Asano Stamped Nagura

Asano Stamped Set

Jyun Mikawa Nagura 

Mikawa White Nagura are quarried in the Kitashitara district of Aichi Prefecture. In the mine, there are 12 layers or strata including two layers of Tenjyou and Botan. Out of the 8 usable veins, the most often used for honing straight razors are Botan, Tenjyou, Mejiro and Koma.  

Kousuke Iwasaki and Nagayuki Asano developed a quality-control system for grading and authenticating Mikawa Nagura. Each piece was carefully inspected, and subsequently ink-stamped to qualify the layer and quality of each stone. Eventually, Morio Sakamoto inherited these stamps, and he continues to qualify each piece of Nagura today. 

The mine was closed in 1976, all ‘new’ Nagura are cut from large pieces of stock that was mined and stored before then. It seems like no more Nagura will be taken from the mine, and the supply is dwindling. As a result, the prices of Nagura are going higher each year; Koma has become increasingly rare and exceedingly expensive.  There are private collectors that share, trade, and sell Nagura – but opportunities to purchase those stones are rare.

Other Types of Nagura

There are pieces of Mikawa Nagura that do not have the Asano stamps. These non-stamped Nagura can be very good; I have several pieces that are quite excellent. However, there are reports of bad examples with hard inclusions that can damage a blade. Before using any Nagura – it should be tested and inspected carefully. Even after a stone has passed muster, it should be checked regularly; Whether it’s stamped or not – Botan and Tenjyou are known to have sand lines running through them.   

Chu Nagura can be white or striped, but it does not come from the Mikawa mine. Chu is used by Togishi in the traditional sword polishing progression where it precedes Koma Nagura. There does seem to be many grades of Chu, or at least there are a lot of stones sold as Chu that are quite different. I have had a few pieces from different sources; all were very good and quite easy to work with, and the one I kept is quite versatile. 

Similarly, Tsushima Black Nagura is sourced elsewhere; it is mined underwater on the coast of Nagasaki. Allegedly, there are two types of Tsushima Black, one from the ocean mine, and the other from a mine in the mountains. The Ocean type – called Ocean Blue by many woodworkers – is a very interesting stone that cuts and polishes very well. The pieces I have can be compared to a combination of Mejiro and Koma; they start off more coarse than most Koma but they break down very well. The Tsushima Ocean mine is also closed, and it is becoming increasingly rare also. 

Iyoto is another type of stone that is often cut into small pieces can be used like the other Nagura listed here. Iyoto can be very useful in that there are many grades from coarse to fine along with varying degrees of hardness. I’ve had many pieces that were excellent and comparable to the different types of Asano-stamped Nagura. It’s been said that the mining of Iyoto stone predates the existence of most, if not all, other mines in Japan. 

Using Nagura on the Awasedo

In use – these Nagura are rubbed on the Honzan to create abrasive slurry. For one example, when sharpening a razor – Botan is often the first stone. When working the blade on the stone, the slurry slowly breaks down while gently removing steel. To refine the edge further, the Awase is rinsed off and new slurry is generated with either Mejiro or Tenjyou. I use both in a progression and I move from Botan to Tenjyou and then Mejiro. Many users stop at Mejiro, while others, including myself, finish the progression on Koma. The final polish is done on the Awase with either water or a fine slurry created with a Tomo Nagura. 

Many people have decided to assign a ‘grit’ to these Nagura. While I understand the desire to do so for the sake of conversation, I also find it to be misleading and very possibly completely inaccurate. Instead – I’ve simplified my approach to using these stones. Coarse is coarse, fine is fine – and I leave it at that. 

To me – all of these Nagura are more than just simple slurry stones.

Each one presents its own special personality that opens doors to new discoveries.   

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© Keith V Johnson 2014 - 2018