I want to improve my knifes performance

Friends, welcome back and thanks for being here,  it is really cool to think that people are reading what I write. Knowing this, I really do my best to make sure what I do put here is as accurate as I can possibly make it and it is based on experiences that I have.

Also key is the fact that I am not trying to sell you anything, if I say the Naniwa Chosera 1,000 is my favourite 1k stone,  I don't sell them and Chosera certainly doesn't pay to me to use them. So my preferences are based on the performance of that stone in my world of sharpening kitchen knives.

Let's talk about improving the cutting power of an average knife, the knife I own such as the Grohmann 8 inch chef or the Wusthof and Henckels 8/9 inch chef knife.

I'm not just taking about sharpening it, that's obviously going to improve it but can we make it better....heck yeah.

We need to see "sports knife"  one that comes out of the box not just sharp but truly awesome to cut with, it just makes your work in the kitchen so much better. Why can't all knives be like that?

Take a look a Tojiro DP 8.3 inch chef knife, it's ferociously sharp right out of the box and it is a dream to use, the reason is simple, there are two reasons, it has a great edge but it's the geometry of the knife that supports that edge and that combination makes it a dream to use. (It happens to be cheaper and a better steel that any of my own knives to by the way)  Yeah I sell them but I don't stock them, I just get them when folks ask for them. Believe me I wouldn't risk my reputation on a crappy knife for the 20 bucks I make on one of them.

Back to the reason it is so cool to use, it is thin, yes it's really freakin sharp but it is thin, sharp and thin are in.

We can do this to our thick knives, yes we can already get them sharp but we make them feel sharper and slice through food effortlessly by thinning the knife behind the primary edge. This is something a good sharpener should do anyway, we need to maintain the geometry of the knife as it gets older and gets sharpened regularly. If I sharpened my own knife which is 25 years old by working on the primary edge only, i.e. the cutting edge, that knife would be so thick by now it would be useless, a real chore to use, it could be very sharp but still not able to easily through protein and veggies. It would be like a wedge, I would have to use a lot of force to achieve my goal in the kitchen.

My knives when new were to thick to begin with so I thinned them immediately and this is common,  for my customers it is fine as long as the owner is warned/enlightened about the process and desired results.

To thin a knife, one needs patience and a really nice coarse stone and of course, medium and high grit stones and knowledge of the procedure.

Thinning is about angles and selecting an angle that will  remove the metal that makes the knife thick,  the area directly behind the primary edge, the secondary bevel. Basically, you want to trim the shoulders of the knife.

Now some knives are already thin, a Shun for example, that is thin enough, although I don't find that they hold an edge, they are nice and thin.

The thickening process usually just comes with time, as the knife is sharpened the primary edge is reduced, it migrates up towards the middle of the blade, it's only natural for that to happen so that is way thinning is necessary to prevent that. As I said, I think many knives are too thick to begin with.

What I do to thin a knife is to paint the shoulders of the knife, the area I want to work on and I make sure that sharpie mark extends right to the edge.

When I said it is about angles, to grind the metal in this area, I will need to lower the sharpening angle, if I just wanted to sharpen the primary edge, I would have to sharpen at 19 degrees for example but to hit that secondary bevel, I need to sharpen at a more acute angle, 15 degrees perhaps.

Remember there is Geometry Maintenance and Geometry Adjustment.


To maintain the knifes geometry, I can grind metal at 15 deg, the thinning angle and sharpen the knife at 20 deg. Or I can sharpen the knife at 15 degrees, i.e. grind away at that angle until I have hit the edge and then raise the angle to 20 degrees (factory angle).  I wouldn't have to do this all the time of course, it's just depends on how often the knife is sharpened.  This doesn't necessarily improve the cutting performance, it keeps the knife in top shape though, the way it came.

Now the other approach, the way to adjust the geometry of the knife is to choose a more acute angle and sharpen the knife at that angle until the knife is sharp and you keep it like that. It has a more tapered appearance but you have knocked down the shoulders of the knife and you will definitely see an improvement in cutting.

What you could do here is to apply a Koba, a 15 deg angle will test the steel of a soft knife so a Koba (Micro bevel) will help in this case.

I think the important thing to remember here is that you need to be aware that sharpening a knife at the factory angle over and over and over will have a negative impact on the performance. A knife is tapered, thick at the Spine and tapers down to the edge. So you have to maintain that and you can tell after a while if that knife looks different, it will look thicker and it won't sharpen the way it should.

Machines do not have a "Thin Me" setting by the way, this is one of the drawbacks of electric grinders. They are quick and easy yes which is to say that they easily change the geometry of your knife and they do it quickly and not in a good way.

This diagram which I have posted before brilliantly illustrates thickening, the thickening process is accelerated by sharpening of course, so you need to sharpen regularly but be aware that a little thinning is required.

 Now these beauties do not need thinning right away, they are hand made and ridiculously thin and will blow you away in the kitchen. However, we still need to maintain the geometry of even this fantastic pieces of art.

Peter