Exploring the theories of "Orange Peel"...

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RogerRock
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Re: Exploring the theories of "Orange Peel"...

Post by RogerRock » Wed Apr 29, 2020 12:59 am

The "Orange Peel" shown on the proof coins pictured is a planchet issue! The devices show no effect of
the dimpled surfaces that cover the field. IMHO
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messydesk
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Re: Exploring the theories of "Orange Peel"...

Post by messydesk » Wed Apr 29, 2020 1:49 am

I wish they hadn't used that term. The cause of this on those two coins is, as discussed, not what we know as "orange peel" on other coins -- severe die erosion. It would be interesting to examine these to see if there is any loss of detail to go along with the funny fields, as there is on business strike orange peel coins. Another thing to note is that the fields still appear to be mirrored, and the first thing to erode on a die is the mirrored surface.

The actual cause may be a collapsed die. The same $10 sold at the CSNS auction in an NGC PR65+* holder, where the characteristics of a collapsed die show a bit around the date. The upgrade brought an additional $1200 all in, so the crackout artist probably lost on this one.

I took a look at John Dannreuther's two-volume Volume IV on proof coinage to see what he had to say, and he made no mention of it under either 1898 coin, and only noted one die state. The pictures shown also didn't have this effect. One coin shown on PCGS CoinFacts seems to, and I did see other issues that showed this effect to a lesser degree. Another thing was that if I understand his notations correctly, the proof mintage of 75 eagles was struck in four separate runs, although that might not mean anything.
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vampicker
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Re: Exploring the theories of "Orange Peel"...

Post by vampicker » Wed Apr 29, 2020 1:56 am

Ten years or so back I watched Chris Pilliod give a presentation on this subject. He had access to a scanning electron microscope and got fantastic images in exacting detail. Whatever the cause, it affects the fields and stops dead at the devices.
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messydesk
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Re: Exploring the theories of "Orange Peel"...

Post by messydesk » Wed Apr 29, 2020 2:08 am

Sort of like this, but this has a halo around the devices. Different striking pressure and speed, though.

1881-O VAM 16 (PL reverse)
Image
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Longstrider
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Re: Exploring the theories of "Orange Peel"...

Post by Longstrider » Wed Apr 29, 2020 3:09 pm

Not to be a smart ass🐍 Sorry.🐍
Last edited by Longstrider on Wed Apr 29, 2020 3:36 pm, edited 3 times in total.

vamsterdam
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Re: Exploring the theories of "Orange Peel"...

Post by vamsterdam » Wed Apr 29, 2020 3:31 pm

I do not see this a planchet issue on the gold coins in the article. those flat mirrored surfaces would flatten out planchet issues. and proof planchets are not made one side at a time. I have , or have had, lots of planchets, proof and business strike and they are very baggy and not too pretty. proof planchets usually are much nicer, due to being tumbled with small pellets that makes them more uniform. I showed chris pilliod a vam or two with these crazy surfaces. he could not give me a definite answer. I think I showed him 1883o vam 1c, and 1889o vam 13b.

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Re: Exploring the theories of "Orange Peel"...

Post by RogerB » Thu Apr 30, 2020 3:50 am

At the risk of warping space-time, I present the following for whatever help it might offer in understanding the various “orange peel” – or whatever citrus you might prefer – effects. Be glad it not nicknamed "pineapple pimple."

“Orange Peel” Effects

Examination and very limited testing done a few years ago indicates that "orange peel" as shown above and on several varieties, and the rippling effect seen of some proof coins have similar causes. Differences in appearance are attributable to severity and not to completely unrelated processes.

First, this is a die defect. Planchets have no impact on what is visible.
Second, proof coin field rippling will gradually subside with use, unless there are other production difficulties. Circulation coins, with their more pronounced surface irregularities typically become rough and shed planchet and die particles that further damage the die.
Third, there are two interdependent causes to the resulting appearance. If either are missing, the die (and coins) will look normal.

Background

All coinage dies go through a multistep manufacturing process. The final steps include multiple cycles of pressing (squeezing) against a hard steel hub followed by heat annealing (softening) to reduce die hardening caused by the hub impression. (This is commonly called “work hardening.”) It can take up to 9 squeezes from a hubbing press to complete image transfer from the hub to a silver dollar working die.

Following the final transfer squeeze, a die is annealed again so a mintmark can be added and the surface lightly smoothed to remove burrs and other defects caused by metal fatigue, slippage and topography alterations inherent in heat treating steel. The soft die face is then dipped in dilute sulfuric acid to remove any oxidation products, oils and other debris.

If the die is planned for proof coin use, the surface is given a preliminary semi-polish to further smooth the surface in preparation for final mirror-like polishing. This is very light and by itself has little effect on final appearance of a proof coin.

At this point we have a die ready to use except for final hardening and tempering. It is here that “orange peel” can occur. Hardening and tempering are heat treatment processes that require careful control of time, metal temperature and atmosphere. If a die were simply hardened, it would be excessively brittle. Crystal structures would be large and prone to sudden deformation – sometimes under far less external force that needed to strike a coin. (I know – the metallurgists out there are having “conniptions,” but readers are not specialists, so hunker down for the ride.) To relive some, but not all of the brittleness, the die must be cooled and tempered – again a heat treatment that demands very close control. If tempering fails, the die will be either too brittle or too soft for use.

Orange Peel
The 19th century practice was to do polishing or other surface treatment on soft steel, then harden and temper; this would “lock-in” the surface. But due to irregularities in steel alloy content and uniformity within the metal, hardening could also distort the surface, including the radius of curvature (i.e., “basin”) of a coinage die. The solution was to bring only the face of a die to heat, then re-surface and finally temper the full die. This was a manual process requiring skill and experience.

It is here, in the middle of these final steps, that “orange peel” is created. The extreme effect, as clearly seen of certain Morgan dollars such as 1883-O VAM 1c or 1889-O VAM 13b. The problem is created when an assistant where the tempering is done attempts to rebasing a die but uses too much pressure on the abrasive basin disk against the die. This causes parts of the incompletely tempered die field to flow and warp in a characteristic manner shown in several photos mentioned above. The field is affected only in places where tempering is uneven and is prominent next to the much harder edges of sunken relief in the die. Similar surface deformation is encountered under analogous conditions in steel tool and die manipulation and polishing.

Orange peel on proof coins, in its more accurate analogy with citrus fruit outer texture, is also caused by excessive pressure by a rotating polishing tool. It occurs when an assistant tries to work too quickly and unintentionally produces a gently irregular rippling surface. This is both mirror-like in detail (from the jewelers rouge or other very fine polishing grit), and irregular in surface height. Mirror-like polishing exaggerates the visual effect.

If either poorly controlled hardening and tempering, or excess abrasion pressure are absent, the range of “orange peel” does not appear.

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Re: Exploring the theories of "Orange Peel"...

Post by vamsterdam » Thu Apr 30, 2020 8:04 pm

Hmm. So this explanation isn’t too far from Leroy’s concept of an overbuffed die. Since i am a very visual learner, i think I’d need to see a visual tool to figure this out. It could aee this explanation as to why part, but no t all of a die dhows chipping, and distortion. It always affects the fields and sometimes stars, but really doesn’t affect other devices.

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Re: Exploring the theories of "Orange Peel"...

Post by messydesk » Thu Apr 30, 2020 8:27 pm

What the "overbuffed" explanation doesn't seem to account for on many of the Morgan reverses is the halo around the devices. On the dies, this would be a raised ridge, which should be the most vulnerable to rebasining the die, yet it survives this process.
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RogerB
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Re: Exploring the theories of "Orange Peel"...

Post by RogerB » Thu Apr 30, 2020 10:32 pm

The "halo" is one of the possible results. This is well known by makers of hi-end silver serving pieces and engraved ware.

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Re: Exploring the theories of "Orange Peel"...

Post by RogerB » Sat May 02, 2020 1:21 am

One small addition that might clarify this for readers.

Washboard Road Peel
Here’s a real-world analogy. The mechanism is not completely identical, but the mechanical factors producing the observed result and similar. “Orange peel” is created much like a washboard road. Every road, regardless of composition or age eventually develops a rippled, irregular surface: dirt, gravel, residential asphalt, concrete, or deep-footed German autobahn – doesn’t matter. The controlling factors are pressure, abrasion and repetition.

For a die, pressure equals force from the operator; abrasion is the grit and shape of emery; repetition equals the rapidly rotating basining or polishing disc.

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Unc90o
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Re: Exploring the theories of "Orange Peel"...

Post by Unc90o » Sat May 02, 2020 8:01 pm

In reading the Background portion from Roger’s post; for circulation coinage (not proof coin). In my opinion, it sort of offer explanations for the overbuffed or halo effect. We know that not all dies were made perfect back then and some has metal impurities. Using 1881-O VAM-16 as an example.
Following the final transfer squeeze, a die is annealed again
At this point, the die is soft and the metal impurities is weakend.
…and the surface lightly smoothed to remove burrs and other defects…
Here, the metal crumbled around the edges of some devices. I’m no metallurgist, but I think the area around the edges (a cliff if you will) are most vulnerable to break apart.
…The soft die face is then dipped in dilute sulfuric acid to remove…
This process then smoothed the crumbled areas to what we’ve seen or called as overbuffed.

Again, just my thought.

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Re: Exploring the theories of "Orange Peel"...

Post by RogerB » Sun May 03, 2020 2:02 am

Interesting thoughts. Yes, there are really multiple things happening at the same time which create the distortions noted on coins. My short comments are a vast over-simplification of a complex chain of interrelated events.

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messydesk
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Re: Exploring the theories of "Orange Peel"...

Post by messydesk » Sun May 03, 2020 2:03 am

Here's Chris Pilliod's article on the subject.
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blh74
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Re: Exploring the theories of "Orange Peel"...

Post by blh74 » Sun May 03, 2020 3:37 am

Maybe I`m not getting it. Wouldn`t the high pressure of the die smooth out the problem?

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Re: Exploring the theories of "Orange Peel"...

Post by RogerRock » Sun May 03, 2020 4:52 am

Just read Chris Pilliod's article about "Orange Peel" on proof gold coins (1881 $5).
The reference to grain size of gold metal becoming greatly enlarged due to overheating during
annealing stage of planchets is very interesting! According to Chris Pilliod's analysis, the "orange peel"
exhibited on the coin (1881 $5) was not a die feature. "It was property of the planchet."

I stand by my original statement that the "orange peel" on the proof gold coin pictured is a planchet
issue! :roll:
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vampicker
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Re: Exploring the theories of "Orange Peel"...

Post by vampicker » Sun May 03, 2020 1:59 pm

While they look similar, the stuff we see on Morgans and gold proofs are two different things. The weird crumbling on Morgans is in the die - it reproduces the same pattern on all examples at a similar point in the progression.
It's different on the gold we're talking about. Here's 3 examples of the 1898 $5 proof from the same Heritage auction. Reported mintage of 75 pieces from one die pair. Take a look at the reverse on each. The pattern in the fields differs on each example.

https://coins.ha.com/itm/liberty-half-e ... ion-071515

https://coins.ha.com/itm/liberty-half-e ... ion-071515

https://coins.ha.com/itm/liberty-half-e ... ion-071515
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RogerRock
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Re: Exploring the theories of "Orange Peel"...

Post by RogerRock » Sun May 03, 2020 3:45 pm

vampicker wrote:
Sun May 03, 2020 1:59 pm
While they look similar, the stuff we see on Morgans and gold proofs are two different things. The weird crumbling on Morgans is in the die - it reproduces the same pattern on all examples at a similar point in the progression.
It's different on the gold we're talking about. Here's 3 examples of the 1898 $5 proof from the same Heritage auction. Reported mintage of 75 pieces from one die pair. Take a look at the reverse on each. The pattern in the fields differs on each example.

https://coins.ha.com/itm/liberty-half-e ... ion-071515

https://coins.ha.com/itm/liberty-half-e ... ion-071515

https://coins.ha.com/itm/liberty-half-e ... ion-071515
Thanks for pointing out the direction of the original post about "Orange Peel" on Proof Gold Coins!
It seems difficult to focus vammers on off topic denominations!!
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