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 Replies: 24 / Views: 3,255 |
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Moderator
 United States
56855 Posts |
What Pete said. John1  |
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Bedrock of the Community
United States
62064 Posts |
Pete2226 has the correct term. "linear plating bubble." But the term "gas bubble" is used on Mike Diamond's site: http://www.error-ref.com/gas-bubbles/But note on his examples they are rounded in shape. (like a bubble) |
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Moderator
United States
23522 Posts |
Quote:Would this be a case of Feeder Finger Damage? I think it's too straight and long to be a gas bubble. Feeder Finger Damage ought to look more like a "polished" area on the coin, because that's what feeder fingers do. They're flat, like a feeler gauge, and rub the die rather than gouge it in most cases. |
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Pillar of the Community
 United States
5964 Posts |
It doen't seem to fit any of the categories. The "chip" looking part is solid, it's not going to pop or anything. Could it be a series of linear plating bubbles with a coincidental chip? It goes nearly rim to rim, and seems to branch off at each end. It's odd.
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Moderator
United States
23522 Posts |
A search of this forum for the term "linear plating bubble" will clear up any doubts. This is not exactly the first one we've seen.
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Pillar of the Community
United States
5964 Posts |
Thanks, it is my first linear plating bubble. That search option is pretty neat. I also learned it can go over features, where a crack or gouge doesn't because they don't penetrate the die that deeply.
I am going to assume if it wasn't in a "line", it would merely be a plating bubble.
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Moderator
United States
23522 Posts |
Underneath the copper, the zinc sheet stock is likely to be striated from being rolled out. When you consider that the copper cladding amounts to 2.5% of the total weight - kinda high for a thin layer - you can see they planned on the copper helping to smooth that out. It's easy to imagine a bubble following a striation, as you can see on this coin.
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Pillar of the Community
United States
5964 Posts |
Yes I can see that easily indeed. It's actually an air bubble isn't it? I know air is gaseous.
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Moderator
United States
23522 Posts |
It's like this: Zinc is a popular material under the correct installation circumstances for architectural cladding, roofing, ornaments and stuff. Here's a quote from a major producer of those materials (bold mine): Quote:
There are no issues with zinc in combination with metals other than copper and mild steel. When zinc contacts copper in the presence of an electrolyte (such as water) a galvanic reaction will lead to corrosion of the zinc and subsequent failure of the roof or wall cladding. Run-off from a copper surface to a zinc surface must be avoided under all circumstances. We're building our coins from that combination. And people wonder why I am constantly disparaging Zlincolns? Collect them if you want, but they won't last to pass on to your heirs unless you seal them air tight. One nick in the coating, exposing the zinc, and that coin is done. |
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Replies: 24 / Views: 3,255 |
First Page
Posted 04/14/2015 11:30 am
