How is the blue blade finish applied to a katana and how durable is it?
Updated Feb 2026
The blue blade finish on katana in this collection is a surface treatment applied after the blade has been forged, heat-treated, and ground to its final geometry. The treatment involves controlled oxidation or a coating process that produces a stable blue coloration on the steel surface. The result is an even blue finish across the blade that is considerably more durable than paint but should still be treated with care appropriate for a finished steel surface. Under normal display conditions - indoor placement away from moisture and abrasive contact - the finish maintains its color and appearance without intervention. Handling the blade with bare hands transfers oils and moisture that can eventually affect the finish's appearance over time; handling with soft gloves or a clean cloth and wiping down the blade after examination is the appropriate care routine. Avoid contact with water, cleaning solvents, or abrasive materials. The underlying 1045 carbon steel or manganese steel base gives the blade real structural integrity regardless of the finish, and the full-tang construction ensures the blade and handle are one continuous piece of steel.