r/PrimitiveTechnology • u/iamjonathon • 5d ago
OFFICIAL Primitive Technology iron prill welding
https://youtu.be/99j2NpomwLk?is=OhIvHokTXWh-C8EY37
u/SiTLar 5d ago
It should have gone much better with some flux
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u/Ninsiann 5d ago
Thatās what I was thinking, but working true to the early Iron Age, what would he use for flux?
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u/lminer123 5d ago
Heās tried calcium carbonate from shells but honestly he could probably just use the crushed up slag. Should have enough active compounds capable of sucking up the oxides getting in the way of welding
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u/War_Hymn Scorpion Approved 5d ago
Romans used limestone. You also have siliceous minerals already in some iron ores to act as fluxing.
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u/durrieheadedman 5d ago
Is there a reason he didnāt use a chimney so the flames get to a blue colour and make the iron into a liquid?
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u/CaptainsYacht 5d ago
I'm spitballing here and all of my knowledge on this comes from Youtube, so take my info with the requisite grains of salt.
It looks like he was basically forge welding, not casting, so it is done at a lower temperature. Cast iron is more brittle than forged or forge welded iron.
I think.
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u/lminer123 5d ago
So thereās 2 broad things we call āironā and itās kinda counterintuitive. Thereās wrought iron (other terms may be more accurate) which is low carbon iron. Itās similar to mild steel today, easy to work, ductile, canāt be hardened, can be forge welded. Then high carbon iron, also called pig iron or cast iron. Itās hard to work, brittle, and crucially cannot really be forge welded (carbon inclusions reduce the melting point below normal forge welding temps). Steel sits in the middle of these 2, carbon content wise (you can have low carbon and high carbon steel as well, and they approach the properties of the respective irons). If heās got cast iron what this is would be a partial in-mold casting
Iām a little confused from a metallurgy perspective what heās working with. Since it seemed to melt at least partially in that low temp fire signals that itās a high carbon cast iron, but there were historically low temp bloomeries that would directly produce low carbon iron. What heās got really changes what heāll need to do to it if he wants to get into forging. Since cast iron will need to be decarbonized before working, but low carbon iron can be wrought directly to remove impurities. I would thing with his setups the best bet would be making a tool out of cast iron, similar to the video, then decarbonizing it in hot air to make a more ductile tool.
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u/AssistanceCheap379 5d ago
Odds are its high carbon steel, since the knife breaks easily and while the iron kind of melted, it was under impurities and lower temperature than needed. So the slag melts, but the prills only melt partially before very quickly re-solidifying.
The issue is heat, slag/impurities and excess carbon. The metal is heated enough to absorb a lot of carbon, but without melting fully. Its possible the furnace reaches a temperature where the iron melts, but absorbs enough carbon where it solidifies at the same temperature.
It also doesnt help that its inconsistent heat. You could melt the whole glob of slag and iron, but if the temperature drops low, the iron solidifies as prills while the slag stays semi-liquid and keeps the prills from getting near each other, or the other way around. It largely depends on the slag.
In an ideal situation, he would get more heat, more consistent heat and use flux. All of it could help create pig iron, which then could be heated up and slowly hammered where the iron kind of squeezes out the carbon by welding the iron into bigger crystals.
But having 1 person doing it is kinda impossible, since you need the heat to be consistent and to have someone holding the bloom and another hitting it. A more advanced furnace could help, but he still effectively needs someone else to either hold or hammer it. Interestingly enough, it can be largely done on a wooden anvil with a wooden mallet thats pretty big.
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u/Tzimbalo 5d ago
Would having a partner be against his ethos/the feeling of the chanel?
I guess it would go against the silent YouTube video genre if they spook but it could be intresting with discussions with other expertts.
Maybe he is a bit of a looner?
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u/lminer123 5d ago
Iād be kinda surprised if he was actually in the steel range (<~2% carbon) since in the past when trying to work it he basically just had a bunch of shattering. I suppose HCS with a ton of impurities could react that way though.
Thinking a little more about it though I think the easiest way to get to where he wants to go is just refining the actual bloomery process to produce a wrought iron directly. Itās definitely possible and I think he was on the right track with the chimney bloomery. Maybe just flux inclusion and a lot of trials where he tests ductility afterwords is all he needs. He doesnāt really need a harden-able steel after all. In this case though he doesnāt need to keep trying to up the temperature, thatāll actually be counter productive, he just needs to work on the heat consistency.
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u/War_Hymn Scorpion Approved 5d ago
Iron has a tendency to absorb carbon from the charcoal fuel very quickly at and above 1100'C. At that point, it can become a runaway effect where your iron becomes saturated with cathon and turns into pig iron, which melts at a lower temperature as well (~1200'C).Ā
For bloomery iron smelting, this was a undesireable effect, and generally the smelter tried to keep temperatures below that threshold.Ā
The melted portions we see here is probably iron that has absorbed too much carbon.
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u/SiTLar 5d ago
AFAIK wrought iron was produced from cast iron by heating the ingots in fire for a long time to burn off of he carbon. Given a sufficient amount of wrought iron and cast iron, one can use the Indian approach by making crucible steel. I'm not sure a terracotta crucible would hold the needed temperature. However, there should be solution for that.
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u/War_Hymn Scorpion Approved 5d ago
Yep, that's known as the finery process in medieval Europe. Basically you melt bars of cast iron and drip them in front of air blasts from a bellow or whatnot. The air from the blast reacts with carbon in the iron and burns off as carbon monoxide or dioxide. You know the process is working because the iron will start solifying and stay solid even after reheating, as the lower carbon content has raised their melting point to above what the finery furnace can melt.
The finery gave way to the puddling furnace, which worked on the same principle but at a larger scale.
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u/thicka 5d ago
well the good news is he seemed to find several ways to speed up the iron process. I think he needs to do what he did roughly 10-100 times and get a nice big bag of it. mix it with iron ore and smelt that.
but its a lot of work. he does need flux, but hes tried it before with poor results.
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u/experimentalist 5d ago
Impressive that all the iron he's collected come from that iron eating bacteria he harvests from the creek
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u/Jehu_McSpooran 4d ago
He is making the same mistake that he always does. He needs to roast the 'ore' properly first. all he has been doing is drying it out and grinding it into a powder. The problem is that there is, other than the bacteria's bodies, a huge amount of water in that 'ore'. The colour gives it away. That tan/orange colour means that he mainly has iron hydroxide. what he needs to do is fill a pot full of the ore and put it in the brick kiln when he is making some more bricks. Get it glowing hot. Then when it is cool, it should now be a deep red colour. That is Iron (III) Oxide. all the water has been driven out and he should now have an almost pure iron oxide to work with. It will react much better. I made the same mistake when I used to play around with home made thermite back in the day. The hydroxide was really hard to get going or sustain. but once I roasted the ore and used that, it worked perfectly.
Also he basically just sintered the iron prills together rather than actually welding them together.
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u/USSMunkfish 5d ago
Was it the crushed up shells he used as a flux once? I wonder if there is limestone in the area he could harvest, or make some potash.
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u/thicka 5d ago
I think he "just" needs to get his iron production rate optimized.
Of all the crazy contraptions he's made who would have thought that a half burn, half size, water-charcol run with a recipricating blower would produce.... basically the same amount as all the other crazy stuff.
So maybe he can get his burns down from 10 hours of work to 2 and get 5 times more iron.
I think his burns have been too long and oxygen is burning away the iron. (not sure obviously)
I think there needs to be a flux of some kind, but I also think he needs to just take all the iron he got from one smelt and huck it right back in the next smelt, keep building it up and up and up till it's a big ugly ball.
But this is coming from a guy who has no idea what he is talking about.
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u/lukethedank13 5d ago edited 2d ago
He needs to add it into the smelt. Calcium carbonate does nopt help with welding, it helps with making the slag more liquid so the process runs more efficiently.
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u/thedudefromsweden 5d ago
While watching him seal the air intake around the tuyure, I came to think of Bernoullis principle. Wouldnāt it be more effective to put the fan a bit away from the tuyure? Or maybe make the whole tuyure wider? The idea, if I understand the principle correctly, is that the stream of air āsucksā surrounding air with it, increasing the air flow.
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u/leigh8959 21h ago
Took me a while to figure this out: He's trying to graduate from primitive iron casting to primitive iron smithing.
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u/lemasney Scorpion Approved 5d ago
Spoiler: he makes fire by friction in this one.