Need advice. Just cleaned some pennies and the turned bark brown. Help!

Trunkman

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I just bought a rock tumbler and threw some modern pennies in there that I recently dug up. The pennies were pretty stained/dirty. I put in a couple of tablespoons of vinegar, 2 tablespoons of CLR, a half teaspoon of salt, a little Dawn, gravel and a quarter cup of water.

I checked the tumbler every half hour and the just kept getting darker until they became dark brown. I don't get it. I watched some videos, did what they did, but got terrible results. I then tried it with just gravel, salt and vinegar - no better. See pic.

Any advice on how to get these back to a copper color would be appreciated as well as tell me what I did wrong. Thanks.
 

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They look similar to the results I get. Pick out the crusty zincs and those are ready for the Credit Union coinstar!
 
I just bought a rock tumbler and threw some modern pennies in there that I recently dug up. The pennies were pretty stained/dirty. I put in a couple of tablespoons of vinegar, 2 tablespoons of CLR, a half teaspoon of salt, a little Dawn, gravel and a quarter cup of water.

I checked the tumbler every half hour and the just kept getting darker until they became dark brown. I don't get it. I watched some videos, did what they did, but got terrible results. I then tried it with just gravel, salt and vinegar - no better. See pic.

Any advice on how to get these back to a copper color would be appreciated as well as tell me what I did wrong. Thanks.

Were you changing the water at the half hour? In the video below, the guy is using the same chemicals as you, but only in the final tumble. Like so:

-2 hours with water and gravel
-Rinse thoroughly
-2 hours with water and gravel
-Rinse thoroughly
-2 hours with water and gravel and chemicals
-Rinse thoroughly


The idea is to stop the coins from effectively getting dyed as they tumble. So, you get as much off as you can purely through abrasion, rinsing the water as much as practical, and then strip them chemically. It would be interesting to see how his final fun would look without any gravel to limit the abrasion (and loss of details) to only the coins rubbing against each other.

https://www.youtube.com/watch?v=ZH0neCSuw9s
 
Vinegar is a mild corrosive. Drop it from your recipe. Might also be the CLR. When I tumbled any pennies, I used only salt and lemon juice in water, with some silica sand.
'Course, they were non-collectible zincolns, so no real harm done. They came out a nice, clean, mat copper color.

Roger
 
Thanks for your comments. I think I'll cut out the vinegar and clr. I'll also do some cleaning without the gravel to start. That video was helpful too.
 
I only use water and a bit of dish washing detergent in with some gravel to clean pennies. . I run the tumbler at least over night. Modern zincs might get some more treatment.
I use vinegar and salt to clean clad only.
 
I see no problem with them, they look good, like circulated one cent pieces.
I’m not one to waste electricity running a tumbler all day, they’re pennies. Defeats the whole purpose as far as I’m concerned.
Why you want to take ‘em to the fair?
 
Don't over think it

A cup of pennies, a half cup of lemon juice 3 knuckle sized rocks for 15 minutes. Rinse and take to the bank or roll. Do yourself a favor and throw out the rotted and bent coins first.
 
I cleaned them 2 more times with just dawn, water and gravel. They look good now. Thanks for all the advice!
 
I cleaned them 2 more times with just dawn, water and gravel. They look good now. Thanks for all the advice!

Cool! I cleaned a small batch just for demonstration to see the results without any CLR.

You might notice I'm using jewelers shot instead of gravel. I think it's a bit easier on the details than fresh aquarium gravel, but more effective than aquarium gravel that's tumbled smooth after having been used for many hours. I think the jeweler's shot stays in that "just harsh enough" sweet spot longer. Either way, the results would be about the same for old copper Lincoln pennies.

The photos:

1. Before cleaning.
2. To show water level in tumbler. Barely above the coins.
3. After two hour tumble in warm water, rinsed, and mostly dry.
4. Repeat.
5. After two hour tumble in warm water, two table spoons vinegar, pinch of salt, and squirt of dish soap.

The first 2 hour rinse is typically all I do for copper Lincoln pennies.

The second rinse is marginally "better" as far as shine, but detail is starting to get lost on the most worn coins.

The final "chemical tumble" stripped the coins and did give them a shine, but even with a small amount of vinegar and salt it was was so corrosive it started to cause surface damage (i.e., pitting) to some of the coins. Plus, additional tumbling caused further loss of detail. There was a 1920s wheat in the mix that completely lost its date.

The overall result likely would have been better by cutting the 2nd tumble down to 1 hour, and the third tumble reduced to a mere 30-45 minutes.
 

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Thanks ToySoldier for the great play by play. Pictures and all will make it super easy for me to try next time. Your results look really good.
 
Harbor Freight tumbler using water and a drip of dish detergent worked great for me. I did all my clad and the wheaties and nickels that were virtually unreadable and they came out great.

Steve
 

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Oh, guys.......please don't mix your clad with your pennies when cleaning. Everything gets a copper-tinted wash, and it spoils the appearance of the clad.
I'm not a numismatist, and I know that.

Roger
 
This is what I use. 30 minute cleaning with 15 minute 2nd wash. I actually drop the 2nd wash, sometimes. I'm just trying to brighten them up. They come out great. White vinegar, rock salt and rocks. I don't change my rocks, I just rinse them after each wash. I also don't have a scale so I just tried to match the quantity of stones to his. Works for me. Good Luck, Dave

https://www.youtube.com/watch?v=KJZD6RRqu6U&feature=youtu.be
 
I use clr and vinegar with a squirt of dish soap for clad silver colored coins. I use the same mixture minus clr for pennies. The pennies come out nice and shiny. And I use gravel, but you have to change it out after awhile. And yes dont mix copper with your nickels dimes and quarters unless you want them to be copper colored too.

Sent from my SM-G975U using Tapatalk
 
gravel, water, a bit of dawn dish soap and a splash of ammonia (which is a base) will do a better job of cleaning while leaving the natural color. You don't need a lot of ammonia to do the job. I would not use acidic solution (i.e. vinegar) to clean copper.
 
cleaning dug up coins

I use a Thumblers Tumbler with a double barrel.
I use one barrel for copper coins and one for clad coins.
I only put some white vinegar and a little bit of salt then let them tumbler for about 45 minutes or less.
I put pea sized gravel in the drum that stays there after each use.
The clad tends to turn a light gray after tumbling them with the vinegar and salt solution , but I just rinse them and then tumble them again with vinegar only for about 30 minutes or more if needed.
Never mix the copper coins with the clad or it will cause the clad to become a brownish color.
Hope this helps.
 
Zinc pennies turn that color when they are washed.
I normally discard the ones that are very corroded or crusty.
I have my detector set to zap them out since most of the time they are in sad shape.
 
Vinegar is a mild corrosive. Drop it from your recipe. Might also be the CLR. When I tumbled any pennies, I used only salt and lemon juice in water, with some silica sand.
'Course, they were non-collectible zincolns, so no real harm done. They came out a nice, clean, mat copper color.

Roger

right! dawn alone should probably produce decent results. :)
 
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