How do you joint the edge? I have found it to be a delicate thing to master at this level of refinement.Just be aware, according to Sakamoto, re Gilmore video, Mejiro can be finer than Koma, again base stone dependent.
I have had better luck finishing on Tomo Nagura than, Mejiro or Koma Mikawa. I have a wide selection of Tomo Nagura and have tested against all my base stones to find which produce the best shaving edge for each stone. I cannot predict which edge will be better by looking at the bevel and edge, only by shaving.
My usual Nagura progression is Tsushima, thick-ish slurry, (it will quickly give you a Kazumi bevel and remove stria) from a near mirror, 8K Fuji bevel, to Tenjyou with thinnish slurry, then a hard Tomo Nagura thin slurry to finish. Some hard stones finish well on a thin 600 diamond slurry.
Once I have a finished edge I like, very lightly joint the edge, strop on firehose and on Chrome Oxide on Polyester canvas,(to remove any burr) about 10 laps and reset the bevel to finish, about 20-30 slow laps, on whatever slurry I finished on. Strop on clean vintage Kanoyama flax linen and Kanoyama leather to finish.
If you do not have an assortment of Tomo to test, but do have other stones, try using the end of your base stones, just ensure that there is no hard Kawa, skin on the edge or file the corner away from the Kawa so that you are making slurry from the stone and not Kawa.
I find if I use the Tsushima to first set the bevel and lay an even Kazumi base, I need less slurry to refine the bevel and edge. Slurry can be added, removed and refreshed or thinned as needed.
I add water to rehydrate slurry, then wipe half the stone with a damp sponge, to thin the slurry by half, and continue removing half to get to finish slurry, usually twice for super thin finish slurry. This slurry will not have a lot of steel in it, if it does, make new slurry.
Another thing to try is a micro bevel on thin finish slurry or the SG20. 3-4 laps on a Kapton taped spine.
Bottom line is you really do need to calibrate your Nagura, Mikawa or Tomo to each of your base stones for best performance.
I was not intending on finishing on the koma slurry. I have few options for the final nagura, but i need moore time to experiment. Yellow’ish Nakayama stone on hard Shobu is used usually.
I have a giant Tsushima nagura bench stone which i am trying to find a spot for in my progression. That dry feeling sort of smooth out if i use a nagura on it. Nagura on naguraMy Shiro Suita is also trying to find it’s place. It turned out to be much finer then i thought. It gives a really nice kasumi finish, but it is hard to say where it fits in.
Really important dilemmas, i know