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Tadatsuna White Steel Kamagata Usuba 180(7")
Japanese Kitchen Knife Review

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Tadatsuna Shirogami Kamagata Usuba 180(7")

My first knife from Awataguchi Ikkanshi Tadatsuna - Shirogami(White Steel) Kamagata Usuba. I've heard all the compliments about Usuba type knives on the knifeforums.com kitchen knives section. Frankly, I don't consider usubas that appealing. They look rather weird with their chisel like appearance. Still, once I saw the Shirogami Kamagata Usuba, which is simply an usuba with rounded tip that also forms some sort of the tip, I knew I'd have to buy it. For the record, I found it in Takeshi's store, at Aframes Tokyo. At that time I was more interested in Shirogami steel knives what in an usuba of any type, but for one I liked (sort of) kamagata shape, then I wanted to test white steel knife. So, I've had whole two reasons to buy the knife, and very often I don't even need a single reason to buy a new knife. As you can see it was a perfectly justified purchase ;) Not that knife nuts need any justification for their knives.

General

- Very generally, kamagata usuba is a subtype of usuba knives. Like I said above, this is an usuba with more rounded tip. Obviously, as a quality piece of Japanese cutlery Usuba arrived packed in a nice box with Tadatsuna logo. Tadatsuna style saya was strapped to the box. I've written about I Tadatsuna himself and specifics of his wood sayas in my review of Tadatsuna 270mm Shirogami Gyuto review. Initial inspection was done as soon as I opened the box. I sincerely with I'd have to report a perfect blade, except it wasn't. As far as grind lines and fit went it was all perfect. No gaps between the handle and the blade, tang entry point is well sealed. Main problem was the back side of the blade which was scratched up pretty bad. Initially, I thought I got an used blade by mistake. Takeshi confirmed that he sent the box straight from Tadatsuna. So, if anything it slipped quality control at their factory. In the end I've decided to keep the knife. Since Tadatsuna discontinued the white steel knives at least for the time being (2009), it was rather unlikely to get a replacement. Besides, Takeshi gave me discount for the damaged blade. Scratches or not, the blade was extremely sharp. No other problems aside from the botched sharpening job on the back side. Either way, 280$ knife shouldn've been like that. Seems like I've got bad luck with Tadatsunas in general. Gyuto has a loose handle, kamagata usuba has scratched up blade... On the other hand knife performance is great (after resharpening, but about that below) and all the other Tadatsuna users are just raving those knives. Nevertheless, for now I am on hold with new Tadatsunas though.

Blade

- The blade of the kamagata usuba is 180.00mm(7.09") long and 4mm thick. Usubas in general are more powerful and more precise knives compared to Nakiris, so that's why heftier blades. Blade is exactly 45mm wide. Given usuba geometry its width is the same except for the first 15-20mm. As it is still an usuba, the blade is chisel grind. Right side of the blade has Tadatsuna logo. Urasuki is slightly concave as usual. The rounded tip provides finer point for delicate work. Works ok for small items, like destemming strawberries. Can't say it's the most comfortable knife for that type of work, paring knives work much better for that. Other than that nothing interesting to report on the blade geometry. The edge is a straight line and that's it.

Initial edge was very sharp. I still gave it a few passes on 0.25µm diamond crystal loaded leather trop. Then stropped on the plain leather strop. After that I've proceeded with some test cutting. The first test item was the red radish. And the results were simply devastating. Unfortunately, the devastation was inflicted upon the edge, not so much on the radish. Well, not that it was intact. Kamagata Usuba did cut through the radish, I've sliced it and it was very smooth cuts too. However the edge was severely rolled pretty much all the way wherever it has touched the radish. I was both, unhappy and very puzzled with the result. Never had a knife blade behave like that on me. From what I know that does happen with very soft steel knives, i.e. whatever fails the heat treatment somehow. On the other hand, even failed heat treatment was strange explanation for the damage done by radish. I couldn't come up with any better solution than to resharpen it again. I've started with 2000-3000 grit Japanese natural Aoto waterstone, followed by 8000-12000 grit Kitayama synthetic Japanese waterstone. Next was the usual finishing with 0.5µm and 0.25µm diamond spray and plain leather strop. Same cutting test was repeated and the same devastation was inflicted on the edge. I started seriously suspecting the defective knife, namely failed heat treatment.

For couple days I didn't do anything, just communicated with Takeshi about the problem. He suggested to return the blade, but I was reluctant. Then, next weekend for some reason I have decided to sharpen the knife again, but I've measured the edge angle first. Interestingly it came out ~5°-6° For the record, angle was measured as arcsinus of the blade height above the stone, till mid spine divided by blade length. Pretty accurate. That was very low and I've decided to try more realistic 15° edge. Bear in mind this is the single bevel edge. The other side is flat, i.e. 0°. This 15° would translate into 7.5° per side for more conventional V edge. Anyway, 15° included angle proved to be successful for all subsequent cutting tests and actual use. Which is where the edge is since then.

Because of all those problems and my suspicions about the heat treatment quality of the kamagata usuba knife I have actually tested the hardness of the blade. In general this isn't a luxury you can afford daily, unless you have a Rockwell tester in house. And even if you do have it, then each testing leaves a visible dimple mark on the blade. So, unless you intend to redecorate the blade with multiple dimples, it's better to refrain from multiple testing ;) Since I have no RC tester at home, I've had to take it to the local heat treating company and had the testing done there. That was on March 24, 2009. RC tester showed 15HRC on the jigane and 62.3HRC for the Hagane. Which is pretty close to what the rumors said about Tadatsuna hardness 63-64HRC. In the end, it wasn't a failed heat treatment. And for now I keep it at 15°.

Handle

- Kamagata usuba original handle was made of Magnolia Wood. Approximately 150mm long, D shaped handle which is quite popular in Japanese knives. As you can guess, D type handle thanks to its ridge isn't ambidextrous. Well, for the correct hand it is pretty comfortable and I haven't had any negative feelings about it either. D handles are kindda funny. On some knives they work real good, on others I simply hated them, like on Shun 200mm Gyuto. One of the characteristic features of Tadatsuna handles is their width, or thickness. They're quite wide compared to most of the Japanese knives I've ever seen. On the other hand they're really comfortable. So far I've had WA type handle on the Tadatsuna White Steel Gyuto and D type handle on this usuba. Both worked well, except the handle on gyuto became loose. So far I've gone through all styles of cutting with my usuba and the handle was pretty good. Longest cutting session with Kamagata Usuba was approximately 2.5 hours long, as usual it was non stop cutting, with prepared ingredients. I didn't get any cramps in my fingers, nor any sore spots on my palms, so I rate the handle as really comfortable. And as usual, I am going to replace the handle with a custom one from Stefan Keller.

Usage

- Pending.

Specifications:

  • Blade - 180.00mm(7.09")
  • Thickness - 4.00mm
  • OAL - 315.00mm(12.4")
  • Steel - Shirogami 62-64HRC
  • Handle - Magnolia Wood
  • Weight - 158.00g(5.34oz)
  • Acquired - 03/2009 Price - 279.00$

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Last updated - 09/01/11