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Blistering: Blistering is the formation of bubbles
resulting from localized loss of adhesion and lifting of
the paint film from the underlying surface.
Possible Causes:
Painting in direct sunlight or on a surface that is too
warm, especially when applying a dark-colored
solvent-based coating.
Application of 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 latex paints,
which allow water vapor to escape without affecting the
paint film).
Exposure of a latex 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.
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.
In any case, sand, scrape and then prime any exposed bare
wood. Coat with a top quality acrylic latex exterior
paint. |
