Slit the bubble, clean out old paste, glue the flap back down, then smooth it flat to dry.
AB-01Work out what caused the bubblePress the bubble gently. If it feels dry and springs back, it's almost always old paste that's lost its grip — a simple fix. If the patch feels damp, cold, or the bubble keeps coming back after it dries, stop. That points to a damp problem behind the paper, and papering over it will just fail again.
AB-02Protect the area and gather your toolsLay a dust sheet under the wall to catch drips and scraps. Have a sharp craft knife, a fine brush, wallpaper repair adhesive, a damp sponge and a seam roller ready before you start, so the glue doesn't dry out while you hunt for tools.
AB-03Cut the bubble openUsing a sharp craft knife, cut a small cross (X) through the centre of the bubble, or a single slit along a pattern line if there's one nearby to hide the cut. Cut through the top layer only — press lightly so you don't score into the wall underneath. A new, sharp blade gives a cleaner cut than a worn one.
AB-04Lift the flaps and clean underneathGently peel back the four small flaps you've cut. Use the tip of the brush to flick out any dust, flaking plaster or old dried paste from underneath — this is usually what's stopping the paper sticking. Don't tear or overstretch the flaps.
AB-05Apply repair adhesive under each flapLoad a little wallpaper repair adhesive onto the fine brush and work it under each of the four flaps, right into the corners. Don't overload it — a thin, even coat is enough, and too much will squeeze out and mark the pattern.
AB-06Press flat and roll the seamPress each flap down in turn with a clean finger, then run the seam roller over the patch from the centre outwards to push out any trapped air and excess glue. Wipe away any adhesive that squeezes out straight away with a damp sponge before it dries.
AB-07Hold it flat while it driesStick a small piece of low-tack masking tape over the patch to hold it flat as the glue sets — don't use anything stronger, it can pull the paper off. Leave it for a few hours, or overnight if you can.
AB-08Check, tidy up and touch up if neededPeel off the tape once dry and check the seams are sitting flat and the pattern lines up. If the cut is still faintly visible, a soft artist's pencil in a matching shade can help disguise it. Fold away the dust sheet and put tools away.
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