Thread: Nagura Honing - Video tutorial

Nagura Honing - Video tutorial

The procedure:



Nagura are fine polishing stones mined from Miwamura Mountain in North Sitara, Aichi prefecture.
They do not come from Nagura Mountain as many people mistakenly think.
There are 4 main strata of Nagura from coarsest to finest :

Botan (ボタン), Tenjyou (天上), Mejiro (目白) Koma (コマ)







Those naguras come in different grades:
Superior high grade (特級上), High grade (特級), Superior Selected grade (別上) Superior grade (上級)


Those grades are not related to fineness but rather to appearance, the color ranging from pure white to yellow, or with reddish streaks.
Koma is very valuable for sword polishing, and is much more expensive than the other naguras.It is very close to Mejiro as far as final results are concerned.


For best results it is important to get quality nagura of proven origin.
Although there are fake naguras out there, the real ones have the Asano stamp.





Places that sell quality nagura are:


Japanese Natural Stones
Mandara carpenter’s tool shop



To successfully use nagura for honing razors one needs to use a base stone that is harder than the nagura themselves, in my video I use hard Oozuko Asagi as a base stone.
The razor I used has the bevel set already; I would not try setting bevel with nagura because it is just too slow for that.


I start with Botan Nagura, I create a medium slurry and proceed with circles and x-strokes.
I typically do series of 10 to 20 circles until the slurry changes color to light gray. I use medium light pressure at this stage of the honing, the slurry will change color in 40-60 circles. When the slurry changes color, I raise new slurry but thinner and also less than the first one and continue with circles with light pressure. With the first slurry the scratches on the bevel have been worked on and now only polishing of the bevel needs to be done. For that reason less slurry will do the job faster.
When the slurry changes color I keep going until it thickens, at which point I start dilution and use no pressure the weight of the razor only.
To dilute I simply rinse the razor and keep honing using 10 circles followed by 10 x-strokes then dilute again. It takes me 3-4 dilutions before I am ready to move to the next Nagura.


Once I am done with Botan, I rinse the stone very well to avoid cross contamination, then I move to the next finer and slower Tenjyuo nagura.
The slurry consistency and honing routine is exactly the same as with Botan nagura.
After Tenjyuo I clean the stone and move on to the finest and slowest Mejiro nagura.
The final step of the honing process is optional, but I choose to use Tomonagura, a piece of polishing stone that creates very fine slurry for final polishing of the edge.
The Tomonagura routine is again same as with Nagura.
At the end I like to finish with water only.


Although assigning grits to natural stones can not be done due to the nature of the stones, from my results I would estimate Botan nagura is ~ 6k range, Tenjio ~8k, and Mejiro ~10k, Koma ~15k.
My personal tomonagura is in the 20-30k, it is a soft Nakayama Tojiro that I got from So.

Tomonagura can be any piece of fine finishing stone as long as it is softer than the base stone, one can also use tmonagura cut from the base stone itself.