Knife Sharpening Using Traditional Methods: The Advantages of Pressure

Hi folks,

In this article I want to talk about the two things that changed my sharpening life, these two things helped me make knives that I sharpen sharper than they have ever been and it's pretty simple. I have talked about them both before:

* PRESSURE
* TIME, ANGLE, PRESSURE - Equalization.

PRESSURE

As you know, well as some of you know, I use four levels of pressure to sharpen and I do it every single time. I call then P4, P3, P2 and P1 with the "P" standing for Pressure and the numbers simply being a scale from Heavy Pressure (P4) to Feather Light Pressure (P1)

In and effort to make this as clear as possible, because I don't want anyone to thing that the numbers indicate pounds of pressure, i.e. P4 is 4 pounds, we can simply call this:

BURR FORMING PRESSURE (P4)

BURR REMOVAL PRESSURE (P3-P1)

Also, there are a couple of important points to remember as I move along:

1. Burr Forming Pressure (P4) is the heaviest amount of pressure I use and I only use this once during the sharpening process, it is the level of pressure that I require to raise a burr and once that is done, once that burr has formed from tip to heel on both sides of the knife, I never use that level of pressure again on that same knife.

2. Burr Forming Pressure is not a constant, defined level of pressure, it may vary for each knife. So if I pick up a knife that is very dull, like every single knife in the picture above, than I require a substantial level of pressure to form the burr, it only makes sense. However, if the knife is not too bad, dull yes, but the edge is not deformed or in terrible condition, I will tone that level of pressure down a little.

My burr forming pressure needs to vary because my goal is to create a burr that is as subtle as I can make it, I don't want to blindly grind metal away by picking up every single knife and treating it the same way. So I use the appropriate level of Burr Forming Pressure to get the burr formed.

You can experiment with this, pick up the knife and use a moderate level of pressure to see if the burr is forming in reasonable time frame, 1-3 minutes. If nothing is happening, then you can adjust the pressure.

The time required to form the burr using BFP (Burr Forming Pressure) will differ depending on the knife itself, whether it is soft or hard, stainless or carbon. It will depend on the stone you choose to start with, is it a 400 grit or a 1,000 grit stone. Also, your level of skill will be a determining factor.

The important thing to note is that these factors will play a role in how long it takes to form the burr, you can use the same initial level of pressure whether you are starting with a 400 grit stone or a 1,000 grit stone. You never want to be pressing down so hard that you lose control of the angle stability or it becomes comfortable.

The bottom line is that you need to pick up each knife, look and feel the edge and form a sharpening plan:

*Stones to use from start to finish

*Burr Forming Pressure, how much do I need to start.

Actually, before I start any sharpening of a knife a series of plans unfolds.

Sharpening Plan

DAMAGE PLAN : Do I need one and if so, make it happen, repair chips or the tip etc.
THINNING PLAN: Do I need to thin the knife and if so, to what degree?
SHARPENING PLAN: What progression of water stones do I need, what Sharpening Angle?
REFINISHING PLAN: If the blade is scratched up, do I need to fix that, the handle?

My Sharpening Process

Pressure

STAGE ONE - BURR FORMING PRESSURE

If after inspecting the knife to determine my sharpening plan, I see that the knife is very dull and it is a hard knife, (58-67). I know that my burr forming pressure will be heavy and I will start on a coarse stone, 220-400 grit. I also know that I will also use a 1,000, 5,000 and possibly an 8,000 grit stone depending on the knife itself. (High quality Japanese will mean an 8K finish)

As my sharpening begins I use heavy pressure on the 400 grit stone. I move from tip to heel and then back from heel to tip on the right side of the knife. I then feel for a burr on opposite side of the blade and if there is none, I continue this pattern until one of two things happen: The burr forms, or, no burr forms after 2-3 minutes. Either way I flip the knife to either continue the burr forming process (if no burr was formed on the first attempt or, to form a burr on the opposite side (If I did form a burr). ( The reason I flip the knife after a few minutes where no burr formed, to achieve a balance on both sides of the knife. If I were to continue grinding on one side for several minutes to form a burr and did not do the same on the other side in terms of time spent, the bevels would not be consistent).

Once I have successfully formed a burr on both sides of the knife, consistent in size and running from heel to tip, I then reduce pressure by roughly 50%. I NEVER use P4 or burr forming pressure again on the knife that I am working on. So BURR FORMING PRESSURE HAPPENS ONCE.

Here is where I have fine tuned the sharpening process to achieve the second most important change I made to my process.

In an effort to achieve uniformity and consistency in bevels I follow the procedure below for the remainder of the process.

STAGE TWO

BURR REMOVAL PRESSURE

Since I have achieved a burr, it is now time to remove it and it is important to strive to finish with an edge that is as clean as possible, free from any metal fragments that interfere with truly sharp knives.

Continuing on the COARSE stone, the same stone I used to form a burr, I move from tip to heel and from heel to tip on the right side of the knife. I now flip the knife and move from heel to tip and tip to heel. (This is the way I sharpen, if you start at the heel on both sides of the knife that is fine).

This is P3 Pressure: Light

(Remember, you don't want to form additional burrs here so it is a challenge with a coarse stone not to but with practice manipulation pressure this way, it will happen)

NOW I reduce the pressure again and still on the coarse stone I again move from Tip to Heel and Heel to Tip on the right side and flip the blade and move from Heel to Tip and Tip to Heel.

This is P2 Pressure : Very Light

Now for the final stage on the coarse stone I just "strop" the knife using trailing strokes, 3 strokes per side. This is the final stage for this stone before I check the edge.

This is P1 Pressure: Feather Light

EDGE CHECK

This is another extremely important and simple act that really made a big difference for me. I hold the edge under a good light and look for any reflections on the edge. If I have not removed the burr that is normally visible to the naked eye under light, it will be revealed here. It is easy to see. If I do see any reflections, I just go back to P2 pressure, very light pressure and repeat the process and then check again under the light. I concentrate on the area of the edge where the reflections appeared. (You're holding the knife with the edge up here. This is the final check before moving on to another stone.)

STAGE THREE

BURR REMOVAL- REFINEMENT ON MEDIUM/FINE WATER STONES

Now that the hard, critical work is done, i.e. burr formed and initial removal process complete, I switch to a medium stone, 1,000 grit.

Now starting with P3 pressure, which again is nice and light, I repeat the process as laid out above, moving from tip to heel and heel to tip on both sides, then I do the same with P2 pressure and finally the stropping motion (P1) and the pressure is feather light here, as light as you can get it.

Now, I move to my finishing stone, usually a 5,000 grit stone and repeat the process and would do the same if I was going to use an 8,000 grit stone.

My final act may be stropping on bare leather.

That is it, this all takes me about 12-15 minutes on a dull knife. Don't worry about the timing. The burr forming, P4 pressure stage can take anywhere from 1 minute to 7 or even more. It will depend on the steel, the condition of the knife, the burr forming stone you use and your skill.

The second important element that added to my sharpness levels and consistency, and, aesthetics was Time, Pressure and Angle and trying the best I can to equalize those on each side of the knife. (On a symmetric knife that is, 50/50 grind)

I don't count strokes, so what I do is to work from tip to heel and heel to tip on both sides as evenly as I can. I do my best to maintain the same pressure and angle but all this takes time to learn. The knowledge that I should do this, or try to do it at least was for me, the most important thing.

I really hope that this is all clear and that you got something from it.