How should I maintain a carbon steel ninjato kept on display?
Updated Mar 2026
Carbon steel requires periodic attention to prevent surface oxidation, especially in humid environments. Every two to three months, remove the blade from its saya and apply a very thin coat of choji oil or a neutral mineral oil using a soft, lint-free cloth. Wipe away any excess - a heavy oil coat can attract dust and degrade the wood interior of the saya over time. Avoid touching the blade surface with bare hands during handling, as the acids in skin oils are enough to initiate spotting on polished high-carbon steel. Store the piece in its saya in a stable, low-humidity space away from direct sunlight, which can fade the wood finish. With these simple habits, a 1060 carbon steel display piece will hold its appearance for years.