How should I maintain a gray-finished ninjato on display?
Updated Feb 2026
Begin with a soft microfiber cloth to remove fingerprints after each handling session, since skin oils accelerate tarnish on exposed steel. Every two to three months, apply a thin layer of choji oil or food-grade mineral oil along the blade using a lint-free applicator, then buff away excess. For the gray-finished saya and fittings, a dry cloth is usually sufficient; avoid silicone-based polishes that can leave a sticky residue. Position your display away from direct sunlight and heating vents, because UV exposure fades lacquer finishes and temperature swings promote condensation that invites surface oxidation.