Paint blisters are bubbles which occur on painted or other finished surfaces. They most often occur with Acrylic and Latex paint finishes, though they can also occur with oil based paints.
Causes of Paint Blisters
Paint blisters most often happen within a day or so of applying a new coat of paint. The common cause of paint blisters is a separation between paint layers. Blisters are also called bubbles. Blisters can occur either indoors or out, though temperature and high outdoor heat, especially direct sunlight, are a more common cause.
It is never advisable to paint an outside surface when it is hot to the touch. Houses in summer will often be too hot to paint. It is best to paint the side which will be in the shade for the rest of the day. Also, you should never paint a surface which is wet, which can also cause blisters to arise.
TIP: Our expert painting advisor, Edward Kimble adds, "Painting a hot surface is not good, and you should always try to paint in the shade. If direct sunlight is on the surface being painted, the paint will simply dry too fast to be able to apply it, but rarely would it blister. Blisters or bubbles mainly show up when a wet surface is painted. In the summer, if you have a day or two of heavy rain, you should allow at least one dry day before applying paint."
Using Paint Conditioners to Prevent Blisters
Paint conditioners can slow down the drying time of paints when using them in hot weather. Flotrol, for water base paints, or Penitrol, for oil base paint, are the most commonly used conditioners and are both excellent products.
TIP: Edward suggests, "These additives are helpful, but they are not cheap and are not absolutely necessary."