Cleaning coins in a rock tumbler

[Waterdog]

I have been cleaning coins with a rock tumbler with vinegar with a little salt with aquarium gravel and they come out great in about 1/2 hour. I have been saving the coins, clad in one container and pennies in the other. Today I was showing one of my buddies my clad and noticed that some of the coins had a green tint on them. Any ideas of what causes the clad to turn green ?

 

[jim tn]

I clean mine with the same mixture and way you do. The liquid comes out green on mine, but after a good rinse the coins aren't green. Maybe make sure you also rinse the gravel good? HH jim tn

 

[WaterWalker]

If the coins are from salt water beaches, the green is cause by galvanic action between the coins and copper minerals in the beach sand.
Gold rings that have been sized or a piece soldered to it can also exhibit the green crust. for the same reason. Yellow gold usually has copper
in it. Clad coins and nickles have copper in their mix. The dissimilar metals, salt and water set up the galvanic action for this to occur.

 

[John-Edmonton]

I tried salt, vinegar and water once with pennies, and my tumbler lid blew off because of the chemical reaction building up too much pressure. . Be careful! I just use water, and the coins come out just as clean, as the coins use each other for abrasion and these is no staining. Quicker cleanup too!

 

[GO VA]

Never do what I am saying in this post to anything you think could have any value other than face value of the coin.That being said the red clay here in Va. can be very tough to get off, so for non valuable clad coins I use Stainless Steel Shot Tumbling Media Jewelers Mix with filtered well water and a FEW drops of Dawn dish detergent in a Thumler's Tumbler Heavy Duty Rotary Rock Tumbler (15 lb) and I think the tumbler has as much to do with it as anything because I could never get good results using the same media and detergent in a smoth barel tumbler. I don't think you would need to go to this extreme and $$$ spent in other areas where there is better soil but I don't have a problem with discoloration afterwards. As to minimum time it takes, I cant say, I run it in my garage from the time I get home from work and get it loaded until the next day when I come home from work. Again this is for soil that can be like concrete mixed with glue and this tumbler and media cost's a lot more than most will want to spend so don't think you need to go to this extreme, I have tryed a lot of different things but just stating what works for me here in the soil conditions I have.

 

[John-Edmonton]

Using the Stainless Steel Shot Tumbling Media works well too. You need to get the batch where the pieces are different shapes and sizes so as they can get into tiny places on the coins. I use mine to clean up jewelry and silver coins. It won't scratch them, but leaves a beautiful shine on them. The method is also one of the best ways of cleaning up silver chains. A word of caution.....wash only objects made of the same material ie silver with silver, copper with copper. If you toss in a copper penny washing clad quarters or silver quarters, the batch will be stained with a brown color.

Here's a video I made - https://www.youtube.com/watch?v=cbuiV3RJou0