Katana Sword Maintenance Kit Guide
Maintaining and dissassembling a katana is a pretty straight-forward process. In this guide, we'll be making it even easier by walking you through each step.
The most important point when maintaining a Japanese sword is to keep a light layer of oil on the blade. This prevents moisture from getting in and rusting the surface of the steel. Real, functional Japanese swords are made of carbon steel, and unlike corrosion-resistance stainless steel blades, they are very susceptible to oxidization. This is especially important with high-end katana, as re-polishing a blade in the traditional way can be very expensive. Not only does the blade need to kept oiled, but it should be cleaned and re-oiled every so often when not in use, and after every cutting session to ensure the blade is kept in good condition. If you live in a very dry climate you may only need to clean and maintain the katana twice a year, but in humid climates you’ll need to do it once or twice a month. It should also be cleaned and re-oiled if your fingers or any liquid comes into contact with the blade.
When cleaning the old oil off a blade, you should use a soft, non-abrasive, lint-free cloth cloth or tissue. You do not want to leave fibers behind on the blade when cleaning it. You should always hold the cloth against the spine side, never directly against the cutting edge. Once the blade is completely dry and free of oil, it should be powdered with the Uchiko ball. Uchiko is a fine powder made from a kind of polishing stone, it is wrapped up in silk, with a handle for ease of use. By applying it to the blade, it soaks up any left-over moisture. It’s also a really fine abrasive that helps to clean the steel as it’s wiped off. Tap the uchko ball against the side of the blade while moving it towards the tip, applying powder evenly to the whole blade, then again to the other side, and also to the spine. Take your cloth and again wipe down the whole blade. This will keep the blade in great shape.
Next, we’ll be reapplying a new layer of oil. The Japanese use something called Choji oil which is made of 99% mineral oil and only 1% clove oil for fragrance. This is the traditional option, though there are several alternatives that can be used, such as machine oil, motor oil, gun oil, 3-in-1, and light mineral oil. Dab a small amount of oil on the cloth. Softly move the cloth down the blade, ensuring every inch comes into contact with it. If your katana has a bo-hi, or groove, it should be oiled as well. Inspect the blade against the light and check if any area is missing oil. When the entire blade is covered in a light layer, you are finished.
Finally, we move on to dissassembly. Traditional Japanese swords feature one or two bamboo mekugi pegs inside the handle which serve to hold the blade in place. They are made so that they can be easily removed to inspect the tang, the hidden part of the blade that extends into the handle. If you purchased a maintenance kit for your katana, you likely have a small brass tool known as the mekugi-nuki, which is a hammer with an inserted punch that you can take out and use to remove the pegs in the sword handle. If not, a small piece of wood or flat-head nail can be used as a substitute. The top of the mekugi-nuki hammer can be unscrewed to reveal the punch. Most mekugi pegs are tapered, meaning they have different thicknesses on each end, and can only be removed in one direction. The side of the handle where you can visibly see the peg will be the side it comes out. So once you find this, flip the handle over and push the ito braid aside slightly so that you can hammer out the peg. Hold the punch over it and hammer the end with your mekugi-nuki.
Once the pegs are removed from the handle, the handle and fittings can be removed. For particularly tight-fitting katana, this might be a difficult process. To loosen the handle and free it from the tang, hold onto the handle with your left hand and strike your left hand with your right, jolting it loose. It could take a couple tries before the handle comes loose. Another option is to hold your hand all the way up against the tsuba as pictured above, squeeze, and push up against it until it loosens. Once the handle is off, you can remove the seppa (spacers), tsuba (hand guard), and habaki (collar). It can be reassembled by sliding the fittings back onto the tang in the order of habaki, seppa, tsuba, seppa, and finally the handle. They may not go all the way on properly. In this case, tap against the kashira (butt cap) with a softwood block to tighten the fittings. And there you go, you now know how to maintain and disassemble your carbon steel katana!