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 Replies: 21 / Views: 493 |
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Pillar of the Community
United States
3330 Posts |
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Pillar of the Community
United States
7504 Posts |
Well, the least publisized the better, we need those errors keep coming ........  |
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Moderator
 United States
187446 Posts |
That is a fascinating read! Thank you for writing it and sharing the link with us here.  |
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Pillar of the Community
 United States
6449 Posts |
A very interesting and well written article.
Having looked at thousands of 2006-2025 nickel reverses per year for three years, I can spot a Denver nickel with extreme accuracy just by the surface features. They tend to have a mirror rather than a matte texture, the features have different rounding and blur, and the D nickels often have melted butter central die flow that does not appear on Philly nickels. There are many, many clues that the dies could be polished differently, plated or hardened differently, run under different striking pressure, or run for longer times or different strike frequency.
Why would a lower crown height produce more FFD?
Regarding single squeeze doubled dies, I think there are a number of die manufacturing parameters that are unknown. For example, it is not established that P and D use the same hubbing press. Even if they did, the hubbing pressure, speed, and amount of play in the die collar could drastically affect whether a pop double (class 9.1) forms on a particular die. Crown might play into that, but we cannot assume all other parameters are held constant.
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Pillar of the Community
United States
2213 Posts |
Very interesting and well written.
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Pillar of the Community
United States
3619 Posts |
Excellent numismatic study and a superbly researched topic!  |
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Pillar of the Community
 United States
3330 Posts |
@Brandmeister Thanks for your thoughtful comments! I especially intend to save your observations! Quote:
Why would a lower crown height produce more FFD? Possibly because of a "flatter" die face? Quote:
Crown might play into that, but we cannot assume all other parameters are held constant. I agree, but I think it IS key that differences in crown height IS constant. There is no need to assume all other parameters are held constant, and I do not make that assumption. We KNOW: Documented: Crown heights differ between the two mints Documented: The difference is sufficient to produce measurable coin fill differences Historical record: 1836 established the causal link between die geometry and striking pressure/die failure and that link has continued to be demonstrated throughout the mint's learning curve. Observed data: Philadelphia produces an average of 90%+ of doubled dies, cracks, chips, Cuds, and feeder mechanism die damage. There may be a different explanation for THE primary influencing factor for such skewed incidences other than Crown Height, but I have not heard one with anywhere close to similar extensive supporting evidence. |
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Moderator
United States
94636 Posts |
thanks for this topic - I find it very interesting. May have to read mor about this moving forwards.
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Pillar of the Community
United States
3330 Posts |
Quote:
thanks for this topic - I find it very interesting. May have to read mor about this moving forwards. I while back, I posted this. It is related if you want some more reference leads: https://goccf.com/t/485666 |
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Pillar of the Community
United States
2731 Posts |
Interesting, Pete..thanks for the detailed breakdown. I always assumed the Philly skew in errors and varieties was mainly due to the larger volume of coins minted there, but your data shows the discrepancy is way too large for production numbers alone to explain it.
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Pillar of the Community
United States
3330 Posts |
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Interesting, Pete..thanks for the detailed breakdown. I always assumed the Philly skew in errors and varieties was mainly due to the larger volume of coins minted there, but your data shows the discrepancy is way too large for production numbers alone to explain it. I know! I have found nothing else to explain the skew either. For example, improper annealing can cause decarburization of die steel, thus encouraging chips and cracks. I can find no significant difference in the annealing practices between the mints. |
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Pillar of the Community
United States
3330 Posts |
Quote:
Having looked at thousands of 2006-2025 nickel reverses per year for three years, I can spot a Denver nickel with extreme accuracy just by the surface features. They tend to have a mirror rather than a matte texture I have now received 2 other responses about the "shine" on coins from Denver. I would be interested in someone explaining in more detail exactly how that can happen. WHAT CAUSES A MIRROR AS OPPOSED TO A MATT FINISH? I know, intuitively, that die polishing might be behind it, but I don't understand precisely HOW? |
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Pillar of the Community
United States
6449 Posts |
It could be a feature of the dies. Perhaps there is a difference in the final preparation. I thought I remembered reading that the mints would plate or otherwise prepare the die surfaces to harden them and extend striking life. One thing that I can state confidently is that Denver nickels have a specific surface deterioration pattern that is different from Philly. They are much more likely to develop the melted butter ghosts on lettering—especially reverse lettering—that moves towards the center. I have sometimes wondered if Denver just runs the dies longer, but that would not explain the visibly burnished (D) vs. matte (P) appearance of the nickel surfaces.
However, it is also possible that there are minor differences in planchet preparation between Philly and Denver. I do not recall anyone mentioning the visible difference on other denominations. I will retrieve a few specimens from my weekly CRH that show the pattern.
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Pillar of the Community
United States
3330 Posts |
Quote:
It could be a feature of the dies. Perhaps there is a difference in the final preparation. I thought I remembered reading that the mints would plate or otherwise prepare the die surfaces to harden them and extend striking life. One thing that I can state confidently is that Denver nickels have a specific surface deterioration pattern that is different from Philly. They are much more likely to develop the melted butter ghosts on lettering—especially reverse lettering—that moves towards the center. I have sometimes wondered if Denver just runs the dies longer, but that would not explain the visibly burnished (D) vs. matte (P) appearance of the nickel surfaces.
However, it is also possible that there are minor differences in planchet preparation between Philly and Denver. I do not recall anyone mentioning the visible difference on other denominations. I will retrieve a few specimens from my weekly CRH that show the pattern. The mint has used PVD for numismatic {Proof} coin dies. In 2024, it was reported that "A project is underway at the Denver Mint to install a turnkey cleaning line and PVD coating system for the first time to coat work hubs with low CoF Chromium Nitride coatings." for Circulating Coins, 2024 Biennial Report, Page 8 PVD = Physical vapor deposition is a vacuum deposition method involving plasma sputter bombardment of target material to deposit thin films of that material onto surfaces (i.e., coining dies). PVD coatings are generally used to improve hardness and wear resistance. |
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Pillar of the Community
United States
8724 Posts |
Another great article, Pete. Thank you!
-makecents-
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Pillar of the Community
United States
3330 Posts |
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Another great article, Pete. Thank you! THANK YOU! I appreciate your support and encouragement! |
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Replies: 21 / Views: 493 |
Posted 05/01/2026 10:12 am
