# Coin bending



## Joe S. (May 22, 2013)

After a bit of trial and error, I finially found a way to thin and bend coins that will be useful after a bit of practice. My only roadblock is the burnt black stuff left on the coin after being thinned. I tried a crude method of buffing (I'm a total amateur at buffing and don't have a decent buffing system yet) and it got some of it off, but began to wear down the details of the coin. Any ideas on how to deal with this? The coin pictured is a copper 1981 penny from my pocket, I didn't pay attention to how it was oriented, I just bent it.


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## Sylvanite (May 22, 2013)

Nitric acid?


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## Joe S. (May 22, 2013)

interesting idea, I wonder if that would tone the coin...


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## Nellieteach (May 22, 2013)

How about a pickle solution to remove the CuO like used when annealing copper when making jewelry? Either a home made saturated solution of salt and vinegar that is warmed or a purchased pickle from a jewelry making supply company. If the black is from annealing the coin then a pickle should remove it.


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## Kenny Durrant (May 22, 2013)

I'm curious to how you thined the coin. I use a dremel tool and do it all by hand therefore I can go a slow speed and stop when it gets too hot. I have only done quarters and one dime so cleaning them up was easy with the dremel. I also collect coins and a friend of mine had some acid and we dipped a penny and it cleaned it up but also turned it pink. Didn't like that at all so try that on a coin before doing any other work to it. Good luck.


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## Joe S. (May 22, 2013)

I used a belt sander, a penny will fit snugly into a 3/4" indent in scrap wood made by a fornster bit. Still looking into doing the same thing with nickels. How does the Dremel work? I tried it with one of the grinding stones and it seemed like it would take days to do.


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## Erik831 (May 22, 2013)

Simple Why don't you thin it from the back that won't show unless I'm missing something here??


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## theidlemind (May 22, 2013)

I use a spray bottle of water to keep the coin cool. Go slow, keep the coin cool and there will be no black stuff to remove (other than the normal grime). 
Here is a buffalo that I did last weekend.  I left the patina on it, very little cleaning was done on it.


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## keithlong (May 22, 2013)

Brasso will work well on cleaning the copper as well as brass.


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## Seer (May 22, 2013)

Believe it or not toilet bowl cleaners will take the tarnish off of a coin


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## Don Gaiser (May 22, 2013)

Soaking it in Coka-Cola is surprisingly effective... just don't leave it in too long.


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## Kenny Durrant (May 22, 2013)

I use the abrasive disc with the dremel tool not the grinding stones. When you get to the copper layer it will clog the stone. Like I said earlier I've only done quarters, clad coins not silver. That way I know to stop when I get to the outer layer of silver. When I first see the silver I take two sided tape and tape the coin to my finger a slowly sand until I get a smooth even finish. Don't sand too fast because it still gets hot and imagine that taped to your finger. It will leave a mark. I can do the Texas map and star start to finish in about 30 min. If I do the whole quarter it takes 3 hours including the scroll saw work.


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## dogcatcher (May 22, 2013)

Joe S. said:


> I used a belt sander, a penny will fit snugly into a 3/4" indent in scrap wood made by a fornster bit. Still looking into doing the same thing with nickels. How does the Dremel work? I tried it with one of the grinding stones and it seemed like it would take days to do.



If you take your holder and split it about 2" up with a bandsaw, you can drill a cross hole and with a bolt tighten up the saw kerf and it will clamp onto the penny.   This will also work with other coins when the drill bit is slightly larger than the diameter of the coin.  On some you will need to drill and clamp with 2 drilled holes and bolts to get it to work.  There is a machinist term for the clamping action, but right now it escapes me.


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## Marc (May 22, 2013)

Interesting idea.  I think Eric831's comment about thinning from the back makes sense.  I did just come across an Indian Head Nickel with a date so worn you can only just make out the 28 of 1928.  The 19 is all worn off.

What do you do to keep the nickel level with the rest of the blank?


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## AnachitlPut (May 22, 2013)

Coke a cola works great


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## Joe S. (May 22, 2013)

Erik831 said:


> Simple Why don't you thin it from the back that won't show unless I'm missing something here??



Is there even a way to do it from the front? The grime appears after thinning the coin from the back.

Coke sounds like an easy way to loosen up the grime, I'll give it a shot!

Thanks to everyone who replied!


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## 76winger (May 22, 2013)

Joe S. said:


> Erik831 said:
> 
> 
> > Simple Why don't you thin it from the back that won't show unless I'm missing something here??
> ...



The acid in the coke removes the tarnish really well, would be interesting to see how well it works for the baked on crude you've got. Maybe and initial cleaning before sanding down would help too.


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## SnowLeopard_2001 (May 22, 2013)

You need to be aware that the composition of coins have changed over the years. For instance, since 1982, the penny is copper-plated zinc (97.5 percent zinc and 2.5 percent copper). So the technique that worked on a penny in your pocket, probably will not work on your granddad's penny.


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## Joe S. (May 23, 2013)

Marc said:


> Interesting idea.  I think Eric831's comment about thinning from the back makes sense.  I did just come across an Indian Head Nickel with a date so worn you can only just make out the 28 of 1928.  The 19 is all worn off.
> 
> What do you do to keep the nickel level with the rest of the blank?



No special method yet... Just be careful.


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## Joe S. (May 23, 2013)

Got out to the shop a tried it on a nickel, the Dremel worked out great for thinning, and I used a horsehair-like brush attachment to clean off the grime. Turned out good and I might get one castable on the next few try's!


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## Janster (May 23, 2013)

Vinegar and salt will clean coins w/o any damage. Just do not mix any dollar coins, half dollar, quarters, dimes or nickels with post 82 pennies as they will take on a pinkish tint, then again some folks may too, like that look!..................Jan


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## Janster (May 23, 2013)

Please remove.......double post!


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