1991 Lincoln Memorial Cent DDR

There is a contact mark on the 'E' flattening some of it. The rest looks normal.

It's MD http://www.error-ref.com/push-doubling/

Note on the tops of the letters of USA. That is called split plating. I feel that this is cause by Machine Doubling splitting the plating after the strike. Often we can see that on devices inside of the coins devices:



Also die wear will also be in the direction of the closest rim. So it could be one or the other or both sometimes. But it is not hub doubling. Why Not? Because hub doubling shows on the centers of the devices, not on the sides of the devices and rises up like the devices, not laying on the fields. On a doubled die, the doubling is on the die, not caused by the machine.

To answer your question you asked at the beginning of your post, no, there is no stopping zinc rot. It's my understanding it's an internal problem with the zinc, not just contact with the air. It's this internal combustion that causes zinc blisters to happen in the first place. Sorry it's not better news. Zinc rot will eventually cause the demise of all mid-82 cents and up.