Spread plastic drop cloths over the floor under the area of ceiling you are repairing. Position a ladder under the area so that you can easily access all areas of the repair site.
Fill a spray bottle with 1 to 2 cups of warm water and spray the ceiling area with a fine mist, just until it is wet. Wait until the texture feels soft and scrape off all damaged or discolored texture using a putty knife.
Wait until the ceiling is completely dry and apply a white primer over it using a paint roller to prepare it for the texture material. Wait until the primer dries completely to the touch.
Open a tub of joint compound, also called drywall mud. Scoop out 3 to 4 cups and place it into a 1 gallon bucket. Add water to the bucket a little at a time and stir using a trowel. Continue adding water until the joint compound mix is the constancy of syrup.
Apply the mixture using a 3- to 4-inch-long brush and dabbing the bristles against the ceiling if you have a popcorn texture. If the ceiling is a swirl texture, spread it on in a 1/4-inch-thick layer with a drywall trowel. Then move the bristles of the brush in semicircles to match the swirls. If the ceiling has a crow’s feet or “slapbrush” pattern, apply the joint compound to a long-bristled paint brush and tap it against the ceiling to match the texture.
Wait 24 hours to allow the joint compound to dry and then apply white or cream-colored paint over the entire ceiling with a thick-napped roller to further blend the textures together.