Thread: Jnats - base vs nagura question

There are generally two types of nagura in the jnat 'world', Mikawa shiro (white) nagura and tomo (finishing) nagura.

Mikawa naguras are used in progression and do just what you're thinking, provide a grit progression on a razor finisher without having to buy a set of full size stones. The downside is that most of the modern Mikawa I have are pretty slow compared to a synth. The vintage Mikawa can be very grit rich and a viable option but you have to gamble on them on auction sites. Koma seems to be an exception, the current ones I have are grit-rich, but many are also quite hard, some too hard to practically use IMO.

Tomo nagura do three things: they provide grit and/or slurry; they provide lubrication; and they 'energize' the base stone to release grit.

So does using a tomo of the same stone finish differently than just the base stone? Yes because razor hones usually don't autoslurry at razor pressure and an edge finished on slurry feels different than one finished on clear water. Slurry edges feel smoother and are milder than clear water edges. But if your finisher needs a 'bump' in sharpness, sometimes adding clear water strokes can kick it up a notch. Slurry also allows hard stones that might otherwise scratch or just burnish to be used because it lubricates.

A good tomo+base will allow the base stone to continue releasing some grit. Both Alex G and I have tried transplanting jnat slurry onto plate glass and it stops cutting pretty quickly. This 'energization' of the base stone may or may not happen with non-jnat stones, no harm to try if you already have the stones.

Cheers, Steve

Steve, maybe I need the hunt down a vintage asano nagura set to try

I can say on certain other sharpening stones like a Charnley Forest stone these nagura do a nice job, but based on the cost might as well get a jnat base stone. If you have them it is fun to play with them though.