I know its zinc but I was just reading about the Rockwell test mark and then I came across this. It probably is a blister or die chip but included in pics(pic 9)is what is believed to be one. What does everyone think? That and is die clash responsible for what is seen in each bay of memorial and on roof? Thanks again
A Rockwell Hardness test is done on pure metals and alloys, why in heavens name would it be done on a plated object...uh, sorry @cpm9ball a Crappy Zincoln?
Not sure but example in pick was done on a 1971 Lincoln and is why I was asking. Article from Coneca stated John Devine verified. Article states testing was done before and after 1982.
The OP's coin is not a Rockwell Test Piece, and although I knew John Devine very well, and thought highly of his numismatic expertise, I do not believe that 1971 cent is a Rockwell Test Piece. I saw the RT operation at the West Point Mint back around 2006 or so - and the 'ding' that is placed on the planchet is not that deep, and would disappear under 65-75 tons of striking pressure.
Thank you for the information and being article said a person would have to be there as you have been answers my question. That and I couldn't find more as article indicated, but coin is in really bad condition and had to ask.
The John Divine mark has had its authenticity questioned by me in my paper on the CONECA site and by Mike Diamond. Even the test mark example in my paper has been questioned by Mike...he says microscopic pressure ridges are visible (which I cannot see). There is a debate as to whether a test mark can survive a strike. Mike and Fred are doubtful and the US Mint suspects it may be possible, so makes every effort to make sure that no test marked planchet enters the striking chamber.
When I read about this (hardness test), it frankly didn't make sense to me having done hardness testing in a past life and being around stamping/coining operations for 30 years. The malleable nature of copper under that kind of tonnage essentially liquifies the outer layer of planchet. The likelihood of a penetrator mark surviving seems extremely unlikely. The folks at the mint might have personal experience with this that refutes thought, but on the coining operations I've been around...not a chance. I will check out your paper later. Thanks for the input/history.
At the WP Mint, they were doing it on Silver Eagle Planchets the day I was there, so it is used on varying metals, which makes sense.
Here's the link to Pete's article: Rockwell Hardness Test Marks On Lincoln Cents | CONECA (conecaonline.org) I particularly appreciated the point on the 1995 cent (zinc substrate). The T scale makes sense to me relative to the thickness and softness of the material (it's what I would have done). I am surprised to read that there is some consensus that the penetrator mark would survive the minting process. That said, most coining I've seen done was being done on much larger equipment. Not something that I expected to learn today...but learn I did.
