I gave up using rottenstone and Pumice for finish matting and grain filler because they are abrasives and had this tendency to take the edge off chequering tools. So as an alternative for grain filler Talcum powder works extremely well with non of the abrasive qualities, and as for matting a finished stock I use "OOOO" Wore Wool with a soft wax polish as a lubricant and just in case some Wool strands are left behind I go over the stock with a strong Magnet.

The only lessons in my life I truly did learn from where the ones I paid for!