Freshly painted walls can bubble or ‘blister’ within an hour or it could take much longer, but there’s always a good reason why.
A stable coat of paint is one that has good adhesion to the surface below, be that newly painted plaster or a wall that has had several coats of paint applied previously and over many years. If the paint is able to lift away from the surface below, you’ll see a bubble or blister appear.
This is usually caused by a combination of heat and moisture. If you apply paint over a damp surface, perhaps because you are applying the second coat of paint before the first has fully dried, you can trap moisture in. If the room is warm and the topcoat is now drying faster than the layers below, the moisture attempting to escape from the previously applied paint is trapped. It pushes the top coat of paint away and a blister forms.
Painting a newly plastered wall or ceiling requires more preparation than painting an existing wall. You can’t start painting new plaster directly, but instead, have to take steps to seal the plaster so you get the quality and colourful finish you aimed for:
- Let the plaster dry – thoroughly
- Mix a mist coat – 50% water & 50% emulsion paint
- Apply the freshly mixed mist coat and let it dry
- Finally, apply 2 coats of emulsion paint
- Great job
It is vital that you only apply paint to a stable surface. Get advice from a professional painter and decorator or better still, save yourself the headache and get them to do it for you.