6 Things Flex Seal Tape Won’t Stick To – Do Not Use On Them

You might have bought Flex Seal Tape for your project after seeing the infomercial that claims – Flex Seal Tape can stick to almost anything.

But does that really mean it can stick to anything?

After trying the product myself and discussing the same with industry experts, I have found that Flex Tape is ineffective on certain materials and surfaces under high pressure and temperatures.

While it might stick to surfaces like those temporarily, I don’t recommend relying on Flex Tape in those situations and areas.

This article will discuss in detail – when you should not use Flex Tape – while examining six things, the tape won’t stick to. So, before you start with your project, test it on your material to see if Flex Tape is the right product for you or not.

What is Flex Tape?

FLEX TAPE is a super-strong rubberized waterproof tape that has been specially formulated with thick, flexible backing that can conform to any shape or object.

You can use it hot or cold, wet or dry – even underwater. So, it’s the ideal solution for all your patching, bonding, and sealing needs.

The good thing about the Flex Tape is that it is designed to work almost immediately, and it usually takes around 24 hours for the adhesive to be completely set.

Surfaces Flex Tape Don’t Work On?

In my opinion, even though Flex Tape’s adhesive is strong, it, unfortunately, can’t stick to everything.

This is simply because the pressure, temperature, and type of chemicals present on the surface will all play a part in Flex Tape adhesion’s success (or lack thereof).

Here’s the list of things I’ve found Flex Tape doesn’t adhere very well…

1- Rubber Tires

Although Flex Seal’s rubber-like backing allows it to be flexible and sturdy, it is not as infomercials led us to believe.

According to the manufacturers, their Flex Tape product is recommended for normal hydrostatic pressure. It’s not designed to withstand high pressures, such as pressurized pipes or engine machinery.

This means the raised ridges on the tires (of cars, motorcycles, or bikes) can make it tough for your Flex Seal Tape to adhere.

Also, the high pressure from being used on the road will stop Flex Seal Tape from sticking to the tires for a long, thereby not making the tires completely leakproof.

That said, Flex Seal Tape can be your temporary fix in case you need a quick band-aid solution for a small hole or crack in your tires in an emergency.

2- Water-Repellent Surfaces

Flex Seal Tape will not adhere properly to surfaces that repel water, generally hydrophobic surfaces made with water-repellent material.

When the adhesive on the tape comes into contact with these types of surfaces, it has trouble bonding and creating an even layer.

To check if the surface you’re working with is hydrophobic, splash some water on it. If the water droplets start beading up and rolling off, the surface is not ideal for Flex Tape usage.

3- Siliconized Surfaces

Silicone is a material used to create a water-resistant seal. It’s generally a blend of rubber and plastic, which you’ll find in many different items like caulk, aquariums, lubricants, and kitchen utensils.

The problem with Flex Tape and silicone surfaces is that when the two come into contact, it creates an uneven surface, which makes it difficult for the adhesive on Flex Tape to bond evenly.

In the same way, Flex Seal Tape will not adhere to paint. If you need to seal a painted surface, I recommend using Flex Seal Spray instead.

4- Radiator Hoses

Many homeowners and DIYers think Flex Tape would work perfectly fine on radiator hoses, but this is not true.

The Flex-Seal brand advises against using Flex Tape on hoses and surfaces that are either too hot or too cold.

Radiator hoses connect your vehicle’s engine, radiator, and water pump to move cooling fluid around the engine.

Since the process creates a lot of heat and pressure within the hose, Flex Tape might adhere but will not last for an extended period.

The high pressure from the mechanism will cause leaks, while constant exposure to heat will stop the Flex Tape from setting entirely.

5- Gas and Oil Tanks

Flex Seal Tape is also known to adhere to metal gas or oil tanks temporarily. However, similar to hoses, it’s not the best idea.

The pressure and heat from these types of tanks will eventually cause the taping to no longer stick. Not only that, but this could be a safety hazard as well.

If you try patching up a hole in your tank with Flex Tape, any gas or oil content can still leak through – because it’s strong enough to bond materials together but not good enough at preventing other elements from passing through.

6- Surfaces with Grease Oil or Chemicals

Flex Tape does not adhere well to greasy or oily surfaces and also when used with harsh chemicals like acids, mineral spirits, and acetone.

If you want to use Flex Tape on a typically sticky surface that has somehow come into contact with chemicals, grease, or oil, it’s good to clean the surface first.

The easiest way to clean the surface would be with soap and water, but it could vary depending on what exactly you are cleaning. Once the surface is cleared of residue, your Flex Tape should stick as normal.

What Will Flex Seal Tape Stick To – Does it Work?

Flex Tape can be used for a variety of applications, both indoors and outdoors. Some common uses include:

• patching holes in walls or roofs
• sealing leaks in pipes or hoses
• repairing cracks or holes in boats, RV roofs, or pools
• temporarily patching holes in car tires

The good thing is that the Flex Tape sticks well and works on a large number of surfaces like steel, copper, aluminum, acrylic, glass, wood, stone, cement, ceramics, plastic, and fabric, to name a few.

In fact, Flex Seal Tape’s key selling point is that it works even underwater – a claim they advertise on their website.

If the material is compatible with the tape, it will stick no matter how wet it is. However, some surfaces (such as porous ones) may require a little heat for optimal bonding results.

How to apply the tape?

Applying the Flex Seal Tape is straightforward if you follow the instructions provided by the manufacturer:

1. Clean the surface; you want to apply the tape. Ensure the surface is dry and free of dirt, grease, or oil.
2. Cut the tape to the desired length and width using a sharp knife or a razor blade.
3. Peel off the transparent backing from the tape.
4. Apply the tape to the surface, and smooth out any bubbles.
5. Press down on the tape to ensure it is firmly attached. And allow the tape to set for 24 hours before putting it to use.

For best results on porous surfaces, use a hair dryer to heat the adhesive tape before attaching. Just make sure not to overheat the tape.

Once applied correctly, the tape should be set and get adhered firmly in about 24 hours.

Is Flex Tape waterproof?

Flex Tape holds stronger and longer than other tapes and is water-resistant. Since it’s nearly waterproof, you can use it to cover up leaks.

But take care when applying it to certain areas because high water pressure or incorrect application will diminish its effectiveness.

Flex Tape MAX is another upgraded version of Flex Tape that supposedly covers 400% more area. If you require a more powerful waterproof material, it may work better for you.

A more dependable long-term option would be Flex Seal, a waterproof liquid sealant. Like Flex Tape, it will take 24 to 48 hours to completely bond or cure.

Is Flex Tape Removable – How to Remove it From the Surface?

When Flex Seal Tape dries, it will stay in place for a long without any move.

And because its adhesive is very strong, you would need an adhesive remover to get rid of the tape if you require to at any point of time in the future.

Flex Seal has their brand of adhesive remover (The Flex-Seal Adhesive Remover) – a specialized product designed to work with Flex Tape.

The remover comes in spray form for easy application and works on other tape types as well. So you can be sure it’ll help in your job when it comes to removing any kind of adhesive tape.

The bottom line

Flex Tape is not a long-term solution but works best as a temporary or emergency fix. If applied correctly, it should work and save you a lot of money.

You only need to remember that it doesn’t work on all kinds of surfaces and under extreme temperature or pressure conditions.

Therefore, if Flex Tape is your only option and you have used it in an emergency, you should plan to get the damages adequately repaired or replaced as soon as possible.