Have you noticed bubbles in your paint film? It’s called blistering and results from the loss of adhesion between the paint and its underlying surface.
Blistering can be caused by:
- Painting a warm surface in direct sunlight.
- Applying oil-based or alkyd paint over a damp or wet surface.
- Moisture escaping through the exterior walls (this is less likely with latex paint than oil-based or alkyd paints).
- Exposure of latex paint film to dew, high humidity or rain shortly after paint has dried.
Old painted surfaces will require adequate surface preparation. The first step is to carry out a series of “adhesion tests” to clearly determine the quality of the existing paint work. Simply cut a small X through the existing paint with a sharp blade, press cellulose tape firmly across the cut and then rip off the tape. If the paint comes off, it is unsound and should be removed.
Paint application substrate must return well under 10% moisture content; any moisture ingress must be isolated. Trapped moisture within substrate will compromise new paint system performance and result in blisters and eventual paint system delamination.
More problem solving advice
Have you noticed that there are areas of denser colour or higher gloss where wet and dry layers overlap during painting? For each problem you’ll find a guide to identifying it, its causes and solutions.
If you’ve noticed black, grey or brown areas on your painted surface, chances are you’re dealing with a mould problem. For each problem you’ll find a guide to identifying it, its causes and solutions.