What is the proper way to conserve a copper coin? 0

[dleonard-3]

I've always heard that you should never "clean" a coin, or you will ruin it's collector value.  However, I have also heard of conserving or curating a coin, which isn't considered "cleaning", but simply maintaining and preserving the coin.  The technique is simply to gently remove any debris and gunk which would eventually cause oxidation and corrosion, and apply a very light coat of an inert preservative/protectant.  A clean soft bristle jewelers brush is used to apply the protectant.  I have tried this on several of my Large Cents, with excellent results.  But I would like to discuss proper procedures, as well as any negative effects this might have on the value of my coins.

[physics-fan3.14]

You'll get a lot more responses if you move this to the US Coins forum. 

However, the way you approach conserving a coin depends on what's wrong with it. 

If it is heavily encrusted and porous from long term environmental exposure, you're going to want to remove the crud and stabilize the surfaces. 

If it has verdigris, you'll want to use Verdi-Care, a formula invented by a chemist on CoinTalk known as BadThad. It is quite successful in reversing the chemical reactions. 

If it has PVC, you'll want to use acetone. 

The more damage that has occured, or the stronger the method you use to conserve a coin, the more it will affect the value. As long as there was no permanent underlying damage, something like acetone removal of residue will have no affect on the value. 

[Donnie Camerer]

Can anyone tell me if NGC can remove black spot on copper coins?

[Coinbuf]

2 hours ago, Donnie Camerer said:

Can anyone tell me if NGC can remove black spot on copper coins?

Welcome to the forum, it would have been better for you to have started your own thread instead of posting to this old one.  However the answer to your question is it depends, usually carbon spots cannot be removed as they are imbedded in the metal.  If the black spot is not carbon and instead an organic foreign material then it may be possible to remove it but in most cases it will be obvious that something was removed.  Without a photo of what you are talking about I cannot even begin to decide which you have, and even with a photo it may be difficult to be sure.  If you want a concrete answer send it to the NGC conservation service, they will evaluate the coin and decide if anything can be done or not.