Spray painting can be quite messy and, more importantly, harmful when done indoors without proper equipment set up. Both the volatile compounds in the paint and the risk of overspray makes outdoor spray painting an attractive alternative for those who have a spacious backyard or a garage, for instance.
However, when painting a project outdoors you must take the weather forecast into consideration to prevent your newly painted piece from being ruined by a sudden rainfall.
Water-based paints are generally thinner and will be able to withstand rain after 2-6 hours of drying in sunny weather, whereas oil-based paints are thicker and may need to dry in the sun for 24 hours to not be affected by the rain. Giving the paint an additional 3-5 days in stable weather will ensure that it has reached its peak, making it as durable and hard as it can get.
Regardless of what you’re doing, a big portion of the work is going to be preparation and painting is definitely no exception to the rule. I think it’s one of those things that you really want to get right before you get going in order to simplify the process.
It’s also one of those things that are kind of forgiving if you make mistakes, as most things are reversible when painting, the downside is that they are often very time-consuming.
Let’s look at the different ways you can approach painting when there’s going to be rain and everything surrounding the subject.
So How Long Should You Let Paint Dry Before It Gets Wet?
How much you must adapt to the weather will probably depend on the size of the painting project and the objects you’re painting. Smaller objects can easily be protected from the rain by either placing them in a tent or under a sheet of plastic, as long as the plastic doesn’t touch the paint.
It’s quite obvious the same thing cannot be done when painting the exterior of a house. Well, it can be done but it’s quite a hassle. Nevertheless, when the weather forecast calls for heavy storms, a small tent or sheet of plastic will most likely not be enough to protect your paint against the rain.
The best option is, of course, to execute the paint job during a couple of days of sunny weather.
The general rule is that you have to wait longer the thicker the paint is. Water-based paints such as latex acrylic paints generally need at least 2 hours of sunshine before they’re exposed to rainfall.
If stormy weather is expected, two hours of sunshine may not be enough to create the durable finish you want in order to withstand rougher weather.
Instead, under such circumstances, it’s better to let water-based paint dry for about 6 hours in sunny weather. Oil-based paints, on the other hand, can sometimes call for as much as 24 hours before the paint is somewhat durable and able to resist rainfall.
Oil-based paint shouldn’t be used for exterior painting in southern climates as the sunny weather will cause the paint to crack and peel within a couple of years as it doesn’t have the flexibility needed to endure the many hours of sunshine that it will see during its lifetime.
Now, you may be asking yourself if I’m stupid for thinking that you’ve got 6-24 hours of sunshine at your disposal right before a rough storm.
It may not always be easy to find a gap or to predict the weather with full precision. Perhaps you live somewhere where the sun rarely shines, and where there’s a whole lot of rain on a daily basis.
However, while sunshine is a great bonus, it’s suggested that you don’t paint in less than 50 degrees Fahrenheit to give the paint a solid chance to cure and dry.
Additionally, you don’t want to let your paint dry in an area where there’s excessive moisture in the air as it may cause your paint to not cure properly and, eventually, peel prematurely. The ideal humidity level is between 40 and 70 percent.
What Happens If It Rains on Fresh Paint?
Rain and wet surfaces will make your life hard when it comes to painting. Trying to apply paint to an already wet surface is pointless as the paint won’t be absorbed. But let’s say you’ve already applied the paint and then all of a sudden rain clouds appear and with them – rainfall. Is your project ruined?
It depends. Generally speaking, the rain will wash wet paint off the surface that it’s been applied to unless the paint has dried for long enough or if the rain is light enough. Most of the time you will have to repaint some of it if it’s been exposed to rainfall during the first hours of drying.
Latex paint may feel dry to the touch after an hour but it will still be ruined by rain at such an early stage. At two hours it can handle light rain but might need a quick fix up and at 6 hours of sunlight, it should be able to withstand rain.
When I say your paint project may be ruined, I don’t mean there’s nothing you can do about it. I’m just saying you will probably have to invest more time and money into the project as you will have to repaint it. Before repainting, make sure the surface is completely dry.
Long story short; Rain will ruin a fresh paint job and should be avoided at all cost. If your contractor offers to finish a paint job in the rain you should either switch to another contractor or tell them to wait. Greatness is not achieved during a storm when it comes to painting. At least not when it comes to exterior painting.
Blistering or poor adhesion are common consequences of a paint job done in bad conditions. Don’t let yourself do the same job twice. Instead, look for sunny weather and dedicate those days to finishing the job before it starts raining again.
Is It Ok To Paint in High Humidity?
Temperature and humidity have a major impact on the way that paint dries. Keeping track of both of these is, therefore, essential to avoid painting problems down the road. In addition to weather conditions, you must also take the material you’re painting on into consideration as different materials respond differently to humidity.
This is especially true for a wooden surface as the wood can absorb the moisture in the air, which will reduce the adhesive effect of the paint when it’s applied onto the surface.
When there are high levels of humidity (70%+) in the air, brown and white discoloration may appear on the surface of the paint – also known as surfactant leaching, streaking, staining, and weeping. This occurs when a freshly painted surface becomes wet, causing the water-soluble elements in the paint to leach out, creating brown streaks.
Rain, dew, and condensation can cause surfactant leaching on fresh paint projects. If it does happen, I recommend waiting until the paint has dried and cure before you start fixing the discolored parts. You may damage the paint before it’s completely cured, which will come back to bite you.
However, some companies have taken this into account and replaced the water-soluble components with volatile organic compounds. It should be noted that volatile organic compounds are not eco-friendly and can be hazardous to inhale.
What to Do If It Rains While Painting?
If mother nature decides to surprise you when you’re in the middle of painting your house exterior, you may have a problem. However, as frustrating as it may be, it won’t be the end of the world – even if it may feel like it when the hours you’ve put into it are flashing before your eyes.
Let’s say you’re painting a house exterior and the rain starts to fall while the paint is still drying. If the paint hasn’t dried for long enough it will most likely start streaming down the walls of the house. Try to protect the areas that haven’t dried up by placing plastic covers that prevent the rain from reaching the paint.
If you don’t succeed in doing so, you will have to let the rain take down the paint and deal with the mess. Now that the paint is dripping down your walls, you must take the bulls by the horn. The diluted paint that’s running down your walls must be washed off before the marks start drying. The more you can water down the paint, the easier it will be to remove it later on.
Using a pressure washer is the way to go in this scenario. First remove the paint from the walls then, using the pressure washer, get it away from surrounding surfaces, such as concrete or stone tiles in your garden.
Yes, it’s definitely a frustrating situation but when you’re stuck between a rock and a hard place there’s not much you can do. Removing the paint will be best for now. Relax, reset, and get going again once you’re ready for it. It may be time-consuming but in the end, it’s a cheap lesson that you will carry with you for the rest of your life.