This is a 5000 grit synthetic "nagura" for cleaning up and reconditioning stone surfaces. Unlike natural nagura, the mud from synthetic nagura should almost always be washed away before you begin sharpening. However, this nagura is 5000 grit, so if you are using it on stones that are 5000 grit or coarser, it is not necessary to wash away the mud you create when using this nagura. Nagura like this can be use to clean up a stone surface that has become loaded up with metal or is no longer working the way it should. It can also be used to either impart more scratches to the stone surface, in order to increase cutting speed and tactile feedback, or smooth out the stone surface, to increase polish and scratch pattern consistency. These need a quick soak before using... just until the bubbles stop coming out.