When Wallpaper Lies Under the Paint

Q How should I deal with wallpaper that's been painted over?

A Painting over wallpaper is one of those quick fixes that probably seemed smart to whoever did it, but looks dumb to the one left to deal with the aftermath. Usually, the paint sticks to the wallpaper just fine, but the seams telescope through and sometimes peel loose. And the wall may be peppered with bulges, caused when moisture from the paint softened the wallpaper adhesive and caused it to run.

If the seams are still stuck, you might be tempted to just repaint, perhaps after skimming drywall compound over the seams to make them smoother. Don't take this approach unless you're willing to risk winding up with a room that looks worse than it does now. Wallpaper adhesive is formulated so that it softens and releases when it gets damp, and latex paint contains more than enough water to do the job. Cured latex paint remains somewhat porous, so moisture from a fresh coat may penetrate through the one already on the walls. Covering the old paint with an oil-based primer first would seal it, but the multiple coats add weight, which could trigger fresh problems. "Maybe that would be enough to break the seal of the wallpaper to the wall, or it could make the wallpaper curl up at the seams," says Ron Pietrzak, executive director of the Wallcoverings Association, a trade group. He always recommends stripping the wallpaper and starting fresh.

It's harder to strip painted wallpaper than unpainted wallpaper, but it's still possible. And several relatively new products make the process far easier than it once was.

The main challenge is to get moisture to the wallpaper adhesive. With unpainted wallpaper, that's relatively easy. If the covering is true, uncoated paper, it easily absorbs water. Vinyl wallcoverings block moisture, but most are "peelable," which means you can lift an edge at a seam and peel off the plastic coating to reveal a paper backing, which is absorbent. Some vinyl wallcoverings are "solid-sheet," with a thicker plastic layer bonded to a fabric backing. These just peel off in single-layer sheets.

Except with solid-sheet vinyl, paint complicates the removal process. Paper wallcoverings become less porous, and peelable vinyl wallcoverings become stiffer, so the top layer doesn't peel so well. But you can get around these problems.

Begin by testing a section to see what you're dealing with. Pick a place you don't have to look at often, such as behind a door that's usually open, if there might be a delay between the test and the actual start of work. With a sharp utility knife or a single-edge razor blade, cut through the paint at a seam and see whether you can lift an edge. If you can, try to peel back the wallcovering, as if you were peeling an orange. If you're lucky, you'll discover solid-sheet vinyl that peels off in sheets.

If the wallpaper doesn't budge, head to a hardware or paint store for a wallpaper scoring tool and a jug or tub of wallpaper stripper, along with a plastic tarp to protect your floors while you work. Scoring tools have serrated blades in a housing that keeps the blades from cutting too deeply. Run the tool over the wall to nick the surface, allowing moisture to get through. (The Zinsser Co. introduced the first of these tools, its PaperTiger, in 1985. Today, other companies offer similar devices.)

Wallpaper strippers are far more benign than paint strippers. They are water-based products with wetting agents and sometimes also enzymes. "Buy any brand," Pietrzak says. "But do use these products. They work much better than just going at the wall with water or soapy water." For the least mess, use a gel remover that can be applied with a paint roller.

Because your wallpaper is painted, allow extra time for the remover to work. This shortens the time you must spend scraping and reduces the chance that you might damage the wall. Use a wide plastic putty knife or a wallpaper scraping tool to help lift the wallpaper.

If the wallpaper was applied properly, you should find primer paint or layers of old paint underneath. If someone cut corners on that step, too, you may discover that the wallpaper is glued directly to the paper facing on drywall. If it was, scrape especially gently and don't get any more water on the wall than you need to so that you don't damage the paper facing.

Once the wallpaper is off, you can scrape off most of the adhesive with the putty knife. Remove the rest with a sponge and warm water. Once the walls are dry, use joint compound to repair any nicks. Then apply a water-based primer and you're ready to paint -- or even to install new wallpaper. New types that are just coming on the market use different backing papers and different adhesives so that they are extremely easy to install and to remove, Pietrzak says. To find these products, look for wallpaper sample books labeled as "new technology" and "easy to remove."

Even though it's never a good idea to paint over standard wallpaper, some wallcoverings are made for just this purpose.

Wall liners, also known as bridging material, create a smooth surface on walls that have numerous dings or divots. You can use them to cover highly textured walls, paneling with vertical grooves, or brick or block surfaces. It's wise, but not essential, to fill large gaps with drywall joint compound first.

Anaglypta, an embossed wallcovering made from cotton and pulp, is also designed to be painted. Patented in 1887, it can be used to create surfaces that resemble tooled leather, plaster moldings and woodcarvings.