Medieval Metal Manufacturing

[Shroom Man 777]

Spinoff of that other thread. Also, I am profoundly ignorant of historical stuff, so I wish to be enlightened.

So, how did medieval peasant folks - and even bronze age ancient folks - ever manufacture metal? How did the whole processing go? I can imagine today, we've got miners and machines digging up ores, machines to process these ores and sift dirt and rock away from the metals, and whole furnaces to melt these metals into stuff and then when we've got the purified workable malleable metal, we then manufacture it into swords and guns and swordguns.

But I really have a hard time visualizing bronze-age primitives, and medieval peasantry, ever doing anything remotely like this. All I see in depictions is that we've got blacksmiths putting pieces of metal over a fire and hammering them to become swords. I've never seen, or much less heard about, HOW these ancient people GOT the metals, how they processed them, to the point where the smithy can just hammer them into swords or plate armor.

Did they have mines? So they shoveled dirt with metal in them? Then what? They sifted them? Put them in a furnace? Melted it to a vat of liquid steel or something? How did these bronze age "refineries" look like? How did these medieval metalworks look like?

And how on Earth could medieval dudes even manufacture intricate chainmail? That requires a load of tiny metal pieces that are interconnected to each other. Man, manufacturing that is hard.

I am curious and ignorant. Please helps me.

[Eleventh Century Remnant]

Shallow and open cast mining isn't that technologically demanding; all you really need is the ability to cut wood. Pit props, so then you can drive shallow tunnels, and follow veins of ore- bearing rock.

Hard and dangerous, yes, extremely labour intensive, but not impossible, and the reason in the early iron age iron cost so much. Peat bogs are also good for this- I may be wrong, but the chemical action of the peat erodes away the softer rock around the harder ore and makes it easier to get at.

Once you have hammered and picked the ore out of the surrounding rock, it gets smelted, buried in a pit with layers of charcoal- more labour, more time, more cost- and allowed to heat until the metal melts out of the ore.

This can take weeks and tons of charcoal per ton of ore, depends a lot on how good the ore and the charcoal are. A lot of trees get sacrificed for wood and charcoal in this tech level. Then it gets to the stage you're familiar with.

Going much further than about 100ft underground had to wait until forced draft pumps could circulate air around a deep mine and pump water out, something for the late eighteenth century.

Chainmail is trivially easy to make, actually. Done it myself. Take a lump of metal, heat it up, hammer and draw it out- basically make a thick wire- and wind it round a spindle. Critical is getting the temperature right, too hot and it fuses to the spindle, too cold and it's brittle and awkward to bend. Short sections at a time worked best for me.

The spindle gives it the ring shape, slightly offset of course, and then you take two pairs of pliers- the most difficult part in the sequence is making the pliers, actually, toolmaking was a specialised and highly paid subset of smithing- and close them through each other. Knitting with metal, basically. Riveted mail adds an extra two steps to the process and is unbelievably fiddly, butted comes apart more easily but is vastly easier to fix.

Easy but time consuming- our usual reckoning is roughly a thousand man hours of work to make an elbow-and-knee length mail shirt. The smith wouldn't do it himself, his time's too valuable, it would be apprentice's or minion's work.

Silly story; this happened one year at the Largs viking festival, Jim(the middle one) is sitting by the portable forge making nails, when daft american tourist woman rolls up, kids in tow. Looks at this example of traditional craftsmanship, looks at tired, hung over, unwashed dark ages reenactor, tells children "Now, kids, this is actually wrong, because they did not have nails in those times."

Jim, who has had all the politeness sweated out of him by now, says without even bothering to look up, "Aye, right, they stuck Christ tae the cross with fuckin' duct tape."

[Shroom Man 777]

Very intriguing. I mean, man, laymen like me seldom ever hear about these really intricate and sophisticated procedures done by seemingly "primitive" people to make stuff like the swords they stab people in the face with, and the whole chain of supply from digging crap out of rocks and holes in the ground to melting those rocks in a heap of charcoal until the metal comes out* to finally delivering those chunks of steel to blacksmiths who will hammer them into said swords used to stab people in the face.

*How did they collect the molten steel? Did they have siphons or something to direct the flow of the liquid metal?

[Simon_Jester]

Hard and dangerous, yes, extremely labour intensive, but not impossible, and the reason in the early iron age iron cost so much. Peat bogs are also good for this- I may be wrong, but the chemical action of the peat erodes away the softer rock around the harder ore and makes it easier to get at.

Yes. Another reason bogs are good is that if there's a lot of dissolved minerals in the water, iron deposits out on the streambed and the muck and gravel on the bottom turn into very low grade iron ore over time. It's called bog iron. You're looking for stuff with a reddish-orange bed, like this.* Bog iron is handy because you don't have to dig through solid rock to get at it, but bad in that the quality of the "ore" sucks. For a medieval village, it's likely to be worth it if they have a bog iron deposit nearby.

*Anecdote: The stream in the ravine back of my house actually looks like that; if my area were a medieval village I suspect (without proof) that the local blacksmith would be my next door neighbor and I'd have spent much of my childhood hauling buckets of mud up the slope.

The spindle gives it the ring shape, slightly offset of course, and then you take two pairs of pliers- the most difficult part in the sequence is making the pliers, actually, toolmaking was a specialised and highly paid subset of smithing...

Still is, in a sense; tool and die manufacturers do pretty well for themselves.

Silly story; this happened one year at the Largs viking festival, Jim(the middle one) is sitting by the portable forge making nails, when daft american tourist woman rolls up, kids in tow. Looks at this example of traditional craftsmanship, looks at tired, hung over, unwashed dark ages reenactor, tells children "Now, kids, this is actually wrong, because they did not have nails in those times."

Jim, who has had all the politeness sweated out of him by now, says without even bothering to look up, "Aye, right, they stuck Christ tae the cross with fuckin' duct tape."

I very very much wish I'd been there.
________

Very intriguing. I mean, man, laymen like me seldom ever hear about these really intricate and sophisticated procedures done by seemingly "primitive" people to make stuff like the swords they stab people in the face with, and the whole chain of supply from digging crap out of rocks and holes in the ground to melting those rocks in a heap of charcoal until the metal comes out* to finally delivering those chunks of steel to blacksmiths who will hammer them into said swords used to stab people in the face.

*How did they collect the molten steel? Did they have siphons or something to direct the flow of the liquid metal?

At the end of the process ECR describes, you have iron, not steel. Steel is iron with a few percent carbon mixed in. You can totally make swords and armor out of iron, but steel is better because it's not so brittle (among other things, that being the one I know).

The most straightforward way I can think of to collect the molten iron is... don't bother. You just light up your giant iron ore barbecue, let it cook for a while, then wait however many days it takes to cool down. Then you send some guys with shovels to dig up all the charcoal, and at the bottom of the pit you've got little blobs of frozen iron. Scoop up the blobs, problem solved. Huge pain in the butt, but this is the Dung Ages, so you take what you can get.

Taking your iron and making steel of it is considerably more difficult; that's where the actual blacksmith comes into the business.

But I'm not the expert here. ECR is; stand by for anything I say to be overridden.

[Simon_Jester]

Another note: in the Bronze Age, the process was actually a bit simpler, because copper, tin, and zinc (the metals they used back then) are a lot easier to melt than iron is. You can extract them from the ores more easily, mix the nuggets of frozen metal appropriately, and then melt 'em together in a mold. Iron requires hammering.

The problem in the Bronze Age was that while copper is all over the place, both tin and zinc are relatively rare metals. One of the first trade goods to get shipped around in ancient times was tin (to the point where it actually made sense for Phoenician merchants to sail to England, get tin from the tribes around Cornwall, and ship the tin back to Egypt), and control over tin supplies was important to many Bronze Age societies (I've heard it said that the Shang dynasty in China collapsed in part because of the introduction of iron working, which broke the royal monopoly on bronze, though I cannot prove that this is actually true).

[Sea Skimmer]

Smelting metal is easy. For the earliest humans to do so, the process was literally no more complex then placing ore rocks into a fire, then using a cow skin bellows to blast it hot enough to melt the ore out. The chunks of metal would then be removed and melted again in a second fire to drive out more impurities, and then be drawn into some little sand trenches to create basic metal ingots. The use of clay pots greatly improved the process, as it provided a direct means of skimming off slag and then pouring molds all in one heating cycle. This was figured out by something like 4,000BC IIRC. After that metalworking is a very straightforward development through history.

Metal was probably discovered as a result of humans using copper or lead ore bearing rock to build a fire circle, and then noticing something strange in the ashes afterwards.

[Broomstick]

I wish to point out that several types of rocks are low-grade ores for various metals, and some of them are readily identifiable. For example, malachite:

is a pretty distinctive rock, and it's also a copper ore of sorts. Even better, the rocks around it, some of which are also strongly colored, also have copper.

Iron ores frequently have a reddish or yellowish color that makes them relatively easy to spot.

Gold sometimes occurs in pure form in streams - hence the technique of panning for gold.

So, once you know what sort of rocks produce metal when heated it's just a matter of getting more of those rocks

[Simon_Jester]

I've heard that copper also sometimes appears in pure form, but not from enough independent high-grade sources to feel confident saying so.

[Sea Skimmer]

That’s called native copper. Like gold you can find small but sometimes very rich deposits of copper nuggets. Most metals never occur naturally in metallic form, barring strange occasions like a lighting strike at the surface of an ore vein. But even once you find copper, humans still had to figure out how to work it into anything useful and that meant learn to melt it.

[LaCroix]

Well, in the early iron ages, up to the early middle age, bog iron lumps collected in swamps were the primary source of iron. This iron was concentrated by bacteria, by the way, and is nowadays rarely found. (Like the huge oak and yew woods that once covered Europe)

To make STEEL out of those bogs, you made an about 2/3 man-high furnace of clay, and filled it with charcoal, bog, charcoal, bog, etc. every now and then, you refill charcoal and bog until you run out of material, while a good handful of men rotates at the bellows, keeping the temperature at white-hot. Remember, the ore was not molten, only heated, burning of the impurities as slag. The temperatures needed to actually melt iron were only reached in the near-modern time, but not back then. So the result of a medieval furnace was white-hot glowing steel, not pure molten iron. (I'm looking at you, Jester )

This is how it looks like...


you can see the slag trickling out the spud hole to be. (it is resealed after every smelt, the rest of this furnace is permanent - therefore the artistry)

When everything is done, you break the seal and let the slag pour out.

Then you get the glowing steel (looks spongelike) out with hooks and tongs and put them onto a tree stump (too big for an anvil) and pound the crap out of it with huge wooden sledgehammers (diameter rulez for this work), until you have a compact bar (at this temperature, it is welded together, not just compressed). You might need to reheat it in the furnace a few times to complete this work.

This bar will then be brought to a smith who will estimate the carbon content an then refine the material (like done when making an katana - this starts by using the raw bar, too)), by folding it onto itself until it is about homogeneous. European bog ore and smelting process leads to much mild steel (0.2 to 0.3 carbon content) and little higher quality steel (0.4 to 0.6 carbon content) making damascene welding techniques a necessity to have enough material for work, but loosing about half the material as burnoff during the damascene welding.

When mining started and better ore was available, ~800s, smiths switched to using solely the better material, making tools and stuff out of single quality material.

The chain mail knitting process is correctly described, but most mails had some already riveted or welded rings woven into, to improve strength. Only the tongs to make it are not that complicated, they can be done in a few minutes of work. I made my first tong about ten hours into the craft, and it took about 60 minutes, including making the rivet for the tong.

[LaCroix]

Actually, there was a technique for carbonizing iron/milder steel, which consisted in putting the bar into a sealed container with lots of charcoal dust and then bake this for days at very high temperature. At that temperature, the carbon would seep into the iron/steel, making it a higher quality steel. But that was a terrible expensive and intensive process which was only be done when doing something very expensive to be (maybe a king's sword, if there was no good steel already present)

[Broomstick]

Very rarely, the early smiths (in Africa as well as Europe and Asia) would come across meteoric iron. How convenient, to have a lump of metal fall out of the skies! Some of them are huge, such as the Hoba meteorite. The Greenland Inuit used the Cape York meteorite for iron tools. Use of such material was rare, though, simply because large hunks of sky-iron aren't very plentiful, and for people without real forges working that iron was a matter of laboriously hacking off a piece, the even more laboriously beating it into a useful shape.

It has been speculated that some "magical" swords of antiquity were made of meteoric iron that was purer or stronger or at least different in quality that the iron or other metals otherwise available at the time.

[CmdrWilkens]

While the 163X series has a whole host of issues (I think every time I mention it Thanas has an aneurysm) but the non-fiction parts of the Gazette series make for an interesting read. Here is a Google Books result for a nice segment on Iron that takes a nice high level overview of the issue at hand.

[LaCroix]

I would take this text with a huge grain of salt. While everything mentioned is technically (mostly) correct, the processes he describes to be used in the past are not. The history of iron making before Bessemer is well documented and is redone nearly daily in experimental archeology. I can understand Thanas, but only because I have lots of theoretical and practial knowledge of that work.

Main Errors:

At first, ~1200 degrees is white hot heat, not 'above red hot'(red hot is about 700-800 °C). At white hot temperature, carbon is starting to burn, heating the steel even more in this process. Heat steel to white hot, sparks will start flying and you have a molten piece of pure iron. Without oxygen and in a sealed container filled with enough carbon (which will turn gaseous), it will absorb carbon. But pray that there is no leakage while you do this, or -> pure iron and a huge fireball.

Second, while medieval foundries did produce a lot of wrought iron and mild steel, they did produce good quality steel, too. They just ignored the first two steps he describes (de-carbonizing to wrought iron and then re-carbonizing to cast iron), and used just step three - throw rust into a fire that is nearly white-hot temperature and let it happily oxidize in lots of charcoal.

Third, Wootz is a special kind of ore, which happens to be a very good alloy, since it contains exactly the good impurities we need for modern tooling steel in the right qualities.

[LaCroix]

It has been speculated that some "magical" swords of antiquity were made of meteoric iron that was purer or stronger or at least different in quality that the iron or other metals otherwise available at the time.

Right in one. that was about the best ore available, and of course, it was a "sword" fallen from the sky, a present of god / the gods...

There were also strange fables which are factual. Like Wieland the Blacksmith of legends, who had the sword filed to dust, fed to chickens and then extracted from the excrement and reforged, over and over again, the end result proving to be stronger than ever. While very labor-intensive and wasteful due to loss in the welding, that would work (experimentally proven, including analysis). It enriches it with nitrogen, which is useful for more hardness. Same for quenching in piss - surface hardening through nitrogen in excess of the normal hardening through quenching in water alone.

[Fingolfin_Noldor]

Why does Nitrogen harden steel?

[Sea Skimmer]

The introduction of nitrogen into the metal (thus works on more then steel though not all metals) disrupts the natural crystal lattice structure of the material. This means the steel or whatever, can’t move as easily at the molecular level and is thus hardened. It’s a surface treatment and will not deeply harden metal, but this is the whole idea as you often want a hard surface with a ductile core for things like gears. Of course if you grind the stuff into dust first, then you can reasonably expect to harden the entire mass, but you would lose some of that hardness again in recombining the material.

[PainRack]

The problem in the Bronze Age was that while copper is all over the place, both tin and zinc are relatively rare metals. One of the first trade goods to get shipped around in ancient times was tin (to the point where it actually made sense for Phoenician merchants to sail to England, get tin from the tribes around Cornwall, and ship the tin back to Egypt), and control over tin supplies was important to many Bronze Age societies (I've heard it said that the Shang dynasty in China collapsed in part because of the introduction of iron working, which broke the royal monopoly on bronze, though I cannot prove that this is actually true).

Iron working was introduced during the swan song of the Zhou Dynasty, over 800 years after the Shang had collapsed, so....... yeah, I think that's busted.

I do wonder whether anyone has addressed why the Warring States used iron primarily as agricultural tools rather than weapons though.I not too sure on the timeframe here, but the first iron tools in China were farming equipment and not weapons and it would take until IIRC the Han dynasty for iron weapons to become common.

[LaCroix]

I do wonder whether anyone has addressed why the Warring States used iron primarily as agricultural tools rather than weapons though.I not too sure on the timeframe here, but the first iron tools in China were farming equipment and not weapons and it would take until IIRC the Han dynasty for iron weapons to become common.

I don't know if they used IRON or STEEL. Even in very old, old Rome, while the mass-produced military gladius was made from iron, officers often used brass swords. When quality steel became more common, brass weapons went extinct. So I think it was possible that the Warring States didn't have steel, but plain iron, which is nice for most tools, but not for weapons. A good work-hardened Brass blade would severe chip, bend or break an iron blade.

Steel>>brass>>mild steel>>iron

Addendum:
It might also be that they already had good steel, but it took some time until the Military did trust that new material enough to bet their lives on it. Transition to new technology is seldom fast, ask some of the military guys here about the age of most of the designs the army uses now.

[Simon_Jester]

Well, in the early iron ages, up to the early middle age, bog iron lumps collected in swamps were the primary source of iron. This iron was concentrated by bacteria, by the way, and is nowadays rarely found. (Like the huge oak and yew woods that once covered Europe)

To make STEEL out of those bogs, you made an about 2/3 man-high furnace of clay, and filled it with charcoal, bog, charcoal, bog, etc. every now and then, you refill charcoal and bog until you run out of material, while a good handful of men rotates at the bellows, keeping the temperature at white-hot. Remember, the ore was not molten, only heated, burning of the impurities as slag. The temperatures needed to actually melt iron were only reached in the near-modern time, but not back then. So the result of a medieval furnace was white-hot glowing steel, not pure molten iron. (I'm looking at you, Jester )

OK, OK, I'm wrong. Sorry. Jeez.

Nice furnace, though. Looks very angry and volcano-godlike.

This bar will then be brought to a smith who will estimate the carbon content an then refine the material (like done when making an katana - this starts by using the raw bar, too)), by folding it onto itself until it is about homogeneous. European bog ore and smelting process leads to much mild steel (0.2 to 0.3 carbon content) and little higher quality steel (0.4 to 0.6 carbon content) making damascene welding techniques a necessity to have enough material for work, but loosing about half the material as burnoff during the damascene welding.

Are those "percent" carbon contents, or some more obscure system?

Iron working was introduced during the swan song of the Zhou Dynasty, over 800 years after the Shang had collapsed, so....... yeah, I think that's busted.

Thank you. I should have known not to trust anything I remembered from high school history.

Hurrah for painful learning experiences!

[LaCroix]

That's percent.

everything under 0.3 percent carbon is mild steel (or plain iron). The interesting stuff is the 0.4 to 0.9 steel, because it can be hardened. Usually, .45 to .7 is used for tools and weapons, because the hardness gained by higher carbon content doesn't offset for the increased difficulcy in work and hardening. Higher contents was sometimes used for tools for cold metal works (shears, punches, etc.), but mostly refined (repeatedly folded) until the carbon had burnt of to .7 and used for quality products.

[The Dark]

The problem in the Bronze Age was that while copper is all over the place, both tin and zinc are relatively rare metals. One of the first trade goods to get shipped around in ancient times was tin (to the point where it actually made sense for Phoenician merchants to sail to England, get tin from the tribes around Cornwall, and ship the tin back to Egypt), and control over tin supplies was important to many Bronze Age societies (I've heard it said that the Shang dynasty in China collapsed in part because of the introduction of iron working, which broke the royal monopoly on bronze, though I cannot prove that this is actually true).

Iron working was introduced during the swan song of the Zhou Dynasty, over 800 years after the Shang had collapsed, so....... yeah, I think that's busted.

I do wonder whether anyone has addressed why the Warring States used iron primarily as agricultural tools rather than weapons though.I not too sure on the timeframe here, but the first iron tools in China were farming equipment and not weapons and it would take until IIRC the Han dynasty for iron weapons to become common.

(note: I'm using Wade-Giles instead of Pinyin for transliterating - I'm more familiar with W-G)
According to C. J. Peers' Soldiers of the Dragon, page 29, iron weaponry was "probably" introduced by the Yueh to Wu around 500 BC, about 25 years before the Yueh conquered Wu. Iron armor from the Ch'in period has been recovered in archeological digs, and Ch'u had iron swords and spearheads (although they're noted as being brittle and probably inferior to Ch'in bronze blades of the same era). The low quality of cast iron as opposed to advanced bronze may be why it wasn't as common for the first few centuries.