Bubbles in wallpaper are usually caused by poor wallpaper hanging. If there are a lot of bubbles, the best solution is to replace the wallpaper. However, a small number of bubbles can be removed using the following steps to repair each one individually.
Use a sharp utility knife to cut open the bubble. Cleanly make a cross cut with a vertical and horizontal incision.
Open out each of the four small wallpaper flaps that were created with the cross cut. Use a lining fitch brush to apply a small amount of PVA adhesive to the underside of each flap.
Use a sponge to carefully smooth out each of the four flaps, firmly into their positions in the wallpaper.
