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DECORATING Why’s the paint bubbling on my newly decorated walls?
Unfortunately, there’s no single reason why it occurs. There are a multitude of factors that can cause you problems —whether you are painting wood or emulsioning walls.
Painting in direct sunlight or on surfaces with elevated temperatures can cause rapid drying, trapping moisture vapour and forming blisters. While contaminants, such as oil on surfaces, can cause localised blistering. One of the most common reasons however, is the loss of adhesion with the surface that is being painted. This is typically because the surface hasn’t been cleaned properly, so when the paint dries it starts to lift off the surface.
Preparing walls for painting is essential to getting a decent bubble-free finish. You can clean the surface by wiping it down with a soft cloth and warm soapy water. This will get rid of most dirt and stains —but don’t forget to wipe dry and leave to dry properly before painting. For more stubborn stains or marks, use sugar soap.
How you fix bubbles and blistering on painted surfaces depends on the reason why it has happened. If it’s because surfaces haven’t been cleaned properly then you need to strip back and start again.
If the bubbling or blistering is occurring just on top of the surface, then use a scraper to remove the affected paint, rub down the area with a fine grade sandpaper, apply an oil-based primer and leave to dry as recommended by the manufacturer. The surface will then be ready to paint.
The most common reason for paint bubbling after the second coat is that you haven’t let the first coat dry properly before applying the next one. Or it could be a result of the first coat not having been evenly spread, so some areas have dried quicker than others. So before you add a second coat, make sure all paint is dry. Another cause could be that something like greasy fingerprints have got onto the first coat of paint which is causing the loss of adhesion on the second coat.
The main reason that paint on newly plastered walls starts bubbling is due to moisture trapped in the plaster and it hasn’t been allowed to dry properly. If it’s old plaster then this would indicate that there is a damp problem that needs to be dealt with. Once the problem has been dealt, mould spores or contaminant salts can still reside in the plaster so you may need to replaster before painting.
MOULD TREATMENT What are the signs of underfloor mould
