By the Bouwsector België team, 97 in-house tradespeople · reviewed by Bubbles in wallpaper appear where the paper is not stuck to the wall: because of air underneath, too little paste or a surface that is coming loose. Small blisters in wet paper wallpaper often disappear as soon as the wallpaper dries, because paper expands with the paste and shrinks back as it dries.
If a bubble is still there once everything is dry, it will not disappear by itself. The spot then has to be re-glued, or the drop replaced.
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How do bubbles and blisters form in wallpaper?
A bubble is always a spot where the wallpaper and the wall have come apart. The question is why. The shape, the location and the moment you notice it usually tell you enough.
| Cause | How to recognise it | What is needed |
|---|---|---|
| Air not smoothed out | A soft bubble that you can press in and that springs back | Smooth it out towards the edge straight after hanging |
| Paper wallpaper expands with the paste | Many small blisters in wallpaper that is still wet | Let it dry; keep to the soaking time on the label |
| Too little paste, or paste spread unevenly | A hollow spot that crackles when you press it | Work paste in under the spot and press it flat |
| Dirt or a lump of paste under the drop | A small, hard bump | Open it up, remove the dirt and stick it back down |
| Wall absorbs unevenly | Bubbles on repaired areas or on bare plasterboard | Prime before hanging any wallpaper |
| Old wallpaper under the new | Large bubbles where the old layer comes away too | Strip both layers and hang again |
| Painted too early or incorrectly | Blisters that form during or after painting | Let it dry and assess; sometimes a new drop is needed |
| Damp in the wall | Bubbles on an external wall, sometimes with stains | Deal with the damp first |
Most bubbles form during hanging. A drop that does not get the same amount of paste everywhere, or that is not smoothed from the centre to the edges, traps air. On a wall that absorbs more in one place than in another, the paste dries unevenly. That is exactly why priming before wallpapering is not an unnecessary step.
Conditions matter too. In the product sheet for its non-woven paste, Intervos states that it should not be applied below 5 °C or above 70 per cent humidity. In a cold, damp room, paste dries poorly, and a drop that stays wet for a long time is more likely to come loose.
Do blisters in wallpaper disappear by themselves?
With paper wallpaper, often yes. Paper absorbs moisture from the paste and expands slightly as a result. The wallpaper briefly has no room left and ripples in small places. As the wallpaper dries, it shrinks back and those blisters pull flat.
So wait until the wallpaper is completely dry before you do anything. A blister that you prick in wet wallpaper often leaves a small hole or a crease after drying, when it would otherwise have disappeared. Bear in mind that the drying time of the wallpaper depends on the wallpaper and on the room.
Non-woven wallpaper behaves differently. Non-woven stays true to size when hung and hardly expands. If there is a bubble in non-woven wallpaper or renovation fleece, it is almost always air or a spot without paste, and it will not disappear by itself.
Bubbles that only appear after painting also deserve attention. Water-based wall paint puts new moisture onto the wallpaper. If that happens before the paste underneath is dry, or on wallpaper that is not meant to be painted, the paste can soften again. If you want to paint over wallpaper, first check that the wallpaper is suitable.
How do you repair a bubble that stays after drying?
A single bubble on an otherwise sound wall can be repaired. The approach depends on what is underneath.
- Feel it first. A soft bubble with nothing in it is air or a spot without paste. A hard bump is dirt, a lump of paste or a piece of the wall.
- Air or a dry spot. Pierce the wallpaper with a glue syringe, inject a small amount of paste under the bubble and press it flat from the edge towards the hole. Wipe any paste on the surface away straight away with a damp sponge.
- A hard bump. Cut the wallpaper open with a sharp knife in a small cross or along a line in the pattern, remove whatever is underneath, glue the flaps back down and press them on.
- Let it dry and then check in raking light whether the spot is flat.
On wallpaper that has been painted, such as renovation fleece or glass fleece, a cut often stays visible. A repaired spot is then painted along with the whole wall, otherwise it will stand out as a slightly different shade. If the bubble is larger than a hand, or there are several in one drop, replacing that drop is usually neater than repairing it.
Isn’t a bubble just a cosmetic flaw?
Sometimes, but often it is a warning sign. A bubble shows that the wallpaper is not attached at that spot, and the question is whether that is true only there.
Three situations call for more than a glue syringe:
- Bubbles in many places at once. Then the problem lies in the wall surface or the paste, not in a single drop. A wall has to meet four conditions before it is ready for wallpapering.
- Wallpaper over an old layer. The moisture from the new paste softens the old paste again, and the old layer comes away too. That is why a new layer on old wallpaper so often goes wrong.
- Bubbles on a cold or damp wall. If you also see stains, or smell a musty odour, think first of mould behind the wallpaper before you repair anything.
In all these cases, a bubble that you repair will come back. The wallpaper then has to come off the wall, the cause has to be dealt with and new wallpaper goes on.
What do we do about bubbles in wallpaper?
Prevention starts with the wall. During the site survey we check whether the wall is flat, dry, dust-free and firm. On the day of the work we sand the wall, prime where needed, hang the drops tightly and smooth them out from the centre to the edges. At handover we walk through the walls with you.
If an air bubble does appear later in wallpaper that we hung, it falls under the guarantee: our wallpapering work carries a 1-year guarantee. Simply let us know and we will deal with it under the guarantee on our wallpapering work.
If there is other wallpaper with bubbles in many places, we remove it and hang new wallpaper.
Having one layer of paper wallpaper removed costs €6.99 per m² with us, painted wallpaper €9.75 per m². Renovation fleece, including hanging, filling and one coat of paint, costs €18.99 per m² between 30 and 100 m², €15.99 between 100 and 150 m² and €14.99 above 150 m².
Prices exclude VAT. For the renovation of a home over 10 years old, 6% VAT usually applies.
The work is done by one of our 40 in-house wallpaper hangers, from a team of 97 tradespeople on permanent contracts. No subcontractor, so the same crew from preparation to handover. Hanging, filling and painting renovation fleece in a complete home is 3 days of work.
When you apply, tell us where the bubbles are, how many there are and whether there is an old layer under the wallpaper. Then removal and new wallpaper are already in the free quote you receive within 24 hours. During the site survey we look for the cause, so that new wallpaper does not come loose at the same spot again.
Whichever wallpaper you choose, having your home wallpapered works the same way with us: first the wall, then the drops.
Bubbles that will not go away, and you want to know why?
Frequently asked questions
How do you get air bubbles out from under wallpaper while hanging it?
Smooth the drop straight after hanging with a smoothing brush or wallpaper smoother, working from the centre to the edges. That pushes the air out before the paste grabs. If that does not work, carefully peel the drop back a little way and hang it again.
Why do bubbles appear in wallpaper after painting?
Wall paint puts moisture onto the wallpaper. If the paste underneath is not yet dry, or the wallpaper is not made to be painted, the paste softens again and the wallpaper comes loose in places. Let the paint dry first before you judge whether the bubbles stay.
Does non-woven wallpaper get bubbles too?
Yes, but for a different reason than paper wallpaper. Non-woven hardly expands with the paste, so a bubble in non-woven wallpaper is almost always trapped air or a spot with too little paste. A bubble like that will not disappear by itself.
Can you remove an air bubble from wallpaper with a needle?
With a small bubble in dry wallpaper you can: prick a tiny hole and press the air out from the edge towards the hole. If there is no paste under the bubble, it will come back; in that case inject a little paste under the spot with a glue syringe. Do not prick wallpaper that is still wet.