Hanging new wallpaper gives any room an instant facelift. If the existing paint on your walls is dark, however, you may have to repaint the walls a lighter shade to keep the dark color from showing through light-colored wallpaper. Alternately, painting the wall a dark color that matches the deep tones in your wallpaper will camouflage any gaps where the strips of wallpaper meet. Even if you're only hanging a wallpaper border over your newly painted wall, you'll have to wait until the paint is completely dry.
Latex Wall Paint
Interior latex wall paint contains rubber-like polymers that allow the paint to cure uniformly, creating a smooth surface. Once the paint is dry, it will not reabsorb water, and you can hang the wallpaper without worry. If the paint isn't quite dry, however, the polymers are not yet stable and the paint can swell, pull away from the drywall, and bubble, creating ripples beneath the new wallpaper. The instructions on the paint can list the minimum drying time for adding an additional coat of paint, but you might have to wait longer before you can hang the paper.
Factors That Affect Drying Times
A cool room and high humidity can slow the paint drying process. If the painted surface feels even slightly tacky when touched lightly with your fingertips, it's still too soon to hang wallpaper. Multiple coats of paint will also slow the drying time. A space heater and a fan can assist in drying a newly painted wall.
Priming the Wall
Not all paints seal old water or grease stains, which can eventually bleed through light-colored wallpaper, marring the surface. If you're going to hang wallpaper over the entire painted wall, use a roll-on primer/sealer product instead of latex paint to coat the wall. You can have the primer tinted whatever color you require and the primer will provide a impenetrable surface on which to hang the wallpaper. Depending on the brand of wallpaper you install, you might also have to roll a coat of wallpaper sizing on the wall before hanging the strips.
Wallpaper Adhesion Problems
Wallpaper might not adhere adequately to a wall painted with high gloss paint no matter how long you wait before hanging the wallpaper. To remedy that, you can lightly sand off the surface gloss where you will install a wallpaper border or you can roll a coat of clear primer over the wall and let it dry completely before hanging the wallpaper.