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 Replies: 13 / Views: 4,213 |
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Pillar of the Community
2087 Posts |
See this thread: https://goccf.com/t/158131Joe (badger Mint) and I met at the summer seminar. One day he showed me one of the coins he had produced and commented that he had just noticed that the bottom of the letters on the coin were swallow tailed. Why the importance of this? Well he had cut the base of those letters flat...so the swallow tailing was not by design but is an artifact of striking. For me Joe's discovery was enlightening and it told me a little more about the coins I was collecting. Going back to the coin in the link Joe stated: Quote:I notice that the letters show swallow tails only on the lower left obverse and upper left reverse. Coin rotation and slightly non parallel dies would explain that, am I close? I found the article on broad striking and bifurcated (swallow tail) letters that we discussed at the summer seminar. It is in the 1976 BNJ article titled: "Simon's Cromwell crown dies in The Royal Mint Museum and Blondeau's method for the production of lettered edges" by Peter Gaspar. To be honest I am still learning about this so I have no idea whether you(Joe) are right all I can say is it seems the most likely hypothesis. I have two coins from the same die( there are other marks on both coins that clearly demonstrate the same dies for all three sides were used) but there are differences in the bases of some of the letters and numbers:   Here's what I think based on the little knowledge I have: Both coins were struck in a screw press therefore the striking weight would vary according to the amount of force the mint works applied to the screw press arms. Swallow tailing occurs when the dies hit the blank and the metal does not "flow" to fill all of the design. Too much pressure can expand the metal away from the cavities in the die. Too little pressure just doesn't force the metal enough. In the case of the second picture I believe too little pressure was applied. These coins were struck without a collar too much force could flatten and expand the planchet. My two examples are exactly the same size so that is why I don't think too much force was used. The issue for the Maria Theresa thaler continued in the 20th century. The Royal minted referred to the effect as "Fishtailing". They were asked why some of their later coins were fish tailed. Their dies had no such fishtailing. The theory offered up by Graham Dyer ( now retired from the mint) was as noted above poor metal flow. He also noted that with MTT the edge( always struck first) often acted as a defacto collar by hardening the outer section of the blank. What was intriguing about this for me the Indian Mint ( Bombay and Calcutta) MTTs are of larger diameter than there London mint counterparts and they also have very distinctive fishtailing. In that case I think the larger diameter and fish tailing shows more pressure was used to strike the coins( the dies were all from the same master die set). A little later today I will post a picture of the base of the letters on a Paris mint MTT. I believe it shows the Paris mint faced the same issue photographs of Paris mint master dies show perfectly flat based letters and numbers. Edited by austrokiwi
09/15/2013 07:59 am
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Pillar of the Community
 2087 Posts |
Here is the photo of the Paris mint swallow tailing( the dies have flat based letters and numbers but not the coins:  London mint: actually the base of the letters and numbers closely match the dies....Suggesting to me a more technically competent striking. {I always use the date for assessing London mint strikes against potential Indian Mint examples}  An indian mint coin( stuck from dies produced from the London mint master dies. This is (my inexperienced estimation) "Fishtailing" as opposed to Swallow tailing.....I suspect Swallow tailing is caused by too little pressure and fishtailing too much pressure. Can someone comment on this?  |
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Pillar of the Community
United States
3253 Posts |
I was just thinking about the fishtail effect this morning! Specifically, did those who used these coins assume it was an intentional design element? And if so, did 19th century graphic designers then try to evoke it, thereby creating a whole style of fonts that turned an accident of physics into typographers' art? Would the logo of the Boston Red Sox be the same today, if not for the metal flow anomalies of coinage?  |
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Pillar of the Community
Russian Federation
5177 Posts |
I highly suspect that the shape of the 1 in 1780 also very possibly originally came from a similar accident. I've been seeing that shape (for the relevant digit) all over the place on 18th-century European coins, so maybe it's just normal style of the period  |
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Pillar of the Community
2087 Posts |
Interesting idea except the coins I showed the dates on were struck in the late 1930s. Here is a date ( as its a restrike the date is 1780) from 1793:  |
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Pillar of the Community
Russian Federation
5177 Posts |
Quote:
Interesting idea except the coins I showed the dates on were struck in the late 1930s That's what I thought originally: at some point in the copying process, the date was copied from an example with significant swallowtailing, and whoever copied it had no idea it wasn't intended. The shape appearing in lots of other places on 18th-century coins is a major hit against that theory however (I just looked at a Russian coin from the late 1760s, where the date was close to the middle on a busy design, and again saw the bifurcated shape of the 1). |
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Pillar of the Community
2087 Posts |
I am not sure what you mean about putting paid to theory? I have seen the london mint dies and have photos of the Paris mint dies. The London mint strike closely matches the dies design. The paris coins though are a different matter there is no swallow tailing on the dies but there is on the coins. For the 18th century. I have not been able to track down dies that I can match to coins. However a common appearance could be a factor of common technology
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Pillar of the Community
Russian Federation
5177 Posts |
Quote:
For the 18th century. I have not been able to track down dies that I can match to coins. However a common appearance could be a factor of common technology. I mean that I've seen the bifurcated 1 (though not exactly the shape on the London coin - the ones I saw had a much larger and fatter left branch) on many different 18th-century coins from all over the place (and some of these digits were located in places where they couldn't possibly be swallow-tailing, such as the middle of a busy design). So I suspect that it was actually normal style for the period. Of course, it is very much still possible, especially given the 1793 coin, that the digit on the London coin was, at some point in the restrike chain, copied from a significantly swallow-tailed example. It does look a bit like the 18th-century shape, but not entirely, and if that digit shape really fell out of use by the end of the 18th century (as the 1793 coin seems to prove), the swallow-tailing explanation might well be the only one |
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Bedrock of the Community
United States
12437 Posts |
This phenomenon is a product of radial expansion of a planchet not contained by a collar. A planchet struck without a collar will tend to expand more than a coin struck in a collar with striking pressure also affecting the expansion of an open collar strike. The best way to illustrate this effect is with the following coin-   This V nickel was struck in a collar but the planchet was triple-clipped. The collar could not contain the planchet expansion at the site of the clips so you see significant fishtailing on the peripheral devices at the clip sites but normal peripheral devices on the rest of the coin. |
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Pillar of the Community
United States
3253 Posts |
That's a fantastic picture, biokemist! Worth way more than a thousand words!
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Pillar of the Community
2087 Posts |
Wow what a brilliant example to illustrate the effect thanks biokemist6. Some of that fishtailing near the clip is a match to the second photo I posted.
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Bedrock of the Community
United States
10045 Posts |
This is one of the more interesting threads I've read in a while--well done everyone!  |
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Pillar of the Community
2087 Posts |
That V nickel really had me thinking. As I may have indicated my understanding of this effect is not great. looking at the V nickel I started to see other effects on the letters that I had seem before. Have a look at the "T" and "E" of states just under the clip and then have alook at this error coin:  You can see the swallow/fish-tailing on nearly every letter I was starting to wonder if the "IMI" error( it should read IMP) was due to poor metal flow however looking at the picture again the spacing of the "I" is to well balanced...that said look at the "T" in Theresia part of the cross bar is missing and then look at the "E" just under the clip on the V nickel. With my limited knowledge I am now thinking this coin was a light strike. I had previously assessed this coin as almost extra fine( I am a hopeless grader though) now I wonder if it is, in American terms, Mint state? What ever the grade Joes initial observation at the ANA summer seminar has really taught me something!! Edited by austrokiwi
09/19/2013 05:24 am
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Pillar of the Community
United States
716 Posts |
Great educational thread. This is what I like about this forum. I get to learn something new almost every day.  |
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Replies: 13 / Views: 4,213 |
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Posted 09/15/2013 11:53 am
