Sanding

The process of sanding the joint compound to make it smooth and feathered in with the drywall paper. Large power sanders are often used with 9" circular pads and a HEPA vacuum that sucks up the dust. Grits used are 120-240. 220-240 suggested for lightweight joint compound(Blue or lime colored lid), 120 grit for all purpose heavy weight joint compound such as darker green lid USG.

Source: Jason Lebeau a 24 year drywall industry veteran.