... I began looking at smelting in the early MA when I was trying work on mail armor. Actual examples of mail are few, and often (tho' not always) fragmentary. My idea was to understand the production of iron--a necessary commodity--for comparison reasons. Much of what I read does not go into exact production figures, but from descriptions of what I've read, the large smelting sites seemed to exist so enough iron could be made to be useful. Thus, mail armour was a luxury item owned by the few ...
Thats entirely my take on Early Medieval as well.
There are a number of sweeping changes in the technologies used in iron creation over the years so loosely grouped as 'the Middle Ages'.
My work has centred on the 'Migration Era', post Roman and pre Crusades. Primarily using Norse sources (so Scandinavia, 800 - 1000 as the prime reference). Roman systems tend to be passive air, after about 1100 furnaces use water powered machinery. Good news is that for the most part, Norse furnaces tend to be smaller and thus easier to duplicate.
One thing that people completely miss is the more or less random quality of the individual blooms created. There is a useful limit to the size as well. Although relatively large (10 - 20 kg) blooms are certain possible, it becomes increasingly difficult to manipulate such large masses with only hand tools. Artifact blooms are actually fairly rare, as each represents the expenditure of considerable skill and man power to create, and thus are valuable. In practice there would have been a lot of picking and choosing - individual blooms with quality suited to various objects.
For drawing to wire for mail, you would have to have the highest quality of metal. Here I'm referring to lack of slag inclusions in the starting mass. I'd think extra folding steps at the consolidation of bloom to working bar stage as well, again to reduce these inclusions. Its the slag remaining that causes wrought iron to crack as it is forged. This especially a problem with aggressive forming - and making mail wire is just about as aggressive as it gets!
So just from the problem of the raw material for making mail, you are looking at the 'best quality' metal. Add that factor into your estimates on costing as well. I think too many modern makers totally forget the raw cost in material, with modern wire so inexpensive.
The nature of the metal used is certainly going to have a huge effect on both the labour involved and the quality of the finished mail itself. Unlike modern steels, bloom iron certainly has a pronounced linear texture. Few modern blacksmiths even have any experience with antique wrought iron, and that material is more like later Medieval metals (post 1600) at best. I've worked with this stuff only a bit, and certainly have never attempted to forge it down as fine as would be required for mail making.
The more we learn about ancient methods, the more we realize what a huge undertaking making *anything* actually is.
(Sorry - this is a re-cycled response to an e-mail. With Goderich Celtic starting in 4 days, then the massive DARC at LAM 2010 immediately following, blog posts may be thin over the next five weeks!)