Sunday, 22 June 2014

The Looking Glass Edge

Most knife sharpeners, most, not all,  like to challenge themselves by creating a mirror like finish on the bevels/edge of their knife/knives.

To be clear, in my opinion, one does not need to do this to have a sharp knife but it sure does look nice and for anyone with a passion for knife sharpening, it is rite of passage so to speak, it was/is for me.

I also need to make it clear that knife sharpening is not something you peak at,  there is no summit, you improve, it's a journey with an infinite number of stepping stones.

So how do I do this and keep in mind, it doesn't always turn out the way I want it.

There are some key ingredients:

High Grit Japanese Water Stones, 8,000 and higher. Now you can get a very nice looking edge from 3,000 grit stone, it depends on several things, the type of stone, your abilities and your work on the previous stones.

Patience and Discipline - You need extreme patience when doing this and you need to be in your happy place, free of distraction. The discipline I refer to is your requirement to stick with the first stone until the job is done, I will explain more on that.

Absolutely perfectly flat water stones and near perfect bevels - You must be able to hold the angle perfectly, of course an Edge Pro or Wicked Edge will help set the stage for success but you are going to be repeating motions over and over so control is a must.

The real secret to this is knowing that the first stone you use is the most important one, it sets the foundation for all subsequent work.  This is where you patience will be tested and rewarded. 

Know that if you start with a 400 grit water stone, each stone that follows is merely refining the bevels. That 400 stone will scratch the bevels so you must continue with it until those scratches have just about disappeared. You do this by repeating the motions with less and less pressure and continuously monitoring your work. A loupe will come in handy, magnification will help you spot scratches you've missed and the entire bevel must be uniform. 

This could take an hour or more, this is the key, and you may have to walk away from the work if you find yourself slipping away and thinking about  ANYTHING other than knife sharpening.

So you select and angle and stick with it so that you are grinding from the top of the bevel or Shinogi Line right down to the edge.  The picture indicates a Back Bevel so that entire area needs to be worked on. 

Now you can create a Relief Angle or Compound Bevel by working a different angles, i.e. do the secondary bevel ( identified as a back bevel in this picture) at 15 degrees for example and just work at that angle to create your mirror finish. This doesn't sharpen the knife, it creates a Relief Face, the sharpening at the primary edge is done at a different angle, 20 degrees for example. Believe me, this is going to make your knife very sharp, think of this as extreme sharpening, it's quite effective. The beauty of it is that you don't need to work at the 15 deg angle anymore for touch ups, just the primary edge (20 deg or whatever angle you sharpened at).

I didn't sharpen this knife, I just found the picture somewhere.

Lets assume all your work is at one angle, 20 degrees to make it simple. 

Once you are completely satisfied that you have finished your work with your first stone, move on to your 1,000 grit stone. Remember that if you have left some deep scratches, higher grit stones won't remove them. So you are going to be either punished for rewarded as you move up in grit.

Use a lot of water too, it helps with the polishing and move up in grit until you are happy and every stone in your arsenal has been utilized. 

You will definitely see the bevel taking on a different look when you hit the 4,000 or 5,000 grit range.  

Now it becomes a pressure test........minimum pressure here and lots of water as you move up in grit, make sure the edge of the edge is being hit, remember you want the knife to be sharp, not just beautiful. That mercury look will come eventually and by eventually I mean it could take many many attempts but until you give it a shot you won't know. 

Remember, don't fret about this, you don't need a 5,000 grit stone to make your knife sharp and a sharp knife is really what you need and that should be your priority, learn how to make it sharp first, this Looking Glass Edge stuff can come later. 

We can talk about a third angle later on too, the Micro Bevel which is applied to the Primary Edge at an even higher angle, 30 deg for example. This "Koba" is designed to enhance edge retention, basically, get you through a shift on a knife that was sharpened at a very acute angle.

Cool eh.

Also note that a highly polished edge will mean that the knife has lost it's bite, so it will slice protein like nothing else but it could slide right over a tomato, it won't dig in unless pressure is applied. However, we can get around this, we can have both.....but that is for later. 

1 comment:

  1. Still amazed by the ability you have for sharpening freehand with such a tight tolerance. I certainly don't have it. Might be trying a DIY guided system at least for the first (rughest) wet stone.

    Looking forward for the "that is for later" stuff ;-)