Die Breakdown. What causes the marks you see on coins?

Hey gang!

As most of you know I bought a big lot of old dies used to make tokens in the 20's and 30's. I began examining these dies for things that could translate to collecting denominated collector coins.

Die wear is one of the things that I find it hard to grasp. Used long enough all dies will fail.

Example #1 is a die crack. I have used silly putty as my "planchet" to show what the translation to a strike would be.

 

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#2 Radial Die Crack and heavy die polish/lines.

 

#3 Die Cracks and rim cud.

 

#4 Recut Letter

 

Doug,

If you look at the blow up of example #1 you will see crossing lines. I do believe you are right however that some other cleaning/polishing(?) method would have been used on these dies to cause these lines. These look to be done by hand.

 

Matt

Those are great pieces.

Thanks for posting

 

In Margolis and Weinberg's Book, The error coin encyclopedia, in the section on die polishing, it mentions

When the die is found to produce defective coins due to a die clash, clog, or fill, the press is stopped and the die is cleaned. The cleaning process will often result in a slight change to the die.
In one operation, a brush with strong wire bristles ...which will not bend or flex,The mint technician actually apply the brush to the die face and works it up and back....which may leabe fine scratch marks on the face of the die, This is considered acceptable and the die is put back into service. Until it wears down, the coins struck by that die will contaon fine raised lines in the fields. p.305

In case of clash indentations or more severe cases, they say

I have many coins with die polish lines that do criss cross and not in arcs, that I have no doubts are mint produced. The book noted above has many photographs of mint die preparation, and the only "circular" devices are the grinders they use to make each die Exactly the same height by bunch grinding a group of them on the bottom so the face is not touched.

I do think you are wrong on your statement of no criss-cross and always circular arcs on die polish lines, at least on circulating coins and they are implied to be made by straight line tools and by hand. IMO.

Jim
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I personally don't think that brushing a die with a brush would constitute a polishing... More of a cleaning in my book. I don't think a wire brush by hand will make die steel bright and shiny. Only a heavy duty mechanical polish can do that. It seems that we all have the same idea about what causes the crossing lines we just use different terminology when describing it.

 

I agree. Here's a found-in-change coin that came from dies that had some significant "maintenance".
Lance.

 

Very informative! Thanks for posting the dies.

 

"D) The die finishing lines on this coin are extensive, peculiar and fascinating. Indeed, they are deep, varying in dimensions, and very entertaining. A glass with at least ten times magnification is needed to thoroughly enjoy them, though many are apparent at three times magnification.


When metal brushes and other tools impart lines in the dies, or sandpaper-like patches, raised lines and bumps appear on the coin that is struck with such dies. There are areas on the coin that indicate that portions of the dies were unusually treated such that patches of small, raised shapes resulted.


On this coin, there are an astonishingly large number of die finishing lines, of varying lengths, densities and angles. In some areas, the die finishing lines are somewhat parallel and are spread apart. In other areas, they are close together or even lumped. Many die finishing lines on this coin crisscross. Some die striations are much higher than others (thus in greater relief); some are wider; some are shorter.

Yes, there are many die finishing lines on a large number of Proof Three Cent Silvers and on an even larger number of business strikes. Indeed, die finishing lines are often found on Three Cent Silvers. The groups, patterns, shapes, and variations of die finishing lines and other die treatment evident on this coin, however, are dramatically different, especially when the overall fabric of the coin is contemplated.
I cannot fully explain the fabric of the Eliasberg 1851 Three Cent Silver. There are factors that cannot be articulated.


The individual or group that polished and otherwise treated the dies used to make this coin seemed to have had a great deal of fun. Areas on the dies corresponding to portions of the coin were given different treatments, including differences of degree and differences ‘in kind.’ The result is very cool."
http://www.coinweek.com/featured-ne...ics-the-most-valuable-three-cent-silver-coin/

 

I'm just happy you agree with the coinweek article excerpt I've been plastering in related topics. I can adapt and start using the term "Die Finishing Lines", if you can.

 

Perfect. You win. We'll do it your way. Die Finishing Lines.

 

Is it not possible that the orientation of either coin or the tool was changed to result in crossing polish lines?

 

Alberto-Morell-Philadelphia-Mint-Buffer-Polisher