Did a little edge-testing today.
I had previously reprofiled the factory edge to about 29 degrees inclusive. I went from a Atoma 140 grit, to a Shapton 120, Shapton 2k, and then to finish I went back down to a DMT 600 grit because it's my favorite hone.
The edge I started with was at a BESS score of about 150, and would easily pop arm hair and whittle beard hair. Now, my BESS tester is one of the earlier models that used a little plantern with a cup and would drop the thread down onto the knife fixed into a holder. It's much different than the current BESS testers with the clips of the disposable media, so there's a lot of variablity that can go into the numbers.
After 100 cuts of about 6-8" into corrugated cardboard, the BESS score increased to 202. It wouldn't whittle hair anymore but still shaved hair well and bit into fingerpads during a 3-finger test, and would easily sever a beard hair if I pressed the blade against the hair with my thumb as a backing.
After 200 cuts the BESS score stayed pretty much the same at 205 but I could feel it biting into my finger pads a little less and it would no longer sever a hair when pressed against my thumb.
After 300 cuts the BESS score was still at 204 and I noticed it took a little bit more force to shave arm hair, but still bit into finger pads during the 3-finger test just fine.
After 400 cuts, the BESS score was at 278 but I think this was a bit of an error as you'll see later. It would no longer shave arm hair at this point, but still bit into my finger pads.
After 500 cuts, the BESS score was at 250 and was still biting into finger pads.
After 600 cuts, the BESS score was at 260 and was starting to lose bite against my finger pads.
After 700 cuts, the BESS score was at 309 and it had a lot less bite into my finger pads, and I could notice it wasn't cutting the cardboard as well.
After 800 cuts the BESS score was at 298, and the bite into the finger pads took much more force, as well as did the cutting into cardboard.
After 900 cuts the BESS score was at 317, and it barely had any bite on my finger pads, but still cut cardboard well.
At that point, I was out of cardboard.
That's a large Chewy box (8" D 16" W 24" L) full of cardboard slices from several different boxes, including a cat litter box that had a lot of clay debris on it.
Somewhere along the line, probably thanks to the kitty litter box, I ended up getting some micro-chipping on the edge. I had to use a 60x loupe to see these, and could barely feel them with my fingernail. I could not see them under natural lighting or high illumination with no magnification at all, and the edge would still draw cut printer paper pretty clean, though some of the microchips did lead to some tearing of the paper.
After all this was done, I used the Shapton 2k to grind most of the microchips out. I ground one side until I felt a burr, which took probably 2 or 3 minutes at most, and then I finished it on my DMT 600 grit again. It's now poppping arm hair and whittling beard hair at a BESS score of 140.
Overall I think this is pretty great performance. After filling up that box with nearly 1000 cuts of cardboard, it was still within the "new high end cutlery" range of the BESS scale and cutting up printer paper quite cleanly. I noticed that the BESS score dropped pretty dramatically from 150 and then hung around the 200 range for a while, which matches edge-testing results I've seen on Larrin Thomas's blog and makes sense that the fine-edge was breaking down to a toothier, carbide-rich edge. Ultimately I think I probably could have cut up two or three times as much cardboard as was in the box before it got too dull to cut it cleanly.
I also really like the sharpen-ability. The high vanadium content gave me concern that my Shapton stone's wouldn't be up to it since I think they're most aluminum oxide, but the 2k raised a burr and got rid of the micro-chipping quite well. There was still a small amount of micro-chipping left after examining it again under 120x magnification, but none that was detectable by my fingernail. From the Shapton to the DMT I think it took me all of 10-15 minutes to bring the edge back to arm-hair popping, beard-hard whittling, BESS 140 (which is supposedly about as sharp as a utility razor).
I think the only thing that really gives me a little bit of concern here is the microchipping, but I don't know if that really suggests that it is overly brittle. This is a pretty acute edge geometry I'm using, and the chipping was indeed extremely small, so I think it was simply by merit of the apex being so small that the edge stability simply couldn't hold at that small of a level. However, that said, it was still cutting printer paper fairly cleanly, and it took a new edge extremely quickly which I feel like it would not have if it wasn't as hard as it is.
I think it's a pretty good indication of its edge holding since it never stopped sailing through the cardboard, and only seemed to dull at the most imperceptible levels.
