mitchshrader said:
I'll take the mildest of exceptions to the statement that a yellow coticule and water produces the finest edge. It may be USUALLY the case, but if you use top shelf Japanese stones you're likely to modify the opinion.
I have used "top shelf" japanese hones. In fact. I own one of the Nakayama quarry. The don't leave anything desired for sharpness. The same counts for a well honed Coticule edge. What one likes best for shaving is a matter of preference, as much (or more) defined by the inherent qualities of the razor than the differences between both types of natural hones.
mitchshrader said:
They happen to be more expensive and less agressive, and I've not seen anyone using them specifically for razors..
Japanese natural hones are a well know and much debated topic among straight razor aficionados. We have a few threads about them, but you should be able to find much more on the major shaving forums.
mitchshrader said:
but artisan quality knives that are hardened to Rc 65 *can* be sharpened to 'hairsplitting' sharp. Actually splitting hairs, to show off the edge..
Splitting a hair with an edge is one of the possible outcomes
Hanging Hair Test, discussed in the linked article. You'll notice that it rates 2 on a scale of 5 steps of increasing sharpness.
mitchshrader said:
I think that which stone produces the finest edge would depend on the particular stones being compared. In my collection it's a Takashima Karasu (olive stone with black streaks), VERY hard, IMO 10K-12K grit and useful for not much but mirror polishing and ultimate edge refinement. There's no good reason to strop after using it..
I believe you would reconsider that statement about the need for stropping if you would use your honed edges for shaving your beard. I'm not saying this to claim that shaving with a self honed edge entitles to make more claims about sharpening than using other sharpened tools. But shaving does reveal the properties of an edge clearer than any other use, because the assessment is done by feeling the action at the fingertips that hold the razor, the facial skin in contact with the very edge, and the nerves at the hair roots of the whiskers being severed.
I've honed razors on a Naniwa Chosera 10K, on different Nakayma's, on 3M lapping film up to 0.3 micron, and on Coticules. They all stepped at least 2 points up on the HHT-score, after additional stropping on clean leather. I haven't shaved often with an unstropped edge, but enough to be sure the differences would be significant coming off all the aforementioned hones.
Please not that these kind of performance issues relate to shaving. For carving wood, I only stop edges when I use my Tormek sharpening machine, that's equipped with a leather wheel, dressed with diamond compound. It finishes the edge left by its 600 grit Aluminium Oxide wheel. Tools comming off a Coticule or BBW, I never strop at all, as I feel the effect wears off and falls back to the pre-stropping level, after making one or two cuts. (That's not so for shaving).
It's hard translating general sharpening experience to straight razor honing. I had nearly 20 years of sharpening woodworking tools experience when I started honing straight razors. I though it would be easy for me, but that turned out a big mistake.

:
I am all for supporting all sharpening disciplines on this forum, but we must be careful not to mix up too many truths of one discipline with the other.
I hope that doesn't come across as overly patronizing, as I'm thrilled to finally see an experienced tool sharpener posting in our cozy Coticule corner. Maybe we should open a separate "Tool sharpening" section in this forum.
Best regards,
Bart.