Flex Seal is one of the most popular brands of construction sealants on the market. This versatile product can work on virtually any surface, including roofs, gutters, skylights, windowsills, flashing, downspouts, foundations, awnings, chimneys. But for Flex Seal to fill in all the cracks and holes, it needs time to dry to its full hardness.
Flex Seal dries to touch within 2 to 3 hours and takes 24 hours to cure fully to their maximum strength. While it gets stronger over time, the actual dry time varies with the temperature, humidity, and thickness of the coating.
In the following sections of this article, we provide
- The drying times of some of the most popular Flex Seal products on the market.
- A quick overview of the factors that impact drying time
- Tips on how to reduce drying time
What is a Flex Seal?
Flex Seal is one of the most popular brands of construction sealants on the market. Flex Seals come in various sizes and colors suitable for such applications as fixing leaks, preparing for a storm, or using it as a sealant.
The majority of sealant ingredients include linseed oil, soy oil, and unsaturated vegetable oil usually ‘bodied’ (built up in viscosity) with calcium carbonate.
What does Flex Seal Stick to?
- Roof: Liquid Flex Seal is often used on roofs. It seeps into those pesky holes on your roof covering the leaks and protecting the remaining area from water and sunlight damage.
- Gutters: Is a great option for fixing leaks in gutter seams, joints, and corners. You can also use it to mend cracks and repair end caps to keep rain gutters fully functional.
- Skylight: While it’s recommended to replace the skylight entirely if the glass is damaged, you can use a sealant to fix it if the leak is due to a gap in the roofing.
- Windowsills: since Flex Seal products work with glass, they’re ideal for sealing windows by creating watertight, flexible barrier that keeps the cold out and the heat all season long.
- Foundation cracks: Flex Seal Liquid is thicker than paint and dries into a strong, rubberized coating. For this reasons, it’s the best choice for sealing walls to prevent air, water, moisture and chemicals in and out of your home.
- Wood: Great coating for outdoor furniture by penetrating the wood to provide nourishment and protection from the inside. It will also help prevent wood rot.
What will Flex Seal not Stick to?
Flex Seal does not stick well when used on plastics, rubbers, and certain types of vinyl. So before using Flex Seal on these non-compatible materials, test a small inconspicuous area.
Flex Seal can seal wood, plastic, metal, aluminum, tile, concrete, masonry, cement, fabric, glass, porcelain, drywall, rubber, and vinyl.
Flex Seal Dry Time vs. Cure Time
Dry time is the amount of time a sealant takes to dry or set so that it’s hard to touch, while the curing time is when the roof surface is ready for use.
When Flex Seal dries, it has a nice texture and doesn’t feel tacky or sticky. That means it’s dry to touch, and you can go ahead to apply your paint or urethane.
Most Flex Seal products will not reach their full hardness until the end of their cure time. Like we’ve mentioned earlier, cure time takes longer than dry time, usually 24 hours. You can’t apply paint or urethane on Flex Seal until it has reached the cure time.
After curing, it’s not recommended to walk on your roof because the coat will rub off. However, if you’re using it to seal cracks and holes, you won’t have any problems.
You can use Flex Seal on a wet surface or moist environment during an emergency roof leak. However, to get the best results, apply it on dry surfaces. Apply a second coat once the surface is completely dry for the seal to last long.
How Long Does Flex Glue Take to Dry?
Flex Seal glue can dry to the touch in as little as 1 hour. However, it fully cures in 24 – 48 hours and reaches maximum strength in seven days. After this, you can touch or start using the surface.
How Long Does Flex Shot Take to Dry?
Flex Shot forms a tacky coating in about 20 minutes and dries in 1 hour. Depending on temperature and humidity, you have to wait for 24 to 48 hours for it to cure fully. After drying, you can remove excess product with a dry paper towel.
Actual Drying Times of 20 Popular Flex Seal
Since there are 12 different color options, drying times vary by the type and color of Flex Seal you choose.
Below is a table depicting the actual drying times of several Flex Seal products so you can have a rough idea of how long it takes.
Factors that Affect Flex Seal Drying Time
Several factors impact the drying time, such as the Flex Seal color, temperature and humidity, coating thickness, and the surface you’re coating.
Temperature
Many sealant brands recommend an ideal temperature to apply their products. For example, flex Seal recommends sealant application surface temperature be between 0°F to 100°F. Only when it’s fully cured can Flex Seal withstand temperatures from -20°F to 140°F.
Flex Seal cures faster in hot summer months and slower in cold winter months. While higher temperatures will make the sealant dry faster, that’s not necessarily a good thing.
If it dries quickly, it might crack, which might be worse than a slow drying time, which is why you have to be cautious when applying in very hot temperatures.
Humidity
Just as low and high temperatures can affect the dry time, so can moist and humid conditions. The ideal humidity for Flex Seal to dry is 60 percent or greater.
If the air is too humid, the sealant will take much longer to dry than necessary. If the air is less humid, the sealant may become too thick within a short period of time, making it challenging to apply.
Also in the event of an emergency, you can use Flex Seal on a wet surface or humid environment. But keep in mind that it will take time for the sealant to adhere properly or you have to wait for the surface to completely dry.
Coating Thickness
Depending on your project, Flex Seal Spray provides thin and even coats on surfaces. Thin coats don’t only dry faster; they appear more even on the surface, and it’s easy to apply a second coat if need be.
Applying thick coats of Flex Seal makes it take a little more time to dry. You have to give it about 24-hours to cure fully before applying a second coat.
Don’t try to speed up the drying time using unorthodox methods because that will only make the inner coat sag or drip in hot weather and crack or peel in the cold winter.
Materials
The type of material you’re applying Flex Seal will also impact its drying time. This is largely due to the varying porosity of different materials.
Wood, plastic, glass, metal, aluminum, tile, concrete, cement, masonry, fabric, rubber, porcelain, drywall, and vinyl dry quickly because they tend to suck on the sealant causing it to dry quickly.
On the other hand, do not use Flex Seal on vinyl or foam because they react poorly to the sealant and may warp or dissolve the sealant.
Also, you don’t want to apply Flex Seal on some materials under certain conditions. For instance, it’s not recommended to use the product where it can be subjected to high heat or pressure (such as engine radiators) or gas tanks.
Condition of the Surface
Flex Seal dries faster on dry surfaces. While you can also use it on a wet surface or damp environment during an emergency, it adheres much better when applied on a dry surface.
If the surface is dirty, greasy, or oily, you may want to clean it because Flex Seal adheres better on clean surfaces. If the surface is rusty, try removing the rust as much as possible using sandpaper or a scrapper.
If you can see the light passing through the material, you’ll need another coat of Flex Seal to fill the gap. Again, it’s recommended to give the first coat 24-48 hours to fully cure before applying the second coat.
Ventilation
If possible, then it’s better to use Flex Seal outside. However, if you have to use it indoors, it’s important to ensure the area is well ventilated. Open doors and windows to get fresh air flowing and prevent vapor from building up inside the room.
Fresh air flowing inside the room helps accelerate the evaporation process, causing Flex Seal to dry faster. Stagnant air won’t absorb as much moisture from the sealant, increasing its drying time.
So, by improving ventilation in the room, you give the spray a better chance of evaporating, causing the sealant to harden more quickly.
How to Make Flex Seal Dry Faster
While waiting for Flex Seal to dry and cure requires a lot of patience, you may want strategies to help it dry faster. So, apart from applying this sealant in the best weather conditions, you can also use a fan to improve the ventilation in an enclosed space.
As the fan increases the air distribution across the room, the absorption process that causes the sealant to evaporate and harden is also improved.
While heat is known to improve the drying time of various sealants and adhesives dry faster, it’s not recommended for Flex Seal. You do not want to apply Flex Seal around heat, sparks, or open flames. And you don’t also want to smoke around Flex Seal.
Here are other ways to make Flex Seal dry faster
- Apply in the optimum temperature ( 32 and 120 degrees Fahrenheit is ideal )
- Apply thin layers
- Prepare the surface properly before application
What about cure time? How can you make Flex Seal cure faster?
As discussed earlier, cure time is the amount of time the sealant takes to reach its full hardness and full strength. We also know that cure time is significantly longer than drying time for Flex Seal. It takes about 24-48 hours for Flex Seal to cure fully.
The best way to make this product cure faster is to apply it in high temperature and low humidity conditions or outdoor in the sunlight, so summer seems to be the best time to use it.
If the first coat isn’t enough, you can apply a second coat after the first coat has dried. Again, you can confirm if it’s dry by touching the surface – if it’s tacky or soft, it’s not dry or fully cured.
Flex Seal Drying Time FAQs
How Long Does Flex Seal Take to Dry?
Flex Seal dries fairly quickly and is usually touch-dry after 2-3 hours but cures fully to its maximum strength in 24-48 hours. While the seal gets harder over time, the actual dry time varies with the temperature, humidity, and thickness of the coating.
What Happens if Flex Seal gets Wet before it Cures?
If Flex Seal gets wet before it cures completely, its formula won’t perform as intended. That means it will take more time than advertised to dry and cure, or worse, the rubber surface you were hoping to create to fix the leak will be compromised. If the latter happens, you’ll have to remove the seal and start the project over.
Does Flex Seal Spray Work on Wet Surfaces?
You can apply Flex Seal on a wet surface or moist environment during an emergency. However, Flex Seal applied to clean, dry surfaces will likely adhere better and last longer. The biggest concern with wet surfaces and Flex Seal is longevity, so you have to reapply Flex Seal once the area is completely dry.
How long does Flex Seal Last on Roof?
Depending on the environment, number of coats, and maintenance, Flex Seal is advertised to last for 30 years without cracking, peeling, or losing its strength or seal properties.
However, Flex Seal is only good as a temporary seal, and many roofing professionals don’t use it as a long-term solution to roof leaks.
Is Flex Seal Sticky When Dry?
If you want to know if Flex Seal is dry, then all you have to do is touch it lightly with your finger, and if it’s not soft or tacky at all, and doesn’t come off on your finger, then the surface is dry and sealed.
How Long does Flex Seal Last Once Applied?
Flex Seal will last up to 30 years without fading, drying, cracking, yellowing, or deteriorating. However, it’s not a permanent seal; its lifetime depends on the environment, the number of coats applied, and maintenance. A thicker coat of Flex Seal will be far more durable than thin coats.
Conclusion
While you can find all this information about Flex Seal drying time by reading the directions on the can, it’s important to remember that other factors can also impact how quickly and slowly the sealant will take to dry.
Temperature and humidity are environmental factors that can significantly affect drying time. If the weather is hot, dry, and less humid, how long the sealant takes to dry is increasingly reduced. The surface of the material and how clean, dirty, oily, or greasy it is will also cause Flex Seal to dry quickly and smoothly or slowly and unevenly.
Even how the sealant is applied can impact dry time. For example, thin coats will take less time to dry than thicker coats. Keeping all of these factors in mind when using Flex Seal is key to ensuring your desired results.