A different question. I have been collecting 17th C to 20th C farthings since the day at school when I won a 1/- (one shilling) bet from my friends, who took their time to pay me. The reason? They paid me with 48 farthings, which were then still legal tender but which were no longer minted and rarely seen in circulation. OK, my problem: I recently bought a 19th Century farthing on line at a reasonable price for its condition, but to my horror, when it arrived I found that it had been cleaned with metal polish before posting it to me. I had a few strong words with the seller but since I needed the date I got him to agree to a hefty refund, but now I want to know if there is a simple way to undo the damage, darken the coin if not restore its patina. I have tried, with modern coins various measures - eggs, ammonia etc, but the results are totally unsatiafactory. Do memebers have any suggestions?
Sadly there is no way to undo the damage done. Once it's been cleaned the only possible "solution" is to circulate the coin until all areas damaged have been worn down. You might be able to improve the eye appeal by letting it re-tone in an album or paper flip, but I wouldn't use chemicals, eggs, potatoes, etc...
Liver of Sulphur mixed with water will instantly darken a coin. You'll want to experiment first with some other coins to get a feel for how strong to mix the solution and how long to leave the coin in it. Rinse with water when finished.
The sulphur trick may work. I have also found applying a thin coat of vegetable oil and then leaving the coin on a sunny window ledge will gradually darken the tone. It may take weeks or even months but at least you can pull it out when you are happy with the result. Once done, give it a quick wash in Acetone to remove any remaining oil.
I agree with The Meat man on his suggestion. Liver of sulphur may be found at most drugstores. A copper coin cleaned with metal polish could have left a protective coat on it. Your coin may have to be recleaned to allow the sulphur to react with bare metal. A dip in a mild acid such as diluted vinegar may prove necassary for retoning to work. Again, use other coins as experiments until you get a feel for what may work.
Yes sulpher powder works, I've done it. The longer you leave it in the powder the darker it will go, so just 10 minutes to start with. Or Put it in a brown paper bag alongside a banana skin, seal the bag and wait 24 hours.
I used liver of sulphur when I was a jeweler. Would mix it with a little water to make a paste and brush into the places where I wanted a dark surface. Just be aware that it smells like rotten eggs and working with it outdoors or with a good ventilation fan is highly advised.
These solutions sound horrible. Just my opinion but I’ve gotta say it. Best wishes on whatever you do.
I have about a dozen or so Columbian halves from 1892-3 that I purchased for melt value in the early 1990s because the person selling them to the dealer had spiffied them up with silver polish before selling them. I put them on top of the ranch gate and let them sit there for several years in the hot summer sun and they nicely darkened again.
Search the web for “Dillers Coin Darkener” or Deller’s Darkener. The name seems to vary, but the compound is meant to darken cleaned copper.
