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Zinc cents and post-recovery decay.

August 29, 2017 03:25AM avatar
The majority of all the pennies we recover today from urban settings are going to be the modern type (part of 1982 and everything since). The 97.5% Zinc has a copper plating accounting for 2.5% of copper in the mix. That copper is so thin, especially with typical wear, that chemical reaction to the inner zinc core is sure to occur.

I have also experienced some slow decay of recovered modern zinc cents if they have only been unearthed and left 'as-is' or even if they were only rinsed off to remove surface dirt. But I don't stop there. I noticed that even just rinsing them off or cleaning with a soapy solution the better appearance often only lasted a short while and they might discolor a bit, or I would see new or larger pitting and holes.

So I started cleaning my coins at the end of every month. I do rinse all loose soil off of the coins first, and I do tumble them in a two-barrel Lortone tumbler using white aquarium gravel. However, I go one step further before they ever get to the tumbler.

I use my 'Pre-Treatment' of all coin groups after separating them (Copper & Zinc Cents and most modern smaller-size Dollar coins, then Nickel coins, then all the 'clad' Dimes, Quarters and Half-Dollars), and that 'pre-treatment' prior to tumbling them seems to help curb or slow the decaying process.

I use a plastic peanut butter jar and lid, and put in a batch of presorted coins that would go in the tumbler. I then use a toilet bowel cleaner, such as Lysol brand that I used to buy at Dollar Tree or other budget store, and squirt that liquid in to just cover the coins (pennies in this instance) then tighten the lid and shake to mix all the coins and TB cleaner to make sure all outer surfaces of the coins gets 'treated.'

After the coins have been shaken around and sit in the jar for maybe 4 to 5 minutes, no longer, I pour the liquid and coins into a plastic soft margarine container. I then squeeze the container to pour the liquid back into the plastic peanut butter jar as it can be reused quite a few times. The plastic margarine container with the pre-treated coins is then filled a few times with running water and I shake or stir the coins around and get all the solution removed.

The coins are then tumbled, using aquarium gravel, one good squirt of Dawn dish soap and just covering the coins and aquarium gravel mix with water. I only tumble them for 30 - 45 minutes, then pour them out in a strainer to separate them from the aquarium gravel tumbler mix, rinse them off and lay them out on a terry-cloth towel to dry. Once dried, I put them in glass jars on my book shelves for display ... until I decide to cash them in.

I can check my cleaned Zinc cents and find that none of them show any apparent signs of new or continued pitting or decay, and I have a large jar with a few thousand modern zinc cents, many of which that were cleaned with the steps mentioned above in 2013. I think the pre-tumbling treatment I give them not only helps get rid of most of the crud and discoloration of most coins, but it also seems to curb the decaying process.

Monte

"Your EYES ... the only 100% accurate form of Discrimination!"

Stinkwater Wells
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Subject Author Views Posted

Cashed my coins

Remfire 353 August 27, 2017 10:18AM

Re: Cashed my coins

Sodbuster 222 August 28, 2017 09:49AM

Zinc cents and post-recovery decay.

Monte 334 August 29, 2017 03:25AM

Re: Zinc cents and post-recovery decay.

Sodbuster 218 August 29, 2017 08:46PM

Mike, I tumble Zinc & Copper cents, as well as

Monte 231 August 31, 2017 04:34AM

Re: Cashed my coins

Remfire 236 August 28, 2017 12:18PM

Sounds like a lot of coins come through their life in good shape.

Monte 258 August 28, 2017 01:24AM



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