K390 vs S110V - Some Observations

[ejames13]

I thought it'd be interesting to compare these two steels, since they're both offered in high performance production variations of several popular Spyderco models. This isn't going to be terribly scientific, just some things I've noticed in sharpening and use.

I recently sharpened both my K390 Police 4 and S110V Military on my Edge Pro after the factory edge had deteriorated to the point I no longer enjoyed using it after touch ups on my DMT 1200 DiaSharp plate. Surprisingly, I found K390 much slower to grind than S110V, requiring substantially more effort to set the bevel. Granted, I reduced the edge angle by a degree or two on the K390 Police vs keeping the factory angle on the S110V Military, so there was necessarily going to be a little more grinding involved. But the Military had a fairly large not-so-microbevel from a lot of touch ups and perhaps a botched sharpening or two by the previous owner. I successfully set the Military bevel with a Moldmaster 320 stone without too much effort. When I took the MM 320 to the Police, it was super slow going. I pulled out my 140 grit diamond plate to speed up the process, and it still took longer than I would've liked. Finally apexed, and the burr was considerably smaller than normal when apexing with this stone, reinforcing the notion that this steel is difficult to grind. Once apexed, the rest of sharpening process was relatively comparable between the two, with the S110V requiring maybe a little more effort and care during final deburring.

I finished the Military on the Moldmaster 400, stropped with 1um diamond, then bare leather. Cut up a few boxes into thin strips until the edge would no longer catch hair on the back of my head (which happened relatively quickly). It was fairly unresponsive to stropping with 1um diamond. Took it to my DMT 1200 for a touch up, and it was far less responsive than any other steel I've tried. Took more time and effort than usual, but I got it back to shaving. Cut a few more boxes with the same result - shaving sharpness dropped off quickly, but remaining sharp enough to cut cardboard til the cows come home. I took it back to the EP for a fresh apex and this time used the stock EP 220 and 400 grit stones. The EP 400 stone leaves one of the best finishes of any stone I have. I like it better than my Shaptons or Moldmasters. I was surprised it had no trouble with S110V. Just a little slower than normal. No stropping this time. Just straight to cardboard. Same result. Shaving sharpness lost fairly quickly, but was able to bring it back with the DMT.

I finished the Police on the EP 400 after the aforementioned painfully slow bevel setting, stropped on 1um diamond, then bare leather. Cut up about the same amount of cardboard as with the Military. It seemed like the Police held that shaving sharpness longer. However, I know we have two different knives with different blade geometries here. At this point I attempted the same stropping procedure as on the Military, but the Police was far more responsive. It came right back to shaving. No need to hit the DMT stone at all. I was really pleased with how easy it was to bring the initial sharpness back after eating a bunch of cardboard.

All in all, I'm pretty disappointed with S110V and pretty pleased with K390. The effort required to get the edge I want on S110V doesn't seem worth it given how quickly initial sharpness drops off and how difficult it is to bring back. K390 on the other hand, despite the difficult grinding, seems to keep that initial sharpness longer and is considerably easier to bring back once lost.

Those are my very unscientific observations on these two steels. What's your experience been with them? Which do you prefer and why?

[RustyIron]

Those are my very unscientific observations on these two steels. What's your experience been with them? Which do you prefer and why?

My experience with S110V is limited, so I can't give a fair evaluation. But I probably have more knives with K390 than any other steel. I find the material isn't particularly prone to chipping, but nor is is prone to rolling. It just keeps on going and going. Sharpening is pretty easy, I think because it doesn't like to form a burr that you need to get rid of. The stones I use are EdgePro diamond matrix made by Columbia Gorge. Occasionally I'll use a diamond plate if I'm impatiently removing a lot of material, or if I'm just looking for a different effect. I can put a polished or coarse edge on K390, and both perform nicely.

[vivi]

I appreciate the corrosion resistance of 110V but otherwise prefer K390. It has a better sharpening response for me too.

[bdblue]

I recently sharpened both my K390 Police 4 and S110V Military on my Edge Pro after the factory edge had deteriorated

I've read a few times about potential problems with the factory edge although I don't know that I've seen hard evidence of this. Is there a chance that you need to sharpen away more of the original edge before you can do a true comparison?

[zuludelta]

Those are my very unscientific observations on these two steels. What's your experience been with them? Which do you prefer and why?

I have multiple knives in both S110V (Native 5 Lightweight, PM2, Manix 2, UKPK) and K390 (Delica 4, Endura 4, Dragonfly 2, Lil' Temperance 3 Lightweight) and I've used them extensively at work. My own subjective and unscientific observation is both steels hold their working edge about as long as each other, although K390 seems to hold its top-end sharpness a lot longer (and just to complicate matters & throw in a third steel in the mix, I find CruWear holds its top-end sharpness longer than both S110V and K390, but doesn't hold its working edge as long as either). With regards to sharpening response, I don't really strongly favour one over the other, though if push comes to shove I might go with K390.

As to which I prefer and why, it's highly context-dependent. Several years ago, I worked in a frigid environment (working in subzero temperatures ranging from –18°C to –30°C) and the bulk of my work cutting tasks involved breaking down a lot of wet and/or frozen industrial cardboard and other abrasive materials like polypropylene/nylon pallet straps. How much? On a slow day, I cut maybe 60 linear feet of wet/frozen cardboard, and on a really busy day, I cut up to five times that amount (300 linear feet!). During this period (which lasted nearly 3 years), S110V served me very well and was my preferred steel for a work folder (this was before the introduction of MagnaCut). It had a near-Salt level of stainlessness and working edge retention that could see me through three to four weeks of work before it started to feel like I was putting significantly more force behind the cutting/slicing motion than I normally do. Under such conditions, I would be lucky to get two weeks' worth of shifts out of S30V/S35VN before needing to resharpen and for non-PM steels like 154CM, VG10, LC200N, and BD1N, I'd be lucky to get a week (on very busy weeks, I would have to sharpen these non-PM steel knives almost every day!).

Now that I don't work in those conditions anymore and corrosion-resistance isn't as big of a priority as it used to be, I find myself picking K390 over S110V most days, given the choice between the two (though to be honest, I'm actually okay with even just VG10 these days for my work folder since I don't do as much cutting in my current job as I did in my previous one). While I've never had issues with S110V chipping with normal work use, I guess I just like knowing that if I accidentally hit a steel beam or a nail, my K390 knife theoretically stands a better chance of making it through with an intact, undamaged edge. Although I guess the main reason I reach for my K390 knives more often than my S110V knives now that stainlessness is a less important consideration for me is—with the exception of the Native 5—I just prefer the ergonomics of the K390 designs that I own over the S110V ones.

[kerrcobra]

I prefer K390 over S110V as well. I prefer Maxamet over S110V too, but K390 is my favorite of Spyderco's production steels. Rex45 is, of course, my all time favorite.

[Brock O Lee]

I prefer K390 for work knives because I like how it sharpens and deburrs. It holds a front-end sharpness noticeably longer than S110V in my experience. It is also a few points harder than S110V, which gives it more strength and better edge stability.

S110V’s corrosion resistance works exceptionally well on the UKPK though. I usually carry it in the waistband with no rust concerns. It is a light user and it stays sharp pretty much indefinitely.

[Manifestgtr]

I’ve used and sharpened both of these pretty extensively

K390 is a clear winner in the sharpening department. Things like reprofiling take a minute but after that, it’s all good. I’ve never had a major issue getting a screaming sharp edge

S110V is similarly difficult to reprofile…but it also takes a light/precise touch to get a truly sharp edge. It just takes a little longer and seems to respond nicely to alternating passes

[Spyderfreek]

I’ve used and sharpened both of these pretty extensively

K390 is a clear winner in the sharpening department. Things like reprofiling take a minute but after that, it’s all good. I’ve never had a major issue getting a screaming sharp edge

S110V is similarly difficult to reprofile…but it also takes a light/precise touch to get a truly sharp edge. It just takes a little longer and seems to respond nicely to alternating passes

What's great about k390 is it will still take a razor sharp edge even if you're using an extra coarse DMT with too much pressure. I can't speak to s110v but stuff like Maxamet will chip if you do that. K390 can be time consuming to grind but it's otherwise very forgiving to sharpen.