Most bubbles you see in wallpaper are just air pockets. But sometimes, a bit of debris causes the pocket. In order to tell the difference, press on the area and see if you feel anything. If you do, cut a small X on the wallpaper with a utility knife, remove the debris, apply a little adhesive to the back of the wallpaper, and press it back against the wall. Smooth out any ripples.
If the bubble is an air pocket, simply slice the wallpaper carefully. If the wallpaper has a pattern, try to cut along the pattern to conceal your work. Apply adhesive to the back of the wallpaper and gently push it back onto wall. Remove any excess adhesive and use your hands to smooth out the paper.
How to patch wallpaper:
1. Find a remnant of wallpaper that matches the piece that needs to be replaced. Cut a section that is slightly larger than the damaged area. Apply it to the wall over the damaged area with removable tape. Make sure the pattern lines up.
2. Take your utility knife and cut through both the wall paper patch and the wallpaper that is on the wall. This will ensure that you have a replacement piece the exact same size as your opening.
3. Remove your patch and wet the damaged area. Gently peel the damaged piece away, being careful not to dam age the surrounding areas. Scrape away any excess glue or wallpaper in the area. You may need to use a hot, wet washcloth to ease the glue off the wall. Make sure the wall is clean and dry before you continue.
4. Apply adhesive to the back of the patch and carefully place it in the clean, dry area. Make sure the pattern matches up.
5. Smooth out the patch with your hand or a ruler, making sure there are no bubbles.
6. Wipe away any adhesive that might have oozed out with a damp washcloth. Let dry.