For whiskering you will wind up doing it at least 4-5 times, but probably more like 6-7. You can drop down to 320 grit for the last few, and ultra fine steel wool between coats of the varnish. Though technically you are smoothing the finish, you are also knocking any nubs off that stick through it too. I tried using rotten stone for 1 between-coat smoothing on my last gun, and the dust seemed to collect in every nook and cranny of the carving, so was pretty frustrating. I went back to steel wool and the buffing cloth after that. The fine London gun makers (Purdey, H&H, Boss etc.) use it, but they don't have stocks with carving, and their checkering is not cut to final depth yet.