A large copper - how to clean it properly?

[brianc053]

Hi everyone. I went back to the farm again this morning before work and I was lucky enough to locate this large copper with a lot of green patina on it.

Right after digging it I decided to control myself and NOT just wipe off all the dirt, because with past coppers from this location I've lost the green patina - and some of the image from the coin - by cleaning the dirt too aggressively.
At the car I used a toothpick to remove the large amounts of dirt and I gently used a toothbrush to start to clean one side, and I did NOT recognize the image as a US Large Cent - so I immediately stopped any further cleaning. (It may have been Britannia from a KG that I saw, but I'm not sure yet.)
I actually grabbed a handful of mud and put the coin in the mud, and then in this plastic shell that I had in the car, and brought it home.
The coin is still in the mud in that shell.

So - how should I properly clean this coin? What are the steps I should take to try to keep as much of the green patina and as much of the images on both sides as possible?

I'm going to show self-restraint here and try to do this one right.

Thanks in advance for your advice.

- Brian

 

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[Rich in Central PA]

Brian, well since nobody replied I'll take a stab at it. It's a judgement call. Some coppers come out of the ground with a nice green patina which require no cleaning. Some coppers start flaking as soon as it hits the air after being in the ground for 250+ years. It would be best for you to identify the copper first before you take any cleaning action. But if you must clean it, and you want to get all the green off, then a soft bristle toothbrush with drops of dish washing liquid might be your first choice. If you are intent of taking the green off completely, then electrolysis might be your next step, but if you don't have any experience with the latter, then I would hold off, because you might ruin it beyond identification. I'll let somebody else explain that procedure. Good luck............Rich

 

[eman1000]

I would let it dry out and then lightly take the remaining dirt off with a toothpick and leave it. Much more than that and I usually ruin them

They make a special set of pencils that I haven't tried that are supposed to be great, but usually a light toothpick will reveal the details.

 

[Digger RJ]

Nice!!! Hope the detail comes out for Ya!!! Congrats!!!

 

[IDXMonster]

Bench grinder with a wire wheel! Just kidding....the old copper can be tricky, watch the replies closely and be patient above all.

 

[brianc053]

Thanks everyone. I want to try to keep the patina if possible - I love the way it looks.
But it often flakes off, so it sounds like being gentle is key.
I’ve made the mistake of using water and soap and a toothbrush before, and it’s taken the patina - and some of the image/dates - away. That’s want I to avoid this time.

I’ll try letting it dry and using a toothbrush to gently remove the dirt.
I actually have the Andre’s Pencils - in serious about this preservation even if I don’t know how to do it. They’ve been very useful with some other coins. But I need to safely get the dirt off without losing the image/writing first.
Here it is with the case opened up. Looks like it’s 28mm in diameter.

 

[brianc053]

Update 1: here’s my setup for cleaning.
And it looks like removing the mud removed a tiny bit of patina (visible in the middle mud) but didn’t do significant damage.

 

[Tpmetal]

Thanks everyone. I want to try to keep the patina if possible - I love the way it looks.
But it often flakes off, so it sounds like being gentle is key.
I’ve made the mistake of using water and soap and a toothbrush before, and it’s taken the patina - and some of the image/dates - away. That’s want I to avoid this time.

I’ll try letting it dry and using a toothbrush to gently remove the dirt.
I actually have the Andre’s Pencils - in serious about this preservation even if I don’t know how to do it. They’ve been very useful with some other coins. But I need to safely get the dirt off without losing the image/writing first.
Here it is with the case opened up. Looks like it’s 28mm in diameter.
View attachment 1907177

In cases like these I clean under a stero microscope using distilled water and a very very fine abrasive pick like tool( its a 600 grit super fine dremel bit basically, but not used in a dremel, rather a non rotating hand tool). Most people don't like that answer for coppers though( they freak out when i mention using water), takes patience and the right tools and going very very slowly. You get the surface of the coin to hold a bit of the distilled water on top while you work, which helps the dirt float away as you gently work it away with the tool. then once clean to a point i feel i am not taking off patina or i get the right contrast i want, I heat the coin to dry and saturate with renaissance wax while still hot to soak in and help hold the patina together. Other than that your options are let it dry out and go at it with a tooth pick, which I find with the patinas you describe to result it loosing chunks of patina.

 

[brianc053]

Thanks Tpmetal for your thoughts.
Here’s Update 2: I used a toothpick (remove thick dirt) and then Andre’s pencils, and I did not flake away any patina, so what you are seeing is the best the coin can be.
And it’s ugly. I can’t see any writing or images that are clear yet. But I feel confident that I didn’t hurt the coin - nature and 200+ years did this to the coin.
I think we will ID it at some point, but I had hoped there was more of the images/writing and I think it’s gone.

I’m not done yet though, just taking a break.

And I captured 7 min of video of me doing the cleaning so I’ll share that at some point too.

 

[Tpmetal]

Thanks Tpmetal for your thoughts.
Here’s Update 2: I used a toothpick (remove thick dirt) and then Andre’s pencils, and I did not flake away any patina, so what you are seeing is the best the coin can be.
And it’s ugly. I can’t see any writing or images that are clear yet. But I feel confident that I didn’t hurt the coin - nature and 200+ years did this to the coin.
I think we will ID it at some point, but I had hoped there was more of the images/writing and I think it’s gone.

I’m not done yet though, just taking a break.

And I captured 7 min of video of me doing the cleaning so I’ll share that at some point too.

View attachment 1907184View attachment 1907185View attachment 1907186

Some simply can not be saved, but its great practice giving it a try regardless!

 

[brianc053]

Update 3: I see a feature that will hopefully help with identification. (And I hope these updates aren’t annoying).
Does this help anyone with ID? I won’t be able to study coin images until tonight.

 

[Woodsy]

Update 3: I see a feature that will hopefully help with identification. (And I hope these updates aren’t annoying).
Does this help anyone with ID? I won’t be able to study coin images until tonight.
View attachment 1907187
View attachment 1907188

Give them a vinegar bath and brush with a toothbrush. Let them soak for about an hour first.

 

[Fossils]

I would say possibly a draped bust but the orientation seems a bit off. It seems that the bust is right-facing at least.

 

[brianc053]

Update 4: Thanks for the suggestions of a Draped Bust. Here is a side by side with another Draped that came from the same farm.
I can see matches on both sides where I’ve marked arrows.
Now I’m wondering if I should remove ALL the patina (since it isn’t helping and is actually making it harder to ID).

It’s also weird that two different Draped Busts from the same field came out of the ground so different.

 

[Rich in Central PA]

Judging by the comparisons of the obverse in your last 2 pictures, it's looking more like a matron head. I do see the outline of the forehead. Could be a Draped Bust also but I'm leaning towards a Matron Head. Either way, it's corroded badly to be of any value, but its the thrill of the find and identifying it that matters............Rich

 

[Steve in PA]

Definitely a draped bust. I would use the andre's pencils on it. There is enough detail in the base metal that if you can remove the green, you will be able to make it out better.

 

[grasshopper]

Definitely a draped bust. I would use the andre's pencils on it. There is enough detail in the base metal that if you can remove the green, you will be able to make it out better.

agreed

 

[cheffer]

Cool post, love your pics and the discussion, I think you're spot on with a DB

 

[brianc053]

Thanks again everyone.
Here’s another pic after using the Andre’s for a while on it. I think I’ve taken it as far as I can with the Andre’s. The face is pretty clear (1 to 2:00 position) and if I look with a magnifying glass I can see a bit of the neck’s profile (5:00 position) and the back of the head (11:00 position).
I don’t think the date will ever be recoverable.
But Steve in PA do you have suggestions for removing the green? It’s so hard - I used the Andre’s scraper on the reverse in an area where I wouldn’t be upset if I damaged it, and it did nothing to scrape away the green.
That leaves chemicals I guess. But hydrogen peroxide will dry it our and snow pits badly, and vinegar would be worse - right? Other fluids?

I also have “Classic Coin Conditioner” but that’s more of a final coat to make the details pop. It doesn’t do anything to the green hard crust.

 

[Steve in PA]

When I have a coin like that I will rub it aggressively between my finger and thumb using a wet paste of baking soda. I will also use a pencil eraser. The smoother you can get it, the better it will look.