There is no doubt that the lighting/razor angle is different in the Nak photo, it also appears to be zoomed out a bit.

But when I look at it at home, where I can experiment with the lighting and such it's a similar phenomon, that's all I'm saying.

Just for educational purposes, I'm curious what makes you say that the Nak is releasing larger particles. It seems like you are saying it's releasing some larger than .5 micron, which may or may not be true, I just want to pick your brain a bit.


Quote Originally Posted by mparker762 View Post
Sure. I have a couple of microscopes as well. And I see similar sorts of scratches, depending on the angle of the light. But what I'm seeing are *not* the scratches from the shapton 30k - they're the scratches from the lower-grit hones, brought into sharp relief by the polishing action of the shapton which polishes the tops of the high ridges. In the photos you linked to, notice that in the shapton shot there are large, fairly contiguous areas on that bevel that look a bit flattened and polished, where the grooves aren't as prominent. There are three irregular bands of these going across the length of the bevel, one at the very edge that may be a microbevel, and two more farther back on the bevel. One or all of those bands is likely where the shapton is honing - my suspicion is it's the one at the edge itself, because...

The nakayama-finished blade actually has a rougher edge - don't look at the bevel, look at the edge itself - there is a distinct regular sawtooth pattern on the nakayama edge that isn't present on the S30k edge. This again demonstrates pretty solidly that neither the nakayama nor shapton edges were effectively sharpened on those hones, and that the edges are still hopelessly compromised by the remnants of their 1k honing striations. Verhoeven demonstrated in his paper that when viewed under an electron microscope, blades only show a regular sawtooth pattern up to about 2k grit, beyond that the edge gets thin enough that the steel at the edge is simply too weak to sustain the sawteeth. When I compare edge roughness between hones, I set the lighting and contrast so that only the reflection off the edge shows up, this reduces the distraction of the bevel appearance since all you have to look at is the thin white line interrupted by the occasional microchip. Any sawtooth pattern that is showing up means that I need to go back to the 4k or 8k hone and clean things up before going back to the finishing steps.

The real reason the nakayama bevel looks "finer" is the loose particles in the slurry are rolling around underneath the bevel and leave behind a finish that under magnification looks like it's been sandblasted, and this changes the way the light reflects off the surface minimising the appearance of the underlying low-grit scratches. If those edges had been honed properly then neither razor would show any grooving pattern at all at that magnification, there would be no sawtooth pattern at the edge. From looking at those partially-honed bands on the S30k picture, you might predict that the properly-honed S30k bevel would look like a mirror (and you would be right), and from looking at the sandblasted-grooves on the Nakayama picture you might predict that the Nakayama bevel would look like a sandblasted mirror (and you would also be right).




Sorry, but unless you've got a microscope at least 1,000x, then what you're seeing aren't the scratches from the nakayama or shapton, and I'm doubtful that even at 1000x that an optical microscope could resolve scratches of this size.

Secondly, while it's true that the particles from the Nakayama are always breaking down, it's also true that new large particles are always coming out. So this isn't a win-win scenario - those small broken-down particles may well be smaller than the ones on the Shapton30k, but those new fresh particles coming out are larger than the ones in the Shapton. And I've never heard anyone claim that the particles in the Shapton don't break down. Certainly on mine it gets finer and finer over repeated uses after I've lapped it, which makes me think that the abrasives are breaking down as well.





I don't think you're dissing shapton, I just don't believe that those photos you linked to are particularly useful except as a negative example.

I get similar levels of sharpness out of my shapton 30k and nakayama asagi. If either is superior it isn't by much, certainly not enough to worry about since there are ways of getting much higher levels of sharpness. So if I'm going for sharpness I really don't care if the nakayama is 10% or even 30% better than the shapton, because the edge is only gonna be there for the few minutes it takes to haul out the newspaper or 0.1 micron diamond or 0.05 micron aluminum oxide.