should be delivered at the end of this month). 

A few more questions, what sulfer substance did you use, and what kind or brand of Renwax do you use? 
I don't know if this last one is available in Belgium.

Edited December 5, 2023 by mc9

[Limes]

Job well done! I see that the colour has become a bit more pale, compared to the earlier colour, but I dont find that a nuisance at all. 

Im saving the description of your process for own use, if you dont mind 🙂 Also, I too am interested to know what you did with the sulfer and how. 

@mc9, you could try renaissance wax, its for sale here in the NL at various shops (furniture, metal detector hobby, etc), so I'm guessing it should be available in Belgium too. Don't buy it outside the EU, you'll pay import tax and high shipping fee. It's a wax that contains microcrystalls, seals of the coin from outside elements and gives it a bit more of a shiny look. There are several topics about it on coin fora, e.g. Cointalk, and not everyone is positive about it. 

[Spaniard]

@CPK

Great result!...Well worth the work involved and agree the remaining detail is really nice...

I'm sure you did bake the coin slightly before adding the renwax?

I actually like how the disfigurement from the previous bd attack adds to the character of the coin..Well done!

[Furryfrog02]

Congrats!
The time and effort were worth it. 
Despite the corrosion on the back of Augustus' head, it is still a very handsome portrait and the coin was definitely worth saving. 

Thanks for sharing!

[CPK]

3 hours ago, mc9 said:

@CPK
A great result! I myself did the same process last month on an AE, axle from Augustus and Agrippa.
A light bluish cast remains. In the meantime I have ordered verdi care, in the hope that this discoloration can be removed. 
(should be delivered at the end of this month). 

A few more questions, what sulfer substance did you use, and what kind or brand of Renwax do you use? 
I don't know if this last one is available in Belgium.

Thanks!

This is the liver of sulphur I used, ordered from Amazon:

Amazon.com: Liver of Sulphur Gel, 1 Ounce Bottle | SOL-610.01 : Arts, Crafts & Sewing

I put perhaps a teaspoon's worth in a cup of warmed water. It works pretty quickly. After the coin is dark enough, remember to rinse it in a baking soda solution to remove and neutralize the sulphur. Just for kicks, I put a modern copper-plated zinc US penny in along with the Augustus coin; the penny darkened quickly, and by the next day had holes eaten in the copper coating.

The Rennaissance wax I used is the branded stuff, also purchased on Amazon:

Amazon.com: Renaissance Wax Polish 65ml : Home & Kitchen

[CPK]

3 hours ago, Limes said:

Job well done! I see that the colour has become a bit more pale, compared to the earlier colour, but I dont find that a nuisance at all. 

Im saving the description of your process for own use, if you dont mind 🙂 Also, I too am interested to know what you did with the sulfer and how. 

@mc9, you could try renaissance wax, its for sale here in the NL at various shops (furniture, metal detector hobby, etc), so I'm guessing it should be available in Belgium too. Don't buy it outside the EU, you'll pay import tax and high shipping fee. It's a wax that contains microcrystalls, seals of the coin from outside elements and gives it a bit more of a shiny look. There are several topics about it on coin fora, e.g. Cointalk, and not everyone is positive about it. 

Thanks! Yes the color is a bit more pale reddish, not quite as warm and golden, but hey you take what you can get. 🙂

[CPK]

3 hours ago, Spaniard said:

@CPK

Great result!...Well worth the work involved and agree the remaining detail is really nice...

I'm sure you did bake the coin slightly before adding the renwax?

I actually like how the disfigurement from the previous bd attack adds to the character of the coin..Well done!

Thank you!

I did bake the coin a bit, BEFORE doing the soak and everything...but no, I didn't do it before applying the wax. 😬 I hope that's okay? I did dry the coin very thoroughly over an hour or so before applying the wax.

Edited to add: one of the reasons I didn't bake the coin again was because the first time it darkened and discolored the coin, which I didn't want happening again just after I had gotten the coin's appearance to my liking.

  

2 hours ago, Furryfrog02 said:

Congrats!
The time and effort were worth it. 
Despite the corrosion on the back of Augustus' head, it is still a very handsome portrait and the coin was definitely worth saving. 

Thanks for sharing!

Thanks! I think the DIVVS AVGVSTVS series featured some of the nicest portraits of Augustus. I'm just glad this one turned out half-decent! 🙂 

 

Edited December 13, 2022 by CPK

[dougsmit]

A question for all people with Bronze Disease survivors:  After how long in remission do you consider it safe to stop making regular check-ups?  That is why they call it 'Coin Cancer'. 

Titus has been in remission since 1988.   

[mc9]

@dougsmit,

Hallo Dougsmit,

With what or how is the coin treated in 1988 ?

Thanks, MC9

[dougsmit]

3 hours ago, mc9 said:

@dougsmit,

Hallo Dougsmit,

With what or how is the coin treated in 1988 ?

Thanks, MC9

I have no idea.  I bought it post treatment.  Then, I believe most treatment was digging away at the metal until you reached solid.  When do you find references to chemical treatments starting to me mentioned? 

[mc9]

I made no reference to any chemical cleaning as far as you are concerned, my question was how the coin was cleaned. 
You have answered this one. ( you have not preserved the piece, someone els did ).