What angle should a knife be sharpened at?

This blog is about two of the differences which have struck me between Japanese and Western culture and why the Japanese make the best blades in the world.

During the two years we spent developing TOG Knives, our chefs in London noticed the blades of initial prototypes becoming chipped during professional chef bashing, including chicken bones. I wrote to the bladesmiths in Seki and asked what angle they had been sharpened to. I was expecting an answer like “10 degrees, Knifemaster”. I waited for three weeks and it transpired that the delay was because the company had a sent a sample TOG blade to an engineering research institute who cut a thin slice (cross section) of the blade. They then used an electron microscope to photograph it at three different magnifications and analysed the angle at each magnification, both for the traditional Japanese blade design and an alternative version for the Western market. I love Japan.

What angle to sharpen a knife at 1

Knife Sharpening Angle 2

What angle to sharpen a knife at 3

So, the differences that struck me are:
1) You wouldn’t get a response like that from a Western company and
2) Japanese people treat their possessions with more respect and care and use each tool only for its intended purpose.

The bladesmith’s response to the chipping was that in Japan people would use a cleaver or dedicated heavier knife (eg. the ‘Deba’ for fish bones) for such a task. In the West, where we expect more robustness and versatility from our knives and often use whichever knife looks like it’ll work, that can mean traditional Japanese knives get chipped. So for TOG we specified a more robust blade, slightly thicker than it would be for a Japanese market and sharpened at 10° each side rather than 5°. It’s still less that the 20° each side you might see on a German knife and so it’s still unbelievably sharp, but it also means that TOG blades are more durable than a lot of Japanese knives. We repeated the professional chef bashing and the new blades didn’t chip.

The black electron microscope photos below show the TOG cross sections. The top one shows the initial prototype (traditional Japanese design) and the second shows our revised design for the Western market. Note that there is no rounding of the edge whatsoever even at x500 magnification!

What angle to sharpen a knife at - Results 1

What angle to sharpen a knife at - Results 2

What angle to sharpen a knife at - Results 3