How was mail manufactured historically?
I am wondering what our mail enthusiasts theorize about how maile and the source wire material was made before late medieval era. A couple of puzzles I don't have a firm opinion on;
1) Was the wire mostly formed by manual forging in anvil grooves, by sheering plate into strips and drawing, or completely random variations of both. (History of drawing equipment for iron alloy wires has been difficult for me to find before 15th century, but, that does prove it was not done.)
2) Were the raw materials used to make mail wire specific to one region of origin (statistically uncommon iron purity and phosphorus)? Or was the knowledge of how to make easily worked wire of chemical composition that we see in actual specimens (possibly from highly wrought iron worked in charcoal with a phosphorous adding material such as bones) something done over a wide range of Northern Europe?


I have been looking at the most detailed analysis of mail fragments I could find. I noticed that the few examined over a span of several centuries for chemical composition turned out to be uncommonly high purity iron (carbon less than 0.06%), with what would today be considered high phosphorus content (0.1 to 0.13%.) It could be a coincidence, but this is what higher quality "drawn iron wire" was at the beginning of modern industrial history before the chemistry and control of carbon were well understood. (Reference 1800's suspension bridge cables, harpsichord strings... today Rose type B piano wire is probably the only example..but is only available up to 0.8 mm diameter which is a little small for mail.) This composition also can be ductile with progressive hardening throughout cold work. If done just right, mail MIGHT have been fabricated with much less annealing steps than some discussing use of mild steel wire today seem to advocate.
Re: How was mail manufactured historically?
Jared Smith wrote:
oday Rose type B piano wire is probably the only example..but is only available up to 0.8 mm diameter which is a little small for mail.


I've seen a good few peices where links of around the 4.5-6mm in diameter have been made using wire that fine, in the collections of a few museums.

rather you than me to make an entire peice out of that size though...
1. It is fairly certain that the Romans practiced wire drawing.
There are at least two draw plates dating to the Roman period
Dimensional consistency of Roman mial links can only be explained by witre drawing
Alignment of slag inclusions are consistent with wire drawing.

2. Only high quality bloomery iron can be pulled through a draw plate. If the slag inclusions are too many or too large then the wire will constantly snap while being drawn. I don't think that the metallurgical properties of wire or mail can be used to tell where it was made since good quality iron would have been widely traded.
The addition of phosphorus decreases the ductility.
The quality is damaged. I think iron + phosphor was no good to be draw.
The Egyptians and Sumerians used the process to the jewelry.
The Romans certainly for the iron. and 'doubt if they used a machine to produce in large quantities. Personally I think possible, as building a machine for drawing is easy. The Romans built things much more complex.
Ciao
Maurizio :)
Dan Howard wrote:
I don't think that the metallurgical properties of wire or mail can be used to tell where it was made since good quality iron would have been widely traded.


That was my expectation too. So far, I have had problems making an archeological case for trade of iron ores with chemistry that has been found in mail artifacts near the early time period of mail's history.

Since iron was used as a form of currency close to Roman era in Cumbria, I tried to find evidence of "currency bars" having composition indicating foreign origin, and composition similar to that of period mail. The few bars that have been found were judged to be of local ore and pretty low in phosphor. (The Historical Metallurgical Society: Archaeology Data Sheet No. 8 has some discussion of the issue. I have not seen international trade of wrought ores indicated within Northern Europe until much later than the early period of mail. Ingots and bars seem to normally be of more immediate region origin until some point within "Medieval" era.) Similarly, the metallurgical analysis of 3rd / maybe 4th B.C. era mail found on the Hjortspring boat in Scandinavia came across as if the author did not consider trade of ores. (The entire cargo found within the boat appeared to be obvious plunder from other Celtic regions, so possibly the mail was just assumed to be foreign booty as well.)


Last edited by Jared Smith on Fri 06 Nov, 2009 8:34 pm; edited 1 time in total
Dan Howard wrote:
1. It is fairly certain that the Romans practiced wire drawing.
........
Alignment of slag inclusions are consistent with wire drawing.

Only high quality bloomery iron can be pulled through a draw plate......


I pretty much agree and assume all of this as well. There seems to be little archeological interest in (or possibly just few finds) of early fabrication methods of iron/steel wire, and tools. Some papers discuss scrap materials found at Roman fabricae /"factories", but seldom seem to discuss tools, even broken ones, also being found. One 2% carbon high quality tool steel punch suited for making 6 mm diameter holes is known from roughly 2nd century B.C. Scandinavia. It is not known what the punch was actually used for. The dies of draw plates are normally evaluated for hardness and toughness to assess what kind of alloy they would have been suited for drawing. Most discussions I have seen of early draw plates assume that they were used for materials much softer than iron based on the hardness of the dies. But, as you say, the quality of some of the Roman mail fragments suggest "perfect" wire. I can't imagine it having been hand hammered. The existence of the above tool steel grade punch suggests to me that drawing dies suitable for soft, fairly pure iron could have been created with technology available at the time.

Another possibility is that early drawing of iron wire was only done as a final finishing step. (Over sized rough forged wire could have been formed manually to save wear on low hardness drawing dies.) It seems to be theorized that early attempts of "finish drawing" with moderate carbon dies could have enabled people to draw a couple of meters of fairly good final geometry wire before having to reposition to new holes in the dies or replace the drawing dies. This explanation still seems like a really inefficient and impractical explanation to me though.

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