Sharpening Single Bevel Japanese Sushi Knives

[Michael Bates]

So, I tried sharpening my Kasumi Yanagi Sashimi 10.5″ (270mm)blade (from Yoshihiro cutlery) and quickly found myself outside my skillset due to the configuration of a single bevel edge (about 20 to 23deg) with a very large radius (almost flat) backside and extremely hard steel (Shiroko High-Carbon Steel (White Steel)). My first mistake was to attempt to reprofile to a flatter angle (15 deg)using coarse grit stones (100). The edge steel is very hard and brittle (62-63 HRC) and because of this when I got close to the edge, I fractured it . It didn’t help that during the reprofiling process I sharpened in 2 directions. I am fairly sure the large grit on a down stroke was the wrong thing to do and did the majority of the damage. To correct the damage I did took many hours. I was finally able to obtain an edge, but because of the length of the blade, saw a large angle change near the heel and blade tip. I’ve decided to live with this, but am now purchasing a much more expensive knife (Yoshihiro $420 Blue Steel Ao-Ko Namiuchi Deba Sashimi Knife 7.7″ (195mm))and want to properly sharpen it. Looking for any tips or suggestions.

[Blunt Cut]

When shaping an edge with less than a few micron thick, regardless of stroke direction the abrasive must be within certain reasonable range, i.e. less than 20um. 100 grit is around 130um.

The Kasumi jigane is just soft iron, so this clad layer get abraded almost instantly. Now all the pressure will be concentrated on the core/hagane white steel. So using very low pressure is recommended, especially abrading with large hard blocky fixed abrasive (such as a diamond plate).

As for the kasumi haze use waterstones for that.

[Mark76]

Interesting topic and if more people have experience, please let us know!

I have got a Takeda yanagiba. It’s double beveled, but has a very acute angle (less than 10 degrees per side). This is too steep for the WEPS, but to be honest, also too steep for practical use, so I put a 15 degree microbevel on it. If you’ve got a single-bevel yanagiba, 15 degrees on the edge side may still be too steep.

Indeed, don’t use your coarse stones on them. I’d start with the ceramics and then work up in grit size to see which stones abrade properly without damaging the edge.

If you want to emphasize the haze, waterstones are the best for this, as BluntCut wrote. According to the pros (Ken), some Japanese waterstones work best for this purpose.

Molecule Polishing: my blog about sharpening with the Wicked Edge

[Mark76]

I just saw a similar topic: http://www.wickededgeusa.com/index.php?option=com_kunena&func=view&catid=20&id=6652&Itemid=63

Another entry for the FAFQ :cheer: .

Molecule Polishing: my blog about sharpening with the Wicked Edge

[Author]

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