The Pressure System: 4 Levels Of Pressure To Sharpen Your Knife
I would like to describe the purpose of the four tiered pressure system and how to approach it, especially for novice sharpeners. I think it’s fantastic that you want to learn to sharpen.
Here is the video. By the way, for those who have been following my blog for a while you will know that I really like the video playlist by Jon Broida of Japanese Knife Imports. It is in my opinion the most comprehensive set of videos on sharpening that I have seen. Jon has added the pressure video to his play list (with my consent) so for him to like it, that is a cool thing.
Video: Sharpening A Kitchen Knife Using 4 Levels Of Pressure
The Shapton Stone Combination Used By Peter Nowlan In The Video:
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In general terms, the systems purpose is for a sharpener to get the absolute most out of every water stone used in a sequence, whether it is one or four, or more. The ultimate goal of the system is created the cleanest edge possible and for the pressure system to work at it’s best, proper manipulation of pressure is necessary. I know that some folks use a sweeping technique to sharpen, I don’t, so if you want to try the pressure system I am pretty sure it will still work for you.
The most important thing to be able to get a grip on is gaining the ability to adjust your pressure, especially once the Burr has formed. You do NOT want to continue sharpening with a level of pressure on the stones, especially the coarse stone that keeps creating burrs. So a really delicate touch is what will bring out the most in the system. Until you get used to this, i.e. holding pressure and and your sharpening angle, just use medium/light pressure throughout.
Sharpening Pressure Levels Explained
The levels of pressure are from P4-P1 and this is just a designation I chose, I prefer NOT to equate the numbers to actual degrees of pressure, i.e. P4 does not necessarily mean 4 pounds of pressure.
The reason I say this is so that nobody feels locked in to using 4 pounds of pressure initially, to form the burr, you need to use the amount of pressure necessary to create a burr on the knife you are sharpening. It may be very very dull and therefore require more pressure than a knife that is not so bad, so you wouldn’t need to use that much pressure. HOWEVER, in the process of going from P4 down to P1, P4 is still the most pressure you will use, whether it is 4 or 2 pounds.
P4 – therefore is the most amount of pressure used to form a burr on both sides of the knife and P4 pressure is only used once in the entire process with one knife. As soon as the burr is formed you need to reduce your starting pressure by 50%. LESS is MORE, go easy to start and adjust as necessary. In other words, when you approach the knife with the intent of forming the burr, use moderate pressure to start and see how it goes, if you think you need to notch it up a bit, do so but just be vigilant. (More on that at the end)
P3 – is a significant reduction in pressure, still on the same stone but remember, you do not want to form another burr so just be mindful of that, especially on those coarse stones. Your goal is coarse stone refinement, just cleaning the edge and you don’t need to spend much time at these level of pressure. I just go from heel to tip and then back from tip to heel and then flip the knife and repeat. Then I lower the pressure again to P2.
P2 – Pressure is very light pressure, this amount of pressure would not form a burr on a coarse stone, well it would take an eternity, it is that light, it is very a very soft and focused movement as you CARESS the stone with the edge of the knife, all at the same angle of course, as close to it as you can manage that is.
P1 – This is the least amount of pressure you can manage to maintain without dropping the knife. This is really a nice and very easy motion as you move that edge over the stone from heel to tip, tip to heel then repeat on the other side. (Or if you start at the tip, from tip to heel and back from heel to tip)
As for timing, the most amount of time that I spend during the entire process is at P4 pressure and the creation of the burr. After that, with the hard work done, the subsequent pressure drops occur very quickly, there is no need to linger on the stones at each level.
Now….what about when you have gone through P4-P1 and you think you are ready to move to the next stone?
Don’t be too hasty! This is the moment that you should inspect your edge and see how it looks and feels. The first thing is look at the edge closely under a good light. So I am holding the knife in a position where I can see the entire length of the blade and I use a really good source of light.
What I am looking for is any telltale signs of “not quite done yet” and these will leap out at you. I look for any glint of light that is reflecting off of metal that is still clinging onto the mother ship. Tiny fragments that just don’t want to let go, fragments that I missed.
In this shot you can see the white light that is clearly visible on the edge. So when this happens, I just go back to P2 pressure and make a few passes on either side of the blade but I am focusing on those areas, I am only applying the pressure as I move to that area. Then I stop and take another look and sometimes it takes a few passes but it will disappear and when it does, you will be rewarded with a very sharp edge. Trust me, this little bit of extra diligence is going to allow you to make your knives very sharp indeed.
Conclusion: Tips On Using The Pressure System
To summarize, please get comfortable with working at one level of pressure, P3 or P2 and attaining the ability to maintain angle stability as you move the knife over the stone. This just takes practice, and the more comfortable you get, feel free to start manipulating pressure the way I have laid it out.
Also… this is just something I started doing a couple of years ago, don’t feel that if you completely ignore the pressure sequence that you won’t get your knives sharp. I just encourage you to give it a try. I can tell you however that I have received many many emails from people who told me it helped them out, quite significantly.
Obsession leads to discovery, I don’t get paid by anyone if you use the pressure sequence, I am simply sharing something that works for me, it has worked about 10,000 times and it has never not worked for me.
REMEMBER- P4 pressure is only used to create the burr and never repeated on the same knife. Maybe I should have called it P4B pressure. If you think about it though, it will make sense, why would you use that much pressure again when moving from a 400 to a 1, 000 grit stone for example?
Feel free to leave a comment if you have any questions and suggestions too. Thanks for reading.