Stephen Dodd Hughes, a custom maker who wrote the article on sanding muzzleloader maple stocks in "Gunsmithing Tips & Projects" uses a paste of rottenstone and Permalyn filler rubbed into the walnut pores using a piece of cloth, then wet sanded off (this is designed for walnut, and does not work is there is complicated carving). This rubbing in then wet sanding off is done until the pores are filled and all remaining filler is removed from the surface. It has a strange, grey color after the sanding, but the final coat of Permalyn produces a fine, smooth finish.