Spring is a time for new beginnings: new plant growth, new birth, new coats of paint. After the drab grayness of Utah winter, a fresh coat of exterior paint can be just the burst of freshness you need to move into the new season. Exterior painting may not be as straightforward a project as you may think, however. There are many factors in play as the weather warms up, and these need to be considered carefully before painting begins.
How Long Does Paint Take to Dry?
The biggest determining factor for how long paint takes to dry is the kind of paint in question. Paints are typically oil- or latex-based, and they have different physical and chemical properties. Latex paint tends to dry more quickly, sometimes within an hour until the paint is dry to the touch and four until it has dried all the way through.
Drying times for oil-based paints require more patience: typically 6-8 hours at minimum to become dry to the touch and a full 24 hours before the paint is ready for a second coat. Check the can of paint you’re working with for more specific drying times, keeping in mind that even those values will be affected by your exterior painting environment.
Finding the Right Environmental Conditions for Exterior Painting
Mother Nature reigns supreme when it comes to the right time to do your exterior painting. Ambient temperatures and other climatic conditions should guide when you pull out the paint brush. This means there is no one-size-fits-all time to paint exterior walls; the right time will depend on where you live. If you want to avoid repainting sooner than you had planned, keep a careful watch on your weather.
Too Cold
No one jumps up to take care of their exterior painting during the winter months. The reasoning is two-fold: 1. Being outside for extended periods of time to do chores is uncomfortably chilly and 2. Paint doesn’t cure well in the cold. This is true no matter what kind of paint you use for your exterior painting job, but water-based exterior paints especially don’t handle the winter chill with grace.
You should wait for moderate to warm temperatures before painting your exterior, the industry consensus being 40°–90° F for oil paints and 50°–85° F for latex (which are generally better for exteriors). This is the standard for daytime temps, when the paint is actually being applied. It is also critical that overnight lows don’t compromise the paint’s ability to cure properly. Watch the weather forecast and make sure that temperatures aren’t predicted to drop below 32° F at night for several days after painting. Otherwise, dew can form on surfaces and cause the water in the paint to evaporate too slowly, compromising its ability to resist cracking.
Too Hot
Believe it or not, weather that is too hot can also mar a perfectly good paint job. While colder temperatures lead to longer drying and curing times, higher temperatures can bake the surface you are trying to paint. Hotter conditions don’t have a hard and fast rule beyond what was stated above, but you can judge based on the temperature of your exterior walls. If you can’t hold your hand on the wall for a few seconds without pain, wait for the temperature to fall.
Humidity
Atmospheric water content is a huge factor for when exterior painting is appropriate. High humidity can lead to water vapor forming or droplets pooling on your new paint job. It can also interfere with paint’s ability to adhere to your walls, resulting in paint bubbling or peeling off. It can also cause paint to leach, which is highly unattractive, and it can inhibit paint’s protective film layer from developing, compromising the protective qualities of the paint.
Be on the lookout for 40%–70% humidity before you start painting. This is especially important if you are painting wood, which tends to wick up moisture from the air, causing it to swell, or crack if the air is too dry.
Rain
As an extension of the humidity principle, make sure rain is not on the horizon before you start painting. This is not a matter of not getting dripped on: your surfaces need to be dry in order for paint to cure properly. You’ll also need 4–8 hours of dry weather after the paint is applied.
Wind
Take care that you don’t paint your exterior on a blustery day. Wind can cause your paint to dry too quickly, leaving signs of streaks. Worse still, it can blow dirt and debris around to get stuck in your drying paint. The smaller the breeze, the better.
