Proper Cleaning of coins found via metal detecting.

[Rainaer-migration]

My father is an avid metal detector junkie and has many finds from various places.. many of the coins he digs up have mineral deposits from being on the bottom of a lake for 50+ years or in the earth for as long.. My question is a general question on how to properly clean coins of this age and condition so that the true faces, dates, and values can be found without doing more damage to the coin than if it were left uncleaned?

 

Thanks.

[RMontgomery]

This question actually falls under the Numismatic Conservation Service and this would be the company I would recommend contacting to properly answer your question.

 

My own personal experience is that coins found in the ground or in the water generally have permanent damage such as corrosion or environmental damage. Corrosion is obvious enough in that the coin's surface will be etched or pitted from the elements. Environmental damage may be successfully removed, yet there may be permanent pitting on the surface once the surfaces have been revealed. This would be especially true of copper and nickel coinage. Silver would be more impervious to environmental damage, although permanent staining of the surfaces could result. Gold, being the toughest of the metals, would have the highest degree of success against environmental damage.

 

Traditional "cleaning" methods, however, are frowned upon by numismatists and that is why contacting the Numismatic Conservation Service will be a good first step in determining your next move with these coins.

 

They can be reached at 1-866-NCS-COIN which is a toll free number.

 

Rick

[spy88]

Rainaer, as I also am into metal detecting for coins, I would tell you this.

 

There are two and only two reasons for you to clean your coins.

1) To attribute them and 2) To see if they CAN be attributed.

BUT YOU DO NOT WANT BARE METAL UNLESS IT HAPPENS FROM EITHER PROCESS BELOW.

 

If you can do the first without cleaning, and the coin may have value, send in for further cleaning. If you cannot attribute, there are only two methods I would suggest you try.

1) Soak in DISTILLED water in sealable container for 3-4 days. If this doesn't work well enough, hold container of coins under faucet to flush out the dirt that did come off (so you do not have to handle them) and re-soak in distilled water for another 3-4 days. Flush out again. If this still does not allow you to identify the coin---

2) Soak in olive oil for anywhere from a week to several months. This is by far, the slowest method but also the next safest. When the oil turns dirty or loose dirt starts to accumulate, put in a small amount of soft soap (NOT DISH SOAP!)and hold under faucet to flush. Do this 3-5 times to remove most/all oil and dirt. Examine coins. As soon as you can identify, remove from oil. DRY THOROUGHLY with a hair drying heat gun. Those that are still unrecognizeable, repeat oil soak. If twice isn't enough, send them in for pro cleaning.

These two methods are the safest and most widely accepted forms of cleaning old (ancient) coins and should work for your 50 year olds.

DO NOT USE A BRUSH OF ANY KIND AT ANY POINT!!!

 

There are those who will say not to do anything to them and send them all in, but I think this would be a waste of the professionals time and your money if the coin(s) were so worn or so commonplace as to be of melt value only. And from personal experience, this will be the rule rather then the exception.

IMHO

David