VerdiChem Success on High Grade Ancient Coin!

Recently I purchased a high grade Justinian I 40 Numis struck in AD 541. The coin in the auction pictures looked great but in hand I recognized a growing evil. Verdigris!! I nearly died. This was active light green powdery oxidation. This would surely be the end of the coin. Untreated this large coin would have gotten smaller and smaller and eventually turned into a flaky, green and indistinguishable piece of worthless metal.
As a chemist by trade and a hardcore ancient coin collector, I felt I understood enough of the process to successfully stop and reverse the process, without damaging the relic.
The coin flaunts a very even chocolate patina and a strong strike. It presents clear and defined fields over a large surface area. A lot of flat area that if damaged would hurt the coins appeal.

I felt as though spot treatment would not be enough considering concentration of the Verdigris along rim edge which covered a solid third of the coin. I have had the coin for a little over a week and have been able to measure the the growth of the Verdigris and it was a rapid growth increasing in surface area approx 20 percent in that time. A rate that I have never seen on any of my coins. I knew I would have to act fast, in order to conserve the relic.

I have several of the popular chemicals at my disposal. I have reagent grade Acetone, deionized water and Xylene at my disposal. So I had several options.None of these seemed appropriate. Water or Acetone would be unreactive in this case and I suspect that the Xylene would or could dissolve unknown organic components of the patina. I needed to preserve patina but I needed something tough acting.

This required some serious thought, at the risk of destroying a 1500 year old historical masterpiece. I used all the research tools available to me, here on the CCF and neighboring CoinTalk. I spoke to a collector friend of mine who is also a physicist, (really). He inspected my coin I explained to him the situation. Immediately he recommended Verdi-gone and Verdi-Care now called Verdi-chem with the ReAct2 sealer additive. It was actually pioneered by a member here.(He may step forward and make comment if he likes.)I thoroughly read his instructions and MSDS and was impressed with his "typical results" page.

In a nutshell I deviated from his instruction in that I did not use a toothpick (provided). I used a galvanized screw to abrade the afflicted areas, using very small light circular motions under magnification. The toothpick did nothing but take some "dust" off. I was very careful not to make contact between the screw and the "good" portions and only with the most deeply affected area, making sure to not touch the patina for fear of damage. I submerged in entire coin in a screw tight glass jar with slight sloshing for 1 hour. I removed the coin and blotted dry with a paper towel, and I applied some of the product to a cotton swab and "worked" the areas gently in a circular motion. I carefully used the screw again and repeated the process, 3 times.

After 3 hours of air drying, I was presented with this handsome piece of Ancient Chocolate.



The mint mark - where the "I" was afflicted...



The before and after....the lighting is slightly different, there is no difference in the brightness of the coin.


This is the stuff you need to buy if you have Verdigris you need to get rid of. Soft and gentle on patinas really effective on Verdigris oxidation.



The guy who invented this deserves the Nobel prize.

 

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Ive used it too and its been great.

 

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I have a bottle on my nightstand. Unfortunately the bottle leaked, but thankfully it was still in the plastic baggy. I will be ordering another bottle shortly. It leaking was my fault, btw.

What? Others don't spend their evening before sleep treating BD?

Btw, I will name the creator. Its Badthad. Anyone needing this great product, but it from him here. I believe he gives a slightly better deal to CT members.

 

Aww I paid top dollar $20 off ebay. Oh well. I know you got to make the difference that ebay soaks up and paypal takes.

 

Great work Anoob, i think you should look at each of your coins often. i have found coins that didn't have at one time now have a little green dust. i drop in olive oil and brush them off wash in warm soapy water and pat dry. You should also put them in a new flip.

Just to understand your process..you soaked it for an hour, pat dry, then picked at the bd area, you did this three times...

 

Eng- Correct, I soaked for an hour, pat dry and picked at it. Soaked for an hour, pat dry and picked, soaked for an hour and patted dry. Total of 3 hours of soaking. I timed each of the intervals. :58 min, :56 min, and 63min.

 

Btw, longer soakings do not hurt. Sometimes I just put it on the coin and let it sit overnight or longer. It never has damaged a patina in my experience.

 

yea I just didn't want to take the risk of making it "brassy."

Do you know if this stuff has a shelf life?
Does it rub off over time? I "play" with my coins frequently.

The next one will be my Elam Tetradrachm, thats got some green specks on it but they are not spreading.

If I reuse the fluid will it redeposit the removed material on another coin?

 

Thad would be the one to answer your questions, but I never reuse the liquid. I do not want to risk spreading BD between coins. Even the flip a coin was in gets tossed if it had BD. I simply let the liquid sit there and do its work, and remove if some liquid is still on the coin. If "cured", then I put on Renwax to try to seal it, and into a new flip. I then put my brass tool, (if used), in some Verdicare as well to try to prevent "infection" on other coins.

Like I said though, hopefully Badthat will post here. He is the expert on it of course.

 

I hope he chimes in, I would love to publicly acknowledge this guy's genius.

 

Does Badthat have a website, contact...

 

I am sure he does but here is a cheaper place to get the juice.

http://www.wizardcoinsupply.com/products/verdi-care.html

 

Thanks Master Noob...

 

I'm pretty sure that Wizard is Thad's primary distributor. The eBay account selling it is Thad's, I believe, but Wizard is cheaper. Oh, and Thad includes a couple toothpicks and instructions/MSDS. Wizard includes nothing.

 

Great thread describing the benefit(s) and application of Verdi-Chem.

This coin with bronze disease has a real history of disease. It was minted during the Plague that killed almost everyone back in 541. 1500 years later, this coin was sick & Dr. Noob has cured it. :thumb:

I trust that Dr. Noob washed his hands after his careful handling of this plague coin.

 

Thanks for sharing and the kind words!

First off, the product's name is VERDI-CARE™.

Sure is a nice coin, looks like you did a good job at the conservation. I've studied the methods used by ancient collectors in depth. Ancient coins can be quite difficult to conserve and they usually require methods that would make a modern collector (me) cringe. It's good that you picked a more conservative method for such a beautiful coin! The only part that scares me was the screw, I don't recommend that because it could have caused serious damage. Always stick with soft implements. The hardest thing I'd ever recommend is a thorn....and those are REALLY hard on my scale.

Only two things I can suggest for future conservation.

1) Verdigris and it's feed materials are acidic. The corrosion contains both organic and inorganic acids. It's good to soak for at least a few hours in distilled water with a tiny bit of baking soda dissolved in. The lightly basic wash will help to neutralize the acids because, as you can image, they play a critical role in the self-propagation of verdigris. People often use the term "bronze disease" (which I hate) to describe hydrochloric acid based-verdigris (copper chloride). Neutralization of HCl is important to older, heavier verdigris. If you want to be ultra conservative, you can just soak in distilled water with the hopes that some of the acids will solubilize. However, most distilled/deionized waters tend to be slightly acidic which is why I recommend tweaking the pH up a hair with baking soda.

2) Always physically work a coin while under fluid. That way you're assured a well lubricated surface which helps prevent the removal of patina. I just use a lab breaker with the coin and just enough fluid to cover it. Start with only up and down motions, let it sit for 10 minutes, come back and try up and down again. Sometimes gunk will come right off after a few tries. If that isn't working, then start with a slight rubbing action...using very light pressure....barely touching the problem. Again, let it sit and try again. Keep repeating this and only increase your implement pressure slowly. If you're not making progress, sometimes it's best to let it soak for 24 hours. After that, start over with the tapping motion and work your way up.

 

so what was the bottle that the OP posted a pic of, that said verdichem?

 

That's my company name.

 

It's the same bottle. If the bottle were rotated slightly, the name "Verdi-Care" is on the right end of the same label.

 

OK, I didn't recognize it because I'm still working on a bottle that had the plain white label.