Woodgrain Surfaces and Lamination on Early Lincoln Cents 0

[ProfHaroldHill]

Both are effects of poor alloying of the coinage metal and it's not uncommon to see both effects on one coin. The 1923-S with the rim to rim flaw on obverse, has the sort of woodgrain reverse that appears at first glance to be harsh cleaning.

 

[ProfHaroldHill]

The 1921-S at bottom has only light woodgraining, but the reverse has a unique lamination at the N in ONE where the surface seems to peel away from the right upright of the N, leaving a 'new' upright in its place.

[DWLange]

This was my take on the woodgrain effect in copper and bronze coins. Bear in mind that it was written 18 years ago and may not be absolutely current in some respects (the photo of me certain is not!).

https://www.ngccoin.com/news/article/726/

[VKurtB]

The fact that the cracks are roughly in the same directions as the striations, when both are present, argues for a common cause.

[ProfHaroldHill]

2 hours ago, DWLange said:

This was my take on the woodgrain effect in copper and bronze coins. Bear in mind that it was written 18 years ago and may not be absolutely current in some respects (the photo of me certain is not!).

https://www.ngccoin.com/news/article/726/

Thanks DWLange! And this is a good opportunity to thank you for your "Complete Guide to Buffalo Nickels".

My softbound copy is the second most 'thumbed' book in my modest numismatic library, behind only Breen's Encyclopedia of US Coins, (hardbound, fell apart completely.)

I got my copy in 1994 and your "Gallery of Errors" section was amazing... a great window on errors long before the internet could provide anything like it. 

[RWB]

A series of careful spot readings with a really good XRF should show changes in alloy - if the assumptions commonly made are correct. The same for any alloy differences mentioned in Mr. Lange's article. Delamination of bronze and brass alloy is commonly traced to copper oxide and impurity inclusions in the metal, not the alloy itself.

Frankly, I disagree with the alloy theory. I suspect final planchet cleaning/whitening was the culprit.

[Moxie15]

I have wanted to respond to @DWLange since he first posted but I have delayed as I do not wish to cause trouble or to disrespect Mr Lange.

I doubt the reason he gives for the phenomenon some call 'wood grain' toning. When metals are alloyed they normally are not stirred. Many years ago I worked in a foundry for a while and they would put the metals and carbon of other 'ingredients' in a pot bring it to a desired temp for a certain amount time. I do not see how this would cause lines in the coins when it toned. I think it is caused by some other problem like impurities. I would like to ask if you came by this information from original research?

 

[ProfHaroldHill]

19 hours ago, RWB said:

 

Frankly, I disagree with the alloy theory. I suspect final planchet cleaning/whitening was the culprit.

If so the effect on the surface would have worn away before the coin's reaching EF40 grade.

The sub-EF coins shown above amply indicate the effect is within the metal, and not on or in only the surface, as would be found on coins subject to improper planchet finishing.

[RWB]

When the US mint mad

Just now, ProfHaroldHill said:

If so the effect on the surface would have worn away before the coin's reaching EF40 grade.

The sub-EF coins shown above amply indicate the effect is within the metal, and not on or in only the surface, as would be found on coins subject to improper planchet finishing.

Possibly, or maybe not.

The "wood grain" appearance is so common that the same alloy problem would have to affect hundreds of melts every year. Plus planchets were purchased from Scovill and other vendors for decades, yet the effect remains.

I think one of the above posts has a typo, also. The mints actively stirred every melt to ensure mixing. Without that the alloy metals would segregate and the ingots would be condemned - meaning it all would have to be done again.

As mentioned before - an awful lot of "coin theories" assume Mint employees were ignorant dolts, incompetent and habitual liars --- but we won't go down that dirt road.

[ProfHaroldHill]

3 hours ago, Moxie15 said:

Many years ago I worked in a foundry for a while and they would put the metals and carbon of other 'ingredients' in a pot bring it to a desired temp for a certain amount time. I do not see how this would cause lines in the coins when it toned. I think it is caused by some other problem like impurities.

 

The lines are formed when the ingots are drawn and rolled into blanking strip. The rolling is always along the length of the strip, never 'side to side', so the lines are always nearly parallel, if not parallel.

The streaks are not a form of toning, they are the structure of the metal made visible by inefficient alloying/mixing. They can run all the way through the coin.

Some make 'lines', some just display mottling.

[ProfHaroldHill]

3 minutes ago, RWB said:

When the US mint mad

Possibly, or maybe not.

The "wood grain" appearance is so common that the same alloy problem would have to affect hundreds of melts every year. Plus planchets were purchased from Scovill and other vendors for decades, yet the effect remains.

I think one of the above posts has a typo, also. The mints actively stirred every melt to ensure mixing. Without that the alloy metals would segregate and the ingots would be condemned - meaning it all would have to be done again.

As mentioned before - an awful lot of "coin theories" assume Mint employees were ignorant dolts, incompetent and habitual liars --- but we won't go down that dirt road.

I've participated in plenty of foundry pours, about 90 feet from where I now type, and I've actually studied this effect 'in depth'. (Pun intended.)

I'm always happy to post in order to help others have a broader understanding of a topic, when I can, but 'debating' the cause of a well known and very much understood metallurgical phenomena is not something that I wish to do. 

 

[ProfHaroldHill]

"Woodgrain surface" probably isn't a good term to use, but it seems to be prevalent, so I used it here. It's actually a little misleading, I think. 'Woodgrain planchet' would probably be more accurate.

Edited October 19, 2020 by ProfHaroldHill
punctuation

[RWB]

2 hours ago, ProfHaroldHill said:

The lines are formed when the ingots are drawn and rolled into blanking strip. The rolling is always along the length of the strip, never 'side to side', so the lines are always nearly parallel, if not parallel.

The streaks are not a form of toning, they are the structure of the metal made visible by inefficient alloying/mixing. They can run all the way through the coin.

Some make 'lines', some just display mottling.

Then good XRF measurement should show that. Why don't CuNi coins show a similar effect. (We'll skip the fragile WW-II alloy mess.) Having seen no data to support improper/incomplete alloy mixing, and understanding the care taken by the mints in preparing alloy I remain highly skeptical of the alloy theory.

Yes, ingots were always rolled length-wise. They were sometimes coated with lard, too. The "wood grain" samples I've seen span multiple kinds of strip treatment, but all have similar post-blanking/upsetting cleaning.