Flex Seal Dry Time (& Speeding Up Tips)

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Reviewed by
Eral Kadrija

Tony Adams

Flex seal fixes holes, cracks, and water leaks. However, the sealant must dry (and cure) before it can protect surfaces. So, how long does it take to dry?

Flex seal takes 2-3 hours to dry to touch and 24-48 hours to cure. However, its dry time depends on the room temperature, humidity levels, and thickness of the coat.

For instance, during cold or humid conditions, its solvent evaporates slower so the sealant also dries slower.

Dry Time Between Coats

It takes Flex seal 24 hours to dry enough for a re-coat. To know if the finish is dry enough for a re-coat, touch it. If it feels moist or soft, it hasn’t dried yet. If the finish is hard and dry, you can re-coat it.

For the Flex seal to dry, its solvent must evaporate. Its evaporation process depends on the humidity levels and room temperature. The lower the humidity, the faster the finish dries.

If you re-coat it too soon, the finish will turn sticky. That’s because the solvent will be trapped between the two coats and won’t evaporate fully. Since the solvent didn’t evaporate, the old coating will still be wet, preventing the new coating from sticking.

Flex seal is made by combining rubber and solvent. Once the sealer is applied, it seeps into the cracks and holes of the surface to seal it. The solvent turns the Flex seal into a liquid form and dissolves it so it can seep through the tiniest cracks and repair them.

Flex Seal Cure Time

It takes Flex seal 24-48 hours to cure. For the sealant to cure, the solvent must evaporate and the coating must harden and compact. The curing process occurs through the solidification of the rubber paste. Once the sealant has cured, it becomes waterproof and strong enough to support daily weight and use.

There’s a difference between the drying and curing time. To dry, the solvent must evaporate from the coating. However, the rubber paste must solidify, and the coating must harden and compact for the sealant to cure. The solidification of the rubber paste and the hard (& compact) coating helps it to cover cracks and leaks.

However, the size of the crack and the thickness of the coating determines the cure time. For instance, larger cracks require more Flex seal paste, which will take longer to cure. Conversely, smaller holes don’t require much of it, meaning the sealer dries (and cures) faster.

As a rule of thumb, the longer it takes to dry and cure, the stronger it becomes.

The Flex seal coating must cure before exposing it to water. On average, it takes 24-48 hours for the Flex seal to dry enough to handle exposure to moisture. If it will be used outdoors, manufacturers recommend its application 24 – 48 hours before the rain starts.

If You Re-coat Too Soon:

If you re-coat the Flex seal too soon, the sealer will take longer to dry. This is because the existing coats don’t have enough time to dry and solidify, creating a moist and weak base for successive coats.

When you apply the next coat over the moist base, you slow down the evaporation and drying process of each coat, causing it to take several hours to dry.

It can also cause variations and patches in the finish. This is because the coatings will not dry evenly, causing some parts to appear darker or lighter than others.

Re-coating too soon can cause the Flex seal coating to turn sticky or tacky. While a tacky finish can be fixed, there are cases where it can’t, and you must remove and re-apply it. So, always leave enough dry time between coats.

How To Speed Up Flex Seal Drying Time?

Since the Flex seal dries through evaporation, increasing the evaporation rate will speed up its dry time. To increase the evaporation rate, increase the air circulation and the heat around the coating.

1. Use a Hairdryer

Use a Hairdryer

A hairdryer will increase the heat around the coating; this also increases the evaporation rate.

Here’s how to do it:

  1. Use the medium settings of the hairdryer.
  2. Set the nozzle of the hairdryer 2 inches away from the coating.
  3. Move the hairdryer around the coating for 5 minutes.
  4. Wait 10 minutes.
  5. Use the hairdryer again for 5 minutes.
  6. Leave the coating to dry naturally for 6-10 hours.

Tip: You shouldn’t fully dry the Flex seal coating using a hairdryer. That’s because the coating won’t harden or compact naturally, so the finish will be weak.

2. Apply It Outdoors

The higher the air circulation around the coating, the faster it dries. So, applying Flex seal outdoors means that the coating will dry faster. However, the Flex seal coating shouldn’t be exposed to rain as it can ruin the finish. Also, you must shield the coating from dirt or debris as it can ruin it.

3. Use a Dehumidifier

Use a Dehumidifier

You can make the coating dry faster by reducing indoor humidity. Humidity refers to the atmosphere’s moisture content (or water vapor).

The higher the humidity level, the slower the coating will dry. So, if you reduce the humidity levels, the Flex seal will dry faster. The ideal humidity level must be between 30% and 50%.

To reduce the humidity levels, use a dehumidifier. Follow the manufacturer’s guide to learn how to use the dehumidifier. For best results, run the dehumidifier for 24 hours after application.

Tip: To make Flex seal cure faster, you need to increase the airflow around the coating. You can do this by ensuring proper room ventilation.

Final Words

It takes Flex seal 2-3 hours to dry to touch, 24 hours to dry enough for a re-coat, and 48 hours to cure. However, its drying and curing time depends on the humidity levels, the thickness of the coat, and the number of coats.

To speed up the dry time of Flex seal, use a hairdryer, or dehumidifier, or apply the sealer outdoors.

Tony Adams

Tony Adams

Woodworker, Interior and Exterior Painter, Flooring Specialist

Tony is a professional painter and an author of DIY Geeks. Tony has completed over 1,000 painting projects for his clients. It's safe to say he knows what he Is talking about.

Eral Kadrija

Eral Kadrija

Lead Editor, Home Renovator

Eral has a passion for home renovation and repair. Over the years, he has bought, renovated, and sold 7 old homes. Using his experience from different DIY projects he created DIY Geeks.

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