I've read so much about grease-filled dies and saw many examples here in CT. While researching online, all I get are mostly photos of the end products - like this one that I have. (I call it my 192 Berty E-Cent. LOL.) But what I'm after is to understand why the grease within the recesses of the die doesn't just get displaced and then "splash out" under all the tons of pressure during the strike. When I think of grease-filled dies, I envision putting one ice cube tray over another one which is filled. Then the water in the lower tray would just get displaced. Why doesn't that happen to the grease in the die during the minting process? I've viewed numerous videos on the minting process, but none goes into that part in detail. Thanks for your help.
Simple.. The grease becomes compacted. It turns really hard inside the spaces of the Die. It's not liquid or viscous at that moment.
Did you ever go water skiing...when you come off those skis, the water is HARD!!! Similarly when the die strikes down, the grease or oil resists being compressed and gets HARD!!!
Reminds me of a demo I saw once where a gallon jug is filled to the brim with water and a cork is inserted in the neck. A rap on the cork transmits to the jug (since the water can't be compressed) and the bottom breaks out.
Occasionally the impacted debris will come loose and fall out which can result in a "dropped letter" and show up on the next coin struck. NGC explains it better: https://www.ngccoin.com/news/article/557/
Water is incompressable. Doug's head is filled with water. Doug's head is incompressable. Or is that incomprehensable?
No, but come to think of it now, a friend of mine busted his eardrum when he fell off his water skis. I recall thinking it was odd that water could do that.
@thomas mozzillo, is a "dropped letter" (Photo 5 in your link) considered a mint error? Or, like a grease filled die, it's not.
I don't think it's considered an error. Check this site: https://en.wikipedia.org/wiki/Mint-made_errors This is a great site to learn from: http://www.error-ref.com/
Why doesn't it "splash out? Think about this, as the die makes contact with the surface of the planchet and the field of the die starts forcing into it all the incuse device areas are now SEALED. Nothing in these devices areas can get out. As the die forces further intot he planchet the meter continues filling those device cavities. Gasses in the cavities can be compress and the metal eventually fills the void completely. But liquids (and we can consider the grease to be a liquid) are incompressible for all practical purposes so the grease stops the planchet metal, but can't "squirt" out because the planchet has sealed it in.
Thanks! I understand now. But still, how I wish I've got a few photos of the striking process to see and really appreciate it. Youtube and U.S. Mint videos don't go into the nitty gritty. Anyhow - thanks for the very thorough explanation.
