A katana is steel that wants to last centuries — but only if you tend it. Caring for a blade is a quiet ritual that takes minutes and rewards you for years. Here is how we do it at the workshop, and how we recommend you do it at home.
Why steel needs tending
Bare carbon steel rusts. The enemy is moisture, and the most common source of it is you: skin oils and fingerprints are mildly acidic and will etch the surface over time, especially across the hardened temper line where the metallurgy is most active. The fix is simple — keep the steel clean, dry, and lightly oiled. If you want to understand why different steels react differently, our steel guide explains the trade-offs.
Wiping and oiling the blade
After every handling, wipe the blade down with a soft, lint-free cloth to lift fingerprints and any moisture. Then apply a thin film of choji oil (a light mineral oil traditionally scented with clove) using a clean cloth or oiling pad — a few drops is plenty. Wipe along the flat, never across the cutting edge. Re-oil every few weeks for display pieces, more often in humid climates or after any contact with skin or air.
Handling the edge safely
Treat the cutting edge with respect even on an unsharpened blade. Always keep your fingers behind the edge, draw and sheathe slowly and deliberately, and never run a cloth along the ha with the edge facing your hand. Hold the sword by the handle, not the blade.
Storing the saya
Store the sword horizontally with the scabbard positioned edge-up, so the blade rests on its spine rather than its edge — this protects both the ha and the lacquer interior. Keep it out of direct sun and away from damp; avoid leaving a freshly oiled blade sealed in the saya for long stretches in high humidity, as trapped moisture is the usual cause of rust spots. Done consistently, this routine keeps your katana looking the day it left the forge.