Sharpening Japanese knives
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This is a new subject for me, as I was gifted an Aritsugu Wakogoro knife by my sister in return for sharpening her kitchen knives. She and her mate were in Japan on vacation and she found an outlet shop where you’d buy knives and they’d sharpen them for you as you waited. She warned me to be careful, as it was VERY sharp! I chuckled, thinking of the times I’d warned others the same way.
When I got the knife home, I clamped it in my WE vise so I could examine the edge with my USB microscope. I have small pieces of UHMW tape on the face of my ‘scope, so I can slide it easily along the edges of knives I sharpen. I was stunned to see that the edge would bite aggressively into the UHMW, making it difficult to do much sliding. In short order, the UHMW had been cut completely through, requiring immediate replacement. VERY sharp!
https://tcmeyer.smugmug.com/Knife-Stuff/i-Xg5zvzQ
I then went on youtube, looking for Aritsugu Wakogoro and found a video of an Aritsugu shop in Kyoto which seemed to match my sister’s description. She confirmed that this was indeed the shop she visited.
https://www.youtube.com/watch?v=Cdwd98EadAQ
On inspection with the ‘scope, you can see that there are two separate grind lines along the edge. Of course, they are convex in form. The first grind pattern is longitudinal to the blade. The video shows this being done on a wide-faced drum-type wheel. The craftsman holds the blade horizontally at the very top of the wheel, moving the blade back and forth, while making contact only at the same tangent point. This seems to me to be very clever, as he can see plainly that he’s holding it at the correct angle. In fact, he’s probably varying the angle slightly to form the convex profile.
From the there, the blade is moved to a craftsman (maybe the same guy?) who works the blade on a flat waterstone to put the final edge on it. I should look more closely at the blade, as there may be a microbevel at the very edge.
Once the blade is sharp, it is handed off to an engraver, who engraves your name (or whatever else you might deem appropriate) in kanji characters on the back side of the blade. Mine says “Meyer” or whatever the engraver wanted to insult me with as I’ll probably never really know
. The engraving is quite deep and from the video the steel is apparently quite soft, which begs the question; How hard is the edge?So far, the only thing I’ve tried to slice with it is a hard section of Johnsonville Summer Sausage (I’m only about six miles from the Johnsonville plant). Pretty impressive! Woohoo!
Cool knife and video! I’m really interested to hear how the edge holds up to extended use. What is the steel?
-Clay
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I watched one of these “How It’s Made” episodes in which they showed the production of traditional straight razors at the Solingen plant. One of the final steps was to press the edge flat against the fellow’s thumbnail (it could be that he used his ring – I don’t remember clearly). The edge was thin enough if the edge would flex under the pressure applied. To be clear,there is no attempt to touch the nail with the sharp edge or to “run your nail across the edge.” The test was to check for thinness and flexibility.
Here is that particular episode.
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