Here is one scenario – you paint a new colour onto a wall that has previously been painted and while the paint is still wet you notice it bubbling up! Then, when you rub the bubble it bursts and leaves the original plastered wall showing! Now you have an uneven surface.
Another scenario – you roller a coat of white on the ceiling in the bathroom and the old paint comes off on the roller! EEK!!
The worst case I have seen of this was in a stairwell in a renovated house and the paint on the walls of the stairwell was coming off in sheets like wallpaper.
Why does this happen?
It happens when newly plastered/skimmed walls or ceilings aren’t given enough time to completely dry before painting. The temptation is to start painting as soon as the plasterer has left the building but plaster takes longer to completely dry than you might think.
If the plastering has been done in the winter months it will need several weeks to thoroughly dry – please don’t be tempted to wack the heating on full blast to try to speed up the drying process because the sudden rise in temperature can cause different problems.
Another reason it occurs is when the initial coat of paint on the new plaster is bog standard silk applied undiluted directly to the plaster.
Or the bathroom ceiling has been freshly painted on the new plaster which has never had a chance to dry because the bathroom is in constant use and then someone has a shower before the paint is dry. Disastrous.
On old plaster doing this – give it a light sanding and apply a thinned coat of matt paint – thinned with water to make it sloppy. Allow to dry thoroughly and then paint as usual.
On new plaster – the plaster should be given plenty of time to dry. Don’t rush this process.
Once dry, the first coat of paint on the new plaster should be matt (preferably white) and it should be thinned with water so that it is sloppy. Paint all the plaster with this mixture. It is your undercoat. It will sink into the surface of the plaster and give you a sound base for painting.
Allow to dry. Won’t take that long because it will soak into the new plaster.
Paint on another coat and leave to dry – Overnight.
Now, you have prepared the plaster for painting and will avoid bubbling and peeling in the future.
Paint in the colour of your choice.