Help a complete novice clean his coin!

You seem to be the most chemically astute person on the boards, desertgem. I'll give olive oil and soap a chance, and switch to verdicare if it doesn't work. I may be stuck with a stubborn patina, but that's acceptable as the coin is 2000 years old and the outlay was minimal. I'm looking at the project as an experiment, succeed or fail.

 

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I read some where (years ago) about somebody using tooth paste on coins brought up from a ship wreck. As I recall, he liberally applied the paste to both sides of the coin and let it sit overnight, then, in the morning thoroughly rinsed the coins off with water. If I remember correctly, the results were adequate, but remember, the person who did this was already dealing with a damaged coin.

 

Toothpaste sounds one step harsher than olive oil and verdicare, but if those don't work, I'll give it a whirl.

 

Just be careful John. Experiment with something that is not dear to you........

 

Yes indeed. I'll try it first on some uncleaned ancients that are obviously culls.

 

A few months in olive oil ( change occasionally) shouldn't hurt at all as the patina is over the metal, and there may be small cracks which would allow oil to get under the edges. Since it is an experiment, after a few weeks try some thermal cracking by moving it into a freezer for a few hours and then quickly into warm oil ( such as warmed massage oil temperature, not deep frying ) Since the metal and the overlying patina have different expansion coefficients, it might help.

I like desert patina on ancient coins, and think it is a preservative as once the metal is covered by a thin layer, the surface of the coin is protected from atmospheric reactants. Here are 2 references, one easy read and one much harder.
I became interested in silicates due to "Water glass" used in lapidary work and pottery glazes for a previous hobby.

general reading : http://www.asdn.net/asdn/chemistry/silicates.shtml

much harder ( .pdf): http://www.ceramics-silikaty.cz/2005/pdf/2005_04_287.pdf

 

Thank you very much desertgem!

 

http://www.celatorsart.com/cleaning.html

Page #1 is fun. Subsequent pages are more enlightening. Please let me know what you think of this link.

 

There seem to be some good tips in there, thank you! I'll try a combination of things that everyone's suggested. Perhaps I should get a lot of uncleaned coins for practice before the Nabatean arrives - they tell me it takes at least 3 weeks for mail to get to the US from UAE.