How to maintain your Japanese Sword

First and foremost, do not attempt to polish or clean the blade with any abrasives. Without experience, you’re likely to scratch and damage the surface of the blade, leading to difficulties in restoring the blade properly later (loss of material, exposure of core etc.).

Machine polishing / buffing should never be attempted. This can damage the features of the blade (especially with any heat generated). Whilst it might make it look superficially shiny, you’re potentially removing the distinctive features that make traditionally made blades unique.

The nakago (tang) should be left unmodified. These are deliberately left to create a black rust. Any fresh, red rust can be treated with oil (traditionally choji oil, but a mineral / “gun” oil without additives should also be acceptable).

Also, never touch the blade with your bare hands – acidic oils and dirt will cause rust! If you do by mistake, please clean the blade properly.

Preparation

It should go without saying, but your sword is probably incredibly sharp! You need to find a safe, quiet area – without the risk of anyone distracting or bumping into you. The obvious risk of injury, as well as the potential damage to the blade should be kept in mind.

Basic steps – with a bare blade

• With a soft, clean cloth (microfibre will do), fan any obvious dust / dirt off the blade, then wipe along the length in a single direction, from the nakago (tang) to the tip.
• Some people then apply uchiko powder to remove any dried oil etc. This powder is actually slightly abrasive itself, so I generally avoid it for any regularly maintained blades, in good conditional and current polish. If applied, repeat the above step (with a clean cloth, shaking off any powder between wipes).
• With a soft, clean cotton cloth (or tissue) coat the blade in a thin layer of oil. Don’t use an excessive amount, as this will eventually build up (and trap dirt) in your saya (scabbard). Instead, just enough to provide a near-invisible film of oil.

Video

This is a video by Paul Martin, a former curator at the British Museum – and a recognised expert in the field (check out his books too).