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Thread: Process of making Tamahagane
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Process of making Tamahagane
My understanding has significantly increased after watching these and I thought some of you might find it informational if not interesting to say the least.
Now know why it's so expensive and they sure weren't kidding when they said the process for manufacturing Tamahagane is well over 36 hours. I've been up longer than 36hrs before but it sure as hell didn't entail working under severe intense condition. Indeed, it doesn't get much closer to perfection than this.
What is Tamahagane or Traditional Japanese Steel ?
YouTube - The traditional Making of a Samurai Sword (Katana)
Property Type: Japanese Sword Forging
Steel is iron that contains carbon, so the more carbon a steel has , the harder it is. Most of the Japanese sword smiths are working with the traditional steel that is better known as tamahagane. In Japan there’s only 1 official smelter left. This Japanese style smelter is called a tatara. The tatara relies on the propensity of very hot iron to combine with carbon in its vicinity to produce steel.
In the tatara, it is the burning charcoal that supplies the carbon. These typical Japanese smelter is made of clay, about 5 feet wide, 48 inches tall and 15 feet long, where it’s walls are 10 inches thick.
One operating cycle of the tatara takes 5 days. One day to build the walls (clay and sand), 3 day’s to smelt and 1 day to remove the iron out of the tatara. In this 5 days process , they need about 13 tons of charcoal and 8 tons of satetsu (black sand) to produce 2 tons of iron and steel, which is called Kera.
About half of this Kera is composed of steel ranging from 0.6 to 1.5% carbon and it is this portion that is called tamahagane. Only Two thirds of the tamahagane is of a good quality. The rest of the Kera can be used for forging swords if another separated forging operation is done, this process is called Oroshigane, where carbon is added or reduced.
Every time Tamahagane need to be made, the tatra needs to be rebuild. Its walls must be build out of clay bricks. The mixture that is used to make the bricks does contain a large amount of sand (silicon oxide) which makes the tatra resistant to fire and melting.
Since the forging process of a sword produces a continues loss of carbon, most of the smiths like to start with tamahagane that has an carbon content of 1.0 to 1.5% to forge the kawagane (jacket steel).
A billet of tamahagane from the tatara furnace is very big (as you can see in the video) and includes various qualities of steel. The big ‘rock’ of Tamahagane is broken into many small pieces to check the quality.
From here on the smith can choose the right pieces and start the forging process of this katana.
Here's another
YouTube - Nihonto TV on Discovery Channel
Tamahagane is smelted very much the same way today as it has been for centuries. As always there are considerations taken into account. People being as close as they are to one another in Japan, the smelting process has an immediate and direct effect to the surrounding land; usually shared by farmers. So, as it goes they came to an agreement and limited the manufacturing of Tamahagane to three weeks per year in some areas.
This social contract is an understanding and mutual agreement between land users sharing their environment with a Tatara. I get the sense there are only a small handful of Tatara throughout all of Japan, so don’t think this is norm for Japanese; but it is a great example.
The Tatara, or Japanese smelter, has virtually no mechanization. Once started, the process is a 72 hour commitment on behalf of the Tatara master and his crew. They continuously shovel prepared charcoal into a huge burning oven made of clay. The main ingredient, iron sand, is usually collected from the riverbed nearby. The sand and river, of course, is the dual reason farmers and the Tatara share land.
At the end of the three day/night fire, an uneven mixture of iron, nickel, silicon, carbon and other elements is formed at the bottom of the Tatara. The clay walls are smashed and a meteor looking piece is hauled from the base. Altogether the final solid mass weighs well over a ton. It’s then processed into small pieces and distributed mostly to sword smiths in Japan.
It’s understood that Tamahagane manufactured in Japan should not leave the country for sword production purposes in other countries… although I don’t know if it’s an illegal act or not, the fact it would be mostly frowned upon is enough to enforce the unspoken rule. The only flexibility I’ve seen with this rule has been for demonstration purposes, when Japanese smiths travel to other countries.
Tamahagane is the impure base material for the Japanese sword. It’s the core element in the most famous weapon manufactured. There are many variations and practitioners outside of Japan, but in Japan it has been carefully preserved and resurrected (since WWII) to a point where many consider today’s practitioners as good any era.
More info on steel
What I thought was interesting was when narrator admitted to only being trained with calculators and such. That he's never been able to properly judge steel temperature by gauging it's color.
I wonder if it's same process they use when it comes to applying hamon on the kamisori.
Cliffs:
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Originally Posted by thebigspendur
