|
Common Issues for Exterior Surfaces
|
 |
|
Blistering
|
|
Possible Causes
|
|
- Painting in direct sunlight or on a surface that is too warm, especially when applying a dark-coloured solvent-based coating
- Applying an oil-based or alkyd paint over a damp or wet surface
- Excess humidity or other moisture escaping from inside through the exterior walls (less likely with acrylic paints, which allow water vapour to escape without affecting the paint film)
- Exposure of a acrylic paint film to excessive moisture in the form of dew, high humidity or rain shortly after the paint has dried, especially if there was inadequate surface preparation and/or a lower quality paint was applied
- Application of a very dark acrylic paint to an old painted timber surface that has previously been white or a light colour, particularly in areas that receive full sun. This causes the timber to heat more than previously and will stress old underlying coating.
|
|
|
Solution
|
|
- First, determine whether or not the blisters go all the way down to the substrate. If they go down to the substrate, the problem may be due to moisture coming from inside.
-
Take steps to remove the source of moisture, if possible. Repair loose caulk and consider installing vents or exhaust fans.
-
If the building has wood siding, install siding vents in areas where blistering has occurred. Remove blisters by scraping and sanding, prime any areas where bare wood shows, and repaint.
If the blisters do not go all the way to the substrate, the problem is probably not related to moisture coming from behind. Rather, the blisters are likely from painting a warm surface in direct sunlight or exposing the paint film to excessive moisture. Blistering between paint layers where there are many layers of old paint indicates that one of these old paint jobs has become unsound.
-
In any case, sand, scrape and then prime any exposed bare wood. Coat with an ultra premium quality acrylic exterior paint. |
|
|
|
|
|
|
|
|
|
Wattyl Solagard
|
|
10 Year Guarantee
|
Guaranteed against flaking, blistering and peeling* Read more >>
|
|
|
|
|
|
|