Thanks to all. Way more info than expected. I know perfectly understand the make-up of the stone material, and how it functions for blade material removal.

I can fully understand that the particle size may be equivalent to "1000 grit" but because so little of individual particles are revealed at the matrix surface, they behave more like a low density (particles/mm˛ on the surface) abrasive surface. Because the matrix is nearly as hard as the abrasive bits, and reveals so little of the particles, it cuts like the equivalent of a much higher "grit" stone. Surface particle density being low would cause the low stock removal rate.

I will try and get a picture before too long and add it to the thread.

Regards,