09-06-2006, 03:34 PM
It's important to be careful and remember that the idea of 'THE method' is wrong- the one thing we should all recognize by now is that there were many methods in use at any given time for making or doing just about anything. Just as is the case with respect to uniformity, consistency of production is a modern idea- completely inappropriate to apply to ancient times. Clearly the article I mentioned shows that each piece examined shows evidence of different material/ methods of manufacture- forge welding, hot working, cold working, decarburisation, iron, steel, possible rolling, etc. Sadly with such a tiny sample having been examined, not much in the way of artifactual evidence to back up any method particularly well, we're left with mainly supposition. And that's a very dodgy thing indeed.
Sure, hammer forging to make plate seems a reasonable possibility- it's clearly the easiest method, however it's not exactly the most efficient, and it's a little difficult to imagine so many smiths getting the even thickness plate that it seems Roman armor had. Rolling would achieve this but there's only circumstantial evidence to support its use- no artifacts or direct mention by a literary source are known.
Looking at copper alloy pieces, however, one sees a remarkable smoothness and evenness to the metal that begs the idea of something a little more than just a hammer. It's not easy to achieve even thickness of very thin metal by hammering, and virtually all the copper alloy artifacts in my collection seems quite uniform and clean. No hammermarks, no rippling and an even thickness is what I see in almost every piece. In addition, the shallow incised lines along the edges of some forms of segmentata fittings are so nicely-placed and even that anything other than a roller-type machine to make them seems hard to believe. It was these observations that first made me wonder about rolling to produce sheet metal- or rather, to finish sheet metal- no one is suggesting that rolling was a single method of producing sheet metal from ingots Sean- doubtless it was forged quite a bit until it would have been thin enough to roll (if in fact it was). However that hammering need have been only 'quick and dirty'.
A rolling mill is a fairly simple, hand-operated device that is widely available today for producing a desired thickness of sheet metal and wire, and it would have been well within the technological abilities of the Romans. Pressure isn't applied per se- it's built into the machine by virtue of the proximity of the rollers. Modern rolling mills are adjustable so one can gradually thin out metal by decreasing the roller separation on subsequent passes, however there's no reason several dedicated thickness mills couldn't have been used to achieve this. A Roman one could have been quite a small machine too- remember the widest plate of a segmentata was actually quite narrow, no more than 9.5cm for a Corbridge cuirass. A strong frame, a good long crank arm for leverage- it'd be an easy machine to operate for any completely unskilled person.
Doubtless hammering a method used to produce iron plate for armor- but was it the only one? I find that hard to believe. I even have my doubts that it was the main one given how much more efficient and effective rolling is. The Romans were clever and had some impressive technology for the time- it's a mistake to just assume they wouldn't have developed and used a device as simple as a rolling mill given the sheer volume of sheet metal they used. Of course it's also a mistake to assume just because they had some great technology that they must have also had rolling mills- assumptions with no direct evidence of anything are hazardous to say the least :wink: We therefore can't say any method is right out or far more 'correct' than another without a whole lot more evidence. So for now, I think it's fair to say that hammered steel is just as acceptable for reproductions as rolled is
As a related aside- does anyone know what methods for producing sheet steel were in use during medieval times or the renaissance? Neither, it seems to me, were radically more technologically advanced than Roman times so might shed some light on things.
Sure, hammer forging to make plate seems a reasonable possibility- it's clearly the easiest method, however it's not exactly the most efficient, and it's a little difficult to imagine so many smiths getting the even thickness plate that it seems Roman armor had. Rolling would achieve this but there's only circumstantial evidence to support its use- no artifacts or direct mention by a literary source are known.
Looking at copper alloy pieces, however, one sees a remarkable smoothness and evenness to the metal that begs the idea of something a little more than just a hammer. It's not easy to achieve even thickness of very thin metal by hammering, and virtually all the copper alloy artifacts in my collection seems quite uniform and clean. No hammermarks, no rippling and an even thickness is what I see in almost every piece. In addition, the shallow incised lines along the edges of some forms of segmentata fittings are so nicely-placed and even that anything other than a roller-type machine to make them seems hard to believe. It was these observations that first made me wonder about rolling to produce sheet metal- or rather, to finish sheet metal- no one is suggesting that rolling was a single method of producing sheet metal from ingots Sean- doubtless it was forged quite a bit until it would have been thin enough to roll (if in fact it was). However that hammering need have been only 'quick and dirty'.
A rolling mill is a fairly simple, hand-operated device that is widely available today for producing a desired thickness of sheet metal and wire, and it would have been well within the technological abilities of the Romans. Pressure isn't applied per se- it's built into the machine by virtue of the proximity of the rollers. Modern rolling mills are adjustable so one can gradually thin out metal by decreasing the roller separation on subsequent passes, however there's no reason several dedicated thickness mills couldn't have been used to achieve this. A Roman one could have been quite a small machine too- remember the widest plate of a segmentata was actually quite narrow, no more than 9.5cm for a Corbridge cuirass. A strong frame, a good long crank arm for leverage- it'd be an easy machine to operate for any completely unskilled person.
Doubtless hammering a method used to produce iron plate for armor- but was it the only one? I find that hard to believe. I even have my doubts that it was the main one given how much more efficient and effective rolling is. The Romans were clever and had some impressive technology for the time- it's a mistake to just assume they wouldn't have developed and used a device as simple as a rolling mill given the sheer volume of sheet metal they used. Of course it's also a mistake to assume just because they had some great technology that they must have also had rolling mills- assumptions with no direct evidence of anything are hazardous to say the least :wink: We therefore can't say any method is right out or far more 'correct' than another without a whole lot more evidence. So for now, I think it's fair to say that hammered steel is just as acceptable for reproductions as rolled is
As a related aside- does anyone know what methods for producing sheet steel were in use during medieval times or the renaissance? Neither, it seems to me, were radically more technologically advanced than Roman times so might shed some light on things.
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