Notes on Japanese Knife Asymmetry

210 Global chefs knife turned fat sujihiki

This is one of the most important things to learn about using or sharpening kitchen knives. I learned this from a blacksmith in one of the more famous knife forums online and wish to share with you what I learned and then some.

Surprisingly, there are people who mess with the asymmetry of their knives. Some would even go to the point of changing the bevels on their knives. A friend of mine once had her Global knife reshaped into a 90/10 bevel thinking that It would cut easier. I don't know if it was poorly done (shouldn't have done it the first place) but the end result was her taking it to a knife shop and having it reground to its original form. With that much abuse and metal shaved off, her 210mm Global chefs knife became a small slicer. Still looks awesome though.

Almost all Japanese knives are asymmetrically ground. People think that their bevel's asymmetry is variable, and so they can change it to whatever they like. What they don't know is, the knife itself including the blade face is also asymmetrical.

You can't just change your bevels, say from a 70/30 ground knife to a 50/50 or even a 90/10, just because you think it'll work out better. The edge or bevel road is not the only thing asymmetrical on your knife. The whole thing is. So by you changing the symmetry or lack thereof of your knife, you just ruin the knife itself. You will find yourself wedging on the things you cut and will find your knife harder to use. It will not function as straight as it used to. I tried this once, and my knife steered in other directions.

If you want your knife to work properly, just stick to what the blacksmith did originally. It was made that way for a reason. If you find yourself dissatisfied and think that maybe the problem lies with you not having the ratio of asymmetry that you like, let me be the first one to tell you that you are wrong. You have to sharpen the bevels on your knife as close to how the knife is ground asymmetrically as a whole. This will enable the knife to resist wedging and steering. It will work as what it was intended to do.

Instead of trying to change bevels, you should practice free hand sharpening. You should know and feel if you're hitting the bevels when you go to a whetstone. Always look at the part of your knife where metal is abraded. Never go in taking out steel without checking what or where you're taking it from. The key point is practice. Never rely on sharpening guides as they are misleading especially on an asymmetrically ground kitchen knife. Sharpening degrees do not correspond to where your edge or blade road might be. If they tell you to sharpen at so and so degrees, that measurement always depends on the knife too. Having said that, free hand sharpening is the best method to get the precise edge that you want. All you need to do is spend time on it and practice your skill.