The Anatomy of the Katana

AnatomyOfSwordLogoFor my last post, I talked about the importance of black gums for dogs and my failure to understand why some drivers refuse to move to the right when they are not overtaking. After talking about that stuff, I then wrote a post about the anatomy of rapiers. Today, we move almost as far as you can get from rapiers—geographically, philosophically, and designally. I know it’s not a word. But symmetry is important, dammit. Today, we visit Japan, to talk about Katanas. No, I don’t mean that literally. No one is going to Japan. Well, many people are going to Japan, but we are not included in that. Unless, of course, you’re going to Japan. In which case, please bring me back a katana.

There is a lot of similarity between the knight’s arming sword (discussed in the first of our Anatomy series) and the samurai sword. Both were seen as ideological weapons. Both sword types had deep spiritual value in the culture. Both were used only by the upper members of society that had been given the privilege to use them. And both are used in really, really cool movies.

The katana was typically used by Samurai, who were the only warriors allowed to wear two swords. And while the knightly sword was deeply invested in the knight’s religion, the katana was deeply invested in a samurai’s honor. And when a sword has that much value to an upper class warrior, you can bet the construction of that sword is going to be amazing. And man, were they ever.

A true Japanese katana, made by a master smith, is two parts artwork, two parts killing device, and one part liquid coolness (it’s true. Japanese swordsmiths pioneered techniques for liquefying coolness). The blades of these fine swords were made from differentially tempered carbon steel, which is a really fun and impressive term to drop in conversations, or just to say. Go ahead. Say it. Differentially tempered, high-carbon steel. You actually gain two IQ points every time you say it.

What does differentially tempered mean? I’m glad I asked myself that question. When a sword is differentially tempered, it means that the sharp edge of the sword in heated at a different temperature than the back (or dull) side. Why do they do this? Another fantastic question, Roberto! Why thank you Roberto, you’re too kind. No, Roberto, *you* are too kind. And full of awesome. And you, sir, are made of liquified coolness. Um… where was I? Why? That’s right. Why would you heat the edges at different temperatures. To answer that, let’s talk a little about tempering in general.

When you temper a steel sword, you are putting it through a process of heating and cooling that makes the metal harder. Hardness is important for blade sharpness. The harder a blade is, the better the edge it can hold and the longer it can hold it. But hardness is a double-edged sword. Although katanas are single-edged. And the hardness itself isn’t actually a sword, it’s a part of a… I … there’s… my God, it’s full of stars… I may have just broken the space-time continuum with that analogy.
Anyway, the harder a steel becomes the better the edge it can hold, but the more brittle it gets. Japanese sword makers were well aware of this. So how to get a brilliantly sharp sword that can cut through a dead prisoner—yeah, that’s reportedly how they tested the edge of their katanas, on executed prisoners)—and still get a strong sword that won’t break when struck? Yeah, it took a while for me to get there, I’m sure you’re there already. If you heat the sharp edge at a higher temperature, and the rest of the sword at a lower temperature, you get a super-hard edge, and a strong, more flexible spine.

But how do they heat a curved sword at different temperatures? A round kiln? No, silly, with mud! Alright, technically it’s called *clay*, which is just an uppity word for mud. Sword makers paint the non-edge parts of the blade with a thick mud. When the blade is heated, the parts with the mud on them don’t get as hot. Tada. Differential tempering. Blades that have been treated in this way are left with a beautiful line pattern between the edge and spine. This wavy line is called a hamon, which means ham in Spanish. Why Japanese swordmakers named this line after a pork product from the Spanish language is a mystery to this day. The hamon usually undergoes a regime of polishing to make it look even better.

What else makes katanas such good weapons? Well, steel folding, of course. Swordsmiths fold the steel of Japanese katanas over and over again. Most likely because most sword makers started life as origami artists, and it’s good that they did. Because all this folding does two things—it pushes out the impurities in the steel, and it reduces the carbon content. Japanese blacksmiths weren’t the only ones who folded steel, of course, pattern-welding is a type of steel folding that goes back to the Celts, and possibly earlier. But Japanese swordmakers used the technique to perfection, getting just the right amount of carbon in their blades and creating brilliantly strong blades.

Image converted using ifftoanyAnd now for the illustrated portion of our blog post. I have listed some of the most common parts of a katana below, and spoken briefly about each of them. Have a close look, because these will be on the test.

Kashira – Buttcap. Google does not have a great sense of humor when it comes to any joke that I think of when describing buttcaps. In the interests of good ranking, I will simply say that buttcaps are the cap at the end of a katana hilt. And repeat buttcap again while I snort.

Ito – This is the silk wrapping that covers the same of the hilt. The combination of silk and rayskin gives both grip and comfort. I have shoes made from silk and rayskin for just this reason.

Same – I’m not going to make the same old joke about the same. I’m just going to say it is the material that covers the hilt of a katana. Traditionally, this is made from ray skin, because of the rough texture. Because of this ray skin, Many modern martial artists have changed their strike cry to, “Remember the Croc Hunter!”

Menuki – a decorative charm wrapped into the ito. These serve a few purposes. They cover the wooden peg (called a mekugi) that secures the tang to the hilt of the sword. They also provide the swordsman with additional grip and allow for more creative expression.

Tsuba– A huge brass instrument played in Japanese bands. Also, the guard of a sword. This guard keeps enemy blades from riding the steel highway down to your knuckles. Tsuba are typically either rounded or square.

Habaki– A metal collar that keeps the katan firmly in it sheath (sheaths are called saya).

Shinogi– a ridgeline in the blade. Not to be confused with the hamon. Or Shinobi, which was a late-80s video game that I was two quarters short of finishing at the mall arcade.

Mune – the back edge of the blade.

Hamon Line – remember that differential tempering stuff I was talking about? The hamon is the line differentiating the higher-temperature temper and the lower-temperature temper. Every traditional katana has a different hamon line. In fact, swordmakers could be identified by the unique hamon line they created in their swords.

Ji – While we’re talking about differential tempering, I should mention that the softer, back section of the katana is called the Ji.

Ha – While we’re talking about differential tempering, I should mention that the harder, front section of the katana is called the ha.

Kissaki – The tip of the katana, always slightly rounded.

There are many other parts to a katana. In fact, pretty much every inch of a katana has a name. The groove (hi) the grain of the metal (hada), the tang (nagako), even the hamon line, where it curves up into the tip, has a name (boshi). The anatomy of Japanese swords is a breathtakingly deep subject, and this post is only the first step on your journey, Grasshopper.

Did I miss something? Did I get something wrong? Feel free to challenge me—but bring your sword, tough guy. Because… well… because we can look at it and talk about it and swing it around and stuff.

See you next time, when we talk about the anatomy of the gladius!