Steel Smelting Question

K

Kevin Barry

Joined
Jun 3, 2017
Messages
8
Yes, it's another post about smelting your own steel.... sorry LOL
So I love making traditional Japanese style blades, and have recently wanted to make a sword set for myself, all by hand, using my own smelted steel. I have researched the tatara, and last summer I tried making basic bloom steel with some scale I collected. This worked but it wasn't like the Tamahanage I was looking for. I wanted to know if anyone knows either where to buy true iron ore online, or if anyone has tried using black iron oxide mixed with sand or something (the oxide powder they use in ceramics). Thanks for the help!
 
I wouldn't use something made for ceramics unless I knew exactly the composition.
Japan never had many natural resources .Their iron is iron oxide bearing sand . The process of smelting then is to reduce the iron oxide to iron , then forge and fold to get a evenly distributed mix.
 
mete said:
I wouldn't use something made for ceramics unless I knew exactly the composition.
Japan never had many natural resources .Their iron is iron oxide bearing sand . The process of smelting then is to reduce the iron oxide to iron , then forge and fold to get a evenly distributed mix.
Click to expand...
The composition of the iron pigment I found was straight FE3O4. I also found a composition chart containing samples of Japanese iron sand and it said that their sand is roughly 88.4% FE3O4 mixed with silica and other materials. My plan was to mix silica sand with the pigment to try to match those Japanese samples and see what happens
 
You could just buy iron sand as mined, e.g., https://www.amazon.com/MagZenTM-Natural-Magnetic-Magnetite-Black/dp/B01NAY2WN0/ ("magnetite iron sand" is a good search term; you'll find sellers on alibaba if you're after a ton or a few tons).

Yes, the Japanese iron sand ore (after separating the iron ore grains by washing (traditionally) or magnetically (modern)) is mostly magnetite. Mixing it with silica sand might help, but the end product depends on more than just the ore. Notably, the clay walls of the tatara are a significant (the major?) source of silicates for the slag. You might need to mix more silicates in with the ore if your furnace walls won't be source of silicates. Don't know how important matching grain size would be for getting Japanese-like tamahagane.
 
Timo Nieminen said:
You could just buy iron sand as mined, e.g., https://www.amazon.com/MagZenTM-Natural-Magnetic-Magnetite-Black/dp/B01NAY2WN0/ ("magnetite iron sand" is a good search term; you'll find sellers on alibaba if you're after a ton or a few tons).

Yes, the Japanese iron sand ore (after separating the iron ore grains by washing (traditionally) or magnetically (modern)) is mostly magnetite. Mixing it with silica sand might help, but the end product depends on more than just the ore. Notably, the clay walls of the tatara are a significant (the major?) source of silicates for the slag. You might need to mix more silicates in with the ore if your furnace walls won't be source of silicates. Don't know how important matching grain size would be for getting Japanese-like tamahagane.
Click to expand...
I found this blog page last night which has excellent descriptions of the process they used if anyone is interested: http://www.samurai-sword-shop.com/blog/building-and-operating-a-kera-oshi-tatara/ My plan was to construct a much smaller test furnace, using almost identical construction to that in the article with the same sand clay mixture for the furnace lining. The reason I'm focusing on the ore mixture so much is because that's the only variable in the smelting process that I can't seem to get close to perfect. I really which I could find cheap magnetite ore online but I might have to try the iron powder-sand mixture and see how it goes
 
What's important in tamahagane is maintaining an average temp of 1,200. At that temperature, you won't produce a melt for blooming. What you get is a spongy lump that's part silica, un-smelted magnetite, part iron, part pig iron (ultra-high carbon iron) and carbide steel. I'm not a deep expert with tamahagane but with silica, the less the better. Tataras use the purest magnetite sand available.
 
hank_rearden said:
What's important in tamahagane is maintaining an average temp of 1,200. At that temperature, you won't produce a melt for blooming. What you get is a spongy lump that's part silica, un-smelted magnetite, part iron, part pig iron (ultra-high carbon iron) and carbide steel. I'm not a deep expert with tamahagane but with silica, the less the better. Tataras use the purest magnetite sand available.
Click to expand...
Do you or anyone know how to maintain that temperature throughout?
 
Kevin Barry said:
Do you or anyone know how to maintain that temperature throughout?
Click to expand...

Much easier now than it used to be; a high temperature electric furnace will do it. But you won't necessarily get a tatara-like result, because the tatara isn't at a uniform temperature, and doesn't maintain a constant temperature over time. The hotter parts give you high-carbon steel, the cooler parts low-carbon iron, and the too-hot parts cast iron.

From photos I've seen, Chinese small-scale "tamahagane" making, for swordmaking, is done is electric furnaces. Don't know how much their product looks like tamahagane before forging, but it's a fair imitation after.
 
Kevin Barry said:
Do you or anyone know how to maintain that temperature throughout?
Click to expand...
as timo said, a tatara cannot really maintain a uniform temperature. AFAIK, using the dowel method (a pole made of hard wood), hardening/tempering temperature from 650 to 820 degrees centigrade causes the dowel to smoke and turn black as soon as you insert it to the fire. the smelting temperature (beginning 1,000 deg centigrade) causes the dowel to fire up almost immediately.

tatara masters stay awake during the 3 days of charging to make sure the right temperature is maintained.
 
hank_rearden said:
as timo said, a tatara cannot really maintain a uniform temperature. AFAIK, using the dowel method (a pole made of hard wood), hardening/tempering temperature from 650 to 820 degrees centigrade causes the dowel to smoke and turn black as soon as you insert it to the fire. the smelting temperature (beginning 1,000 deg centigrade) causes the dowel to fire up almost immediately.

tatara masters stay awake during the 3 days of charging to make sure the right temperature is maintained.
Click to expand...
Thank you everyone for your imput. My plan is to start with a test tatara measuring 2 feet long by 1.5 feet wide and deep. It will be constructed with clay bricks and a homemade ground clay- sand mixture for the lining. I'll use 4 oxogyn inlet pipes on each side and a old salvaged blower for the air power.
I'm going to use the FE3O4 powder mixed with 20% silica sand (to give it as much authenticity as possible and avoiding using pure iron oxide). I will start with 20 pounds of iron sand analog and as much charcoal as needed. I'll add a 1/2 pound of iron sand analog and 1 pound of charcoal very 10 minutes for 5 hours. After I will extract the Kera, quench and break apart to see what happened! I'll begin to gather the materials and hopefully will be able to start construction within the next week or two, and I'll post updates as I go.
 
Paul Champagne, swordsmith used to collect his own iron sand from the riverbanks in New York, local to him. However, he was not running a tatara to produce a bloom. I have seen at least one Chinese maker that was getting bags of the sand.
http://www.swordforum.com/forums/showthread.php?91862-HandMade-Real-HandMade-Katana-Sword

Jesus Hernandez is at the top of the list for American smelters, similarly running more vertical furnaces. FWIW, the traditional Japanese tatara are the shape they are to produce a very large volume of usable steel.

Cheers

GC
 
Yes, check out Jesus Hernandez's site. He has information on how to build a small furnace and use rebar and charcoal to smelt iron.
 
You must log in or register to reply here.
Back
Top