Japanese swords forging video

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Bob Hubbard

Bob Hubbard

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MA-Caver

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The auto press/hammer definitely speeded things up for the craftsman as compared to 12-16th century craftsmen who had to fold the metal by hand.
I am at a loss as to the "mud" he painted on the metal and baking it.. presumably this is a hardener and thus how traditional blades had that scalloped look to the edges?

The other vids were very interesting to watch as well.

Good finds.

Thanks Bob.
 
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From what I read, it helps control the speed of cooling and the curve of the blade.
 

Chris Parker

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The application of clay along the cutting edge of the sword prior to cooling is for exactly what Bob said; as the shaped blade is put into the water, the clay acts to slow the cooling along the edge, meaning that it contracts slower than the back of the blade, "pulling" it into the familar curved shape. It also allows the edge to show particular crystaline particles, giving the hamon, or edge pattern. A skilled smith can create pretty much whatever pattern for his or her hamon they want, often having personal favourites that they become known for.

This is a big part of what gives the Japanese sword it's particular properties, an incredibly sharp edge, a graceful curve, and the flexibility to absorb the impact of use. While various aspects (such as the curve and hamon) can be rather beautiful, it should be remembered that these aspects are there primarily because it makes the sword a more efficient cutting tool. And a big part of that comes from the application of the clay, and the tempering/cooling process that involve it.
 

MA-Caver

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The application of clay along the cutting edge of the sword prior to cooling is for exactly what Bob said; as the shaped blade is put into the water, the clay acts to slow the cooling along the edge, meaning that it contracts slower than the back of the blade, "pulling" it into the familar curved shape. It also allows the edge to show particular crystaline particles, giving the hamon, or edge pattern. A skilled smith can create pretty much whatever pattern for his or her hamon they want, often having personal favourites that they become known for.

This is a big part of what gives the Japanese sword it's particular properties, an incredibly sharp edge, a graceful curve, and the flexibility to absorb the impact of use. While various aspects (such as the curve and hamon) can be rather beautiful, it should be remembered that these aspects are there primarily because it makes the sword a more efficient cutting tool. And a big part of that comes from the application of the clay, and the tempering/cooling process that involve it.
Thanks bunches on that... really.

You gotta wonder about something. Try letting your mind go back as far as possible to the FIRST time someone thought about using clay to do this. How did they come up with the idea? Was it accidental? Pulling it out of the fire/hearth and burning their hand and dropping the piece in mud and picking it up and dropping it into the trough and voilia! Or was it intentional? Either way ... ingenious.

Oh the things you learn on Martial Talk dot com. :uhyeah:
 

MBuzzy

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I was just wondering about the same thing. I mean, a modern scientist could come up with something like that, but when they figured that out, how much did they really understand the physics of impact and the properties of steel? I would guess that it was intentional and some genius just thought it up!
 

MA-Caver

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I was just wondering about the same thing. I mean, a modern scientist could come up with something like that, but when they figured that out, how much did they really understand the physics of impact and the properties of steel? I would guess that it was intentional and some genius just thought it up!

That is also just as likely... but I would guess there was a lot of trial and error involved as well.
 

Chris Parker

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Hey Caver,

Thanks bunches on that... really.

You gotta wonder about something. Try letting your mind go back as far as possible to the FIRST time someone thought about using clay to do this. How did they come up with the idea? Was it accidental? Pulling it out of the fire/hearth and burning their hand and dropping the piece in mud and picking it up and dropping it into the trough and voilia! Or was it intentional? Either way ... ingenious.

Oh the things you learn on Martial Talk dot com. :uhyeah:

Allegorically, the story goes that originally the Japanese used straight swords (which they did, based on the Chinese forms), and after a battle the Lord of the area would inspect the weapons, and then give his praise to the swordsmith who made them (some versions mention this as the Emperor doing the inspecting...). One day the Lord walked straight past the swordsmith without even looking at him, a terrible thing! The swordsmith in question, named Amakuni, then went onto the battlefield to inspect the swords for himself, and found that every single one had broken.

Depressed, Amakuni retreated into his forge to meditate on how he could improve his weapons. As is typical of these old Japanese tales, he had a vision, in which he was shown a new way of forging a sword, giving a single edge on a curved blade. Soon enough, the local area found itelf engaged in another war again, and the warriors went out armed with Amakuni's new sword. After the battle, the Lord went straight up to Amakuni (before even all the warriors of fame, the commanders, and those who distinguished themselves in the fight itself), saying "Truly you are the greatest of all swordsmiths!". Amakuni bowed low, and after the Lord left, he went to see the results of his labours. Not a single blade was damaged.



Okay, so that's the legend associated with it. Really, though, the Japanese sword is rather a miracle in and of itself in many ways, a huge number of unlikely circumstances led to it's development. The particular iron ore used is highly unusual in it's lack of impurities, it is smelted in a clay furnace known as a tatara for about 3 days and nights to add in the necessary carbon to turn it into steel, refered to as tamahagane (during which time the furnace is never left untended, to the degree that the head of the furnace doesn't sleep during the smelting process), then there is the ability of the swordsmiths to judge the amount of carbn in particular parts by the colour without any temperature devices, and so on.

So I think that a lot of trial and error went into it, but exactly how it was all discovered in the first place is kinda lost to us. Remember that until after WWII, swordsmithing was highly secretive from one forge to another, with the only reason it got less secretive afterwards was as a way to preserve the skills (as many highly skilled masters died before, during, or soon after the war, with their approach being lost). There are tales of rival swordsmithing apprentices suffering rather severe punishments for trying to learn the secrets of anothers smithing, such as the exact temperature of their cooling water trough (for putting the tip of a single finger in to test the temperature, the rival apprentice had his hand severed).

Bruno can probably add a fair bit to the metallurgical aspects, if he drops by....
 

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