Wheel of Topics #23

Another topic from the past: How the Katana blade is forged. Although I did this topic before the fleet fusion, I didn't kept a copy of it, so this one may be a bit different.

It all start with many pieces of steel. Soft steel for the inner core and hard steel for the outer part. The reason why they use two kind of steel is to use their best quality and reduce their mutual defect. Hard steel(high carbon) is used to keep the blade sharper during the lenght of the battle, each hit not affecting its sharpness too much. Because it is hard it doesn't bend when hit, so a good hit could break it. The soft steel(low carbon) is used for it's flexibility, keeping the weapon in one piece when hit. Because it is soft, its edge become blunt rapidly and the weapon can bend and stay in its position. By placing a piece of soft steel inside a shell of hard steel, they keep the piece flexible and the edge will stay sharp. If some of you think: "why they don't used a kind of medium steel?" let me tell you this: most compromise between the two kind of steel keep none of the quality and possess all their defect to a lower level, making it useless for weapons.

Now that they a core of soft steel wraped in a piece hard steel, they heat it enough to fuse the metal together but not too much to change their composition. Then they hammer it flat, fold the piece, fuse it again, and start the cycle again creating many layer of soft and hard steel, creating a strong yet flexibler structure. They can fold the metal up to sixteen time, depending on the talent of the artisant and the desire of the customers, higher grade sword usualy have more layer(and more fold). Once they finish the folding process, they start to shape the weapon into a straight blade(yes, straight, I'll explain it later). With the blade shaped, they now start the tempering process.

They use a special quenching technique that will make the edge harder while keeping the flat side(the spine and sides) unchanged. To do this they cover all the blade with a mix of clay and other mineral, keeping the mix very thin around the edge. They put the sword in the fire again for some time and put it in water. The clay mix is a good heat insulant, so when the blade is put in water, the thinner part of the clay will let the edge to cool rapidly and the thick part will let the back and side to cool slowly. When metal is heated, it expand. Some alloy, when cooled rapidly will retain most of its expansion, and this is how the curve is made. The edge retained its new size while the back was slowly shrinking when cooling, giving the sword a slight curve. With all those difficult step, a single mistake anywhere within the production will make the final result useless.

If all the steps where made properly, they send the sword to a sharpener artisan to sharpen and polish the sword until it have a mirror finish. They start with coarse stone, followed by gradualy finer stone. They polish the entire sword to make it go through the ennemy with greater ease. The polishing process takes up to three weeks, that added the the few week needed for the smithing, place its production time to almost two month, and its only a sword from a common artisan. What could a master do in the same amount of time...

Grim the pirate