Japanese Natural Whetstone Shohonyama Umajiyama 1729g from Kyoto

This is Umajiyama Namito from Kyoto, Japan. Suitable for finishing knives and tools. Umajiyama, his mine, connects with Ohira, Mizukihara, so there is usually a similar type of natural whetstone. Water permeability is good, Uniform, Moderate hardness. smooth and stable to sharpen.

Dimensions: 76-79mm × 211mm × 38mm (approx.)

Weight: 1729g

Granularity: fine 6000-8000

Nagura is unnecessary, but using it will definitely speed up the process.

An excellent finishing stone for knives and carpentry tools.

Hardness: 4.0-

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.