Japanese water stones are available as natural and as synthetic stones .
Today mostly synthetic stones are used , in which the grinding bodies are bound in different ways and resolved during the grinding process .
The different types of stones by grain size::
- Schruppsteine (grain size : 80 - 240) : used for grinding and shaping of scratches and defects , ie for repair - or for rough shaping.
- Grinding stones ( grain size: 800-2000 ) : they are used to the "basic clarity" to produce a cutting edge
- Polishing stones (grain size : 4000-12000 ) to the sharpness produced by the grinding stones to further refine and at the same time to remove the last scratch of grinding in order to obtain as flawless and smooth cutting .
The grain :
It is really important to know that the grain size in Japan has a completely different standard than in Europe , ie a grain- 1000s in Japan by no means corresponds to a 1000 grain in Europe. A Japanese stone with a grain J8000 (Japanese JIS standard) is about a European F2000 (European FEPA standard) .
Worth knowing seems to me also that the grain sizes are standardized only up to 8000 grain in Japan! Everything beyond this is just believe in the manufacturer !
Before use, the water stones have to be put in water for several minutes so that they completely can soak in water. This is necessary to ensure that enough sharp abrasive particles can be loosened during the grinding process. Even during the grinding operation, water has to be added to the stone repeatedly. They should really not "run dry".
Even the Japanese stones are not quite as hard as the European . This means that it is relative easy to get a notch in the grindstone during the sharpening process.