Quote Originally Posted by mparker762 View Post
Yup. There seems to be a big difference between shapton and norton's grit sizes. The shapton 8k feels noticeably finer than the norton 8k, for example, but the norton 8k is about 3 micron while the shapton 8k is only 1.8 micron.
If you look at the Norton table you can see that their water stones tend to be equivalent to sandpaper with half the grit size. For example, a 4K is equivalent to 2K sandpaper. Maybe Shapton changed that to make their grit the same as sandpaper.

I believe sandpaper is done with a screen, so 2K sandpaper has no particle larger than 2K. Norton uses an average, so the particles in a 4K stone may be as large as 2K particles, as long as the averagew is 4K.