Japanese Natural Whetstone Tsushima Black 541g from Nagasaki Pref.

Tsushima Natural Stones were originally used as nagura to create a suspension on the surface of natural stones to improve the graininess and bite of the stone at the cut edge. Tsushima stones are suitable for all grinding stones, from pretreatment to finishing. Very clean, no blotches or lines. One side (sharpening) at Tsushima is ready to use, all other sides are covered with cashews. ...

These are natural stones, which means that each is slightly different. It is a lifetime investment for people who have sharpened their knives and tools all their lives.

Dimensions: 77mm x 171mm x 15mm

Weight: 541g

Grain size: 6000-8000

Excellent pre-finish - finishing stone for knives, razors and tools.

Hardness: 3.5

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, it's not just the sharpness of natural stones that is achieved. After you use natural stones, you will not want to switch to artificial ones.