The 4000 is a resinoid or resin bonded stone, it is semi-soft in that it generates mud easily with out a nagura or flattener and has a fast cutting action of a big variety of steels. The Takarazukushi 4000 is a super versatile finish, really great for hard high carbon stainless steels and carbon steels alike, especially for knives that benefit from a bit of extra bite in their polish as well as making a great fast pre-polish for knives that will get an extra fine synthetic or natural stone polish.

The Bernal Cutlery Takarazukushi 4000 stone is a resinoid stone (not a baked ceramic) and should not be left to soak indefinitely, and both should be allowed to dry outside of sun and wind and not allowed to freeze wet.