How Long Does Flex Seal Last

One of the most well-known building sealant brands available is Flex Seal. With Flex glue, almost every surface, including roofs, gutters, skylights, windowsills, flashing, downspouts, foundations, awnings, and chimneys, withstand the harshest weather.

However, to get the best from the products, Flex Seal fully cures to form a tight bond and stops leaks dead. The application of Flex Seal is as simple as directing the nozzle at the surface and pressing it down to get the desired bead thickness.

It is flexible and durable and offers amazing instant grab technology, so it sticks where you want it. The Flex glue dry time means it is touch dry in two to three hours, but it takes 24 hours to fully cure and reach optimum strength. However, the actual dry time will vary based on temperature, humidity, and thickness.

Flex Seal products how long to dry

In our guide, you can learn more about the Flex Seal products, such as can Flex Seal be applied to wet surfaces or can you apply flex glue underwater. By the end, you’ll find a range of products suitable, and most of all, you can find out, once flex glue fully cures, how long will the repair last? (Learn How Many Wheel Chocks Do I Need)

What is a Flex Seal?

Flex Seal Liquid Rubber Sealant Waterproof Spray on Caulking Coating One of the most well-known building sealant brands is Flex Seal.

Flex Seals are available in various sizes and hues, making them ideal for sealing leaks, storm prep, and other uses.

The extension tube screws onto the Flex Shot can, and once you have the extension tube affixed, you can reach those areas not otherwise possible to plug your leaks.

Flex Seal Tape and Flex Seal Glue are two other popular products in the range.

What will Flex Seal Stick to?

Roof: On roofs, Liquid Flex Seal is often used. Your roof’s annoying holes are filled with it, sealing up leaks and shielding the remaining surface from harm from the elements. You’ll also discover Flex Glue UV resistant properties stop it from breaking down in sunlight.

Gutters: You’ll discover Flex Glue resistant to breaking down when you seal joints, seams, and corners of leaking gutters. You can also use it to fix end caps and patch cracks.

Windowsills: Flex Seal works with glass and is ideal for sealing windows. You can also remove flex glue from glass easily if you accidentally smear it.
Cracks in Foundations: Flex Seal Liquid dries to a robust, rubberized coating thicker than paint. It is the most acceptable option for sealing walls because it stops chemicals, water, moisture, and air from entering and leaving your property.

What Will Flex Glue Not Stick To?

Flex Seal does not adhere effectively when applied to some kinds of vinyl, rubber, and plastic. Therefore, test a small, discrete area before applying Flex Seal to these incompatible materials.

Flex Shot Take to Dry

How Long Does Flex Glue Take to Dry?

Flex Seal adhesive takes as little as an hour to become touchable. But it takes 24 to 48 hours to cure fully, and it takes seven days to reach its peak strength. The surface is now ready for touching or use.

How Long Does Flex Shot Take to Dry?

Flex Shot forms a sticky coating in about 20 minutes and dries in 1 hour. Allow 24 to 48 hours, depending on the temperature and humidity, for it to completely cure. You can use a dry paper towel to wipe away extra product after drying. Here you can find some factors that affect drying and curing time.


Sealant brands prescribe an application temperature. For example, flex Seal advises applying sealant at 0°F to 100°F. Flex Glue withstands -20°F to 140°F when fully cured.

Flex Seal cures faster in summer than winter. Higher temps make sealant dry faster, but that’s not always beneficial.

You may ask, will flex glue shrink? If it dries rapidly, it may crack, which is worse than a slow drying time, so be careful in hot temperatures.


Moisture and humidity affect dry time just as low and high temperatures. Flex Seal needs 60% humidity to dry.

Too much humidity will slow sealant drying. Less humid air can cause the sealant to thicken quickly, making it challenging to apply.

Flex Seal can be used in a wet emergency. However, remember that the sealant needs time to bond effectively or the surface to dry entirely. It is here, you could ask, can flex glue be used underwater? Of course, it can, yet the drying and curing process can take longer. (Read Can You Leave Your Car Parked At Walmart)

Coating Thickness

Flex Seal Spray applies thin, even applications depending on the project. Thin coats dry faster, look more even, and are easy to reapply.

Applying thick Flex Seal coats slows drying. Before applying a second layer, wait 24 hours.

Unorthodox drying procedures will cause the inner coat to sag, leak, and crack or peel.


Flex Seal’s drying time depends on the material used. Different materials’ porosities cause this.

Wood, plastic, glass, metal, aluminum, tile, concrete, cement, masonry, cloth, rubber, porcelain, drywall, and vinyl absorb sealant fast.

Vinyl and foam respond poorly to Flex Seal and may deform or disintegrate it.

In some cases, you shouldn’t use Flex Seal. For example, it’s not recommended to utilize the product in high-heat or-pressure environments (such as engine radiators or gas tanks).

Surface Conditions

Dry surfaces dry Flex Seal faster. In an emergency, you can apply it on a wet surface or moist environment, although it sticks better on a dry surface.

Flex Seal attaches better to clean, non-greasy surfaces. Using sandpaper or a scrapper, remove rust from rusty surfaces.

If light passes through the material, add another application of Flex Seal. Again, wait 24-48 hours before applying the second layer.


Use Flex Seal outside if possible. However, if you have to use it indoors, it’s crucial to ensure the room is sufficiently ventilated. Open doors and windows to circulate air and prevent vapor buildup.

Fresh air speeds up Flex Seal’s drying by accelerating evaporation. Stagnant air won’t absorb as much sealant moisture, slowing drying.

Increasing airflow gives the spray a better chance of evaporating, causing the sealant to solidify faster.

How to Make Flex Seal Dry Faster

Flex Seal dries slowly, so you may want to speed up the process. When applying this sealant in good weather, you can use a fan to promote ventilation in an enclosed space.

The sealant’s absorption process improves as the fan distributes air over the room. The heat helps sealants and adhesives dry faster, but not Flex Seal. Heat, sparks, or open flames should not be near Flex Seal. (Learn How To Store Camp Chairs)

Flex Seal on Wet Surface

Flex Glue FAQ & Flex Shot FAQ Section

How Long Does Flex Seal Take to Dry?

Flex Seal is touch-dry in 2-3 hours and fully cured in 24-48 hours. The seal hardens over time, although drying time depends on temperature, humidity, and coating thickness.

What Happens if Flex Seal Gets Wet before it Cures?

Flex Seal won’t work if wet before it cures. It will take longer to dry and cure, or the rubber surface you want to create to patch the leak will be compromised. If so, remove the seal and start over.

Does Flex Seal Spray Work on Wet Surfaces?

In an emergency, you can use Flex Seal on a wet surface. Flex Seal adheres better and lasts longer on clean, dry surfaces. However, wet surfaces and Flex Seal don’t last long, so reapply once the area is dry.

How Long Does Flex Seal Last on Roof?

Flex Seal is guaranteed to survive for 30 years without cracking, peeling, losing its strength, or losing its ability to seal surfaces, depending on the environment, the quantity of coatings, and maintenance.

However, Flex Seal is only effective as a short-term seal, which is why many roofing specialists don’t use it as a permanent fix for roof leaks.

Flex Seal Liquid FAQ

What size can I purchase Flex Seal Liquid?

Flex Seal Liquid can be bought in 2.5-gallon containers.

How much can one cover?

The number of coats needed and the surface when applying Flex Seal Liquid affect how much coverage you get. However, the following areas are frequently covered by our sizes:

  • Large 16oz – up to 18.75 sq. ft.,
  • Jumbo 32oz – up to 37.5 sq. ft.,
  • Giant Gallon – up to 150 sq. ft.
  • MAX Size – up to 375 sq. ft.

What is the shelf life of Flex Seal Liquid?

When properly stored, Flex Seal Liquid has a 24-month shelf life. A skin may develop on the can’s surface if left open for a long time. To avoid peeling over, remove the lid immediately and permanently replace the lid after each use. Remove the top layer if skinning does happen, then use the product.

Will Flex Seal liquid rubber expand and contract in the summer and winter?

Flex Seal Liquid stretches, stays flexible, expands, and contracts. It will not shrink, crack or peel when appropriately dried.

What temperatures can I apply Flex Seal Liquid?

The optimal surface temperatures for applying Flex Seal Liquid rubber are between 32°F and 120°F. In addition, flex Seal Liquid can tolerate temperatures between -80°F and 350°F once thoroughly dried.

Can I dilute Flex Seal liquid rubber?

Since Flex Seal Liquid is pre-made and ready to use, it must be applied immediately. Never mix it with water or solvents.

Can I apply Flex Shot temporary seal on a wet surface or when raining?

Flex Seal Liquid should always be applied to a dry, clean surface free of grease and oil.

Applying the product amid a downpour may cause part of it to wash off. Therefore, we advise using it for at least 24 hours before any significant snowfall, hail, or rain.

Can I use it to repair a gasoline tank?

Flex Seal Liquid should not be used to seal a gasoline tank or any other container containing flammable liquid. (Read Traeger Vs Camp Chef)

Can I paint it?

Flex Seal Liquid cannot be painted over with most conventional paints once thoroughly dried.

Will Flex Glue Clear retain clarity when cured?

The Flex Shot clear product dries to a crystal-clear bond.

Flex Seal FAQ

Is Flex Seal Liquid food grade?

Flex Seal Liquid isn’t approved to be used in food preparation areas.

Can I apply on a wet surface?

In an emergency, Flex Seal can be applied to a wet surface. However, reapply Flex Seal once the area is dry to ensure longevity.

Can I paint it on or brush it on instead of spraying?

Yes, you can paint, brush, roll, or directly spray the Flex Seal. However, we recommend Flex Seal Liquid for these applications.

Is Flex Seal Clear the same formula as Flex Seal Original?

To give Flex Seal Clear transparency, there are changes to the formula. Thus the spray is thinner, and multiple coats may be required.

Flex Paste MAX

Flex Paste FAQ

Is Flex Paste part of the MAX Line?

Yes, get 100% more in the Flex Paste MAX.

What is Flex Paste?

Flex Paste is an incredibly thick rubberized paste that immediately covers holes, cracks, and gaps.

Flex Paste dries to a strong, flexible, watertight, rubberized coating that keeps out air, water, and moisture.

What size and color can I purchase Flex Paste?

Flex Paste comes in black or white and in the following sizes:

  • 9oz cartridge (caulking gun required)
  • 1 lb. jar
  • 3 lb. tub
  • 6 lb. tub
  • 12 lb. MAX tub

Can I use Flex Paste on plastic and rubberized surfaces?

Flex Paste adheres to many surfaces, yet it may not stick to certain plasticized or rubber surfaces.

Can I use Flex Paste on a wet surface or underwater?

Flex Paste can be used underwater and on dry or wet surfaces. It’s non-soluble and dries underwater. Apply generously and firmly for optimal results. Once dry, Flex Paste turns flexible and watertight.

How much coverage will Flex Paste provide?

One pound provides 10 linear ft at 2 inches wide with a layer thickness of approx 1/16th inch.

What can I use Flex Paste for?

Flex Paste is perfect for DIY, repairing a roof, sealing cracks, and plumbing repairs.

How to preserve Flex Paste?

Flex Paste begins to cure when exposed to air. To ensure a fresh, usable product, you’ll find a protective foil on the surface of the Flex Paste and a silica gel packet.

Do not mix dry and fresh Flex Paste.

I lost the protective foil.

Cut a piece of aluminum foil larger than the Flex Paste container and cover the paste after use.

Does Flex Paste remain flexible?

Flex Paste dries into a robust and flexible rubber.

Will Flex Paste shrink?

Flex Paste won’t shrink, crack or peel.

Can Flex Paste be painted?

Once cured, you can paint it any color.

Is Flex Paste chemical, UV, and mildew resistant?

YES, once cured, Flex Paste is resistant to these.

Can I dilute Flex Paste?

NO, Flex Paste is ready to use.

What is the maximum pressure Flex Paste withstands?

Various factors can affect Flex Paste’s maximum pressure. Flex Paste can tolerate a wide range of hydrostatic pressure depending on layer thickness, surface type, and fracture or hole size. Test Flex Paste only after fully cured.

Can I store Flex Paste outside?

Replace the foil and silica packet after each use and close the lid tightly to prolong product life. Keep Flex Paste cool and dry.

How do I remove Flex Paste?

If you apply flex paste and need to clean Flex paste off, do so with a damp cloth when wet, or wait until dry and use sharp tools.

Can I use Flex tape on a tank of gas or oil?

No, do not use Flex Tape on any gas or oil tank. This is because flex tape forms a seal, yet not for such compounds.

Many users found flex seal works well in combination. For example, prep surfaces with Flex seal aerosol and then apply flex tape, which sticks much better.

Flex tape works on many surfaces that are smooth like Flex shot, although flex shot can get inside to seal cracks whereas flex tape covers gaps

How Long Does Flex Seal Last