What Will Flex Seal Not Stick To? (We Did THIS To Find Out!)

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What Will Flex Seal Not Stick To

Flex Seal is for sealing and repairing leaks. But, there are some surfaces that it won’t stick to. These include silicone, polyethylene, nylon and Teflon. Additionally, don’t use it on hot surfaces or areas near flames or high heat sources.

Read the manufacturer’s instructions and test it on a hidden area before using. Think of Flex Seal as duct tape on steroids. It’s versatile and waterproof, able to seal almost anything – except broken hearts!

What is Flex Seal?

What Will Flex Seal Not Stick To

Flex Seal is a popular waterproof adhesive product. You can get it as a spray can or liquid coating. It’s used to fix leaks and cracks, and to seal surfaces to prevent water damage.

This rubberized coating sticks to most surfaces – metal, wood, concrete, and plastic – you name it!

When applied correctly, Flex Seal creates a strong bond. It’s resistant to weather, heat, and extreme pressure.

Plus, it provides an insulating layer. This helps regulate temperature and reduce noise. However, it must be used as directed for the best results.

What won’t Flex Seal stick to? Greasy or oily surfaces, and those with dirt or debris. Plus, it may not work on fabrics or cardboard (highly porous materials).

For maximum adhesion, you need to clean the surface first. Use soap and water to remove dirt and grease. Then let it dry completely before applying Flex Seal.

List of Surfaces Flex Seal Can’t Stick To:

Materials Flex Seal Does Not Stick To
1. Plastic
2. Glass
3. Aluminum
4. Ceramic
5. Metal
6. PVC
7. Fiberglass
8. Wood

Surfaces that repel Flex Seal?

Flex Seal is great for covering cracks and leaks. But there are surfaces where it won’t stick. Here are some examples:

  • Wet surfaces. Dryness is important for adhesion. Wet surfaces won’t work with Flex Seal.
  • Oily and greasy surfaces. Engines and kitchen appliances need special sealers.
  • Unprepared surfaces. They need to be scoured and cleaned first.

All adhesive products have limits. Even though Flex Seal is popular, specialized sealers may be needed. Solutions are available. Try Flex Shot Clear for PVC pipes or FastCap 2P-10 Super Glue for wood and metal. Don’t forget to read instructions!

Finally – Flex Seal sticks to almost everything, but nothing sticks to a bad attitude.

Tips for Using Flex Seal:

Flex Seal is a powerful adhesive. To get the best results, you must use it correctly. Here are some tips:

  • Clean the surface before applying Flex Seal for strong grip.
  • Spray multiple thin layers instead of one thick layer when sealing large cracks.
  • Don’t use it on surfaces like silicone, vinyl, or Teflon.

Humidity can weaken the bond. So, to ensure proper drying and adhesion, use it indoors with good ventilation.

Also, when using Flex Seal in high-pressure areas like water tanks, it’s best to be patient. Allow adequate time for the seal to settle and cure.

It’s amazing how Flex Seal can even fix leaky gutters! But, it won’t stick on greased-up pigs.

What should you not use Flex Seal on?

Flex Seal is a popular liquid rubber sealant that is used to seal and coat a wide range of surfaces. While it is an incredibly versatile product, there are certain surfaces that you should never use Flex Seal on.

For instance, you should avoid using Flex Seal on surfaces that will be exposed to a temperature higher than 200°F, as the sealant can break down and lose its adhesive properties.

Similarly, you should avoid using Flex Seal on surfaces that will be in direct contact with food or drink, as the chemicals in the sealant can be harmful if ingested.

Additionally, you should avoid using Flex Seal on surfaces that are constantly submerged in water, such as the bottom of a swimming pool, as the product is not designed for underwater applications.

Is Flex Seal a permanent fix?

Flex Seal is not a permanent fix, but it can provide a temporary solution for leaks, cracks, and other damages. The product is designed to seal and protect surfaces from moisture, air, and other elements, and it can withstand extreme temperatures and pressure.

However, over time, the seal may weaken or break down due to wear and tear or exposure to harsh conditions.

Therefore, it is important to use Flex Seal as a temporary fix and address the underlying issue as soon as possible to prevent further damage and ensure a long-lasting repair.

What will bond to Flex Seal?

Flex Seal is a popular sealant that is widely used around windows and doors. This innovative product is designed to bond to a wide range of surfaces, including metal, wood, plastic, and many others.

In addition, Flex Seal has excellent adhesive properties that allow it to create a strong, durable bond that can withstand harsh weather conditions and extreme temperatures.

Whether you are tackling a small DIY project or working on a large commercial project, Flex Seal is the ideal solution for sealing around windows and doors.

With its exceptional bonding properties, you can rest assured that your sealant will stay in place and provide long-lasting protection against water, air, and other elements.

What happens if flex seal gets wet before it cures?

If the flex seal gets wet before it cures, it may not be as effective in creating a waterproof seal.

The curing process helps the substance activate and create a strong bond with the surface, but if it encounters moisture before it finishes curing, the seal may be compromised.

It is important to ensure the surface is completely dry before applying flex seal and allowing it to cure properly to maximize its effectiveness.

How long does flex seal last once applied?

Once applied, the flex seal can last for several years depending on the conditions and usage. It is designed to withstand extreme temperatures, UV rays, and harsh weather conditions, making it durable for outdoor use.

However, the longevity of a flex seal can also depend on the surface it is applied on, as well as any potential wear and tear from usage.

It is recommended to reapply the flex seal every few years to ensure maximum protection and effectiveness. With proper application and maintenance, a flex seal can be a long-lasting solution for sealing and protecting surfaces.


Flex Seal has amazing adhesive qualities – but there are certain surfaces it won’t stick to. Wax paper, silicone, Teflon and polyethylene are not compatible with Flex Seal. Plus, oily or greasy substances can’t be bonded with it.

It’s important to remember that Flex Seal works best on clean and dry surfaces. Dirt, debris and moisture can reduce its effectiveness.

Flex Seal is a great option for many materials like plastic, rubber, wood or metal; however, high temperatures can reduce its adhesive power.

The famous myth of using Flex Seal to patch a boat and sailing it across a lake twice without sinking was tested and found to be false. But, Flex Seal still has some awesome capabilities in the right circumstances!

Frequently Asked Questions

Q: What surfaces will Flex Seal not adhere to?

A: Flex Seal will not stick to surfaces that are made of silicone, plastics, rubber, or polypropylene.

Q: Can I use Flex Seal on cardboard?

A: No, Flex Seal will not work on cardboard because it will not adhere to the material properly.

Q: Will Flex Seal work on wet surfaces?

A: Yes, Flex Seal can work on wet surfaces, but it is recommended to dry the surface before applying the product for better results.

Q: Can I use Flex Seal in extreme temperatures?

A: Yes, Flex Seal can be used in extreme temperatures, but it is recommended to use it in temperatures above 50 degrees Fahrenheit for maximum effectiveness.

Q: Will Flex Seal adhere to fabric or clothing?

A: No, Flex Seal is not recommended for use on fabric or clothing as it could damage the material and ruin the item.

Q: Can I use Flex Seal on surfaces that are constantly exposed to water?

A: Yes, Flex Seal is water-resistant and can be used on surfaces that are constantly exposed to water, such as boats or bathrooms.

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