Which Gets Sharper
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I had vowed not to sharpen some Chef’s knives I have bought in the last year until they absolutely needed to be. I wanted to continue to use these knives as ground and sharpened by the makers. To get a feel for the edges as the maker had intended them to cut. In the past I have bought kitchen knives and right out-of the-box without so much as testing the edge for sharpness with newspaper, I’d clamp them up on my WEPS and gone to town. I realized I was judging knives by the edge I sharpened them with, not the edge the makers put on them.
As my taste in knives and knowledge of knives has grown and hopefully improved over the years, I realized I was missing out and doing myself an injustice by not learning from the masters that made these knives, by using them and experiencing them as they were made and intended to be used.
Today it was time to sharpen, for the first time, an 8″ Japanese Chef’s knife, a Gyuto, that’s made of Aogami Super Steel, a partially reactive steel, relatively high in carbon, but still very hard steel; rated HRc 63-64. The beauty of this steel is it’s very easy to sharpen and it gets a very sharp edge.
I had forgotten how easy it was to get cut sharpening a knife. I literally just barely brushed the edge with the back of a finger and I could feel I got cut, while the knife was clamped in the WEPS . Not badly, not deeply, just barely cut, but enough to draw blood. Dang it’s was really sharp and I was not yet finished with my planned progression to be followed up with the leather strops. When I’d finished, I’d have to say its was truly one of the sharpest knives I’d put an edge on in a long time.
My question I’d like to ask, does good steel, in your experience, get sharper than poorer quality steel when sharpened with the same technique and care?
Marc
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In my experience I agree with you. I have 22 kitchen knives and 8 none-serrated Henckel 4 steak knives. The 22 are a mix of Henckel, Shun, Gerber, Aritsugu (new), Masakage Mizu (new). They are a mix of stainless and blue. Best I know is that the blue series (#1, #2 and Super (Aogami)) are all related with additional alloys to enhance edge retention (Vanadium in Super). I have also sharpened friends knives which were of much cheaper varieties (all stainless). I have taken them all through WEPS from full burr verification through 1500 diamonds (occasionally into films and strops). I would call my WEPS skill level 8.5 out of a 10 scale. I am also an amateur metallurgist (3 out of a 10 scale) — although I heavily stress amateur. I have read multiple Verhoeven works but surely would fail any structured knowledge test. Real knowledge of this stuff is at the Phd and beyond level. I think I have learned that the relationship of the sharpness of the edge after sharpening and the retention of the edge can be rather complicated.
I think the most important aspects are: type of steel, quality of the steel, geometry, heat treating and final edge treatment (WEPS). Over the last 2 years I have found that the hands down winner in edge sharpness is my blue steel knives. My test is the ability to take scallops out of bent shiny magazine paper. After my normal progressions, the blue steels can do that with a silky sound and feel. My stainless will not. That being said, I will say that my magazine test can only be done after removing the blade from the WEPS. I suspect that my stainless would gets closer to passing IF I remounted the blade (the alignment guide is a god send) and continued with say double or triple the amount of strokes. I will be trying that in the future.
I like to think of steel as a mixture of clay (martensite, et al.) and glass (various carbides). Some steels have harder, stronger, etc of each. Based on various SEM images I have seen the apex is a combination and somewhat random. When sharpening we are impacting both with the goal of getting the smallest edge width possible in the shortest amount of time. According to Verhoeven the edge widths of around 0.5 microns with smooth sides are achievable although I do not think he considered the diamond films down to 0.1 microns or less. What I am getting at is that the overall quality of the steel (through all steps of the supply chain) to me is a primary driver. It is not always true but the more expensive knives have a better chance of having better quality steel and a more homogenous structure to “allow” it to take a finer/sharper edge.
Holding that edge over time (retention) is much more difficult to test and I use the word test lightly because of the complexities of appropriate test design and execution.
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My test is the ability to take scallops out of bent shiny magazine paper. After my normal progressions, the blue steels can do that with a silky sound and feel. My stainless will not. That being said, I will say that my magazine test can only be done after removing the blade from the WEPS.
When I first read this I was thinking of the salt water clams that people eat rather than the curved-edge cuts. I had to read it three times before my brain figured it out. 🙂
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My experience is mostly on inexpensive knives. I have sharpened one set of Wusthof’s and one of J.A. Henckels both were the classic models. These were very easy to sharpen and took a very good edge. As to the retention so far so good, both of them are being used and holding up well. The sharpest edges I think, so far at least, have been on knives made of high carbon steel, not stainless. Almost every knife I’ve done made of high carbon steel has taken a very fine edge and in my opinion are the best I’ve been able to do. I’ve run into some stainless steel from other countries that has been suspect to say the least! Chipping, falling apart to the point that the angle had to be taken out to 25 deg. in some cases just to hold together. On most other inexpensive stainless they’ve taken a good edge not great. A few have surprised me and taken very good edges as low as 15 deg. and held up well.
To answer the questions MarcH, YES I do believe the steel can make a big difference in your edges especially when your working with angles at 17 deg. and lower. The “cheap” steels don’t like acute angles in my experience, at least for the most part.
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I’ll add that I had the privilege to attend a Bob Kramer sharpening class in NYC (great gift from my son), prior to owning WEPS. It was hand sharpening with our own knives. I had a shun SG2, he had a 52100 custom worth $5K. At the end, he let me hold it and “swing” it around LOL. It felt worth every penny and I swear it could cut the wind. As dumb as that sounds. It’s about supply chain QA and the fanatic attention to detail. Sort of like what WEPS strives for — thanks Clay, from NJ.
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Hey, my initial post may have been lost in the ether LOL. WTF ? I was on a roll !!
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I found a copy of my original post (below), I think it got lost when I was trying to edit it via my phone:
In my experience I agree with you. I have 22 kitchen knives and 8 none-serrated Henckel 4 star steak knives. The 22 are a mix of Henckel, Shun, Gerber, Aritsugu (new), Masakage Mizu (new). They are a mix of stainless and blue. Best I know is that the blue series (#1, #2 and Super (Aogami)) are all related with additional alloys to enhance edge retention (Vanadium in Super). I have also sharpened friends knives which were of much cheaper varieties (all stainless). I have taken them all through WEPS from full burr verification through 1500 diamonds (occasionally into films and strops). I would call my WEPS skill level 8.5 out of a 10 scale. I am also an amateur metallurgist (3 out of a 10 scale) — although I heavily stress amateur. I have read multiple Verhoeven works but surely would fail any structured knowledge test. Real knowledge of this stuff is at the Phd and beyond level. I think I have learned that the relationship of the sharpness of the edge after sharpening and the retention of the edge can be rather complicated.
I think the most important aspects are: type of steel, quality of the steel, geometry, heat treating and final edge treatment (WEPS). Over the last 2 years I have found that the hands down winner in edge sharpness is my blue steel knives. My test is the ability to take scallops out of bent shiny magazine paper. After my normal progressions, the blue steels can do that with a silky sound and feel. My stainless will not. That being said, I will say that my magazine test can only be done after removing the blade from the WEPS. I suspect that my stainless would get closer to passing IF I remounted the blade (the alignment guide is a god send) and continued with say double or triple the amount of strokes. I will be trying that in the future.
I like to think of steel as a mixture of clay (martensite, et al.) and glass (various carbides). Some steels have harder, stronger, etc, of each. Based on various SEM images I have seen the apex is a combination and somewhat random. When sharpening we are impacting both with the goal of getting the smallest edge width possible in the shortest amount of time. According to Verhoeven the edge widths of around 0.5 microns with smooth sides are achievable although I do not think he considered the diamond films down to 0.1 microns or less. What I am getting at is that the overall quality of the steel (through all steps of the supply chain) to me is a primary driver. It is not always true but the more expensive knives have a better chance of having better quality steel and a more homogenous structure to “allow” it to take a finer/sharper edge.
Holding that edge over time (retention) is much more difficult to test and I use the word test lightly because of the complexities of appropriate test design and execution.
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So is time the biggest variable ? That is, given enough time on the WEPS through the same progressions (but maybe more time per progression) will 2 quality blades of different steels yield similar initial sharpness.
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So is time the biggest variable ? That is, given enough time on the WEPS through the same progressions (but maybe more time per progression) will 2 quality blades of different steels yield similar initial sharpness.
Redheads this led me to wonder, after reading what you posted in your first reply, I re-clamped a relatively inexpensive Stainless Steel Chef’s Knife I’m sharpening for a friend. It was pretty sharp but no where as sharp as my Aogami Super Gyuto I sharpened recently, for myself. I sharpened 3 different brand, inexpensive SS kitchen Knives for this friend, all three resulted with a different degree of sharpness. I sharpened all three objectively and chose different points to call them done. Why did I choose that point? Did I short change the friends knives and settle on what was sharp enough and not work at these knives long enough. I’m going to give this one another try and spend more time with more care and more sharpening strokes to try to see if it will get sharper.
BTW, I don’t think this is the case, “that all knives can reach the same level of sharpness with the proper amount of time and care”. I do believe there’s a point of no return that we intuitively learn through our sharpening experiences. Something we pick up along the way. A feel in the feed back and a sound from the stones scratching. It gets to that point we learned through doing it, that’s it, this is it, this is the sharpest edge I’m going to get. Time to put the finishing strop on it. I’m going to see. Is that little quantifier “the word quality” you threw in, the limiting factor and what quantifies quality?
Marc
(MarcH's Rack-Its)I think it’s a pretty well established aspect of knife lore that carbon steel knives can be sharpened to higher degree than stainless steel knives. I don’t know if it has ever been scientifically evaluated, but I’ve seen and heard many people say that is the case.
I think the time question is specific to each person. For me the time it takes to produce a super refined and polished edge is not practical in most cases. I can spend hours doing this on one knife and what I’ve found is that the payoff is usually minimal at best and sometimes even detrimental, not usually worth the effort unless you have a knife that you want to “look” shiny. If the scratch pattern is uniform and even I like the looks of the bevel and the edge is usually very sharp. I love the shapton stones for that very reason. A lot of knives benefit from leaving teeth in the edge in varying degrees depending on it’s purpose. There are of course exceptions. I love that about what we do! There’s always something surprising to keep you on your toes so to speak.
I re-clamped and touched up a chef’s knife I did yesterday with the intention to see if I could do a better job and get a sharper result. I re-sharpened the knife with the same clamping and angle settings as I had logged from the initial sharpening. I paid closer attention to my technique to ensure I maintained flatness on the bevels. I did use a greater number of strokes and tested for sharpness then did more strokes, still, and tested again. I continued this till I was sure I wasn’t getting any improvement. I took more time and care with each stone before I moved on in my progression. I employed and followed the exact same progression with the Diamond Paddles up through 1500 grit. I finished the edge with 4µ, then 2µ cow leather strops with diamond emulsion spray.
The knife was better and sharper than the first try. I brought out the best of this edge, this time. I had short changed the first effort. So the end result is if I spend more time and care I can develop a better sharper edge than doing a quicker less thorough job. I plan on, in the future to take the time and effort to put the best edge I can on these knives. It only takes just a little more effort and just a little more time and more attention to technique.
I don’t think this inexpensive SS kitchen knife warrants or would benefit from a 30k grit highly polished edge followed by a complete strop progression of 6 different grits. The soft inexpensive SS can not sustain that thin narrow beveled apex that my more expensive better steel Chef’s knife will. It would roll over, bend or dent. As sharp as the inexpensive SS kitchen got, with the extra effort, it was still no where near as sharp as my better Chef’s knife, but it was sharp!
Marc
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I have quite a bit of experience with kitchen knives, but little with so-called “super steels”. I will try to resist my temptation to theorize about which factors influence sharpness is and to philosophize about what sharpness and how to test it 🙂 (we have another thread on that).
I don’t think this inexpensive SS kitchen knife warrants or would benefit from a 30k grit highly polished edge followed by a complete strop progression of 6 different grits. The soft inexpensive SS can not sustain that thin narrow beveled apex that my more expensive better steel Chef’s knife will. It would roll over, bend or dent. As sharp as the inexpensive SS kitchen got, with the extra effort, it was still no where near as sharp as my better Chef’s knife, but it was sharp!
That’s exactly my experience. I cannot get crappy no-type steel as sharp as hard carbon Japanese steel (with aogami super and white steel being the ones that I can get the sharpest). The order, in general and in my experience, is the following:
- crappy no-type stainless steel
- soft German stainless steel
- better stainless steel like 12C27 (used a lot in French knives including Laguiole knives)
- best stainless steel (AEB-L a.k.a. 13C26 IMHO): at the same level as many carbon steels
- white steel and aogami super steel (carbon, too)
Molecule Polishing: my blog about sharpening with the Wicked Edge
I agree completely, it seems better steels heat treated properly must have cleaner/better steel which enables them to take a finer edge. Not to belabor this but have any of you done this initial sharpening comparison with a high end stainless (AEB-L or better) and 52100 (or blue/white) ? In the 2 Verhoeven’s documents (in WEPS Knowledge Base) he talks about AEB-L and 52100 being very similar in the ability to take a fine edge (retention is another matter). For quick reference I parsed out the Appendix B “Stainless Steels for Knifemakers” from one of the documents.
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