Before sanding, round up a shadow light, a wide taping blade and a pencil (not a felt tip pen; it bleeds through paint). Map all wide seam work on ceilings and walls to plan how much to sand each seam ...

A close-up image of a popcorn ceiling with a round lighting fixture - MC Media/Shutterstock Popcorn ceilings, though they were quite popular from the 1940s to the 1990s, are rather polarizing today.