Sand the wall using medium-grain sandpaper, which will smooth down large areas of roughness and will buff off any jagged edging. Move the sandpaper in small, circular motions over the entire wall.
Sand the wall using fine-grain sandpaper, which will make the wall feel sleek and soft to the touch. Move the sandpaper in the same small, circular motions over the entire wall.
Buff the wall using a hand buffer, which will remove very small imperfections and will leave the wall extremely smooth. Allow the buffer to move around the entire wall for 10 minutes.
Vacuum the wall and surrounding flooring using a shop vacuum, which will eliminate any dust and debris left behind from the sanding and buffing.
Fill a paint tray with matte latex wall paint, and coat a paint roller in the wall paint.
Apply the paint onto the smoothed wall using vertical roller strokes. Cover the entire wall with an even layer of matte latex paint. Allow the paint to dry for six hours.