PURPOSE: To check loading in a polishing stone and parts pollution as well as to secure stable polishing force, by giving motion to a mass, mixing a proper quantity of soft media of proper grain size, in polishing stones, while dispersing these soft media interposingly among these polishing stones.

CONSTITUTION: As a material for soft media, vegetable, porous fibrous materials such as a walnut shell, a corncob, a wooden chip, cork, etc., are used and among others, those of corncobs, walnut shells or the like are especially suitable for that from the standpoint of proper properties of oil impregnation, abrasion resistance and resilience. A mixing ratio of polishing stones and soft media is proper to be within the range of 3:1 or 1:3. In case of mixing media dry type polishing, a polishing value is larger enough while surface roughness comes to yet denser, and when grain size of each of these soft media approximates to that of each of polishing stone, the polishing value shows the maximum value.