Plaster walls have a smooth texture that many homeowners find desirable. In older homes, the walls may have irregularities and waves, unlike the flat surface of drywall. These waves occur during installation when several layers of plaster were applied over strips of wood, called lath, within the walls. Repainting plaster walls is much like repainting other common wall materials. If old wallpaper is present, soak it with warm water and scrape it off, then wash the walls to remove adhesive.
Cover the floor with a dust sheet. Fill nail holes with patching plaster using the blade of a putty knife. Rub a damp sponge over the mudded areas to remove the residue once it has dried. If hairline cracks exist, squeeze a bead, or line, of latex caulk along the crack and wipe off excess with the sponge.
Fill an empty 5-gallon paint bucket 1/2-way with primer. Mix with a long paint stir stick, then remove and clean the stick. Fill the other 5-gallon bucket 1/2-way with paint, and mix the same way.
Dip the ladle into the primer bucket to fill the ladle. Primer helps block old stains, covers old paint and helps new paint last longer, explains home improvement expert Danny Lipford. Pour primer from the ladle into a trim paint cup then set the ladle on the dust sheet. Dip the tip of the trim brush into the cup to load it with primer. Apply a narrow outline of primer around the perimeter of each wall, around each window and around each door frame. This is known as trimming or cutting in. Rinse the ladle when you are finished.
Hang the bucket grid's two upper hooks on the rim of the bucket with the grid hanging down inside the bucket. Bucket grids remove the need for paint pans, and let drips fall into the bucket, explains This Old House. Attach a roller cover to the paint roller. Dip the roller into the primer. Roll it up and down the grid to remove excess primer. Apply primer to each wall inside the areas where you trimmed. Roll in a zigzag motion, overlapping and spreading the primer as you work. Remove the grid from the bucket in an area close to a sink. Rinse it thoroughly. Let the walls dry.
Fill a clean trim paint cup with paint using the ladle. Repeat the trimming methods to paint the perimeter of the room and around windows and doors using the cleaned trim brush.
Remove the primer roller cover and attach a new cover to the roller. Attach the wire mesh screen to the paint bucket and load the roller with paint as you did with primer. Apply paint generously in the same overlapping manner to spread the paint. Reload the roller with paint often to keep the coverage smooth and even. Allow the paint to dry. Apply two more coats.
When using numerous gallons of paint, empty each can into a 10-gallon plastic storage container to mix thoroughly. If the walls are excessively stained, oil-based sealing primer may be required.
If the walls are crumbling, unstable or sound hollow when tapped with your finger, they require professional repair before painting. Clean your tools before drywall mud, paint and primer dries on them.