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 Replies: 21 / Views: 3,680 |
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New Member
United States
7 Posts |
Hi folks. I recently bought a 1-oz. copper challenge coin finished in a black patina (paid $20 on Amazon). A relative who thought they were doing me a favor cleaned it. I want to restore the black patina. What kind of business can do that? Jewelry repair? Coin repair? I've tried the boiled-egg oxidation procedure, but it only darkened it a little, with uneven results. If you have any recommendations, I'd be much obliged. |
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Pillar of the Community
United States
4415 Posts |
Welcome to the CCF, Dave. Like most serious collectors, I'm averse to cleaning coins. Regardless, circumstances arise at times that do warrant such measures. To each his own.
As a lover of early coppers, I've at times retoned pieces that had been cleaned by a former owner. I've had the best, overall success, using a pasty mix of sublimed sulfur and vaseline. It can be applied with a soft Q-tip and gently massaged into the surfaces. The longer it sits, the darker the coin will become. Generally, after ten minutes, I will use a soft Kleenex to largely remove the paste. Splotchy results can and do result at times. I simply then repeat the process, concentrating on the lighter areas. This mix is likened to Deller's Darkener for coins.
Try experimenting on some common coins before playing with your prized piece ... Good luck !!
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New Member
 United States
7 Posts |
Thanks, EG, I appreciate the reply. I'll give this a try.
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Pillar of the Community
United States
4415 Posts |
FYI, Dave, pics will always draw more responses on the CCF. In your case, before and after pics would be welcomed, I'm sure. Do let us know how you fare on this experiment.
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Rest in Peace
United States
17900 Posts |
If you loved the item you might simply want to buy another if that is a option.
As mentioned, photos would help us help you.
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New Member
United States
7 Posts |
Point taken, gentlemen. The original purchase was the dark-tinted coin. Amazon also sells a polished version, which is what mine ended up as. Just want to bring mine back to the original dark tint. It wouldn't kill me to buy another, but it's become a personal battle.   |
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Rest in Peace
United States
17900 Posts |
I really hate to say this but black paint and rub lightly on gritty sandpaper to turn the top parts back to copper.
Either that or contact the mint that made them and see if they will clue you in on how the finishing is done.
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Pillar of the Community
United States
1326 Posts |
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New Member
United States
7 Posts |
I'm not above going the paint route. :-) Will look into the original process, and maybe using varnish as well. Thank you for the tips!
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Pillar of the Community
 Canada
9862 Posts |
Liver Of Sulfur should do the trick.
Google it.
"Dipping" is not considered cleaning...
-from PCGS website
Edited by DBM
11/25/2016 9:54 pm
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CCF Master Historian of USA Commemoratives
 United States
12253 Posts |
The "black patina" medal appears to be what is commonly referred to as an "antiqued" or "oxidized" medal. This involves submersing a just-struck brilliant finish medal in a solution until it is completely coated (the time the piece is submersed in the solution varies).
Once the medal is taken out of the solution, the high points are buffed to remove the darkening solution. The resulting effect is light-colored relief elements and dark-colored fields.
Without knowing the "recipe" for the darkening solution that was originally used and the manufacturer's process for soaking and buffing the high points, it is very unlikely that you would be able to duplicate the medal's original appearance. Also, the fact that your medal was cleaned likely resulted in its surfaces being impaired/damaged (i.e., scratched) to the point that even if the piece was subjected to the original darkening process, it's likely it would not be possible to return it to its original state.
For $20, I would just purchase another and keep it away from "helpful" relatives.
Collecting history one coin or medal at a time! (c) commems. All rights reserved.
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Moderator
Australia
16806 Posts |
There is a commercially available compound: "Deller's Darkener". It is specifically designed to do exactly what you are asking for, and some variation on it is almost certainly what the mint in question would have used. It basically does the same thing as liver-of-sulfur, rotten-eggs, sodium-sulfide-and-acid, etc all do: cause a reaction with the metal, forming copper sulfide.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
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New Member
Belarus
30 Posts |
I tried to reproduce. I have to take ordinary copper coin and sulfuric ointment, which is bought in a pharmacy. I sealed half of the coin for comparison. Apply the ointment and rubbed his fingers. Coin became black after 20 seconds. I rubbed the coin tough suede and got the result. I did it quickly and inaccurately. Just experiment.   Edited by _w_
11/26/2016 11:01 am
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Pillar of the Community
United States
4211 Posts |
 When in the jewelry business we used liver of sulfur to antique silver but I have never used it on copper. Might get some and try it on some pre 1982 cents and see if it works. |
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New Member
United States
7 Posts |
You guys are great. _w_, thanks for the experiment. Commems, I figure nothing to lose trying it myself...can always buy another. I still can't believe someone would clean/polish a coin belonging to someone else without asking. <sigh>
DBM, I've got some LOS on order. Will post pics when done.
And now for an ignorant question. What are 1982-current pennies, if not copper?
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CCF Master Historian of USA Commemoratives
United States
12253 Posts |
Quote:
What are 1982-current pennies, if not copper? The current cent is copper-plated zinc. Only 2.5% of the cent's weight is copper, the rest is zinc. Collecting history one coin or medal at a time! (c) commems. All rights reserved.
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Replies: 21 / Views: 3,680 |
Posted 11/24/2016 5:53 pm
