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 Replies: 12 / Views: 1,928 |
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Valued Member
Canada
53 Posts |
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Bedrock of the Community
Australia
21788 Posts |
It looks like the first steps toward an arrested lamination of the planchet, after striking.
It may well be impossible to mechanically pick these flakes off, however.
Laminations usually come about by impuritues falling on the surface of the strip of coin metal during the rolling process, then being rolled in.
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Pillar of the Community
Canada
1505 Posts |
it was somewhere in the war!!
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Valued Member
Canada
497 Posts |
I think this is what Hans Zoell called 'mortar set. The mint started to chrome plate dies in 1942 to lengthen die life. Where the chrome plating was starting to chip off, these are the resulting marks struck into the blank. This is noticeable on many coins struck during the war, another result of dies being used up to and beyond their life. 1944 50 cent with mortar set  |
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Moderator
 Canada
10458 Posts |
Another possibility is that the chromium plating on the dies was flaking off (notice that they are only on the fields, and not the devices). Hans Zoell first observed this in coins starting in 1942 (when the RCM first starting plating the dies?), and he called this phenomena "mortar set". (try a Google search on that term for coins). "Discovery follows discovery, each both raising and answering questions, each ending a long search, and each providing the new instruments for a new search." -- J. Robert OppenheimerContent of this post is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. See: http://creativecommons.org/licenses...0/deed.en_USMy eBay store
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Valued Member
Canada
497 Posts |
SPP  |
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Moderator
Canada
10458 Posts |
I guess we were typing our replies at the same time... and you were the first one to hit the <Post New Reply> button....  (at least our answers are consistent)  "Discovery follows discovery, each both raising and answering questions, each ending a long search, and each providing the new instruments for a new search." -- J. Robert OppenheimerContent of this post is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. See: http://creativecommons.org/licenses...0/deed.en_USMy eBay store
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Pillar of the Community
Canada
2632 Posts |
i agree impurities rolled into the metal..mortar set. Here's some more  |
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Moderator
Canada
10458 Posts |
You sometimes find these on George VI 1-cent coins too. So far, I have found them on 1944, 1947 and 1950 dates.
"Discovery follows discovery, each both raising and answering questions, each ending a long search, and each providing the new instruments for a new search." -- J. Robert OppenheimerContent of this post is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. See: http://creativecommons.org/licenses...0/deed.en_USMy eBay store
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Pillar of the Community
Canada
1049 Posts |
SPP, are you meaning like this one, I'm on the fence on this one at it being lamination peel or corrosion. Perhaps leaning more too corrosion?  |
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Moderator
Canada
10458 Posts |
That is corrosion...  "Discovery follows discovery, each both raising and answering questions, each ending a long search, and each providing the new instruments for a new search." -- J. Robert OppenheimerContent of this post is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. See: http://creativecommons.org/licenses...0/deed.en_USMy eBay store
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Pillar of the Community
Canada
2632 Posts |
Similar type of corrosion on this 1884 LC, but it I took a pencil eraser to it and it cleaned it up but took a long time. I was experimenting..  |
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Pillar of the Community
Canada
937 Posts |
"You sometimes find these on George VI 1-cent coins too. So far, I have found them on 1944, 1947 and 1950 dates." - SPP
I've also found them on 1942 and 1943 as well... and the inner ear "1/2 moon" clash above the large bud from 1946 shows the same effect on some coins.
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Replies: 12 / Views: 1,928 |
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Posted 01/05/2015 11:38 pm
