Preparing to Paint Over Wallpaper: You can paint over wallpaper as long as the wallpaper is not peeling and the seams are adhered well. There must not be any wrinkles, creases, or tears in the wallpaper before you paint. You also cannot paint over latex, embossed, or textured wallpaper.
You will also need to apply several coats of paint to create a thick enough finish to completely cover the paper. The number of coats you need to apply will depend upon the shade of your paint. If you are painting over wallpaper, you will likely need to apply 2-4 coats.
Before painting a whole wall, be sure to test an area with several coats of paint to make sure that the weight of the paint won’t cause the wallpaper to peel. Even after applying several coats of paint, it’s likely that you will still see a seam underneath the paint.
With decorative painting techniques such as ragging, colorwashing, dry brushing, and sponging, this is not of high importance, unless small imperfections will bother you. On the other hand, even the most subtle seams could potentially detract from a wall painted in a solid color, as well as one with a more polished finish such as dragging, fresco, stamping, or stenciling.
In these cases, it is highly recommended that you remove the wallpaper before painting, using one of the methods described below. Keep in mind that paint will seal the surface and make the wallpaper almost impossible to remove in the future. If you are painting a wall that you may consider wallpapering at some point in the future, we recommend that you remove the wallpaper prior to painting.