Die polishing. How does that affect the coins?
Actually die polishing doesn't affect the coins, it affects the dies that strike the coins. This shows up as missing areas on the coins struck with that die. There has been some incorrect ideas about die polishing.
But lets start with what does a die look like? The die is a negative of the coins struck. What does that mean?
The coin is a positive. the devices are raised. The fields are in the background. The bust is raised the most and the rim is raised. So what is the negative for the die?
The bust is the deepest into the die. The devices are the less deeper and some devices are slightly lower on the die. The fields instead of being in the background, are not the outside part of the die.
Note on the hub, the positive design is on it. Pressed into the die making the negative on the die.
Note on the die, the devices are mirrored, the bust is deep into the die. The outside of the die is the fields.
So when a die clash happens the fields are polished. leaving the clash marks on the opposite dies thus struck with both sets of devices outlines on each die. Also not the outside edge of the die. The rims are created by the step down on the die and the collar to for that area.
This was a light clash. But not a common one to find. The Jail house cents are the more desired ones:
The deeper the clash, the more devices show up on the struck coins.
When this happens, the dies are polished to remove the clash outlines on the dies. Sometimes when the devices are over polished because of working on an affected area, the over polishing is isolated and really affects certain devices:
On some polishing the die gets reduced with a lot of abrasion:
Even proof dies get altered:So why do certain areas suffer so much abrasion?
Because of the same events happening over and over. Some years are worse than others for this. 1983/4 had a lot of events those years. Note how the 'L' on LIBERTY almost was removed from this die? The dies field was so over polished that the field was reduced to the point where the sunken in devices on the edge of the die, was removed so the rim would not rise above the edge of the coin.
Not how die wear also set in on top of the die abrasion.[b]
So when we say die over polishing what area of the die is affected?
The fields is the easy answer. But the more of the fields affected, the more of the devices and designs may disappear. It is the bases of the devices that are reduced. Not the tops of the devices. Why? Because the tops of the devices are deeper into the die. If the all the devices tops were missing, you would have a blank die. Nothing would appear. It is the pressing in of the devices and design that is hubbed into the die, that creates the devices we see on a coin.
So what are the fields on a coin? Well the easy answer is the areas next to the devices. But even some areas are also fields. The bays on the Memorial cents. They are the fields. So when polishing happens on them, the shallow devices on the coin can go away first. What are the shallow devices? The false columns on the reverse of the Memorial cents are what I'm thinking of.[b]
These 4 extra false columns are located here:
When die clash removal is done to remove the clash marks, these can go away as they are shallow devices.
Another area could be around the face of a bust that is affected by strong die polishing:
The deeper devices are on a coin, the closer they are to field level, the more they will be affected by die polishing. So when a die polishing happens, what area is affected first, the fields.