Saturday, 22 December 2018
I told you it's tough coming up with new material on sharpening. I decided that I would give the one tip that has helped me achieve the sharpest knives that I have ever achieved. I have talked about it before but it continues to prove its value over and over.
It is the LIGHT TEST
As you know I use four different levels of pressure to sharpen, the first level is the burr forming level which is a blend of medium to hard pressure. It always depends on the knife itself, the condition of the edge. I never ever just pick up a knife and start grinding metal away, the metal has to be removed in a controlled manner so it's critical to inspect the edge and feel it to determine the most suitable course of action.
In my case, that always leads me to grab a coarse stone, either 120, 220, 320, 400, 500, 600 or 800 grit with my Shapton Glass 500 being the most common starting stone, the burr forming stone and it is an excellent one.
Now I form the burr on both sides and then as I have mentioned in previous articles I reduce the level of pressure dramatically after the burr is formed to commence the burr removal process. Remember, I only use the first level of pressure, I call it P4, once because I only want to form the burr once, on both sides of course.
Now I start to clean the edge by using ever diminishing levels of pressure on the same stone.
I realize that some folks don't bother with this, they let the higher grit stones do this and they maintain the same level of pressure. I don't like this plan, actually, it used to me my plan but I changed it several years ago. I don't like the idea of relying on my medium and finishing stones to remove metal, I like to get rid of all that I can on the coarse stone.
This brings me to the Light Test.
I look very carefully, and I mean carefully at the edge of the knife that I have finished all the coarse stone work on under a good light. So I have formed the burr and removed it using four levels of pressure, If I have done this properly I should see no light at all. The picture above is greatly exaggerated, it won't be that obvious and again, this is just the way I do things, but it really has made a difference. It just takes a second to look at the edge before putting that coarse, or beginning stone away. If I see no light, I move on to the next stone, a 1k for example. If I do see any light at all, the light is a reflection of metal that is off the to side of the Apex, the primary edge, it is tiny but big enough to reflect light. This is metal that needs to go.
If I do see it, and often it is just in one spot, I go back to the stone with medium pressure and concentrate on the edge area where I saw the reflection, I work both sides of the edge and then just check again. Usually it just takes on more sharpening on the stone to get that edge as clean as possible on the first stone.
NOW, when the edge is clean, when I see no reflections, I have set the stage for a truly sharp knife, the knife will be very sharp at this stage and I am ready to start refining the edge now and the bevels on finer stones.
The light test is very easy to do and it works, it reveals any unwanted metal clinging to the mother ship, it has to go. You can leave it until the next stone but why, why not squeeze every single ounce of goodness out of that first stone and make the knife as sharp as you can with it?
Thank you for sticking around in 2018. I promise to keep the Blog going until I can no longer do that, hopefully for several years from now.
New Edge Sharpening.