Need help with tumbling pennies, question about zinc, etc.

[Muddyshoes]

Hi all,

Back into metal detecting after 10-15 years or so. Decided to buy the Harbor Freight tumbler and clean my coins with it. It works well, but I notice that it seems to destroy the copper coating on the pennies which are mid-80s. I'm assuming that this is because these are zinc pennies? The earlier copper seems to come out ok, albeit with a somewhat brushed look because of the gravel.

I've also noted finding a good number of pennies that look like they have growths on them when I dig them up or some kind of crusting, which I first assumed, before cleaning, that it was some kind of deposit from the ground or fertilizer. Could this just be the "bubbling" or corrosion of the zinc that some people talk about, and which is brushed away by the tumbling, leaving a scarred, steel-color looking coin underneath?

Checking the dates of the pennies that have this problem are all mid to late 80s so that would seem to make sense.

I was using ammonia to tumble with as it seemed to do a better job than just liquid soap and tumbling for about 2 hours.

I'm still not sure if it's something I'm doing to these coins or if just that's what I have to look forward to with cleaning zinc pennies from this point forward. If so, what's the safest way to clean those without destroying the finish, or should mild tumbling not affect the coating unless the penny is corroded in the first place?

Thanks for any help you can provide.

Oh, incidentally, the Harbor Freight tumbler now comes with 5 spare belts... 5! Don't know why they just don't include a good quality belt in the first place.

- Ron

 

[Roscue2]

For many of the zinc pennies that I dig, when I clean them they end up looking like that or worse. That is just the way many zinc pennies come out like when using this tumbler. In the end it doesn't bother me because I send them to the bank or spend them anyway.

Also, the belt issue is not a problem because once the 2 belts I got with it break I'll just use rubber bands. Problem solved.

 

[JimGilmore]

The thin copper breaks down and the zinc bubbles through.

 

[Muddyshoes]

The thin copper breaks down and the zinc bubbles through.

Ah, then that is it. It was weird, I was thinking that the park people were using some really toxic thing that was building up on the coins.

 

[BarberBill]

Many zincs are in bad condition when dug. I had given up retrieving them for a while until I read a forum thread that pointed out that some smaller gold jewelry and other desirable targets ID as zincs. The 2nd one I dug after that turned out to be a small black hills gold ring. So now I usually dig them and junk the bad ones.
BB

 

[MarkCZ]

If I have to dig a Zinc'er "Stink'in Zinc'on" it pretty much has to be thrown away! banks don't want them! (cheap A** money) If I find them fresh lost then I keep'em.

Mark

 

[Monte]

they came out relatively good. Most of them. That was in one particular ground area w/o too much in the way of ground chemicals or fertilizer, etc. I do find some nasty, eaten-up and crappy 'zincs', but most of what I find cleans up okay. I don't mind recovering them because in the same VDI range where most 'zinc' cents read you will also note that most Indian Head and many early mintage 'wheat-back' cents also fall in that range. Some desirable silver and gold jewelry, too, as well as a $10 US gold coin (should you be so lucky).

I don't tumble my coins too long, and I wouldn't put eaten up or 'exposed' zinc cents in a 2 hour tumble with ammonia or other chemicals. I can direct you to printable Coin Cleaning Tips, and if you follow them closely, not using too large an amount of coins per tumble, and rinse well then tumble soon after their 'treatment,' they ought to come out more spendable or bank-ready.

http://www.ahrps.org/_tipsAndTechniques/CoinCleaningTips.pdf

Monte

 

[JimGilmore]

Right now I know I am missing gold but the problem is the park I'm hunting has not been detected in a while in the area I am hunting...So I'm target rich...Once I stop getting 100" coins a day I'll start recovering everything I can..

 

[collins51]

Try putting them in vinegar. It has worked for me around 15 min no more.

 

[reltolbert]

-Peroxide ( 1/4 cup ) in microwave oven for 30 seconds or until boils. Take out the peroxide and put in pennies a few at a time.
-1/4 cup of lemon juice or 5% vinegar and 1 teaspoon of salt mixed together. Put in pennies for 10-30 seconds.
- Tumble pennies and silver with 1/3 small colored aquarium rock / 1/4 full coins with 2 squirts of dish-soap and fill with water 1/4" above those mixtures.
- Electrolysis for all coins in mixture of cup of water and 1 teaspoon of salt.

 

[MarkCZ]

n/t