How to Prepare Rough Plaster Walls for Painting

Move all furniture and interior items away from the wall. Leave about 3 to 4 feet of space. Take off all outlet covers with a screwdriver. Place dropcloths on flooring for added protection.

Vacuum the corners of the wall to remove cobwebs and dust. Run the brush attachment over the walls to suction away additional dust. Clean walls well to remove all dirt buildup. Use a scrub brush and warm, soapy water if walls contain heavy amounts of dirt and grease. Allow walls to dry.

Run 2-inch painter's tape along all adjoining walls and surfaces where paint should not go. Surfaces include doorframes, window frames, ceiling lines and baseboards. Rub the tape well with a plastic putty knife to ensure that no paint leaks under the tape.

Brush on clear polyurethane over the edge of the tape and adjoining plaster wall surface with a paintbrush. This creates an additional seal necessary to ensure that the paint does not leak. Let polyurethane dry about four hours, or according to manufacturer's instructions.

Paint walls with a bonding primer. Use a rough nap roller and roll on primer using even, steady rolls. Ensure that paint gets in all crevices of the rough plaster. Use a chip brush to dab paint into any hard-to-reach plaster pits. The bonding primer will allow the final coat of latex paint to appear evenly and bond well to the rough plaster surface.