Restoring the oxidized blade of a sword or katana

Publication date : August 4, 2008

Last update : February 25, 2024

Steel is therefore made of iron and carbon. Nowadays, metallurgical knowledge allows us to add adjuvants (that's a metallurgical term, not a dirty word) such as chromium or molybdenum to make it, for example, stainless, harder, stronger... Like a recipe, there are an infinite number of variations (called nuances) based on the same basic ingredients. And even more so with recent additives such as vanadium, nickel... Some blades - more decorative in nature - come in black, red, blue... This is a surface treatment.

Whatever it is, the blade of a sword or a katana will always undergo an oxidation reaction when exposed to air or moisture. Even modern stainless steels merely slow down the disintegration of molecules in the presence of oxygen. Molybdenum and chromium don't really make steel perfectly "stainless" either. They merely supercede this inevitable phenomenon. With water, the iron in steel forms iron oxide, or rust. Without protection and appropriate maintenance, corrosion will progress to the surface, and even deep into the metal.

If a fencer is sincere about his or her knowledge of metallurgy and the mastery of blades, he or she also needs to know about certain aspects of maintenance in order to prolong their qualities and use. What can you expect from a weapon whose lack of maintenance renders it unusable?

Traditional steel oxidizes in the presence of air, acid or water. Oxygen in gaseous (air) or liquid (water) form produces rust on steel. Despite its vital importance to life on earth, we have to admit that it attacks - oxidizes - many materials, including metals. As a vital force, oxygen is also a destructive agent.

A katana or a sword are therefore susceptible to oxidation. With the exception of decorative models, where the steel used is usually stainless steel (such as 440), blades need to be maintained.