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Corrosion On Zinc Coins

 
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Author Previous TopicReplies: 15 / Views: 392Next Topic  
Valued Member
United States
216 Posts
 Posted 01/24/2021  5:05 pm Show Profile   Check Diy89Nurm7's eBay Listings Bookmark this topic Add Diy89Nurm7 to your friends list Get a Link to this Message
Greetings!

Looking for info on corrosion of zinc-plated modern coins, especially how it differs from problems seen in copper ones.

I, too, have noticed circles/dots on some coins. Anyone know good sources of info on corrosion of coins, how to slow or prevent, effects on valuation, etc.?

Thanks in advance. Stay well!
Diy89Nurm7
Valued Member
United States
192 Posts
 Posted 01/24/2021  5:47 pm  Show Profile   Bookmark this reply Add PNWType to your friends list Get a Link to this Reply
It is often called Zinc Rot

It happens like most other types of environmental damage, poor storage, humidity, temperature fluctuations, etc

Prevention is generally simple, airtites are a good way to go, 2x2s can also offer some improved protection over sitting in total open air, storage in a temperature controlled area, silica packs or other dehumidifying options

The effect on value is going to be similar to other types of ED, once the coin is damaged it is damaged. The hit to the value depends on whether the rot can be removed or if it has eaten into the coin. In the case of zinc rot, it is almost always the latter
Pillar of the Community
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 Posted 01/24/2021  6:02 pm  Show Profile   Bookmark this reply Add ijn1944 to your friends list Get a Link to this Reply
You might stumble upon a collector who loves extreme examples of (unruptured) Zincoln gas bubbles.
Bedrock of the Community
Australia
18129 Posts
 Posted 01/24/2021  10:52 pm  Show Profile   Bookmark this reply Add sel_69l to your friends list Get a Link to this Reply
Zinc plating is most often applied to coins with a steel core.
Copper plating is also applied to coins with a steel core.

Best and easiest way to find out about the various effects of corrosion in different situations would be do a search on Google Images, and to further extend that research on Google.

The best way to preserve a coin that has not been affected by corrosion would be to store it in an airtight capsule, but such a system nay not be appropriate to your chosen system of storage and display. Capsules only really justified with significantly valuable coins
For myself, a coin that is unaffected by corrosion is just put in a standard cardboard flip. I never use PVC album pages.

As far as value is concerned, a coin that is affected by corrosion is the equivalent of a damaged coin, and thus most of it's value (90%?) is lost.
New Member
United States
13 Posts
 Posted 01/25/2021  12:50 am  Show Profile   Bookmark this reply Add Coin Federate to your friends list Get a Link to this Reply



This is a video from the government about making pennies a long time ago. They wash them in vats with Cream of Tartar (a baking agent similar to baking soda). I think it would work on new pennies since it is a topical wash.

(Please note: I have not tested this method)

https://www.youtube.com/watch?v=egZ6WfXm08w
Valued Member
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 Posted 01/26/2021  6:31 pm  Show Profile   Check Diy89Nurm7's eBay Listings Bookmark this reply Add Diy89Nurm7 to your friends list Get a Link to this Reply
Thanks for the advice. I probably should get some airtights then.

Hard to find a Zincoln in circulation without a small ring or dot somewhere under a loup or scope.

Stay well!
Diy89Nurm7
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 Posted 01/26/2021  9:14 pm  Show Profile   Bookmark this reply Add sel_69l to your friends list Get a Link to this Reply
The only way to get coins that are unaffected by bag marks is buy business strike quality specimen coins that are specifically made for collectors.

As coins for circulation are ejected from the coining presses, they fall onto a pile of already freshly minted coins, and also get marked up when they are transported in bulk. This is where so called 'bag marks' come from.
With Zincolns, the copper plating is damaged, and so sets the scene for zinc rot.
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 Posted 01/30/2021  4:19 pm  Show Profile   Check Diy89Nurm7's eBay Listings Bookmark this reply Add Diy89Nurm7 to your friends list Get a Link to this Reply
Makes sense. Are mint rolls or bags really that good for nice uncirculated coins that are worth the extra cost per coin or are they overrated?

Thanks,
Stay well!
Diy89Nurm7
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Australia
18129 Posts
 Posted 01/30/2021  7:27 pm  Show Profile   Bookmark this reply Add sel_69l to your friends list Get a Link to this Reply
Rolls and bags of uncirculated coins fresh from the Mint have bag marks as mentioned above, and so grade in the MS-60 to 65 range.

Specimen coins from mint sets are usually grade in the MS-65 to 70 range, and most commonly 68 to 70.
However, although more can may be taken in the minting and packaging of specimen coins,
I doubt that any extra care is taken for Zincolns during the rolling blanking and planchet stages, and so the possibility of zinc rot remains under the copper plating.

As we all know, zinc rot destroys the numismatic value if it is present. That may be a problem for mint sets over the long term. I don't know if the Mint takes any extra care for proof Zincolns during the rolling blanking and planchet stages of manufacture.

Perhaps the Mint should make silver proof Lincolns for collectors. I can see a marketing opportunity for the Mint in this respect, and there would be no zinc rot.
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United States
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 Posted 01/31/2021  10:17 am  Show Profile   Check Diy89Nurm7's eBay Listings Bookmark this reply Add Diy89Nurm7 to your friends list Get a Link to this Reply
Thanks for the help.

Stay well.
Diy89Nurm7
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 Posted 02/01/2021  09:29 am  Show Profile   Bookmark this reply Add Big-Kingdom to your friends list Get a Link to this Reply
Look, my opinion, I have zincolns going on 31 years kept in flips and mostly undisturbed that have serious split plating issues. As long as they aren't seeing circulation, i.e finger rub and oils, moisture, ect. the exposed zinc dusts over and it stops and that's it, it's the repeated knocking off of this zinc dust that deteriorates the coin rapidly in circulation from water, hands, pockets, other coins ect.

31 year old, plenty of exposed zinc, just about every device has split plating. This one saw some circulation I'm guessing but I found it early, No idea why the front looks the way it does except for circulation I suppose? Not a filled die although the L in Liberty is missing, the entire obverse is pretty weak but it's got the strange abrasions Left, jacket, face... anyways, I just saved it as an example of split plating on the reverse as a reference:



if zinc is exposed, it's going to create zinc oxide to protect the exposed zinc. If you handle it, the oxide keeps getting knocked off and some more zinc is sacrificed to protect the exposed zinc. Blisters or bubbles if they aren't ruptured are fine, but they are ugly in my opinion.


Edited by Big-Kingdom
02/01/2021 09:38 am
Valued Member
United States
216 Posts
 Posted 02/01/2021  11:33 am  Show Profile   Check Diy89Nurm7's eBay Listings Bookmark this reply Add Diy89Nurm7 to your friends list Get a Link to this Reply
I agree, Big Kingdom. It's hard to find Zincolns without a spot or other emerging issues. I wonder about investing in and preserving high grade ones because they may be or become soon, in very short supply regardless how recently produced.

Even BU rolls have so few without blems.

Stay well.
Diy89Nurm7
Valued Member
United States
103 Posts
 Posted 02/01/2021  4:41 pm  Show Profile   Bookmark this reply Add EDM to your friends list Get a Link to this Reply
Would it be evil to treat zinc coins and Zincolns with a little bit of WD-40 to stop corrosion?
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20084 Posts
 Posted 02/02/2021  9:31 pm  Show Profile   Bookmark this reply Add just carl to your friends list Get a Link to this Reply

Quote:
Would it be evil to treat zinc coins and Zincolns with a little bit of WD-40 to stop corrosion?

Oddly enough that would stop any corrosion. Same with almost any oils or other coatings. You could also spray or coat them with Silicon, Laquer, finger nail polish, Liquid plastic, etc.
Almost anything that seals the surface from everything. Of course putting a coin soaked in oil in an Album might be a bit messy.
just carl
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 Posted 02/03/2021  10:43 am  Show Profile   Bookmark this reply Add jbuck to your friends list Get a Link to this Reply

Quote:
Of course putting a coin soaked in oil in an Album might be a bit messy.
Truth!
Valued Member
United States
103 Posts
 Posted 02/03/2021  1:36 pm  Show Profile   Bookmark this reply Add EDM to your friends list Get a Link to this Reply
True that. It was my understanding that treating with WD-40 and using a soft cotton cloth to gently wipe it all off would leave a residue coating against corrosion?
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