A blister is a pocket of gas or liquid pushing the paint film away from the surface. It looks like one problem but has two quite different causes, and getting the diagnosis wrong means the same blisters return within months of a repaint.
Moisture-driven blisters usually contain water or damp residue and appear on exterior work after rain, or on interior walls with a damp problem behind them. Solvent blistering happens during application itself, when a topcoat is applied too soon over a coat that has not fully released its solvents, trapping vapour under the new film as it skins over.
We puncture a sample blister to see what comes out. Water or a musty smell points to moisture in the substrate. A dry, empty blister with a slightly soft underside points to application timing or heat exposure during a hot spell.
Every blister is opened, sanded back to sound material and re-primed individually rather than skimmed over with a fresh topcoat. On a widespread pattern we take the whole area back rather than patch-repairing a face that will keep bubbling in new places.
No. A blister is a permanent failure point in the film — it will eventually rupture, and the exposed edge becomes a place for water to get further in.
Yes, particularly if a second coat is applied before the first has properly dried, or if it is applied in direct sun on a hot elevation.
Sometimes, especially on solid walls or older render. We check for that before assuming it is purely an application fault.
Send a photograph of the blistered area, ideally with one popped open, and we will talk through what it suggests.
Blisters are either trapped moisture or trapped solvent — the fix is different for each, so diagnosis comes before any repaint.
Speak to a Hampshire commercial decorating contractor that turns up, communicates clearly and delivers a finish that lasts.
