Will Flex Seal Fix A Cracked Bathtub?

A flexible seal is a thick liquid coating that you can apply to things like bathtubs and sinks. It can seal the holes and cracks. One of the most convenient qualities of a flex seal is that you can quickly apply it on almost any surface.

You can use a flex seal to fix a cracked bathtub, but it will not permanently mend. Instead, it will gradually lose its coating. The seal will eventually start to open and ultimately lose its protective coating.

In this blog post, you will know how to do first aid on your cracked bathtub and some long-term solutions.

Will Flex Seal Fix a Cracked Bathtub?

Although you can use a flex seal to fix a cracked bathtub, it won’t fix the issue permanently. Instead of protecting the surface, its protective coating will eventually lose its strength.

A liquid spray coating known as flex seal is used to fix holes and cracks in almost any surface. Before you apply this coating, it’s essential to understand how strong the bond between the surface and the flex seal will be.

For instance, if you’re planning on doing a simple project, such as replacing a leaky bathtub, then a flex seal might be helpful. However, if you want to fix a more permanent issue, such as a cracked bathtub, you should not use a flex seal.

Unlike ceramic or porcelain, a flexible seal does not create a strong bond with the surface. As a result, it won’t fix a cracked bathtub long-term. Even though it can stop the water from leaking, it will eventually seep into the area.

How to Temporarily Fix Bathtubs?

Sometimes, you want to bathe in your bathtub in a few days, or so, so quick fixes are your final resort. Below are some temporary fixes you can apply to your cracked bathtub.

Water Weld

Unlike Flex Seal, water weld works similarly to create a waterproof seal on various surfaces, such as your bathtub.

However, it takes a couple of hours for the water to cure before it can fully seal. Getting water weld wet before it can fully cure can potentially affect the seal’s performance.

Crack Stabilizing Primer

You can use a stabilization primer to prevent a small crack from growing. Although it won’t fill the hole, this product will stop the gap from growing.

It’s essential to fix a crack in your bathtub as soon as possible to prevent it from growing. This step will allow you to think of a more permanent solution.

Repair Kit

You can usually find a repair kit for your bathtub at your local hardware store. These kits are generally a permanent solution if the bathtub’s structure is plastic or fiberglass.

If you have a metal or ceramic bathtub, you might also consider using a repair kit. Aside from the materials needed to fix the issue, a repair kit also comes with various other accessories.

How Long Does the Flex Seal Last Once Applied?

The flexible seal can last for a long time once it’s applied. Generally, how long it will last depends on its applied surface. Also, if you coat it multiple times, it will last longer.

A flex seal can usually last for around a year on most surfaces. It can also be kept clean and extend its life even further.

Many people start using the flex seal surface after it dries. However, if you wait for 3 to 4 days, the character will get better and last longer. Also, applying the flex seal to the holes and cracks will fill them very well.

How to Repair a Cracked Bathtub?

You might have tried various methods to fix the cracks, such as using a plastic or a seal. However, these methods might not work all the time. Instead, you need to find a permanent solution.

Fiberglass or Epoxy Resin

It repairs most bathtubs; some types, such as those not made of fiberglass, can be treated with a resin known as epoxy. This process can be messy and take a bit of practice to get used to.

However, if you’re not a fan of getting messy, the resin is an excellent alternative to mending a fiberglass bathtub.

Foam Insulation

One of the most practical ways to create a waterproof seal is using polyurethane foam. However, this method can be challenging to apply if the crack is small. Another approach to fix this issue is by expanding foam, which will allow you to support and prevent the tub from ever cracking.


If you have a crack in your metal bathtub, you can weld it closed. Unfortunately, not everyone has the necessary skills to do this, so you might have to call a professional. However, a proper weld can make a bathtub look new once again.

Hire a Professional

Depending on the style of the bathtub and the crack it has, some repairs are beyond the skill level of most home do-it-yourselfers.

For instance, if you have a fiberglass bathtub, you should be able to fix it yourself. However, if you have a ceramic, porcelain, or metal bathtub, you might need professional help.

How to Prevent Bathtub Cracks?

If you notice that your bathtub is wobbling or buckling, it’s probably a sign that something will crack eventually. So, before it gets worse, try using expanding foam underneath the bathtub to prevent it from happening in the first place.

Powerful cleaning products are for people who want to rush their way to get the best results. However, they can also weaken the finish of their bath’s surface.

Take care while you’re in the bath to prevent cracks. One of the most accessible routes is to avoid accidentally throwing objects or smashing the tub.

Frequently Asked Questions

Is Flex Seal Safe or Good for Bathtubs?

A flex seal is generally considered safe for use on most surfaces, such as the bathtub. Liquid sprays designed to protect the bathtub materials do not harm the surface. It means that you can use it on almost any type of surface.

Applying the flex seal to your bathtub will prevent water from getting into the tub and maintain its fresh look. It will also dry quickly and will not make the bathtub unsafe.

If you use a flex seal on your bathtub, it will not react with water once it has dried, making it entirely safe for use. Once the flex seal dries, it can withstand any mild water problems.

What Will Flex Seal Not Stick To?

Because of its flexible nature, you can mold flex seals onto almost any surface. However, it will not stick to certain types of plastics and rubbers. The flex seal’s structural properties are not ideal for these materials.

The structural properties of flexible seals are not strong enough for certain plastics and rubbers. They can also not resist silicone. If you want to use a flex seal on an item with silicon parts, you need first to remove the silicon parts.


Flex seals can be used to fix small cracks in porcelain baths, but you should not use them permanently as they might not be able to withstand the pressure of a full bathtub. It could cause the crack to widen, which could cause the issue to worsen.

Usually, you can repair cracks in fiberglass bathtubs with an epoxy coating. However, if they are more prominent, it’s best to call a professional to fix them. This method can help prevent further damage to the bathtub and prevent injuries.