Author Topic: Coin Cleaning - General Comments  (Read 3067 times)

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Offline bruce61813

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Coin Cleaning - General Comments
« on: March 29, 2007, 03:13:40 AM »
  There are many ways and reasons to clean coins. Recently, I acquired some 'uncleaned moderns', they were probably from detector finds. There was one that was a solid lump of copper oxide and clay. In that condition, there was nothing to loose, you will see two sets of pictures, the first is the coin after cleaning. It was identifiable, a Ferdinand I from Hungary,  a dinar.  I had no idea as to what it was, and it appeared to be copper or bronze, and a 'hammered type' coin. with some help, i did identify it, but was surprised to find that it was supposed to be silver. Time and the local soil chemistry had dissolved the sliver. I have a three of these from different years that are in great shape. even with the silver gone, the coin, though brittle and very fragile, still has most of it's detail.

  Okay, enough of the boring talk. The relatively modern coins from the 1500's onwad should not be green, if they are copper or bronze. I do not advicate the use of polish, as it is abrasive, but sometimes the coins need to be cleaned. Green, as in copper oxide, even appears on silver, as copper is added to the silver to harden the alloy. Some paste waxes will remove copper oxide without apparent change to the coloration of the coin. I often use REN wax, and it removes old finger oils and dirt from the coin surfaces without change the tone, even on silver.

Bruce
« Last Edit: March 29, 2007, 03:15:45 AM by bruce61813 »

Offline meirs

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Re: Coin Cleaning - General Comments
« Reply #1 on: March 29, 2007, 08:12:51 PM »
Hi Bruce,
Thank you for addressing one of the topics that puzzles me a lot.
What is REN wax where can I get one to test on coins?

Offline bruce61813

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Re: Coin Cleaning - General Comments
« Reply #2 on: March 29, 2007, 10:12:10 PM »
Hi Bruce,
Thank you for addressing one of the topics that puzzles me a lot.
What is REN wax where can I get one to test on coins?

I should have been more specific, but sometimes being vague brings out questions. REN wax is a clear, microcrystalline wax, it is made in the UK, and it's full name is Renaissance Wax. It comes is different sized containers, but a little of it goes a very lond way, so a little will last a very long time. Here is a link that will tell you about it http://www.conservationresources.com/Main/section_39/section39_08.htm, you should be able to obtain it in Europe. I normally take a small amount and rub the coin with it. It melts easily, and as you rub it in the old surface grease and dirt will be loosened, then I wipe the coin with a soft cotton cloth. There is no need for hard buffing.

  This will not work on dirt or clay coated coins or medals. Those should be treated differently.

Bruce

Offline Figleaf

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Re: Coin Cleaning - General Comments
« Reply #3 on: March 30, 2007, 12:06:54 AM »
Coins dating from before the 17th century (and even many later coins) are difficult to clean, because of their low silver content. If they were buried in slightly acid ground, the copper may have solved partially, while much of the silver is still intact. I have seen metal detector finds where the coin was half its original weight. To clean those takes experience and luck, because the coins are brittle.

- Start with soaking in mineral water and working at the dirt with a wooden toothpick.
- Next, try soaking in olive oil and the toothpick.
- If the coin is still unreadable, try putting it in boiling water, followed immediately by a bath in cold water
- Electrolysis is your next step, but that takes some setting up and careful watching.
- In desparate cases only, put in water with some drops of lemon juice added. This will solve silver, so stay with the coin, take it out and rinse with plenty of water to remove lemon acid as soon as you're happy with the results.

Peter
An unidentified coin is a piece of metal. An identified coin is a piece of history.

Offline Overlord

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Re: Coin Cleaning - General Comments
« Reply #4 on: July 13, 2016, 03:01:04 PM »
I recently acquired some Renaissance Wax for preserving a carbon steel replica sword and was wondering if it could be used on coins. Will give it a shot and post the results.

Offline Levantiner

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Re: Coin Cleaning - General Comments
« Reply #5 on: July 16, 2016, 09:34:34 AM »
I recently acquired some Renaissance Wax for preserving a carbon steel replica sword and was wondering if it could be used on coins. Will give it a shot and post the results.

I understand that for ancients and Byzantine coins it is one of the safest things to use.  It is PH neutral and is easily removed.