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Author Topic: Ancient flans - hot or cold  (Read 2662 times)

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Offline SRukke

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Ancient flans - hot or cold
« on: April 01, 2020, 08:42:34 pm »
Is there consensus on whether flans were struck hot or cold? Up for debate?
Does it depend on the alloy?

All these thoughts while being quarantined.

Offline Robert L3

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Re: Ancient flans - hot or cold
« Reply #1 on: April 01, 2020, 09:04:17 pm »
Are you familiar with the article that deals with this topic/debate in the August 2011 issue of The Celator?: http://community.vcoins.com/celator-vol-25-no-08/

(For anyone who may link to the issue and read the article, it's worth mentioning that a few months later, in a subsequent issue of the magazine, editor Kerry Wetterstrom pointed out an errata in the "cold striking" article from August. He apologized for the the collaged image of the ten strikes that appeared in the article. As he stated it in his October "Editor's Note, "there was supposed to be an illustration of 'ten different examples of coins that were struck cold, from throughout the striking process.' Well, coins 3-10 were the same coin. Mea Culpa!" The correct image, showing all ten different examples of cold-struck coins from the modern dies, was then shown in the November issue, on page 4. That volume is here: http://community.vcoins.com/celator-vol-25-no-11/)



Offline SRukke

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Re: Ancient flans - hot or cold
« Reply #2 on: April 01, 2020, 09:18:06 pm »
I've read a few articles but not this one. Thanks

Offline Jay GT4

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Re: Ancient flans - hot or cold
« Reply #3 on: April 01, 2020, 10:28:22 pm »
A great article.  I've talked to Robert Kokotailo at length about cold striking, or rather he has talked to me.

Offline TenthGen

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Re: Ancient flans - hot or cold
« Reply #4 on: April 02, 2020, 02:42:59 am »
Very interesting! I actually had never even considered that ancient coins might be struck hot. I always assumed that they had bags or trays of cold blank flans around. I'm glad someone had the idea to test it though! It's pretty good experimental evidence that cold striking would have been more efficient with only a small drop off in quality. I'm not immediately aware of any direct evidence or ancient literary accounts that favor either option though.

Offline Altamura

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Re: Ancient flans - hot or cold
« Reply #5 on: April 02, 2020, 05:09:46 am »
Interesting article, but without a single reference to others  ???

In one of the basic books about ancient minting technology by Hasso Moesta and Peter Robert Franke, "Antike Metallurgie und Münzprägung", Basel 1995, this topic is already discussed. They conclude that there is a difference between silver and gold on one side and bronze on the other.
Bronze has to be struck cold because the deformability is much better when the flan is cold (in effect it is much more complicated and also depends from the composition of the alloy).
There is no clear decision whether silver coins have been struck hot or cold, there seem to be indications for both.

Already in 2007 and 2008 a French group around Thomas Faucher did a huge amount of experimental minting and struck 12281 silver coins. The results have been published 2009 by Faucher et al., "À la recherche des ateliers monétaires grecs: l’apport de l’expérimentation", RN 2009, p. 43-80: https://www.persee.fr/doc/numi_0484-8942_2009_num_6_165_2867
They conclude that minting of silver coins probably mostly had been with cold flans but that there had been exceptions as well.

There is also a short movie about these minting experiments on YouTube: https://www.youtube.com/watch?v=4G6vqUWMELo
(and this is available in English too :) : https://www.youtube.com/watch?v=uGsc2TeeAkg )

Regards

Altamura

Offline SC

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Re: Ancient flans - hot or cold
« Reply #6 on: April 02, 2020, 11:16:14 am »
Such views are not universally accepted.

Cope (who was a professional metallurgist) was clear that Roman bronze coins show clear signs of having been struck while hot. Analysis of their internal structure revealed a uniformity of crystal structure and a very fine grain size showing that they had been given a prolonged anneal, perhaps to a dull red heat for several hours, and that the coin blanks themselves had been substantially worked to flan dimensions near to those of the finished coins before being given their final hot striking. Many showed signs of multiple heating and cooling cycles. 

He knew of no other way to explain the crystal structure of the metal.

See: Cope, Lawrence H. 1974. The Metallurgical Development of the Roman Imperial Coinage during the first Five Centuries A.D. Unpublished PhD Thesis, Department of Chemistry, Liverpool Polytechnic, March 1974.

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Offline SC

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Re: Ancient flans - hot or cold
« Reply #7 on: April 02, 2020, 11:36:45 am »
Georges Depeyrot addresses this question in his excellent introductory handbook to Numismatics "Numismatique antique et medievale en Occident", Paris 2002.

He notes that the debate between cold striking and hot striking began in the 70s and was first based primarily on experimentation.  He noted that in the 80s and especially 90s scientific analyses was increasingly done to study the internal structure of coins.

He notes that large coins, especially large bronzes required multiple strikes and this required heated flans to ensure malleability.  But also noted that different techniques were used for different sizes, metals and eras and that not all coins were struck hot.

He quotes the following works:

Bouyon, Depeyrot & Desnier.  Le systeme et la technologie des monnaies de bronze (4e s avant J.C. - 3e s après J.C.), 2000.

Oddy. Metallurgy in Numismatics 2, 1988.

Moesta & Franke.  Antike Metallurgie und Munzpragung, Ein Beitrag zur Technikgeschichte, 1995.


I am not saying this (the hot theory) is absolutely right, but it is what I have relied on up to now.  I would love to know where this debate is these days.

I wonder in the Oxford Companion book addresses it?

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Offline Meepzorp

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Re: Ancient flans - hot or cold
« Reply #8 on: April 02, 2020, 06:35:29 pm »
Hi folks,

This is an interesting topic.

Until several years ago, I had always assumed that ancient coins were struck hot. However, several years ago (before I was a Forum member), an article appeared in the ANA's "The Numismatist" magazine regarding this topic. In preparation for this article, they actually tested both methods. This article concluded that ancient coins were struck cold, not hot. It also conclude that it would have been physically impossible to strike ancient coins hot, for numerous reasons. The main reason is that it would have been extremely inefficient.

The conclusions of that article didn't sit right with me. This was before I had internet access, so I wrote a letter (by snail mail) to the ANA hoping that it would be published in their magazine. But they never published it. I contacted them to ask why. I spoke by phone to the editor of "The Numismatist". I was told that they refused to publish my letter in the magazine because the Board of Directors of the ANA strongly disagreed with my objections. They insisted that ancient coins were struck cold, not hot.

One of the reasons I felt that ancient coins were struck hot is that, on more than one issue, there are references to ancient coins being struck hot. For example, there is the Roman Republic T. Carisius issue (Cr. 464/2) and the Greek Italy Samnium, Aesernia issue (SNG ANS 118-123).

Here are my own examples of these 2 issues:

https://www.forumancientcoins.com/meepzorp/rr_pt38.htm (third coin)
https://www.forumancientcoins.com/meepzorp/gi_samnium_aesernia.htm (second coin)

Why would the ancients have put those devices and symbols (Vulcan, Vulcan's cap, tongs, etc.) on ancient coins if they weren't struck hot?

I actually raised this point in my letter to the ANA and pointed out to them those 2 issues. However, the BOD of the ANA dismissed it, stating that the ancients simply put those devices and symbols on ancient coins for entertainment purposes, and that ancient coins weren't really struck hot.

I am not stating that I was right and the BOD of the ANA was wrong. I am just stating that I felt at that time that the evidence wasn't conclusive enough.

By the way, otl's posts (above) are very interesting.

Meepzorp

Offline SC

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Re: Ancient flans - hot or cold
« Reply #9 on: April 02, 2020, 09:06:13 pm »
This is indeed a fascinating subject. 

Too many of the "cold" arguments rely on a "we experimented and it couldn't be done" kind of argument, which is entirely too unscientific for me.

Just because a modern experimenter couldn't figure out how to strike a hot flan doesn't mean the ancients didn't.

There is a picture by English painter A. W. Devis done circa 1792 that shows two men striking coins at the Calcutta mint while two men in the background work a fire with bellows.  From the article Minting Technology in Mughal India by Najar Haider.  Other old Indian illustrations related to striking coins all have a tended fire nearby.  Haider makes clear the Mughal Indian flans were finished hot, but his wording is unclear on whether the flan was then struck immediately while hot or later. 

On the other hand, Thomas Faucher's 2017 article on experimental striking of Ptolemaic coins finds that while striking larger bronzes coins would be easier if they were hot, he does not believe that they were.  This belief is based on the following:
- the signs of mis-strikes and duplicate show it was hard to strike them and therefore he believes that they were probably striking them cold,
- it is very difficult process-wise to handle hot blanks and coins, and
- the heating would leave a black layer which would have to be cleaned off.
Faucher is a well respected French academic.  But again the paper relies on experimental archeology.

I would really like to see more metallurgical analysis.

Was Cope right, or can what he found be explained away as the effect of heatings during flan fabrication and preparation???

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Offline Altamura

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Re: Ancient flans - hot or cold
« Reply #10 on: April 03, 2020, 03:21:54 am »
… Too many of the "cold" arguments rely on a "we experimented and it couldn't be done" kind of argument, which is entirely too unscientific for me. ...
I don't understand why trying out physically what is discussed theoretically should be unscientific  :-\. Not testing theoretical results in reality is in my eyes unscientific.
There is e.g. a very productive relationship between theoretical physics and experimental physics.  And nobody is arguing that experimental physics is unscientific  :).

… On the other hand, Thomas Faucher's 2017 article on experimental striking of Ptolemaic coins ...
Which can be found here:
https://www.academia.edu/37598729/Coin_Minting_Techniques_in_Ptolemaic_Egypt_Observe_Analyze_Recreate_Notae_Numismaticae_2017_p._71-90
the question of cold or hot striking is discussed on pages 84-85. The conclusion is:
"In conclusion, we do not see any decisive arguments that would prove that hot-striking was used during antiquity, at the very least for Ptolemaic coins."

Regards

Altamura

Offline SC

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Re: Ancient flans - hot or cold
« Reply #11 on: April 03, 2020, 11:14:28 am »
Exactly.  But what is missing from everything I have found so far except Cope is the metallurgical evidence.

Experimental work can only tell us about the thing that they experiment on. We can then try to draw analogies based on what we see in ancient coins

But take Faucher's work.  It was based on experiment compared to a physical examination of ancient coins but not a destructive metallurgical examination.

So he laid out three pieces of evidence:

1) Signs of mis-strikes and repeated strikes proves that many of the Ptolemaic bronzes had to be struck more than once.  He believes this proves they were struck cold - that is why they were difficult to strike and thus took multiple strikes.  But in the Bouyon, Depeyrot, Desnier book looks at the same issue with different conclusions.  The evidence is ambiguous either way - you could still have multiple strikes for hot striking - the flans aren't melted blobs - just slightly softer.  B, D and D believe that multiple strikes were required with hot striking for such large coins.

2) It is hard to work with hot flans.  I am sorry but that is not proof that such techniques were not used, just a fact that modern experiments find it harder.  Maybe the ancients had better processes, or maybe they accepted it was harder and still used the process.   In fact it appears that hot flans were used in some Indian and Islamic production processes.

3) Hot striking would result in black layer that had to be removed.  Again, not proof that it was not done.  Sure it would add another step but several authors have already postulated that this was done - some sort of picking or bath would be easy to do.

Faucher's final conclusion is that there is no evidence of hot striking and the several factor showing it was inconvenient.  But again, his evidence is only based on looking at the coins.

By contrast, Cope's argument was based on the metallurgical analysis of actual coins.  The internal structure provides irrefutable facts about what happened to the metal.  For example, late Roman bronzes were heated and cooled, usually numerous times.

What we don't know, and this I think is the key gap that needs to be explored, is exactly when that heating occurred vis-a-vis the striking.

Maybe the cold school is right and ay heating was done separately and prior.  But I want to see some cold school scholarship that takes into account the metallurgical evidence. Maybe the 1995 German book does.  I don't have it.

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Offline Joe Sermarini

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Re: Ancient flans - hot or cold
« Reply #12 on: May 08, 2021, 08:35:16 am »
It seems likely with the number of different cultures, peoples, states, cities and mints, and the centuries of time involved, that methods may have varied considerably.

I speculate that for any combination of metal, flans, and dies, when cold works well enough, it was probably the most likely method. Few would choose to do things the harder way.
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Offline Ron C2

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Re: Ancient flans - hot or cold
« Reply #13 on: June 06, 2021, 08:32:02 pm »
Hardly definitive, but a few days ago I watched an old "Time Team" episode from the UK on Youtube.  In the episode, where they were digging a roman coastal settlement up by Hadrian's wall (I can't remember the precise season and episode). They often do color pieces apart form actually archaeology, and in this episode they re-created striking sestertii.  They went through the process of making sprue tree molds, casting flans in replica ancient furnaces, and then tried striking them both hot and cold from replica dies, and for hot striking they tried multiple light strikes vs a large single strike. 

Cutting to the case, only a single hard strike on a hot flan would produce a passable sestertius

Not definitive, but I found it interesting nonetheless.
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