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 Replies: 69 / Views: 6,830 |
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Pillar of the Community
United States
5964 Posts |
It's a cinch the roller or roller marks caused the color change. Still trying to figure out how. These lines were inset in the planchet before the annealing and strike. They could affect temperature of the planchet/coin? Maybe trap air/heat at strike?
Edited by CoinMasters
09/05/2015 7:19 pm
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Pillar of the Community
United States
2739 Posts |
The 2001-D dime retains original mint luster, so the odd color would seem to trace back to the Mint. Improper annealing can create this color, but not the lines. Rollers can create the lines, but not the color. But the co-occurrence of these features is far too common to be happenstance.
Error coin writer and researcher.
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Pillar of the Community
United States
5964 Posts |
I think the lines are affecting the temperature of the planchet/coin?
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Pillar of the Community
United States
5964 Posts |
Yep, the lines are adversely affecting the annealing process. Mystery solved. Enjoyed it Mike. What's next?
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Pillar of the Community
United States
2739 Posts |
I suppose one possibility is that the flames used to keep the coil of coin metal hot and malleable both change its surface color and promote the development of roller lines. Then, perhaps, the blanks are not properly cleaned of their surface oxidation layer in the chemical rinse bath. Of course, this is mere speculation, but at least it strives to connect the two seemingly disparate phenomena.
Error coin writer and researcher.
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Pillar of the Community
United States
5964 Posts |
It has to happen somehow.Improper annealing changes color, color changes often with lines, so it leads me to believe the lines affect the annealing. There is probably a flaw to that I am unaware of. Mike, I'm going to have to learn a whole lot more about the minting processes. you will probably have this one figured out while I'm doing that. I am sure there will always be some mysteries, I look forward.
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Pillar of the Community
United States
2739 Posts |
Actually, the idea that the rollers or the heating of the coin metal strip has something to do with brown and gray color of some "stripies" has a big flaw. When the blank is punched out, it should leave the blank with a normal-looking edge. But the edges of these coins are also a uniform brown or gray (even the clad ones).
Error coin writer and researcher.
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Pillar of the Community
 United States
6478 Posts |
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Pillar of the Community
United States
5964 Posts |
I was thinking the color is not just on the surface. If I had one of these coins, I'd cut it in half and see.
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Pillar of the Community
United States
6478 Posts |
I feel like that may not work depending on the method. I assume that cents are all bright red in the center, (the copper ones) and if you have ever seen a BU cent that has hints of the wood grain, they are very light and barley noticeable. For some reason, the lines get darker as the coin circulates. So I don't think that the lines would be very visible on the inside, IF in the inside.
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Pillar of the Community
United States
5964 Posts |
We're talking about clad nickels and dimes.
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Pillar of the Community
United States
6478 Posts |
dangit. I need to follow my own thread better. Lol.
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Pillar of the Community
United States
5964 Posts |
Re- read it Kid, we're working on a mystery. Three heads are better than two.
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Pillar of the Community
United States
6478 Posts |
Just re read it. I need to wrap my head around it. Ill be back in a minute with a response.
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Pillar of the Community
United States
6478 Posts |
Assuming that the sheets of metal are annealed by a flame, Possibly natural gas, before being rolled to proper thickness,
Natural gas contains hydrogen combined with carbon, when such compounds burn in air, hydrogen and carbon combine with oxygen forming - H2O and carbon dioxide respectively. H2O Condensing on the cold metal from the heat could directly affect the annealing process, because water retains heat very well. But that doesn't explain everything. Maybe the brown is cause by the carbon by product not being washed off? But then it would only appear on the side above the flame. Unless the carbon build up on the sheet of metal affects the rollers, and depending on witch side of the annealed metal goes up or down, the carbon would get on both rollers. But then why would they look the same on both sides? So maybe all this critical thinking is useless. But I support the water condensing theory directly affecting the annealing process. But possibly not. I will think more on the subject!
Edited by SilverStackerKid
09/21/2015 11:39 pm
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Replies: 69 / Views: 6,830 |
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Posted 09/05/2015 7:17 pm
