I asked John Price from Radiusmaster what he recommends for belt grits in grinding a knife. His tip was to use a sequence of belt grits 60, 150, A45 then A6 to take it to almost a hand rubbed finish level. This is the smallest number of belt changes he recommends.
A good quality 60 will remove stock without putting too many scratches in. The 150 will clean out the 60 scratches before leaving an even finish. The A45 and A6 Trizac belts put the final touches on. The blade can be quickly hand sanded with 500 wet and dry for a satin finish, or higher grits before being buffed for a mirror polish.