Author Topic: Help in cleaning coins using olive oil  (Read 1489 times)

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Offline Gavema

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Help in cleaning coins using olive oil
« on: June 30, 2015, 12:22:57 PM »
I have recently bought a few copper coins. Some of them are very dark in color making it difficult to read the inscription in them.

I read that putting the coins in olive oil will cleanse them, so that they become brighter making it easy to read them. In that case, how long should one keep the coin in olive oil? Is there any other alternative, which does not harm/damage the coin?

Offline Figleaf

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Re: Help in cleaning coins using olive oil
« Reply #1 on: June 30, 2015, 01:35:41 PM »
It's the other way around. Olive oil will make them darker. Use a soft eraser to make them lighter. Be very careful not to overdo it, or ugly red copper will come through.

Peter
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Offline Gavema

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Re: Help in cleaning coins using olive oil
« Reply #2 on: June 30, 2015, 03:35:57 PM »
Thanks a lot, Peter.

But how about cleaning with baby soap? Will it harm the coin?

Offline Figleaf

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Re: Help in cleaning coins using olive oil
« Reply #3 on: June 30, 2015, 05:52:58 PM »
No problem. Soap will solve fatty substances, not copper. If the dark colour is caused by dirt, this will help. It won't hurt. Make sure you flush and dry the coin well afterwards.

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

Offline Gavema

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Re: Help in cleaning coins using olive oil
« Reply #4 on: July 01, 2015, 06:02:11 AM »
Thank you, Peter.

Offline natko

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Re: Help in cleaning coins using olive oil
« Reply #5 on: July 01, 2015, 12:39:33 PM »
When I was cleaning my small hoard of Romans, I was advised to finish them just shortly rubbing into a bit oily fingers. It would make them more appealing and I guess the patina, which will be darker indeed, would be better preserved.

Alsthough I didn't get the results it looked a bit better (I never bought small brass brushes for finishing the surface, it was not smooth under 10x magnif.)

I have also read online that olive oil is used to soak them for a week or so during cleaning. I didn't try, but experienced people told me it's a big no-no, as bronzes often crack when held so long in the olive oil.

Offline Figleaf

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Re: Help in cleaning coins using olive oil
« Reply #6 on: July 01, 2015, 01:24:24 PM »
FWIW, I once forgot a small batch of Chinese cash coins in olive oil. Over a year later, no damage had been done and the coins looked great. Elsewhere, I gave a similar recipe for smoothening the surface with an olive oil carbon mixture and added that it would be honest to wash it off before selling.

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

Offline Pellinore

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Re: Help in cleaning coins using olive oil
« Reply #7 on: February 03, 2018, 01:28:01 AM »
I put some coins in good quality olive oil for a month: a large Provincial bronze with grey stains, a few severely cleaned Elymais drachms and a thin Sogdian coin. It is time to remove them, I think. How should I proceed: wash with soap, then dry? Just that?

-- Paul

Offline Kopper Ken

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Re: Help in cleaning coins using olive oil
« Reply #8 on: February 03, 2018, 01:41:13 AM »
I just leave mine with the oil on.  I do blot them to remove the excess.  Use a cotton swab. :like:

KK

Offline Arminius

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Re: Help in cleaning coins using olive oil
« Reply #9 on: February 03, 2018, 04:05:38 PM »
Olive oil may be fine if it contains no chlorides and acids. But that´s nearly impossible for a natural grown and usually handled vegetable product.

So i prefer weapons oil and hope the recommended manufacturer knows what the impurities are to avoid on metal surfaces.

Offline Figleaf

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Re: Help in cleaning coins using olive oil
« Reply #10 on: February 03, 2018, 08:45:31 PM »
Arminius is right. Olive oil is acidic, but not very much. In fact, acidity is how olive oil is rated from worst (Spanish) to best (Greek). First pressing is less acidic than subsequent pressing. Beware, companies from one country may source their oil in another country, so e.g. olive oil from an Italian company may be Spanish.

It's best to wash off the oil with lukewarm water. Soapy water will work even better as soap dissolves fat (only on the outside, bathing is no way to lose weight :)). Neutralise with clean water and dry well afterwards. If you really want to coat the coin, use Ren wax, not olive oil.

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