Groovy Coins. How do they get that way?

[Ammoman]

Over the past several months i have run into a few coins that have grooves set within the letters. From a distance the letters and numbers look doubled but a closer look shows grooves giving the illusion of doubling.. I call them "Groovy coins". Can anyone tell me what this effect is and how it is made?
Here is a recently found penny with the grooves.
If you click on the picture you can zoom in for a better look


Thanks for your time!

 

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[l.cutler]

Very common on the copper coated zinc cents, I believe it is something to do with the plating.

 

[Ammoman]

Yes I agree. I have seen this several times. I am just curious about how something like this happens and what the correct term might be. Lol I am sure groovy is not the proper term.

 

[eyemustdigtreasure]

Perhaps these zinc pennies are just getting ready to blow up...!

 

[Ammoman]

Lol indeed or, implode.

 

[PetesPockets55]

I agree it tends to be associated with a plating issue.

I've always wondered if it has to do with the zinc "dissolving" from beneath the copper plating. The copper plating is probably thinnest at the top of the letters if the plating doesn't split at the base.

 

[jeff of pa]

isn't that considered a form of Machine Doubling ?

 

[l.cutler]

isn't that considered a form of Machine Doubling ?

View attachment 1760989View attachment 1760990

That may be it, there is machine doubling, die deterioration doubling as well as the coveted doubled die. Tough to keep them all straight!

 

[unclemac]

bah! zinclons! just BAH! an abomination of a coin!

 

[PetesPockets55]

LOL Unclemac.
So true but they have provided some nice errors and varieties.

And a plating disturbance and MD are different "critters" of the same non-valuble family. Sort of like cow poo and horse poo are similar but they are still poo.