The nature of Tomonagura and using a Diamond Nagura

Hello Tim

I do hope that you get the Okudo soon and that you like the tomonagura that I included. Without handling the tomo that you got from someone else, I wonder how mine would match up against the others. Mine might be just as soft so keep me posted.

Matching tomo requires having enough tomo samples to test with, and it is a little confusing too. In my own shop I relay a lot on a well worn Atoma #600 to perform the same work that some fellows use Botan and Mejiro for, refining the bevel after my 1k or 2k bevel setting stone. The diamond generated slurry is really fast cutting and I find it leaves the bevels in a very good state as the DN (diamond nagura) slurry crumbles from the bundled grit particles made from the DN down to smaller and finer individual grit particles. Using the DN slurry sets the stage for the tomo, and a tomo following the DN slurry has a much easier job.

The trick in matching a tomo falls into that narrow realm, picking out a tomonagura that does not deeply scratch the base stone, but is hard enough to abrade it slightly. Some of the burden on the user is to adjust his/her hand pressure, water content and stroke speed to prevent scratching. With really hard stones this all becomes more critical, and as a matter of fact the same holds true with honing really hard steels on really hard stones. As a purveyor of stones I often have to err on the side of a slightly softer tomo that demands less of the base stone as a slurry source, and this can seem like a miss-match, and I would have to agree if you had to go with your blade directly from the 1k bevel setter to the tomo and the base stone with no intermediate grit source. Going back to my shop, this is where the DN comes into play.

A DN slurry covers a lot of difficult ground when working with very hard stones, it is like a Botan-Tenjyou-Mejiro progression all in one slurry. I find that most users of Asano stamped Shiro Mikawa Nagura do not finish their razors with those 3 or 4 softer stones, they almost always finish with a tomonagura, and then often followed by a clear water polish. If accepting the proposition where the DN slurry can replace the Mikawa progression, then there is at alternate method leading to the tomonagura, and if the tomo has a ultra fine grit particle matrix that at least equals that of the base stone in fineness,  then in practice a slightly softer tomo can bridge that gap between the DN slurry and the clear water stage because the DN slurry has already relieved so much burden after the bevel set. This of course is all predicated that you have a super fine grit particle tomo.

I think that you will find the two tomo I enclosed in the package to be super fine, but as I began with they might be too soft to bridge the gap between 1k and clear water finish alone, if not try adding a DN element in there and see how that  works out. The diamond plate will have to have meet the same criteria as the tomo, one that does not leave deep scratches, so a worn out plate works best. If your plate does leave scratches I think that you might be surprised in the long run how little the negative effects actually are and that those same scratches might be worn down by the end of your honing session.

One more thing. It is cited that a diamond plate prematurely wears out a valuable on of a kind awasedo stone if you use it to raise a slurry. I would be a fool to suggest otherwise. But my choice to use a DN is based on balancing that tiny 50 microns thin skin of that surface sacrificed versus ignoring the superior cutting power of an otherwise very slow cutting hard stone that neither I or my son will ever wear out no matter if a diamond plate slurry is used of not. Almost everyone now used a diamond plate to flatten their stones, and then they just wash away that slurry down the drain. Many fellows flatten their stones before each use and wash away that slurry. If you do this, next time don’t rinse it away,  try using it.

Honing razors is really just a craft, and you can use the word compromise, or adjustments as an integral necessity of the craft. TheAxMethod pares down the stroke count, and treats both sides of the razor equally as a way of minimizing errors that are difficult to track down later. If you edges are sharp enough to shave with, than the ultimately sharp edge is just whispers away, maybe as few as 5 strokes more or less, pressure (more or less), or in the stropping. Focus on those instead of adding groups of 40 or 75 or a 1000 more strokes. The more strokes the better is not a true statement, if it was than 20,000 more strokes would still not be the ultimate. The truth is that these is a plateau in the number of strokes where the greatest and finest finish that any given stone will max out. The secret is to learn how to recognize this state of development, and to stop there and move on to another abrasive or another method.


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