How to Prep Wallpaper for Painting
- 1). Pull down any parts of the wallpaper that are curling or peeling. Loose edges and seams can be easily be peeled off. Alternatively, use wallpaper paste to secure these loose edges and seams back to the walls.
- 2). Spread joint compound onto any areas of the walls that are imperfect. Nail holes, places where you removed pieces of wallpaper (seams and edges that were removed, too) and any other damaged areas of the walls must be filled with joint compound to achieve an even surface. Apply the joint compound with a putty knife, running the putty knife back and forth over the area until the compound is smooth with the walls. Let it dry according to the manufacturer's instructions. Sand the spots smooth with 220 grit sandpaper. Close your eyes and run your hands all along the walls to feel for any other imperfections you may have missed.
- 3). Wash down the walls with a sponge dampened in warm water. Only use a damp sponge rather than one that is soaking wet or you risk softening the wallpaper. Cleaning the walls thoroughly will ensure there is no dust, dirt or other debris on the walls that can interfere with the paint adhering properly.
- 4). Tape off any areas that you don't want painted (such as baseboards, outlets, the ceiling and window trim) with painter's tape.
- 5). Apply a coat of oil-based primer to the walls prior to painting. Let the primer dry completely.
- 6). Check the walls for any areas where the wallpaper may be curling or peeling. Apply joint compound to these areas, let it dry and sand lightly. Wipe the walls with a damp rag to remove any residue from sanding and apply primer again to those particular spots. After the primer dries, you're ready to paint.
Source...