Japanese Natural Whetstone Shohonyama Shobudani Tomae Iromono 660g from Kyoto Japan

 This is the Shohonyama Shobudani Tomae Iromono from Kyoto. Beautiful Akapin Pink & Asagi blue gradation slightly appears. Good for knives. Soft but Strong abrasive power, easy to sharpen, enable to regain the sharpness and it lasts longer. Rich and fine slurry easily comes out. The beige line, it is Namazu means not toxic line. 

Dimension : 91mm×153mm×18mm ( Approx.) 

Weight: 660g

- Grit size:  Fine 8000-10000

- Nagura is not needed but using one will definitely speed up the process!

- Excellent finishing stone for knives. 

- Hardness: 3.0-3.5

The origin of Shoubudani quarry is about 800 years ago.

Shoubudani and Nakayama stones were patronized by the Imperial household, for its superior quality used for polishing swords. These stones have never been traded among the commonality between Kamakura period(1185~1333) to mid Muromachi period (1336~1573). It was at the end of Muromachi when these stones appered within the general market, although the better stones were still monopolised by the royalities, the stones with lines and odd shapes were used by the craftsmen and carpenters, and this contributed to the drastic improvement in quality of their works.

If you are familiar with Japanese natural finishing stones, I suppose you have heard of the name Hon-yama. The name Hon-yama is used by any finishing stones nowadays so it mearly means "finishing stone" now, but this name originally was the nick name for Shoubudani mountain. Nakayama is also one of the quarry from this mountian. Honma Tou-zaemon Toki-nari has been appointed as the leader of mining by the famous Shogun of Kamakura period Minamotono Yoritomo in 1190. Thus the mountain was called Honma's mountain = Hon-yama. "Yama" means mountain. Shoubu-dani and Nakayama stones are the only genuine Hon-yama stone.

The grain size of Japanese lapping stones is quite relative, in any case it is thinner than synthetic stone # 8000. This will give the famous Kasumi coating (cloudy) and prolong the life of the blade. Finish sharpening is done on natural stones, and a smooth, sharp cutting edge is obtained. Japanese natural stones have such properties, because the quality is influenced not by the size of the abrasive particles, but by the shape. This is confirmed by a study by the University of Tokyo. SiO2 abrasive particles are in the form of rounded flakes. They do not abrade, but remove steel like sod, especially on suspension. Thus, not enough steel is removed, but the steel is also removed in such a way that an even jagged edge is not formed, which would be when sharpening on artificial stones.

Using natural stones will allow you to cut finer and at the same time extend the life of the edge. There is a good reason for this. In synthetic stones, the sharpening particles are equal in size, while in natural ones they are not. Consequently, a blade sharpened from synthetic stone will have an even height of serrated teeth, so once those teeth become dull, it will stop cutting completely, but ... when the height is different ... I think you understand my point. It's like shark teeth. They don't break right away.

Also, a natural stone sharpening has a hardening effect on the edge of the blade. This has been scientifically proven by the HRC testing machine, an experiment carried out by the renowned blacksmith Usui Kengo. In fact, the hardness was higher after polishing with a thin natural stone. As you can see, the point is not only in the achieved sharpness of natural stones. After you use natural stones, you will not want to switch to artificial ones.