The Artistry Behind KATSU ZK02 Blades

KATSU ZK02 is a very special knife. Its blade is made of 17 layers of ZDP-189 Super Steel, and the heat treatment from HATTA KOGYO CO., LTD in Japan ensures its remarkable reliability, while the skilled artisans at KATSU KNIVES give this blade a mirror-polished convex ground finish.

When you receive this knife, you will undoubtedly notice the unique pattern on the blade's surface near the spine. It might look like this:

Or perhaps like this:

Or this:

Even the obverse and reverse sides of the blade may appear entirely different.


If you're concerned that the blade has such surfaces due to incomplete grinding, don't worry, this article is for you. You'll realize that your concerns are actually unnecessary because this is precisely the characteristic of the 17 layers ZDP-189 Super Steel.

If you look closely at the blade's spine, you'll see these layers stacked, much like in a multi-layered hamburger.

So, before grinding, the stacking inside the blade may look like the overhead view to the left of the blue arrow in the following image. However, during the grinding, the bladesmiths cannot know what lies beneath the grinding part. This uncertainty not only creates the beautiful linear patterns on the blade, but also determines the final appearance of the topmost layer of the blade. For instance, if the top layer isn't entirely ground through, you'll see a unique pattern where two layers of material are mixed together in total random ways, as shown in the blue arrow on the right side of the image below.

Also, please note that blade smiths will not deliberately pursue a "clean" surface (i.e., the top layer shows only one material). Why? Because these layers are too thin. The ultimate goal of the blade smiths is to made a perfect convex grind blade, and they cannot predict or determine the resulting pattern after the grinding process. One moment they may grind out a surface that appears "clean", and the next moment a "spot" may appear because that "spot" is happened to be the thinnest part of the top layer and it's now ground through, that's it.

This basically is how the distinctive pattern on the KATSU ZK02 blade is created. But the most important thing is, regardless of what the surface pattern of the KATSU ZK02 blade looks like, please believe that this is a masterpiece crafted by experienced blade smiths through hand grinding. Every KATSU ZK02 is well made, and you can rest assured of that.