Things You'll Need
Sponge roller with thick nap
Ceilings can be rough for several reasons. Some of them aren't finished properly. Others are painted poorly. Still others have texture added to the paint when it's applied. This often results in a ceiling with a rough, unfinished appearance. Thankfully, it's easy to fix a rough ceiling using the proper materials. A good drywall primer that gets into all the rough texture will prepare the ceiling for any color of paint.
Sand the ceiling with 100-grit sandpaper to smooth as much of the texture as possible. Wipe the ceiling with a tack cloth to remove the sanding dust.
Apply drywall primer to the ceiling using a sponge roller with a thick nap. The thick nap will work the paint between the rough textures on the ceiling and fill them in. Allow the primer to cure according to the package directions, then apply a second coat.
Apply a flat, latex paint over the primer using a sponge roller. Flat paint is thicker and hides flaws better so it's a superior choice to gloss paint. Allow it to cure and apply a second coat.
Use a sponge roller with an extendable pole to apply the primer and paint.
Use a bristle paintbrush to cut the primer and paint in around the edges of the ceiling.
Always work in a well-ventilated area.