Paint technology has improved a lot over the years. Factors like temperature, humidity, and direct sunshine can effect the quality of results. For example, painting your home in the direct summer sun in Boca Raton or other South Florida towns causes the paint to dry almost instantly and can be very hard to work with.
Despite improvements in paint technology, you still cannot paint your home when it’s raining out.
Painting in Humidity: Air and Surfaces
If you are delaying painting your house due to humidity, you will never finish your project. Boca Raton is never not humid. Even in winter time, we carry some degree of humidity in the air. In rain, dew, or other high-moisture conditions, the main issue is not the dampness of the air but the dampness on the surface to paint.
Humidity Affects Dry Time
Humidity does not have to delay you from painting. In our experience, humidity affects painting surfaces in dry times in the paint.
Very humid conditions mean that the water cannot evaporate at a faster rate than the solvents in the paint. The paint is struggling to cure itself but it cannot do so when it is in such a water-logged state. Using oil-based paints will not help, either. Oil-based paints will encounter the same problems as water-based latex paints.
Optimal vs. Acceptable Humidity Levels for Painting
Optimal relative humidity (RH) levels for exterior painting tend to be in the 40-50% range. Some humidity is desirable for proper drying time. As an extreme example, a dark surface painted in direct sunlight will cure so fast that brush marks remain in place and uneven glossiness (called paint flashing) will occur. Paint that is allowed to dry slower will level out its brush marks and the sheen will remain consistent.
On the flip side, levels in the 70% zone will drastically slow dry time. But these humidity levels should not prevent you from painting either. They simply make the job more slower to finish.
Painting above 85% humidity is not recommended. The paint will remain gummy and gel-like until the RH lowers to an acceptable level long enough for the paint dry. In addition, because the paint has not been allowed to level properly, the texture will remain wavy and otherwise unacceptable.
Temperature and Humidity
One trick of the trade for exterior painting in South Florida, is to time your painting session so that temperatures are on the rise. Consider begining your session several hours before the day’s peak temperature, which is usually late afternoon. By building in a few hours of head-start, you give the paint enough time to do its job.
Start early. But if you begin too early in the day, you have to deal with moisture remaining on the surface from the previous night.
What is the Right Season to Paint?
If you are painting a previously painted surface, you can wait until late morning or about noon, when the dew has dried off of the surface. When the moisture starts to disappear, you can be start to paint.
Uncoated wood is very porous and retains moisture within the wood’s cellular core, even if it feels dry. For situations like this, may just have to wait for a warmer, drier season.
Is Interior Painting Affected by Humidity?
Interior painting is a different matter, with air conditioning, humidity is under control so interior walls are rarely affected by humidity.
Even if you are not controlling the home’s humidity, your HVAC system or even window AC, does the job for you.