Asymmetric Edges - how I deal with them now

Asymmetric Bevels/Edge 

My Approach

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Like most people who learn to sharpen knives, we start by learning the fundamentals and building upon these basic, all important skills in an effort to not just make knives sharp but to continuously improve our edges over time. This drive often leads us into areas, Forums, YouTube, Twitter, where we stumble upon sharpening related topics. One of these is the Asymmetric Edge and in particular how to sharpen it. 

This was another grey area for me and not that important for many years since I never saw a knife with any other grind than a 50/50 bevel/edge. This after all is the most common type of grind that most of us sharpen. My introduction to anything different came with the Traditional Japanese knives, single beveled knives which are sharpened on one side only. 

Over time, I started to see and hear about other type of edges, 70/30 or 80/20 and to be honest, it just added to my confusion. As a driven individual I found myself scouring the internet on the technique to sharpen these knives and discovered two schools of thought: Sharpen one side at a more acute angle than the other or spend more time on one side than the other to keep that ratio constant, it is still I believe a topic of contention and misunderstanding.

So, with that in mind i came to the conclusion that all I have to do the sharpen such a knife properly is to make seven strokes on one side and three on the other,  to maintain the bevel and edge geometry of a knife that has a 70/30 bevel/edge, like the Misono UX10 for example.

My thought process has since changed and once again, I have come to understand that there is, or can be more to sharpening a knife than just the physical, repetitive motion, a motion that has worked in the past. However, what if there was more forward thinking involved, what if we allowed this process to be more than just a simple seven/three strokes or an angle adjustment thing?

    As has happened several times in  the past, my enlightenment on the subject came after a conversation with Jon Broida of Japanese Knife Imports. I have, for several years considered Jon as my Mentor since he has taught me many things.

It is very important to realize that everyone can learn by asking questions, we just need to ask them. This sounds pretty easy but often times, people’s ego will prevent this and thus, they get stuck in their ways and this has the potential to limit awareness and personal growth. I have long since abandoned my ego and as a  result, I am a far more educated sharpener than I was five years ago. I got over myself basically and found the right people and asked the right questions.

How do I approach asymmetric edge sharpening now?

First of all, and again, this is after talking to Jon about it and then following up with more questions, there are two things to consider, the technique and the way the knife performs.  I fussed over these angles without really understanding what they mean, what does 70/30 mean anyway. Is it a ratio of time to be copied or is all about angles? What Jon told me completely changed my perspective and instilled a more logical way to look at this, a more intelligent approach. 

One may ask, what makes Jon’s perspective correct? I rely on Jon and trust his words because I know that he has asked the same questions to the actual blacksmiths and sharpeners in Japan. He has left no stone unturned so to speak, his pursuit for knowledge is relentless and therefore, in my opinion, it is correct, I trust Jon.

In Japan, the blacksmiths who make these knives, these asymmetric edged knives do not measure angles, nor do they care about ratios, they create the knives in this manner following a procedure that has been passed down to them, all by eye and skill and artistry, there are no scientific measure devices in place.  I am not absolutely sure what lies behind the motivation to create an asymmetric edge, an edge/bevel that is uneven only that it creates a certain level of thinness behind the edge which is done to improve cutting performance. 

Since the blacksmith is not measuring the angles, why are we so concerned about it? What if instead we looked  at this through a different perspective, through the eyes of the knife so to speak and the Chef using it?  I believe that when the blacksmith makes the knife and knows that someone will have to sharpen it one day, he assumes that that person is going to sharpen it in a manner that maintains it’s cutting performance. When  a chef (or anyone) buys a Misono UX10 for example and enjoys the way it performs, it then becomes my responsibility as a knife sharpener to ensure that the chef enjoys the way it performs every time I sharpen it and I give it back to him/her.

Until now, I would take such a knife and sharpen it using a ratio of time without a lot of regard to the knife’s cutting performance. Since I know I can get the knife sharp, sharper than new, I would continue to pat myself on the back thinking another job well done.  This thought process has since changed. I asked the right person the right question and now think differently, getting the edge sharp is not the end of the job, it is in fact not the right way, mentally,  to start the job. 

If we think of sharpening as a means of keeping the knife operating at peak performance, than it only makes sense to first of all, ask the person using it, if it isn't you, how the knife does perform. Does it steer to the left or right, does it wedge when cutting a potato?  With this in mind and the question asked, we need to know how to correct a problem if one does exist. The blacksmith in Japan doesn’t just expect the sharpener to start grinding on one side longer or at a more acute angle on one side than the other, he expects us to learn how knife performs and how to maintain that level of performance without even thinking about ratios.

As it turns out the actual technique is not that complicated,  for me, the problem was not understanding what the ratios mean and not having the foresight to find out how the knife is working and to rectify any issues that may exist.

So if a Chef or individual tells me the knife is sharp but steering a little to the left as he slices that tells me that now I have to create a little more surface area on the left side of the knife, and I can do this by sharpening that side at a slightly more acute angle or by spending more time on that side of the knife or both.  Using the sharpie here is key, the corrective action necessary may be very minor.  If the knife is wedging, sharp but wedging,  that means it is a little too thick, as the knife descends into a potato for example, the top of the potato closes in on the sides of the knife so if that knife is thinner from a cross sectional geometry perspective, that issue should be resolved. 

(In japan, many chefs will sharpen more asymmetrically regardless of how much the knife steers, because they are used to dealing with steering from their single bevel knives and so it becomes a force of habit for them and keeps knife movement more similar between single and double bevel knives (as a force of habit)

What has changed for me?

The understanding that as I sharpen a knife, any knife, I should have a clear vision in my head of what it is I want to achieve and this may involve speaking to the person who uses the knife every single day. I don't blindly starting grinding away without taking this step.  I did learn long ago to very frequently stop and check my work, to use my eyes to see how my progress is going. The most significant change in this particular case is knowing that it isn’t as simple as maintaining a 70/30 edge by sharpening at a ratio of 70/30, it is now a matter of understanding what steps I have to take to maintain the cutting performance of that knife because over time that ratio has adjusted, there are no angle measuring devices in play here,  this is freehand sharpening and having the knowledge and tools to keep that knife slicing food the way it did on day one and remembering that day One,  may have been twenty years ago.

I am in no way suggesting to eliminate any asymmetric knife sharpening issues by just grinding evenly on both sides and making both sides even. There is a reason the blacksmith made the knife this way, it is now our responsibility to learn how to keep it this way without oversimplifying the whole angle and ratio thing and applying that to the sharpening technique.  

What my goal is now is to simplify the process by gaining a better understanding of how the knife performs and how to get it back into peak cutting performance if necessary, if I have to adjust my time or angles so be it, I can do that, it's simply a matter or doing a little, work, checking the work and asking the chef to see how the knife feels now. (Since I sharpen for other people this is the case for me).

I can apply this approach to all the knives I sharpen regardless of the grind. Is the knife bent for example, is there anything going on with it that will prevent me from sharpening it properly and if so, how will I  deal with it?

The bottom line is that through Jon I have gained an understating of asymmetry and how to handle it in the future, it is now just a matter of putting what I have learned into action and thereby reaching another personal goal, by moving forward.

     Please note that Jon Broida helped me with this article and is still helping me, there are a couple of things I will be adding but I need to give credit where credit is due.

Peter