“Very mushy details” 1 1

[RWB]

The title is from a post on this thread: https://boards.ngccoin.com/topic/426807-1987-p-dime-possible-error/. It refers to circulation coins from the 1980s.

A useful answer deserves more than being buried in an obscure spot.

Several factors go into the visual sharpness of a struck coin. The most commonly noted are the pressure used to strike a coin, and the softness of planchets before striking. Softer planchets mean that metal flows better into recesses of dies and this increases the uniformity of relief height above the fields. Increased striking pressure has a similar result but the metal tends to recrystallize differently than with softer planchets. Visually there is little differences except under high magnification.

Before changing to clad metal planchets in 1965, the Mint Bureau did extensive testing to determine changes in processes and dies that would improve the durability of equipment. Experimentation continued over several years and one of the more significant findings was that the intersection of relief and the table (field) on a die was a critical stress point and source of metal failure. (This can be seen on Morgan dollars where die cracks often originate and connect these intersections.)

To reduce this stress concentration and thereby increase die life, the Mint Bureau made two significant changes. The first was to make the relief-to-table intersection less abrupt – that is, to smooth the curve and thereby disperse stress along a greater area. The second involved changing the slope of the sides of relief – especially inscriptions. This is the angle between the top surface of a letter and the junction with the table (field). For coins whose reductions and master dies were made before adoption of the Janvier reducing lathe, this is about 10 degrees. For coins made during the Janvier lathe reduction era the angle increases to about 15-18 degrees. Current coins, such as quarters, have a measured relief slope of about 24 degrees.

Our eyes perceive sharpness as a function of contrast. Greater contrast produces greater visual detail and a stronger perception of relief. As the side slope of inscriptions increases, more light is scattered from the shallower angle and the total contrast of a letter with the flat field decreases – making the letter look “softer” and “flatter” even if its height above the field is unchanged. Further, smoothing the intersection of relief and table (field) scatters more light, thereby reducing contrast and apparent sharpness. (The reverse of peace dollars 1922-1928 is a notable example of excessive slope.)

The effects of these, and relief alterations produce coins that are “mushy” or lack the acuity of detail that we see in older coins. During the 1980s some experimental changes were put into production with the result that much of the coinage lacked sharpness and visual clarity.

Modern die making uses machine tools, and these can change the factors mentioned above. But so far the US Mint refuses to return to more acute angles for low-mintage commemorative and NCLT bullion coins.

Edited April 30, 2022 by RWB

[RWB]

The slope on a coin alphanumerical character or design-relief edge is never zero degrees (i.e. perpendicular to the face (table). If the slope is too small, the coin will stick to a die and get smashed against the next planchet. (Ten degrees is near the minimum practical limit.) "Stickiness" is caused by changes in die steel and planchet alloy during deformation, friction, impact recrystallization of alloy, and vacuum suction as the coin tries to release from the die. The latter is a particular problem with high relief coin designs such as 1921 Peace dollars, and 1850 double eagles struck with vertical toggle presses.

Edited May 1, 2022 by RWB

[RWB]

Here is a more visually oriented approach. (Image profile diagram is exaggerated.)

At upper left is a relief image of the word LIBERTY on a current quarter. Blue indicates lower and red higher relief relative to one another. The thin red diagonal line shows were a detailed measurement was taken.

Upper right is a color image showing a selected relief measured range across the L and I, ending just before the letter B.

At bottom is the measured relief beginning just left of the L and ending just left of the B. The light blue/cyan color line is the profile. Red “Xs” mark relief height measurement points. The greatest point of relief on the letter I is 0.028mm above the field; the greatest relief on the L is 0.023mm above the field. The profile shows that the top of both letters is not flat, but irregular. Further, the letter I has greater relief above the field than the letter L. (Is this due to metal flow or die design?)

Notice the red angles where each letter intersects the field. The blue/cyan profile clearly shows broad curvature, and the outside angles are in excess of 114 degrees.

The result of these measurements is to show why modern coins look “mushy.”

 [Measurements made with a Keyence 3D Optical Profilometer, VR-6000 Series.]

Edited May 2, 2022 by RWB

[Alex in PA.]

Very interesting read; thanks.

[RWB]

This might be a clearer image of mushy details on a coin. This is the letter "I" in LIBERTY on a modern quarter. Any metal not parallel to the coin's field (table) contributes to reduced contrast and softer-looking details. Notice the irregular top surface of the letter, and the slight rise in the field adjacent to the letter. (Last photo, I promise. I know everyone's bored stiff with this.... )

Edited May 2, 2022 by RWB

[Coinbuf]

On 5/2/2022 at 1:40 PM, RWB said:

This might be a clearer image of mushy details on a coin. This is the letter "I" in LIBERTY on a modern quarter. Any metal not parallel to the coin's field (table) contributes to reduced contrast and softer-looking details. Notice the irregular top surface of the letter, and the slight rise in the field adjacent to the letter. (Last photo, I promise. I know everyone's bored stiff with this.... )

This last photo gives the best visual of what is going on, very useful.

[Hoghead515]

On 5/2/2022 at 4:40 PM, RWB said:

This might be a clearer image of mushy details on a coin. This is the letter "I" in LIBERTY on a modern quarter. Any metal not parallel to the coin's field (table) contributes to reduced contrast and softer-looking details. Notice the irregular top surface of the letter, and the slight rise in the field adjacent to the letter. (Last photo, I promise. I know everyone's bored stiff with this.... )

Im not bored of it. I found it quite useful and interesting. Thanks for taking the time to share it with us. Cleared up alot of questions I had. 

[RWB]

There are limited practical uses for this technology in American numismatics. It could be used to profile and examine overdates and repunched mintmarks, confirm doubled die coins, characterize counterfeits, produce precise and repeatable distance measurements for relief elements.

 

We already understand that so-called “Longacre doubling” was caused by a punch or logotype being struck too hard when impressed into a working die. This allowed some of the punch matrix to contact the die surface and then transfer to coins.

One small refinement now understood by direct relief measurements is that the original logotypes were too shallow for coin use. That is, the individual letters were not long enough from matrix to top surface to produce a clear impression in a die. These punches and logos were commonly made on individual contracts with outside diesinkers – only a few were by Longacre.

Edited May 3, 2022 by RWB

[VKurtB]

You know an image that might be instructive? The word LIBERTY on a TRUE 1970-S small date cent - not the large date one most collectors have in the small date hole in their albums. 

Edited May 3, 2022 by VKurtB

[Henri Charriere]

On 5/2/2022 at 4:40 PM, RWB said:

(Last photo, I promise. I know everyone's bored stiff with this.... )

Quite the contrary. Some are mesmerized by your gift of oratory. Others, like me, if we are being honest, cannot refute the claims being made, and are intimidated into silence. Great stuff! You've outdone yourself with this command performance!   

[RWB]

On 6/15/2022 at 3:16 PM, Quintus Arrius said:

Quite the contrary. Some are mesmerized by your gift of oratory. Others, like me, if we are being honest, cannot refute the claims being made, and are intimidated into silence. Great stuff! You've outdone yourself with this command performance!

Thank you!

I feel that careful application of technology can help solve any of the mysteries about coinage and about restrikes, counterfeits, authentication and many other details. However, the practical world asks for customers willing to pay for the equipment and work, maintain and archive data, and get it into collector hands with meaningful interpretations?

(Side bar -- the equipment to make the above measurements and pretty pictures starts at about $50k. This one is $70k. I don't expect any coin business will purchase this kind of thing.)

[cladking]

On 5/2/2022 at 1:35 PM, RWB said:

 

The result of these measurements is to show why modern coins look “mushy.”

 [Measurements made with a Keyence 3D Optical Profilometer, VR-6000 Series.]

It should be noted that every single date, mint mark, and denomination modern appears with very sharp strikes.  Indeed, all these changes that have been made will tend to increase the number of sharp strikes or at least to make them more likely but  most coins are sloppily and haphazardly made. Instead of making better coins they lowered standards.    Some dates are very rare with a 100% strike with the '82-P quarter being the rarest.  While the '72-D dime and quarter come with nice solid strikes the "2" of the date is rarely fully formed.  

In 1965 the mint just wanted to crank out as many coins as possible and this meant cutting corners (see what I did there), and running presses ever faster.  To assure the die shops could keep up they reduced pressure and started using dies far too long.  When production finally exceeded demand sometime in late-'67 they just never went back and fixed the numerous quality problems that had arisen with the short cuts.  They had no "customer" because collectors were ignoring all modern coins and the FED was only concerned that they could go through coin counters and be readily identified by users.  Indeed, it was this need to identify the coins that was the chief argument against all the commemoratives including the states coins and starting with the bicentennial quarter.   In 1999 when the states coins began the mint finally had real customers and quality began improving.  

People now days often don't realize just how poor quality was back in 1966.  They see a heavily worn '66 quarter without realizing that the most of that missing detail wasn't worn off the coin, it was never there to start with.  If that G were well made it would look like a VG or a F. 

 

The last part of most moderns formed is the peripheral lettering, often the "LIBERTY".  Finding specimens that are fully struck is difficult.    

Edited June 25, 2022 by cladking

[Henri Charriere]

On 6/16/2022 at 10:34 AM, cladking said:

People now days often don't realize just how poor quality was back in 1966.  They see a heavily worn '66 quarter without realizing that the most of that missing detail wasn't worn off the coin, it was never there to start with.  If that G were well made it would look like a VG or a F....

Finding specimens that are fully struck is difficult.    

Glad you've chimed in! You've hit this problem I've had with clads squarely on the head. I did not know exactly why I didn't like them!   Poor quality...This explains everything!   

[cladking]

Quote

 Poor quality...This explains everything! 

If manufacture weren't bad enough almost every coin was scratched and gouged before it left the mint.  Of course mint set coins tended to fare a little better but now days some dates of these are tarnished!

There are numerous quality deficiencies and even if you locate a pristine well made coin there can be issues with poor surface quality.  There is a tyranny of numbers with these coins because most were poorly made, almost all were put in circulation, and almost no BU rolls exist.   Most chBU's and Gems come from mint sets where finding better made coins is like shooting fish in a barrel.  About 2% (as issued) of the coins in mint sets were Gem and 25 to 80% were chBU dependent on date/ MM/ denomination.  The big difference though between clads made for circulation and those made for mint sets is die wear.  Mint set dies were swapped out after 40,000 strikes where circulation dies could be used for as many as 1,000,000 strikes or 20 times as many coins.  After 15 or 20,000 strikes coins start showing significant evidence of die wear.  

'70 quarters and '72 dimes were also very bad for mushy strikes but every date before about 1978 has these and a few after.

Edited June 16, 2022 by cladking

[CIII]

Fascinating stuff.  

[Henri Charriere]

[Hard to believe I have been bad-mouthing clad coinage for over 50 years without understanding why.  Thank you @RWB and @cladking for clarifying matters!]

[cladking]

Another culprit is the penny.  

It became less than worthless in 1974 which resulted in enormous attrition and soaring mintages which remain high to this day.  Partly it's that people won't bother to take pennies back to the bank but more is that we won't even bother to retrieve them when dropped; they simply aren't worth the effort so many end up in the garbage stream.  Mintages ramped up even higher as the mint converted to zinc and the loss on each one dropped in 1982.  These huge mintages necessitated that the mint produce more dies and that they operate the presses ever faster.  This speed doesn't allow time for the metal to fully fill the die.  When you see a very mushy '66 quarter it is largely caused by the coin shortage and the '80's and '90's issues by the speed needed to make pennies.  They could have bought more presses that wouldn't fit in existing facilities or they could speed up the presses.  They chose the latter.

Not only were the mint sets made with old style presses and new dies but they were made at lower speeds allowing more die fill and more sharply struck coins.   

What I find truly remarkable is how quickly these dimes from the '80's have been disappearing the last dozen years.  Attrition on heavily worn coins is only slightly higher than on brand new ones but the attrition on dimes is soaring.  It's largely the fact that dimes have little purchasing power but by weight they are about the same as quarters which are not faring as poorly.  Perhaps it's as simple as people knowing a quarter makes too much racket in the vacuum cleaner but a dime gets sucked up cleanly.  I just don't know why the rates are diverging so sharply or suddenly.  Quarters have always been the workhorse but even quarters are far less useful than they were 20 years ago.  

[Henri Charriere]

[I live hard by the poorest Congressional District in the nation, which embraces a swath of the South Bronx and upper Manhattan. When I make a purchase producing negligible change, I usually give it back to the proprietor and tell him, Here, this is for all the people who come up short, those who are beggars, and the like. He is always appreciative and gives me a knowing glance. Most appear to be of Yemeni origin.]

The future does not bode well for the coins now in wide circulation.