How should I care for a carbon steel katana in storage?
Updated Feb 2026
Carbon steel — whether 1045, 1065, or Damascus — will develop surface oxidation if left unprotected, so regular maintenance is essential for long-term display quality. Apply a light coat of choji oil (a mineral oil traditional to Japanese sword care) or high-quality camellia oil to the blade every one to three months, depending on your local humidity. Before applying fresh oil, remove the previous coat with a soft, lint-free cloth or traditional nugui-gami paper. Store the sword horizontally in its saya when not on display, and avoid environments with high humidity or direct sunlight exposure. If storing long-term, wrapping the blade in a clean cloth after oiling adds an extra layer of protection. Never leave fingerprints on the steel — the salt and oils in skin contact accelerate oxidation noticeably on high-carbon blades.