Ok I am gonna ask? I have heard this term thousands of times, But never really have heard an explanation on how that happened. Was it a new die and it was greased so not to rust? Did they use grease in the mint to do something and it somehow got on the dies? Can you or someone please explain this to me or us Noobs?
A little about filled dies. Most commonly they are called grease filled for a quick answer. Filled dies I am sure have parts that are grease but they also contain excess metal from striking, debris of sorts, these fill in the devices on the die. And when a planchet gets struck it is missing or partially there.
Grease filled die is acutally under the heading of "Struck Through". check this link for more details.http://www.error-ref.com/struck-through-smooth-viscous-material-grease-oil/
@abuckmaster147 Lon, this is probably the best explanation you will find anywhere. One other tidbit of information that might interest you is that when you are searching (particularly) Mint bags of same-date/mm coins and you find one that is the result of a grease-filled die, it is also possible to sometimes find what is called a "dropped element". A "dropped element" occurs when the grease and debris have compacted in a die from continued strikes and is almost as hard as steel. When it falls onto the surface of an incoming planchet, it can be embedded as a strikethrough. Sometimes it can be retained and sometimes it can fall away. Chris
