"Wood grain" tarnish on Lincoln cents.
RogerB
Posts: 8,852 ✭✭✭✭✭
So-called wood grain toning seems common on some Lincoln cents. Most comments about it claim the cause is improper mixing of copper, tin and zinc.
Is this more commonly seen on coins from certain years or mints? Have there been any objective, modern tests ? If it is improper mixing, has anyone explained how this can occur so widely yet at the small spatial scale seen on cents?
Just curious.
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Most common on S-mint cents 1908-on.
I don't know but I think they are cool looking not as nice as some Lincoln's around, But must of been a problem back then as well.
Hoard the keys.
It is found on all copper coins (see above) but mostly on early lincoln's. Then it trails off until after the war years when the brass from shells (the story goes) was used. IMHO these are the most attractive for now as the brilliant red copper has brilliant yellow streaks.
My favorite copper coins are those coins - mostly Indians - that are brown with "blocky" brass-colored crystalline inclusions in various patterns rather than "streaks."
Very helpful. Source of copper - absent significant impurities - night be immaterial. Shell case brass was melted, copper added and the total alloy the same as in 1942.
Has anyone analyzed the "brassy" spots, or differences between colors? (To me, this should be something of considerable interest toTPGs and authenticators.)
I picked this up at a local dealer for six bucks because I thought it was a wood grain. Was I wrong ?
Michael Kittle Rare Coins --- 1908-S Indian Head Cent Grading Set --- No. 1 1909 Mint Set --- Kittlecoins on Facebook --- Long Beach Table 448
Not just on U.S. coins...
Michael Kittle Rare Coins --- 1908-S Indian Head Cent Grading Set --- No. 1 1909 Mint Set --- Kittlecoins on Facebook --- Long Beach Table 448
Sooo....it affects copper alloys such as brass and bronze?
Correct.
I'll set a reminder to break mine out Wednesday when renovations are done.
Photos courtesy of @robec
Love this one. Looks familiar!!
Jeff
I had my fun with it. Sold it recently.
Lance.
Knew I'd find at least one..
https://forums.collectors.com/discussion/993566/show-off-your-wood-grain-toned-ihcs
???
Successful transactions with : MICHAELDIXON, Manorcourtman, Bochiman, bolivarshagnasty, AUandAG, onlyroosies, chumley, Weiss, jdimmick, BAJJERFAN, gene1978, TJM965, Smittys, GRANDAM, JTHawaii, mainejoe, softparade, derryb
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It also seems to be fairly common on 1908-S and 1909-S Indian Cents.
Frankly I don't care for the look because it distracts from the design in my opinion.
It would be interesting to see a metallurgical analysis of these coins... I do suspect it has to do with the alloy and could (if such records exist) be traced to the source of the copper sheets. Cheers, RickO
The linear appearance of color banding suggest to me something related to ingot rolling, or more likely, the finishing rolls. At present, the location/date distribution of samples posted here, on the various links and elsewhere argue in favor of some part of the actual coining operation as the cause. I think alloy mixing is probably not involved - if it were, we should see a consistent result and distribution.
Even MPL's weren't exempt from the woodgrain appearance.
PR65RB
- Bob -
MPL's - Lincolns of Color
Central Valley Roosevelts
We do...Mostly early Lincolns. Now I'm not going to argue with anyone but the folks at the U.S. Treasury Dept. Office of Technology during Dr. Hunters employment told the ANACS guys in DC that this characteristic (the coins with streaks - "woodies") was caused when the melt was not homogeneous. Then, as the ingots are rolled out the visible discoloration is stretched out.
Unfortunately, at the time, I was not aware of the blocky crystalline patterns mostly found on Indian cents so all I can add, IMO, is that these patterns occurred inside the ingots as they cooled. The "woodies" are like stirring Dark & white ice cream leaving swirls in the ingot. The crystal pattern occurs throughout the entire ingot. I'll need to dig one out and post an image as they are my favorites.
I just can't wait until Wednesday to dig mine out. The purple streaked one was my first 55-S that I got at a show on the east coast when I was 10. It used to be bright and shiny. I didn't notice the grain effect until it toned 30 years later give or take.
None of my examples are ultra 70 etc etc but are pretty cool. IIRC, I have a partial Whitman of them. I'd love to see you folks post some more!!
My type of alloy beauty...
Good information TD!
I love "woody" Lincoln's. I tend to buy them almost every time I come across them. Here's the most colorful "woody" I've come across. It's a '55-S, and it actually looks this way in hand. The yellows and reds with magenta is just incredible. The reverse shows a little bit of the streaking, but nothing like the obverse.
I have been saying for 20 years or more that the woodgrain comes from improperly mixed alloy. More tin and zinc and you have a brighter planchet, going towards brass. Less alloy and you have the darker stripes. A nodule of alloy difference would form into a stripe when the ingot is rolled out. However, I always thought this was common knowledge and didn't need testing. I guess testing alloy differences would be worthwhile, but I doubt it would change the conclusion.
The images of the 1897 cent that @insider2 posted is orange peel, not woodgrain toning. Orange peel comes from annealing the planchets at too high a temperature, perhaps using the same temperature used on silver or nickel. The grain size is much larger at the higher temperature.
Here's a 1909 I found not too long ago. The obverse and reverse are both affected. The reverse actually has some de-lamination happening around the N of CENT in the same direction as the stripes. I think this would help with the improperly mixed alloy theory.
Roger. I have a business strike Franklin with streaks very similar to a Lincoln woody so I had a friend XRF it thinking that if it was it should have more copper and less silver in it. IIRC it was only somewhere around 87% silver. I have shots of the coin and the XRF readout somewhere. I can post them if you like, if I can find the files..
@EagleEye said: "The images of the 1897 cent that @insider2 posted is orange peel, not woodgrain toning. Orange peel comes from annealing the planchets at too high a temperature, perhaps using the same temperature used on silver or nickel. The grain size is much larger at the higher temperature."
As I wrote, I never got to ask the folks who make the coins at the mint or the ones who test the coin is DC about this part of your post. Interesting and may be true.
This is not: "The images of the 1897 cent that @insider2 posted is [called ?] orange peel..." "Orange Peel" is an over forty year old term ONLY used to describe the "plate-like" surface found on Proof Gold coins. Perhaps, some Johnny-come-lately (not you Rick) has usurped the term in error. Heat is definitely involved but the cooled crystal pattern looks nothing like the skin of an orange or any other fruit.
Not just on small cents either:
- Jim
Segregation of silver alloy was well known at world mints in the 19th century. Each had creative, practical ways to deal with it for coinage.
All US cents from about May 1942 forward have had only a trace of tin in them.
XREF can be very helpful but it has to have sufficient resolution to read areas of different color that create the wood grain effect. (At least it's not "knotty pine!")
This article is posted here
Actually it is a metallurgical term. Still in use.
@EagleEye
Thanks for the article, I cannot wait to read it. As I suspected, the term was usurped long after its established usage FOR PROOF surfaces. I already see an image (similar to my post) that is not.
You and Chris will be worthy adversaries with much more knowledge about metal that I'll ever know. Thus, I think all of us will enjoy more from you two and hopefully others will join in.
My goal here is to confine the use of "Orange Peel" terminology to proof surfaces. I'm less interested in what causes it but I cannot wait to learn.
I do know one thing for sure, the coin I posted with the crystalline patterns does not have an "orange Peel" surface in any sense of the term.
Do coins with slippery surfaces have a "banana peel" effect?
The conclusion is that it is a property of the planchet, not the dies.
You see it on proof surfaces because the mirrors bring it out more. The "watery" surface is the grain size of the planchet metal and is not at all associated with the die.
This seems reasonable. Still need to read the article. Until then I did some research. This was posted from an old CU thread by another member:
Here’s Rick Snow’s (Eagle Eye Rare Coins - he specializes in Indian Head Cents) description as to how this occurs:
“After the dies are hubbed and the date is applied, the die is given multiple polishes with progressively finer and finer polish. The last polish given to the dies prior to being hardened gives the field a surface quite like a mirror. This is the deepest mirror attainable on the dies. When the die is hardened, the metal shrinks slightly creating a wavy effect on the polished surfaces. It looks somewhat like the surface of an orange. When you see orange peel on a proof issue you can be sure that it is one of the first examples struck from those dies. Later polishing to the already hardened dies will produce a flatter and shallower mirror."
"I would add that the dies don't have to be re-polished for this look to disappear - after the first few coins are struck, the metal to metal contact from the striking process has its own "polishing" effect and the waviness is minimized to the point where it is no longer visible on the struck proofs. (The same is true regarding the Cameo look of the first struck coins: after successive strikings, this cameo looks disappears, I believe due to the die wear that has initially "polished" away the "roughness" of the recessed devices of the coin die and perhaps also the filling of the recessed portions of the die with dirt, dust, oil, etc. that would tend to minimize the "cameo frost" on the struck coin."
So we probably will not disagree much except for the usage of the term "Orange Peel" and whether it results from the dies or the preparation of the planchet. I hope Mr. Carr can do an experiment for us.
Wow I love copper. There's a ton of info in this thread too. I think this one is attractive
That's what I thought until I realized that silver and nickel coinage do not exhibit the Orange peel. If the theory doesn't fit all cases, then it is wrong.
We'll both be away this week so I'll leave you with this as I still have not decided what causes the TRUE "Orange Peel" surfaces on copper and gold proofs.
When a coin is made the planchet touches the obverse and reverse dies (and the collar). The die is the only thing that affects that particular planchet. What you and others believed before is the treatment of the die caused this characteristic (OP) to be imparted to the Proof surface until the die was refaced or the OP was worn off the die.
Now it seems you believe that the OP is a characteristic found on the planchet before striking and is due to the way the planchets are annealed.
Here is a question for you and Chris: If we examine the total production of a group of Proofs then ALL OF THEM SHOULD EXHIBIT OP for the entire run UNLESS I'm to believe that the planchets for the group were annealed in small batches so that some became more OP than others with no OP. I'll bet you've seen a lot of cases where Proof Indians had no OP at all!
As I posted before, this should be easy to prove one way or another by the folks at any government or private Mint.
Anyway, we both know "Orange Peel" when we see it. The block crystals on the coin I posted cooled out of the melt. They are uniform and completely level to the field. There is no roughness and NO ORANGE PEEL TEXTURE!
Another proof.
Years ago, I attempted to complete a set of Indian Head Cents with woodgrain finish. I nearly completed it before illness overtook my collecting expenditures and I had to sell them. I purchased many of them from Rick Snow. Here are a few of them.
Jim
When a man who is honestly mistaken hears the truth, he will either quit being mistaken or cease to be honest....Abraham Lincoln
Patriotism is supporting your country all the time, and your government when it deserves it.....Mark Twain
I guess to test whether OP is on the die and not the planchet you would have to find repeating OP on two coins from the same die.
So far I like a lot of what I've read. We are going to get to the bottom of this. When metal cools, I believe that the slower it cools the larger the crystal matrix, so I'm thinking that copper and gold planchets may have been prepared differently than those of silver if this characteristic is due to the planchet.
Again, any active Mint superintendent could answer this with examples.
It is not that the planchets were annealed differently, it is that the bronze and gold planchets require a lower annealing temperature and were annealed at the same temperature as the silver and nickel planchets.
The new book by John Dannreuther on Proof gold acknowledges Chis's research.
Orange peel on copper?
Is it correct that no one here is aware of metallurgical analysis having been performed on wood grain bronze or copper coins? Specifically on the alloy differences between areas of different color?
@EagleEye said: "It is not that the planchets were annealed differently, it is that the bronze and gold planchets require a lower annealing temperature and were annealed at the same temperature as the silver and nickel planchets."
I see, The planchets WERE annealed differently than they should have been.
@RogerB said: "Is it correct that no one here is aware of metallurgical analysis having been performed on wood grain bronze or copper coins? Specifically on the alloy differences between areas of different color?"
What's the point. We know the metals that the Mint used to compose the alloy. When they did not mix properly, to exhibit a single uniform color, they each retained shades of their normal color as pure.
PS I'm confident that JD does not misuse the term "Orange Peel" in the book.
RE: "What's the point. We know the metals that the Mint used to compose the alloy. When they did not mix properly, to exhibit a single uniform color, they each retained shades of their normal color as pure."
Actually, we don't "know" that. Where is the empirical data? Why speculate when the technology is available to collect data? (Color is unimportant; it is a by-product of chemical composition - and that is the fundamental question.)