surface finish of metalwork

[dave budd]

We are all used to seing cleanly ground and polished blades, armour and even arrowheads; but I wonder if there is any evidence for these things having been so highly finshed? I ask because while I can see a nicely woven pattern welded sword wanting to be cleanly ground to reveal the patterninig, how many smiths would really have gone to the same trouble for an everyday utensil such as a knife?

Without the aid of modern grinders, the only way to achieve the clean flat surface archaeologically is to laboriously grind with hand stones or to file the surface. Files are expensive bits of kit and I would think that they would only be used for iron/steel parts that needed to be filed to fit (for example).

So, is there evidence for ground or filed finished blades etc?

N.B. a reference to 'shiny' or even 'polished' doesn't neccesarily mean ground and uniform. Shiny can just mean that the hammer scale has been rubbed away (vinegar and sand will do that) and the bare metal buffed up to a reflective surface that still has the forging marks.

[dave budd]

ok, possibly there are no on hand examples either way then

Instead then, how likely do others think it is that smiths would go to these lengths for shiny utensils? :roll:

[Magnus]

If you actually mean utensils, the ones I've seen pictures of don't appear to be rough...they're rather small though and probably wouldn't take as much work to smooth out vs a pugio or gladius blade.

[Matt Lukes]

Yes, there is- the few Lorica segmentata plates preserved in anaerobic conditions, such as the Bank of London breastplate, for example, and the well-known Guttmann Gladius pompeiiensis (marked to C VALERIVS PRIMVS with it's scabbard metalwork) clearly show the surfaces of these iron objects were well-ground and polished. There are a number of spearpoints from Kalkriese and even objects like pila and dolabrae that seem to have smoothed surfaces suggesting finishing (the latter are rippled, but smooth). So it does indeed seem that iron objects were normally ground. It's not an esthetic step but rather a preservation one- forge scale can be somewhat brittle and can flake off in some cases and whatever iron becomes exposed will corrode- but a ground, polished surface is rather less subject to corrosion and it can be easily cleaned, which cannot be done if the scale is present. It seems likely that any non-disposable object would have normally been finished and even some 'more' disposable pieces such as arrowheads would have been as well since you're not usually going to go right out an shoot your arrows, so they would have to be kept clean and indeed might be recovered for re-use.

Truly I'd think the question is more is there any evidence that anything was left with forge scale on? The inside faces of armor plates surely was- in many cases only the exterior can be ground due to the shape, and indeed armor has always only been finished on the outside (even the Bank of London example seems to show this) but that's the only one I know of.

As for mirror polishing, well that's just silly for ancient everyday objects- perhaps Tribunes or whomever might pay someone to super-polish their stuff, but daily cleaning would leave a regular Legionary's stuff dullish.

[dave budd]

Thanks for the examples, much appreciated. I admit that I would like to inspect the pila and dolabrae myself to see whether the surface is smooth through grinding or through the use of flatters/planishing blows. A good smith with the right tools is quite capable of producing a smooth surface straight from the forge.

As for the theory that a forged finish or scale surface rusts more quickjly than a ground one, I have to very strongly disagree! Based oon the fct that I specialise in forged finished blades and all of my own tools (that are usd on a daily basis in the woods of damp devon) are less prone to susting than the parts of the same tool that have been ground to bare metal. True a rough ground bare metal surface will rust more quickly than a smoothly polished one, but the forged surface is not the same thing. Also nobody is going ot care if their arrowhead has a bit of rust on it when the loose the arrow, especially if it is heading for the enemy! It would take literally years of being left in a damp place for an arrowhead to rust away to uselessness, the shaft fwould go long before.

[Matt Lukes]

Well I don't know about the surface of the dolabrae from Newstead- the ones I'm thinking of are in Germany, from Hedemünden, so in examination of them would require something of a trip... here's a picture at least: [url:3vk6jvhr]http://upload.wikimedia.org/wikipedia/commons/e/e8/HedemueMilitaria.jpg[/url]

Now, re-reading the question, I'm a bit unclear- are you talking about if any grinding was done, i.e. that scale was left on, or if a lot of grinding was done to yield a fairly flat, smooth surface? I was proceeding from the perspective of the former- that the scale was removed, but not necessarily that files or excessive time was necessarily used on everything. The multiple examples I mentioned all show surface features of the forging, they're just clean iron or in the case of the dolabra and pila have the exact same smoothness as associated spearpoints and catapulta bolt heads, which elsewhere are clearly shown to be de-scaled. There are examples of better finished pieces though- there's an arrow or bolt head marked to LEGXIX that is very flat and clean-edged (quadrangular in cross-section), has a clean surface, and has striations on its surface that could be file marks- and the few sword blades that are un-corroded were clearly ground nicely ([url:3vk6jvhr]http://www.romancoins.info/112005-legxix-catapult.jpg[/url]).

And it isn't a theory that a polished surface is less-subject to corrosion than a scaled one- it's my experience with my own forged pieces here on the constantly wet Pacific coast... must be something different about our circumstances. Here it's as I said, new iron exposed by scale loss corrodes faster than polished iron (basic chemsitry), and that cleaning the rust removes more scale, which exposes more iron to oxygen. Maybe not a problem for farmers' tools, but less easily accepted for an army- I mean have you ever heard of an army that wasn't anal-retentive about soldiers keeping their kit clean? LOL It's as much to be sure everything is always servicable as it is to keep men busy. Plus if Roman soldiers had to pay for their kit, that's even more of a reason to be sure it wasn't rusting away, no? To use your arrow example, the issue is not whether or not anyone cares if there's rust on it when it's loosed, but rather that indeed the shaft would be ruined more easily, so maintenance on the weapons in general would be important. Nobody's going to ignore the rust and just look after the shaft or vice versa. The same goes for everything- there are elements that are subject to damage (wood, leather, etc.) so must be regularly cared-for and it seems only logical that the iron would be addressed at the same time.

Again though if the idea of scale left on is interesting, then evidence would be important- there's clearly evidence for ground and polished pieces. It's a bit of a tall order though since archaeological iron was for a good while stabilized by treatment with tannins, which has the adverse effect of turning it black (e.g. the Italic D helmet in Worms) so knowing just what is really scale and what isn't would be tricky. I doubt many archaeologists would test the surface to see.

[Marcus Mummius]

It's difficult to judge just by that picture but it seems to me that the pieces in the picture Matt posted were impregnated with an epoxy resin and then the corrosion was ground off to give the artefact what was thought to be the original surface. Impossible to say anything about the original surface finish.

The rippled surface Matt described can very well be the result of the restaurers work too. When an electric grinding stone (often some kind of Dremel like tool) is used to remove the corrosion, the result is often a rippled surface (this is especially the case when the grinding stone is rather small and the surface that was cleaned is quite large).

Vale,

[Matt Lukes]

Do you know that for a fact Jef or is it just that they appear to be so? Not that I doubt your experience, I'm just curious- because if restoration results in appearances that look just like real surfaces might, that puts a serious crimp in the possibility of discerning anything visually...

The dolabra with the Guttmann gladius (Pompeii) on the LEGVI Real Gear Page ([url:3abq9e62]http://www.legionsix.org/images/replicasword.jpg[/url])is likewise black and clean- I'd thought that to be its original surface too, just tanninized? And these also from Hedemünden: [url:3abq9e62]http://3.bp.blogspot.com/_B4ou7O2v_Jk/RXG2Q5UspaI/AAAAAAAAAAM/Mtyb1bkLlEc/s1600-h/hede6.JPG[/url]and [url:3abq9e62]http://4.bp.blogspot.com/_B4ou7O2v_Jk/SVApeh7nmhI/AAAAAAAACBw/QAZC-BENHFU/s1600-h/kalefeld5.JPG[/url] show differentially nice surfaces (like the Guttmann)- would not restoration make them all the same? The catapult heads do look 'original' and as smooth and nice as clearly cleaned/de-scaled pieces like those I mentioned...

[Marcus Mummius]

Hi Matt,

It's quite difficult to discern by looking at the pictures. What would be really useful would be pictures of the pieces before the conservation and restauration, then we would be able to see how they looked when they were found.

The pieces look so dense and smooth... It seems to me that this would be too good to be true. Do you know in what kind of environment they were found? Could be they were just very well preserved, that is of course a possibility too.

Cleaning iron pieces in an acid solution was (and is, alas) often common practice. If these pieces were preserved in a good environment and did have a very good core of bulk metal remaining they could look like this after cleaning. But a bit of the original surface (the bit that had oxidised) will have been dissolved in the acid bath too.

When coating iron artefacts with epoxy resin (something you should never do!) black pigment could be added to give a nice and smooth finish. I know this was also often done, and is still done in many places.

So I can't tell from these picture which object was treated in what way, but I know that A LOT of objects (and especially the iron ones) undergo treatments that make any assesment of the original surface impossible.

Vale,

[dave budd]

interesting pictures there matt, thanks. Is that blade marked LEG XIX really an original?! It's in mint condition and I couldn't argue against the use of a file there!

The thought that was in my head when I started this thread was concerning the complete reshaping/resurfacing of metal. Mostly because I hate seeing replicas with angleground and polished finishes, when I can't bring myself to cheat when I'm making things accurately (no arc welding or angle grinding unless I'm making a modern tool). Also because I teach and demostrate with an iron age forge set up, I appreciate how much hard work is involved in needlesly filing (worse still, hand polishing) surfaces. You pointed out the removal of just the scale, that is something that I hadn't really thought about until recently to be honest, but would make sence as it would give a 'clean' and shiny finish without undue work. it would be easy to descale with acid and the surface can be polished smooth wiht a powder abrasive and leather, though still having the hammer marks evident.

I've looked at other metal work (various periods when i worked in the museum resource centre in Colchester) that have been subjected to various levels of restoration over the decades; ranging from grinding it back to metal (farmer found a medieval axe head and decided to restor it for use!), through the resin impregnations and the chemical scourings. Also the more up to date sonic cleaning or plasma (I'm sure that's not right, but the old brain has forotten it) cleaning of loose or active corrosion. There is no way to tell what the surface finish was if it has been removed, but if it has not been ground off then maybe.

I expect that if you were to cut a section (like that would happen!) trough the metal and etch to show the iron lamella, if the iron flows at the surface then it's a fair bet that the surface had not been ground away; grinding would truncate the grain. The undulating surface left on most rusted metal (and of course most restored pieces) is I guess the result of corrosion eating into the metal as pockets and blisters, the conservation just enhances those marks. BUT,the picture from Wikipedia that Matt put up looks to me like the surface is at least representative of the orignal. The reason I say that is because the dents are very regular forming lines. When I forge those kind of shapes, they have the same arrangements of marks based on my final blows.

as for the forged surface vs ground surface and maintenance, I think we shall have to agree to disagree there :lol: The knife on my belt has been used everyday for the last 2 years and the forged surface is the same as when I first made it. Mind you, I think that most of the scale has now come off and the grey is actually the patina of the metal now! I've never found any trouble with rust spreading on the surface of any scaled tools of mine, when a bit of rust appears I merely rub it off with my fingers (or wirewool if I can be bothered) and it's fine, doesn't seem to spread. Polished surfaces pck up acid and prints like spots on a teenager!

Part of this argument could be completely pointless on account of my tools being made of a single piece of high carbon steel and the Roman ones would be wrought iron on the surface. Iron rusts less quickly and in a different fashion to steel due to the extremely low carbon content and the silica vapour barriers fromed by the slag in the iron (which is one reason why modern architectural restorations are using pure iron rather than mild steel). High carbon steel rusts more quickly than mild steel largely because of the carbon content at the surface (I see a lot of old laminated blades that have a line of rust down the spine showing this nicely), just the same as high carbon layers etch faster in pattern welding. On my blades, the surface just below the forge scale has been decarburised so offering some protection, where as if you grind it away the it is back to high carbon and a large surface area open to corrosion. If it is polished the the surface is sealed a little and corrosion products form more slowly than a ground surface, it is also easier to remove the rust as mentioned.

[Conal]

Dave

There are a few Celtic swords which have what looks like a rough scale finish though this may be a designed finish as it looks very pitted. Maybe this is a cross over from tool production?