How to properly clean up a valuable old copper coin?

[TrpnBils]

I'll keep this short without the back story because I'm going to post a bunch of pictures in Today's Finds later on, but in the meantime...

I found a large cent today that, according to the Red Book, should pull over $1200 in AG condition. Right now it's still got lots of dirt in the crevices and a gentle cleaning with warm water and a toothbrush isn't doing much for that. What's the "proper" way to clean up copper like this? Normally I'd throw it in some peroxide or mineral oil but I've never in my life dug anything worth even close to this valuable so I don't want to make it worse. Is it still safe to go to the water/toothpick route?

I'm not sure if I'd eventually sell it or not, so I mainly just want to get it cleaned up for some pictures...I'd like to do it carefully though in case I do send it in to get graded or something.

 

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[RobRieman]

Some pics might help to figure the best way to clean. Coppers typically do not like water or brushing and sometimes the only detail left is in the patina.

 

[TrpnBils]

Trying to get some together now - it definitely looks better in person than in the pictures though!

 

[TrpnBils]

These pictures do not do this coin justice at all... I couldn't get the camera to capture the COIN instead of the DIRT! In the picture the last 9 is barely visible but it's plain as day in front of me (although I can't tell if it's the 1799 or 1779/8 variety...even looking in the Red Book at their pictures I can't see a difference)

 

[relicmeister]

TrpnBils
You will hear many methods of cleaning old copper coins, but who determines the proper method?
When I find an old copper coin I am afraid of injuring with any cleaning attempt, I do the following ( this is not a recommendation )

I take a piece of spongy urathane (the cabinet liner stuff) and place on it a piece of well-worn scotchbrite (like one used to scrub dishes for a longt time)
I soak it with olive oil and then I rub the coin on it turning it and pressing it all around, and then rubbing it clean with white cotton cloth. This will remove crud and
dark green patina, but with each rubbing and cloth wiping, more and more detail emerges. I also use my fingernails to remove stubborn deposits. When i get to the
point where I don't see any improvement on both sides,I give it a final wiping after I apply some chapstick or lard.
This technique has worked best for me and the coin never comes into contact with water or any other liquid or chemical besides those mentioned. I developed the method myself after nearly destroying several nice coins that could have been saved this way.

 

[TrpnBils]

TrpnBils
You will hear many methods of cleaning old copper coins, but who determines the proper method?
When I find an old copper coin I am afraid of injuring with any cleaning attempt, I do the following ( this is not a recommendation )

I take a piece of spongy urathane (the cabinet liner stuff) and place on it a piece of well-worn scotchbrite (like one used to scrub dishes for a longt time)
I soak it with olive oil and then I rub the coin on it turning it and pressing it all around, and then rubbing it clean with white cotton cloth. This will remove crud and
dark green patina, but with each rubbing and cloth wiping, more and more detail emerges. I also use my fingernails to remove stubborn deposits. When i get to the
point where I don't see any improvement on both sides,I give it a final wiping after I apply some chapstick or lard.
This technique has worked best for me and the coin never comes into contact with water or any other liquid or chemical besides those mentioned. I developed the method myself after nearly destroying several nice coins that could have been saved this way.

Just to clarify, you're actually rubbing the coin with the urethane, not the scotch brite, right?