Sanding takes as long as making the bowl for me, maybe longer. I usually start with 120 grit and work my way up to 1500 grit. I have started with 60 grit when there is a lot of tear-out that I can't get rid of with a tool but the liklihood of scratch marks increases if you start with coarse grits. The better you finish the piece with tools, the higher the starting grit with sandpaper (and the less likely that you will leave sanding marks). I have found that if I patiently and thoroughly sand with each grit (going up in 100 grit increments) there are no sanding marks. I use a dynabrade pneumatic sander that turns 2500 rpm and a variety of disc holders (2" to 5") depending on the size and shape of the piece. I do almost all of my sanding on the lathe.