Many homeowners want to replace their old, tired wallpapered walls with a bright coat of paint. Painting is the easy part. Removing wallpaper is often an involved, tedious process that causes many homeowners to delay updating the room. If the wallpaper is not damaged and has good adhesion to the wall, it may not be necessary to remove the paper before painting. But to ensure that the colors of the wallpaper don't bleed through the new coat of paint, you need to paint the wallpaper first with a primer such as Kilz.
Check the wallpaper for lifts or tears. Glue the wallpaper back to the wall anywhere it is torn or lifting. Patch dents and holes with spackling paste. Allow the spackling paste to dry completely, then sand to a smooth finish.
Wipe the wallpaper with a damp sponge to remove dirt and oils from the surface. Allow to dry completely.
Paint a small area of the wallpaper with Kilz and allow to dry overnight. Check the area the next day to see if the wallpaper is still adhered to the wall and the Kilz is smooth. If the wallpaper pulls away from the wall or the Kilz is bumpy or cracked, you'll have to remove the wallpaper entirely before painting.
Prepare the wall for painting. Turn off the power to the room at the breaker box. Cover wall light fixtures with plastic bags and tape the bags closed with masking tape. Remove all electrical cover plates from the wall. Tape moldings, ceilings and adjoining walls that will not be painted with masking tape to protect them from the primer. Cover the floors with a drop cloth.
Paint the wallpaper with Kilz primer. You can use a roller, a brush or both. Allow the Kilz to dry completely. If color from the wallpaper bleeds through the layer of Kilz, apply another layer to the wallpaper. Once the walls are primed and the color isn't bleeding through, paint the walls as you would normally.