Proper care for your blade is necessary to ensure that no rust/oxidization forms. High-carbon steel, by nature of its physical properties, is prone to rust and requires proper maintenance. A blade should be cleaned and re-oiled after use and never sheathed without proper treatment, as dirt and oils can build up within the saya itself.  If a blade is not actively being used for practice, it should still be oiled two to four times a year, depending on humidity. 

Over time, especially with hard Tamashigiri practice, the mirror finish will begin to scuff and the edge begin to dull. As well, even with proper maintenance, rust may form. Polishing/sharpening of our swords should be undertaken by a trained professional only. The original polish on our blades is done entirely by hand on Japanese stones.