Polished or Toothy finishes

[Enactive]

Aside from in the kitchen, by far most of the hours i have spent using a knife over the past couple decades has been carving wood.

Coming from a wood carving background and preferring zero Scandi grinds for that work, I have until recently gone for more refined and polished edges. Both in terms of edge stability/ wear resistance and especially performance in push cutting, polished edges are better.

Undoubtedly for slicing performance, toothier finishes are better (assuming they are refined enough).

In terms of finish type regarding edge stability and wear resistance-- there are a lot of other variables (including type of steel and the users habits).

As i learn more about blades and sharpening, I am experimenting with coarser finishes on my non-dedicated-wood-carving knives. I have learned a lot on this forum and am working on my skills with sharpening to a high level on a coarser stone. I am still enjoying the challenge of this and hope to continue to improve with practice. I think i first got this advice from Vivi, but it has been reinforced by others including Ankerson, BigBrownBear, Bearfaced, Gringo, Camber and others.

Cliff Stamp also has some good explanations for push cutting vs. slicing performance and types of finish.

[vivi]

My reasoning is that I can get most steels to whittle hairs with just two stones and I can accomplish that pretty quickly. When I spend the time to refine edges more with finer stones I do it for enjoyment. The pragmatist in me has figured out how to get knives sharp as efficiently as possible. The edge junky in me likes to polish up a simple steel once in a while.

I feel the same way. I used to need high grit stones and my strop to get anything close to a smooth shave, but these days I can get a knife sharp enough to pop hairs without touching skin off the medium stones, and can shave cleanly off my DMT reprofiling stone.

There are still times where I prefer a more polished edge. I like it on my chef knife, which I touch up with fine stones at 15dps. I like polished edges on serrated knives because they give them much better push cutting ability while serrations keep slicing aggression high.

But for most knives I won't polish higher than mediums or a fine DMT stone, and if I do strop, it's only once per side.

I've come to appreciate that microserrations make a big difference, especially on PE knives. Polishing them out takes extra time and generally reduces edge holding for me. When a polished edge blunts some, things tend to start slipping around on the edge. Microserrations keep grabbing material in spite of some blunting from use, extending edge life.

If I do take a knife to a high polish, I try to only polish the apex. I'll grind the bevel a few degrees more acute than I want the apex, and leave it at a very course finish. Then microbevel with the higher grits. This saves a ton of time over polishing a whole bevel. You won't be afraid to actually use the knife too, for fear of having to regrind the edge on a course stone then go through the grit progression again.

My Police 4 is a good example. It's a hard steel that takes a while to grind. I left the bevel with a finish straight off my reprofiling stone, then took the apex to a higher polish.

Depends on what you are using the knife for and what you like personally.

In general a coarse edge will outperform a polished edge and by a long shot for just about any sort of use outside of wood carving.

So if you aren't carving wood then a coarse edge will work better in general.

As a side note polished edges also work well on choppers, big knives....

Yep, good info. I'll polish my chef knife, axes and a few bushcraft knives. Machetes I leave coarse so they grab brush better. EDC's coarse.

[Chris_P_Bacon]

Either finish, at factory angles is one thing, and makes for a fun discussion, but if you are seriously wanting performance, lower angles are where it's at.

If you can try different angles, lower than what the sharp maker allows. You will see your edge improve as you get shallower and shallower. Then as you continue that journey, you will get to a point where your edge is too shallow and becomes unstable. Once this point it reached increase your angle, back to the sweet spot. Very time consuming to do all this, I highly recommend the latest version of resin bonded stones if you can swing it.
They don't have the problems that plated diamonds have.

Also: The sweet spot will likely be different for each type of steel, and also different for different hardness's within a same steel type.

Larrin puts it like this: "Edge angle had by far the strongest effect on edge retention, much stronger than the finish it was sharpened to. Edited for brevity. Results based on CATRA Tests.
Ref 1
http://knifesteelnerds.com/2018/06/18/m ... retention/

Dr. Vadim Kraichuk puts it like this "The sharper is the edge the better is retention"
Translates better "The sharper the edge the better the retention". Results based on BESS Tests on a Knife with 24 degrees inclusive.
Ref 2
http://knifegrinders.com.au/SET/SET_research.pdf

Cliff Stamp's concepts and experimental data shows, an edge of 12dps should outperform those of 15 and 20dps, and advocates that knives should have the thinnest edge possible for a given blade steel and task.

BBB, Blunt Cut, Phil Wilson, Michael Christy, among others all push the boundaries of Angles seeking higher performance. Obviously within limits, goes without saying.

[Pelagic]

Oh carbide tearout exists. ...

Hey Hitch, not starting an argument mate. And I fully agree that you can stress an edge with blunt or inadequate abrasives, but I do wonder as to how much pressure would need to be applied to a strop and how much purchase it may offer in order to tear carbides out of the steels matrix? :confused:

Pressure isn't a big issue. The basic idea is that the abrasive is either capable of cutting the carbides or not. If you can't cut the carbides, you'll be only cutting the steel surrounding the carbide. Soon it won't be attached to enough steel and will fall out in sharpening. That's the whole idea. Supposedly, even according to people who think carbide tearout is a prominent issue in sharpening, the effects are only seen when going beyond 3 micron finishes. Which as Ankerson mentioned, only really shines in wood carving. Yet another reason it's not worth worrying about is that the "theory" is primarily based on HRC (abrasives of a lower HRC than the carbides themselves can't cut them), yet SiC stones, from what I can see, generally do not cause carbide tearout despite SiC having a lower HRC than the hardest carbides.

Too long, didn't read: carbide tearout exists, but you should essentially sharpen as if it doesn't. IMO.

[vivi]

Either finish, at factory angles is one thing, and makes for a fun discussion, but if you are seriously wanting performance, lower angles are where it's at.

If you can try different angles, lower than what the sharp maker allows. You will see your edge improve as you get shallower and shallower. Then as you continue that journey, you will get to a point where your edge is too shallow and becomes unstable. Once this point it reached increase your angle, back to the sweet spot. Very time consuming to do all this, I highly recommend the latest version of resin bonded stones if you can swing it.
They don't have the problems that plated diamonds have.

Also: The sweet spot will likely be different for each type of steel, and also different for different hardness's within a same steel type.

Larrin puts it like this: "Edge angle had by far the strongest effect on edge retention, much stronger than the finish it was sharpened to. Edited for brevity. Results based on CATRA Tests.
Ref 1
http://knifesteelnerds.com/2018/06/18/m ... retention/

Dr. Vadim Kraichuk puts it like this "The sharper is the edge the better is retention"
Translates better "The sharper the edge the better the retention". Results based on BESS Tests on a Knife with 24 degrees inclusive.
Ref 2
http://knifegrinders.com.au/SET/SET_research.pdf

Cliff Stamp's concepts and experimental data shows, an edge of 12dps should outperform those of 15 and 20dps, and advocates that knives should have the thinnest edge possible for a given blade steel and task.

BBB, Blunt Cut, Phil Wilson, Michael Christy, among others all push the boundaries of Angles seeking higher performance. Obviously within limits, goes without saying.

Quoted for emphasis.

One more tip:

If you do the above, when you get to the point you see edge damage, give it a microbevel. Most the time the edge will then be perfectly stable.

Say you try 12dps on your VG10 Delica and it works great. 10dps you see chipping whittling wood. So give it a 10dps bevel, then microbevel at 15dps. You'll have a stable edge with significantly better performance than 15dps.

This is one of the reasons I warmed up to serrated edges so fast. I reprofile every plain edge knife I buy from Spyderco. The serrated knives don't need it though. They come ground at 15 degrees inclusive....at least my Pacific Salts did.

I was cutting onions yesterday with a Pacific Salt SE sharpened with the diamond sharpmaker rods and nothing else, side by side with a PE Calypso sharpened up to 16000 grit and stropped. The thinner geometey of the Pacific Salt let it penetrate the material more easily, despite the Calypso having a thinner than factory edge sharpened in a way to optimize it for push cutting foods.



I find it interesting that Spyderco releases SE knives ground so much thinner than their PE knives, even if its the same model in the same steel.

[emanuel]

I like polished edges more and more lately, even on high-carbide steels. I'm not sawing away with my knife that much during my day to day, and when I really need cutting aggression, I use a serrated edge, which puts to shame even the best toothy edge. An issue I had when using toothy edges, particularly when cutting synthetic fibers, is fibrous lint getting stuck to the edge, something that doesn't happen as often with polished edges, be it PE or SE.

So as for my sharpening progression, I go all the way to Spyderco ultra fine ceramic, then finish with 1.5 micron diamond strop on some very hard boar leather my dad made. 12-15 dps usually for most of my knives.

[Pelagic]

I like polished edges more and more lately, even on high-carbide steels. I'm not sawing away with my knife that much during my day to day, and when I really need cutting aggression, I use a serrated edge, which puts to shame even the best toothy edge. An issue I had when using toothy edges, particularly when cutting synthetic fibers, is fibrous lint getting stuck to the edge, something that doesn't happen as often with polished edges, be it PE or SE.

So as for my sharpening progression, I go all the way to Spyderco ultra fine ceramic, then finish with 1.5 micron diamond strop on some very hard boar leather my dad made. 12-15 dps usually for most of my knives.

I like some tooth to my kitchen knives sometimes. Slicing a tomato with a razor sharp 600 grit edge seems better than a highly polished edge or serrated edge.

[Bloke]

Oh carbide tearout exists. ...

... :confused:

Pressure isn't a big issue. ...

I understand the theory and I’ve seen a few micro photos.

I’m just of the impression that stropping compounds in general and the grit sizes mentioned above are unlikely to dislodge carbides. Fact is, I don’t rightly know. :D

I know VC is a little harder than SiC but I’ve sharpened S90V a few times now with Diamond, CBN and SiC and other than the former two cutting a little faster I’m not too sure I could pick a difference in the finished edges plus I maintain edges with a micro bevel cut on medium Spyder ceramic so they all end up the same anyhow. :rolleyes:

It probably wouldn’t much matter if I set the primary bevel on a lump of sandstone. Ah, hahaha! :)

[JonLeBlanc]

Vivi... Cambertree, MeatMan, and yourself always have great edge bevels! May I ask what is your setup?

[StuntZombie]

I used to try to polish my edges to a mirror finish, but lately I'm trying my best to try and replicate the factory finish on the edge. Usually that means using the coarse plate on my Worksharp Guided Benchstone to set the bevel, and just lightly refining the edge using the medium stones on the Spyderco Sharpmaker. It seems to have been working well so far, with the edges lasting longer and being quicker to touch up.

[TkoK83Spy]

Guess I'll just throw away my UF rods after reading all this :p

[emanuel]

I like some tooth to my kitchen knives sometimes. Slicing a tomato with a razor sharp 600 grit edge seems better than a highly polished edge or serrated edge.

I did the same for awhile on my super blue gyuto, but switched back to polished. When you get the edge very very sharp and refined as these simple steels get, it just drops through tomato peel like it's not even there, so I don't feel the need for the toothy grippiness of the edge.

[Pelagic]

I like some tooth to my kitchen knives sometimes. Slicing a tomato with a razor sharp 600 grit edge seems better than a highly polished edge or serrated edge.

I did the same for awhile on my super blue gyuto, but switched back to polished. When you get the edge very very sharp and refined as these simple steels get, it just drops through tomato peel like it's not even there, so I don't feel the need for the toothy grippiness of the edge.

I hear you. I enjoy that as well. But I think I'm more of a slicer with tomatoes, lol, I try not to make excess contact with the cutting board, which is how you lose your edge in the kitchen.

[basedlarrydavid]

As a sharpener/user, I enjoy both coarse(r) and polished edges. It largely depends on the steel, the intended cutting task, and in some instances, aesthetic value. However, I always, always, always go for a high degree of aggression/scary sharpness. Because I’ve got the tools to maintain such edges and I have a bunch of knives I keep in rotation, I never seek longevity over ultimate performance (though with the right conditions, I get both).

In all, I try to learn about the properties of each steel and play on their strengths to get the most out of them.

I tend to leave high-carbide steels (S90V, 10V, S110V, Maxamet, K390) as coarse as I can while achieving a nicely refined crispness. Those super high hardness carbides are what make those steels shine so you don’t want to smooth them out too much. Again, the idea is aggression, even at a microscopic level. I test the edge after each stone. As soon as it will consistently and CLEANLY cut (not necessarily whittle) a free-hanging hair across the entire edge, I’m done. That’s usually around 650-1100 grit. I reduce and remove the burr as much as I can on the final stone and clean it up with a 4 or 2 micron diamond emulsion on wood. Just a few light passes does it.

With high-hardness, lower carbide steels (CTS-XHP, 52100, AEB-L, AS), I like to take them to a very fine, high polish. I find that’s where you get the real aggression, as they don’t have those hard carbides mentioned above.

Also, something very important to note: sharpening stone technology has grown dramatically, even in the past few years. Some of the resin and metallic bonded diamond/CBN waterstones allow for highly polished, fine, stabilized edges with a *ton* of bite. Especially when using diamond abrasives in stropping. I think the common understanding in the past was that polished edges could be very sharp and would push-cut well, but wouldn’t slice well due to the “microserrations” along the apex being polished and rounded. That isn’t the case these days if you have the proper tools and most importantly, proper technique.

[Pelagic]

For some reason it feels like steels that are high carbide AND high chromium like coarse edges the most. I like s110v extra coarse but don't get the same feeling with my limited experience with Maxamet or 10v, which I feel the desire to take them a tad finer. They hold a fine edge longer and that probably has something to do with it. Every time I've ever taken s110v to a very fine, very high sharpness, I never saw it as worth it.

[vivi]

Vivi... Cambertree, MeatMan, and yourself always have great edge bevels! May I ask what is your setup?

Set my bevel with a DMT X Coarse 6" stone, microbevel using the brown sharpmaker rods, everything free hand. Normally I use an 8" XX Coarse + medium spyderco bench stone but I lended those to a friend last year.

The reminds me, I need to get them back....

[The Meat man]

Vivi... Cambertree, MeatMan, and yourself always have great edge bevels! May I ask what is your setup?

I use a Hapstone V7 guided sharpening system for most reprofiling, and with that I rarely go above 400 grit. Usually just start at 220 and finish at 400, then some stropping.

Often, for convenience' sake, I will maintain the edge with a microbevel; however, I have come to prefer the cutting performance of a clean apex sans microbevel. It feels sharper.

[David R]

I was under the impression that knives high in carbides, you leave coarse. If you polish them to an extremely high finish you may have carbide tear out.

Does that sound right?

No, that's a myth, another one of those urban legends that somehow just won't die.

It just doesn't exist.

Some that use diamonds to sharpen have had some issues because the diamonds tear up the apex quite a bit.

That's not carbide tear out, that's chipping due to the torn apex.

So when using diamonds it's best to finish on something else like ceramics or stropping.

Hi Jim,

I'm not seeing that with matrix diamond stones. Surface mounted diamonds sharpen like boulders. I learned the hard way not to apex with them. Matrix diamond stones don't have that problem. I can get a great edge at 600 or 4K with matrix diamonds and have no edge issues at all. And once you apex it takes very few passes with each successive stone. Game changer for me when sharpening steels like K390 and Maxamet.

Also not seeing much edge retention difference between grits over 1K with these. I'll have to try the same knife between 600 through 4K and see how it does.

[Ankerson]

I was under the impression that knives high in carbides, you leave coarse. If you polish them to an extremely high finish you may have carbide tear out.

Does that sound right?

No, that's a myth, another one of those urban legends that somehow just won't die.

It just doesn't exist.

Some that use diamonds to sharpen have had some issues because the diamonds tear up the apex quite a bit.

That's not carbide tear out, that's chipping due to the torn apex.

So when using diamonds it's best to finish on something else like ceramics or stropping.

Hi Jim,

I'm not seeing that with matrix diamond stones. Surface mounted diamonds sharpen like boulders. I learned the hard way not to apex with them. Matrix diamond stones don't have that problem. I can get a great edge at 600 or 4K with matrix diamonds and have no edge issues at all. And once you apex it takes very few passes with each successive stone. Game changer for me when sharpening steels like K390 and Maxamet.

Also not seeing much edge retention difference between grits over 1K with these. I'll have to try the same knife between 600 through 4K and see how it does.

Hi David,

Haven't tried any of those yet.

Been sticking with the Mold Master SIC or Shapton Ceramics all on the Edge Pro.

Have to look into the Matrix stones. :D

Jim

[vivi]

I was under the impression that knives high in carbides, you leave coarse. If you polish them to an extremely high finish you may have carbide tear out.

Does that sound right?

No, that's a myth, another one of those urban legends that somehow just won't die.

It just doesn't exist.

Some that use diamonds to sharpen have had some issues because the diamonds tear up the apex quite a bit.

That's not carbide tear out, that's chipping due to the torn apex.

So when using diamonds it's best to finish on something else like ceramics or stropping.

Hi Jim,

I'm not seeing that with matrix diamond stones. Surface mounted diamonds sharpen like boulders. I learned the hard way not to apex with them. Matrix diamond stones don't have that problem. I can get a great edge at 600 or 4K with matrix diamonds and have no edge issues at all. And once you apex it takes very few passes with each successive stone. Game changer for me when sharpening steels like K390 and Maxamet.

Also not seeing much edge retention difference between grits over 1K with these. I'll have to try the same knife between 600 through 4K and see how it does.

Can you tell me which matrix diamond stones you use? I'm still using regular old DMT's and would like to try something new.