Flatness of Roman Iron Plate

[Matt Lukes]

Hibernicus has recently raised an issue that I've thought about for a while now- just how smooth or not smooth was the surface of roman armor iron plate? His suggestion (please correct me if I'm wrong Sean) is that it wasn't so much so, and for a long time I had thought so as well figuring that it had likely been hand-hammered from billets. But when I saw well-preserved segmentata plates, for the first time, I wasn't so sure. I've attached the one image I have at present and to be honest, it looks quite smooth to me. Sure it's not perfect, but it doesn't look to me to bear a lot of hammermarks from flattening either. The suggestion put forth is that using modern sheet steel is less-than-accurate because the rolling is so precise, but when I look at the plates below, and many copper alloy armor plates, fittings, etc., they all look fairly smooth and don't bear marks that, to me, look pre-product (armor, etc.) fabrication in nature. In fact, the thicknesses of some of the pieces I have in my collection (copper alloy) are so nice, I can't help but wonder if some sort of rolling mill was in fact used to finish the sheet metal. It's not exactly complex technology- certainly not for the Romans- and it would allow a great deal of control over amount of metal used, time involved to fabricate sheet metal, and consistency. Given that the suggestion has recently been made that various thicknesses of iron were used for different areas of cuirasses purposely, the latter element seems rather important.

All this having been said, I certainly can say it's not as 'normal' as one might thing to see hammermarks in iron, or any metal for that matter, from flattening hot- a misconception I had, but was cured of when I made my very first steel object. Prior to that I'd always thought there should be clear evidence of hammerstrikes, but when I actually did it, the product was remarkably smooth. It seems dependent on a number of factors including the size and smoothness (face) of the hammer one is working with, is the iron worked red-hot, whether or not one is really trying to produce even thickness product, and probably most important of all, how flat/ smooth the anvil is. If the anvil is well-kept (something that is stressed in everything I've ever read about blacksmithing), it leaves a nice, smooth face on its side of anything being hammered- and if you end up with 'good-one-side' metal, even for armor, I can see using that side preferrentially- I sure would :lol:

Actually, on that note particularly, all one has to do is look at helmets- even if the exterior is fairly smooth and nice (relatively), the interior and undersides bear all kinds of marks. Certainly care would be taken where necessary and no time wasted where it's unnecessary.

So I'm just curious what others may know about the condition of actual sheet iron artifacts- those where corrosion hasn't damaged the surface of course - with respect to evidence of flattening on sheet metal (so for helmets, only the neckguards probably apply). Is this section of lorica segmentata from Xanten nicer than average or is it reasonable to think it might be of normal quality?

While I certainly agree that a lot of reproductions these days are far too nice- made to modern quality standards (smooth, shiny, straight, etc.)- I don't think that sheet steel, for example, that bears not more than the few marks from fabricating the finished object, is particularly inauthentic. I should think that the artifact from Xanten certainly constitutes evidence that the iron plates of segmentatae could indeed be nice

All information (please be sure you can reference it though) is welcome- I find the subject of manufacture techniques and details quite fascinating :wink:

Vale

Matt

[Neuraleanus]

than we have taken them to be. As another example, consider the Kalkriese breast plate. Hammer marks? None. The Romans were very fashion aware. They liked to look good.

[Matt Lukes]

I definitely agree with that- I was certainly guilty of being an 'ageist', but discovered after examining my first few actual artifacts in detail that ancient certainly doesn't mean crude by any stretch.

[Emeraldweapon7d]

speaking of making plates for armour, can any of you give me any pointers on how to take a lot of molten brass and bronze and bring it to sheet form, step by step and an estimation of how long it would take and what shape of ingot would work best, would the more thin the ingot starts out the better?
basicly what i've heard is lots of cold working and aneeling, because laten metals can't be worked hot. just how badly do they discolour if you do? is the discolouring only on the surface? sorry for all the questions but i've been wondering about this a while now.

[Matt Lukes]

Well discoloration from annealing is easily removed from copper alloys by pickling them in weak acid solutions- 5% acetic acid (regular table vinegar) works well. In fact, if you quench the hot metal in the acid solution, you will minimize the oxide that forms on its surface. Any that does will come off after a little soak. The metal will acquire a pinkish color though, but that can be easily polished off. If you plan to make sheet from an ingot, it's advisable to anneal CONSTANTLY. You also would be well-advised to do your best to keep the edges smooth so as not to have any points that can serve as the start for any cracks. Certainly the flatter the starting piece the better- and the shape would be dependent on what final shape you want.

[Hibernicus]

I have the disadvantage of not having ready access to authentic pieces.. not being associated with a museum collection or having a personal collection or having hands on with a broad sampling of... seg plates for example..

Mostly I rely on the comments of a few experts and their critique of my work.

I have a photo collection but rarely do they show the kinds of things someone wanting to reproduce an item needs to see. Photos leave out a lot of important details.

My anecdote was a section of an ancient helmet I had a chance to handle... iron helmet.. outside was nearly smooth looking but you could see the hammer marks inside, visible to eye and touch. These hammer marks showed how the dome was raised. If you closed your eyes and ran your hand across the outer surface of the dome you could discern the hammer marks. Hold it up to the light, look at it from various angles and you could see tooling marks.

Finished surface?
It is certainly possible to planish a segmentata plate smooth and a flatterer will do a good job of creating a smooth surface.

Just offering an alternate interpretations and option for LEG IX members and RLQM customers

[Matt Lukes]

I have a photo collection but rarely do they show the kinds of things someone wanting to reproduce an item needs to see. Photos leave out a lot of important details.

Oh absolutely- I'm continually surprised at the details I learn from continuing research and hands-on examinations. Makes me wish I could just do a long research trip to various museums in Europe... I wonder if I could write that off my taxes :wink:

My anecdote was a section of an ancient helmet I had a chance to handle... iron helmet.. outside was nearly smooth looking but you could see the hammer marks inside, visible to eye and touch. These hammer marks showed how the dome was raised. If you closed your eyes and ran your hand across the outer surface of the dome you could discern the hammer marks. Hold it up to the light, look at it from various angles and you could see tooling marks.

Ah, okay, but you see that's a semi-spherical raised helmet- it's created from sheet metal by hammering against various stakes and balls so of course there'd be evidence of that- it was the contention that sheet iron should also not be smooth to wit that modern rolled sheet steel is inaccurate that I wasn't so sure about. If it's indeed true, I'd sure like to know- I don't like inaccuracies :wink:

Who are the experts then who've said that the plates should be less smooth and what are their reasons for thinking this?

Matt

[Vlad the Impala]

At last Years Romec David Sim, said that he believed rollers were used, given the accuracy of thickness and the absence of hammer marks.

IIRC there was somthing about how it looked under a microscope which indicated rolling rather than hammering.

the steel was from some of the carlisle scale (i think) and at that time i dont think he'd be able to examine seggie in the same way

[tlclark]

than we have taken them to be. As another example, consider the Kalkriese breast plate. Hammer marks? None. The Romans were very fashion aware. They liked to look good.

It's not just fashion. Any imperfection makes it harder to clean/prevent rust/corrosion. Smoothness has it's own virtues.

Travis

[Matt Lukes]

Ah, quite so. And any abrasive used over time to keep the corrosion at bay will serve to smooth out any surface imperfections too- at least it'd wear down the peaks. I can certainly speak to its effectiveness too- the sheet steel I haven't used yet picks up light rust spotting after a couple of months, but plates I made 9 months ago that I gave burnished finish to by hand wet sanding (to look like they've been continually polished to keep rust at bay in the wilds of Germania or Britannia), are still clean or have only tiny dots of rust here and there.