Strop Sharp versus Mirror Finish
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Achieving a mirror finish isn’t the only reason for polishing bevels.
Yesterday I sharpened a few knives for family members. One was a Wuesthof 12-inch kitchen knife which had 1.5-inches broken off at the tip. Now it looks very much like a Santoku. This is a very heavy knife and immediately brings to mind Crocodile Dundee – “This is a noyfe!” It had never been sharpened with a WEPS and took a while to establish a new profile. I sharpened it to 1000-grit at 18 dps and would normally have left it at that, but I happened to see a set of “strops” laying on my bench which I hadn’t used in nearly a year and decided to try something. The “strops” were of hardwood – hard maple to be specific. One side was loaded with 2.5 micron paste, while the other had 1.0 paste.
I gave each side 60 strokes of the 2.5 micron. Being pretty hard as compared to other stropping substrates, I did not feel the need to lower the angle. On completion, I inspected the bevels with my USB ‘scope. There really wasn’t much to suggest the bevels had been polished, but when I tested the edge on a sheet of paper, it was clear that this was a very, very sharp knife.
We here on the forum have been focused for some time now on achieving mirror edges and may have forgotten. This focus has been on removing scratches – removing metal until you have gone past the deepest scratch. The principle I am reminding you of is that of achieving a higher-performing edge (and bevels). Rather than reaching the deepest scratch, I am polishing the highest ridges above those scratches. Deep scratches don’t effect the sharpness of and edge, so long as the scratch doesn’t go to the edge. It’s the ridges that actually contact the material being cut and polishing those ridges reduces the friction between the bevels and the material being sliced.
Yes, a mirror polished bevel will cut just as well as the bevel which has had its ridges polished. The issue here is why you would expend the effort of achieving a mirror edge, when your real objective is to produce a very sharp knife.
Before film became the sweetheart of us WE aficionados, and I think before the grits above 1000 became available, Clay was selling stropping supplies. I think the first was 5 and 3.5 micron paste on cow leather strops. We were jumping from 1000 to at least 5 micron diamond paste, with no real intent of achieving a mirror finish. The objective was to produce a sharper edge and it worked. The principle applies to film as well as to strops. Try it out. Sharpen to 1000-grit, then go to a low-micron film for a final stage – maybe 6 or 3 micron film.
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I have been loving my 4 micron / 2 micron strops recently. As some of you may recall, there was a period where I hadn’t really figured out how to get good results with the strops and I was skeptical as to their usefulness. That skepticism has been quelled. I obtain a noticeable and often dramatic improvement in cutting performance after stropping just about any finish, be it a 600# edge or a 6 micron edge. Most notably, the knives cut much more smoothly after stropping. Anyone who decided to skip the stops is missing out in my opinion.
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Great post Tom, thanks! I put together the original Pro-Pack 1 after I found myself using that combo over and over, especially on the ranch during outfitting season. The edges were crazy sharp and durable enough to survive field dressing a number of big, dirty and hairy beasts. That work is really tough on a knife because you’re hitting dirt and hair and bone frequently. The biggest issue we ran into with the knives was that they were so sharp we had to be extra careful while skinning not to cut through the hide.
-Clay
Tom, you made me want to share this. I’m in the middle of sharpening a 5″ kitchen utility knife made of VG10 steel. It’s a good knife made of good steel that I’ve really enjoyed using for years. It gets very sharp and holds it’s edge for a long time. I decided to sharpen it, this go round, with the intention of polishing it with Diamond Lapping Films. I just got done with 8000 grit Shapton’s Glass Stones when I read Tom’s Post. This knife at this point is really, really, sharp. Just a couple more minutes with the strops and it would be as sharp a kitchen knife, of this style, that you could ever ask for! Really, scary sharp!
I’ve been playing with the Diamond Lapping Films, as some of you regulars readers know, just to learn about them and to see if I could attain a truly mirrored unblemished bevel. Of course I’ll compare the sharpness and durability of the DLF polished edge to my basic sharpened and stropped edge.
Now I’m feeling like it’s sacrilegious to take a perfectly sharp knife and do this to it! I will continue with the lapping efforts. I truly want to learn how the edges differ. I’ll post my lapping results when I reach them.
Marc
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Good points, Tom. When involved in getting a mirror edge, we sometimes forget that the primary goal of sharpening a knife is getting it sharp ?.
2.5 micron and 1 micron compounds are pretty fine, so if you hit the edge correctly, they should give you a very sharp edge. If you also sharpen the remainder of the bevel with it (and the scratches before are not too bad), you might of course come close to a pretty mirror edge, too, of course. In addition, the WE pastes seem to a have burnishing effect that aid in getting a mirror edge. I’d call it a nice side-effect.
And I couldn’t find a better term for the lapping films than “sweetheart of us WE aficionados”. They may even be more precise than the strops/stropping compounds and work great with me. And you don’t run the risk of rounding the bevel. Since using the films, I use the strops a lot less.
Molecule Polishing: my blog about sharpening with the Wicked Edge
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Excellent points!
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I’m trying to understand all this as well. I just received a grocery sack full of custom fixed blades from a big game guide who is my next door neighbor (well, he’s the closest neighbor at just a bit over 1/2 mile away). He left for a sheep hunt in North BC Saturday, and wanted 4 knives sharpened by then; 2 were the same.
I put a mirror edge on one of those two, and worked on sharpness technique with the other. We’ll see which one he likes best.
In talking with him a bit, he almost never carries a knife on his hunts. He now carries a surgical scalpel with replaceable blades. He just cannot find anybody who can put a good edge on his stuff. I was flattered that he trusted me enough to let me play. I’m pretty certain the WEPS blew him away; hopefully he will continue to use me.
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Good luck with the hunting knives. FWIW, during the first few years of the Wicked Edge, I field dressed a couple hundred elk. That seems crazy now. I settled on the contents of the Pro-Pack 1 as being pretty optimal, but that was before we added some of our other abrasives. There may be some better finishes for field dressing that I didn’t discover, but at least it’s a good starting point. What was important to me was that the knife started sharp enough to make the work easy and lasted through the whole job. In the early days of outfitting, we used a Chef’s Choice, a whet stone or pull-through sharpeners. A knife sharpened on a Chef’s Choice started out well enough but only lasted a quarter of the way through the job. One sharpened with a pull-through device was only good for a few cuts before needing a touch-up. Whet stone results were all over the board but never took me through an entire elk. Once I started with angle guided sharpeners, I was getting through a whole elk with one knife. Once I started sharpening on the Wicked Edge, I quickly got to where I could field dress up to 4 elk with the same knife in a pinch. For us, the field dressing process included skinning, caping and quartering the animal.
-Clay
Errrmmm…field dressing “a couple hundred elk” even in 10 years seems a bit crazy. Yeah, just a little! Amazing work.
The guide told me a couple things: he had switched over to the surgical scalpels initially because of not being able to get a good, reliable sharpener. He could use the scalpel and just switch blades when one got dull. He also did / does this with an “Exchange-A-Blade” system. Hopefully we can get him back to using his customs. He has one nice Siggma
As somebody with advanced terminal cancer, there will be dark days when I complain about things you say for no apparent reason. Please consider this my apology in advance for such times. There will be days that what I say is clearly wrong, making no sense: on these days I will often be argumentative. Please do not "let me slide" at such times, but rather call me out, point out what is factually wrong, and demand I explain my position. Please also consider this my apology in advance for such times.
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Once I started sharpening on the Wicked Edge, I quickly got to where I could field dress up to 4 elk with the same knife in a pinch. For us, the field dressing process included skinning, caping and quartering the animal.
I think about the old line” if I drive faster will I get there before I run out of gas?” I really think a sharp knife is like this. Because it’s sharper you can cut and dress the game faster and easier so you don’t work as hard and don’t apply as much pressure to the knife blade, by needing to press harder, so it doesn’t wear as much and dull as fast, so you can dress more elk, more quickly.
Of course your skill level has improved greatly every opportunity you have to dress another animal as you learn and employ shortcuts and work cleaner and more efficiently. Doing the same chore repeatedly, in succession, allows you to apply changes quickly.
Marc
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Funny what you tell about a Chef’s Choice, Clay. As I told here, I sharpened for a restaurant some time ago with my WE. When I decided it was too much for my free time (over 20 knives every Sunday night), I recommended they’d got a WE themselves and did their own sharpening. There was nobody there who could properly sharpen a knife, so stones were not an option, and knife sharpening services here suck. But they thought using a WE was too difficult for them. In the end they got one of the more expensive Chef’s Choice sharpeners.
And then they found out their knives lasted much shorter than when I sharpened them with my WE. So now they’ve got a WE themselves and have found out it’s really easy to use 🙂 . Everybody happy!
Molecule Polishing: my blog about sharpening with the Wicked Edge
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I think about the old line” if I drive faster will I get there before I run out of gas?” I really think a sharp knife is like this. Because it’s sharper you can cut and dress the game faster and easier so you don’t work as hard and don’t apply as much pressure to the knife blade, by needing to press harder, so it doesn’t wear as much and dull as fast, so you can dress more elk, more quickly. Of course your skill level has improved greatly every opportunity you have to dress another animal as you learn and employ shortcuts and work cleaner and more efficiently. Doing the same chore repeatedly, in succession, allows you to apply changes quickly.
Great point! It also reminds me of our test results on kitchen knife edge retention. One test we did wasn’t extremely scientific but generally simulated a real life scenario – we sharpened identical Victorniox chefs knives, one at 15 dps and the other at 20 dps with the same grit progression, then tested and recorded their sharpness. We threw them in a drawer together with other utensils and used them as randomly as possible every day to cut all kinds of things in the kitchen. After a month of daily use, we tested their sharpness again. The knife sharpened at 15 dps was still considerably sharper than the knife sharpened at 20 dps. To your point about wear – force is one of the main enemies of sharpness. A dull knife immediately requires more force to perform the same cut, so it dulls more quickly. There are a lot of other factors that can impact the edge retention and there is obviously a point at which the angle is too narrow for the steel and fails with minimal force. Discovering that point and then working forward with micro-bevels until you find the optimal setting for the knife is pretty fun.
-Clay
Good stuff gentlemen, great points. I don’t think a “overly polished edge” helps the sharpness and I do believe it can, if overdone, effect sharpness and durability. I myself don’t hunt anymore but almost all of my friends do and I’ve done knives for 10 or 12 of them. All most to a man they prefer their hunting knives around 18 to 20 deg. with a 600 or 800 stone then stropped with 4/2 emulsion on leather for sharpness, just 15 or 20 strokes with each, very sharp. For me the beauty of the strops isn’t the polish, all though I like shiny things as much as the next guy, but the difference in the sharpness of the blade with that technique. The emulsions for me work faster than the pastes but the pastes work very well just not as fast and I have to reload those more often. The leather, especially kangaroo, for me have rendered great results as far as sharpness goes. The fore mentioned hunting knives seem to be durable as well, lasting thru several animals and the touch up usually is just a few passes with 600 or 800 stones and another quick stropping.
Leaving some tooth in the edge absolutely helps certain knifes perform better for the purpose that they were designed for in the first place, in my opinion. When these knives are over polished, whether with strops or films, they lose the tooth in the edge which not only inhibits there intended purpose but also effects their durability. With some tooth left in the edge when damage does occur in the edge, and in the field it will, it’s less likely to loose the material its cutting while a edge with no tooth in it can loose the material and if the damage is enough won’t pick it back up as easily when past the damaged area, resulting in a much less durable knife. The thinner the edge the more likely it is to be damaged regardless of the steel. Harder…more susceptible to chipping, softer more prone to rolling. Another advantage of stropping, at least in my mind, is absolutely the sharpness it provides with the ability of leaving the tooth and some girth in the edge as it leaves the edge slightly convexed. The films can achieve a similar result I think but will probably leave the edge a little thinner than stropping making it a little less durable in my opinion. I’ve just started using them so I’ll find out for myself soon. By putting compound directly on hard wood, if I understood properly Tom, I think you created a strop that performs very similar to the lapping films backed with a hard surface without the polishing effect of the films. NICE!
I’ve also done several knives to 1000 and 1500 diamond and not stropped at all. These edges don’t feel as sharp as they would if they’d been stropped for sure, but are very durable and still perform pretty darn well. I also like this edge very much, thru 1000 or 1500 diamond then 1200/1600, 1.4/.6 ceramics. Not a lot of tooth but works well on certain kitchen knives and I don’t strop those either normally.
Like I said, I too like shiny things and am working on a mirror edge on my Rapid River Yooper Pocket Clip. My intent is purely cosmetic, but if it’s not sharp what’s the point, and I won’t use it for anything practical but just to show it off. The knife is 154 cm steel and I’m sharpening at 20 deg.(fairly thick blade). I’m now on the 1.5 film and will stop at 1 mic. film. My intent is to strop with kangaroo leather starting either with 4 or 1 emulsion depending on what I see and then all the way thru to the .025 PolyCrystalline spray on kangaroo after the films. Probably could have sharpened 30 knives in the time it’s taken to do this one so far. It has so far though satisfied my compulsion and it’s the only knife I’ve tried to do this with so we’ll see if I can deliver the look that I “think” I can and still produce a sharp blade all be it with no practical purpose for the knife.
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Working on prior post when I came back there was Clay’s. The angle the knife is sharpened with absolutely has a effect on the durability. To acute and it’s very easily damaged and to wide of an angle and the cutting edge wears away leaving a very rounded surface very quickly and as MarcH stated you immediately start applying more force and compounding the problem. It has been a eye opener to me to realize this because before the WE I thought the wider the angle meant the edge would be more durable and I was quite surprised to find that this was not always the case. It has been fun to find the most acute angles I could, thinking some of them were ridiculously acute at first, and test the knife and then put a micro bevel on it until the edge became durable enough for use. Many of the hunting knives mentioned earlier I sharpened at 15 deg. and wound up with either 18 or 20 deg. micro on them. Most of them 18. Thanks Clay and MarcH
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