How to fix a crack in a bathtub: fiberglass, metal, and porcelain (AVOID Doing This!)

Don’t worry about having to get remodeling your bathroom if you have noticed a chip or crack in the tub. A bathtub can get a crack if a heavy object falls on it. This type of crack is called a stress crack. There are two kinds of crack, a stress crack, and a hairline crack. The latter appears with the tub being used for a long time.

Local hardware stores sell bathtub repair kits which you can use to fix a crack in your acrylic or fiberglass bathtub. These repair kits can save you hundreds of dollars. You have to use a patch to repair any more than 1/4th inch wide crack.


However, if you have a metal bathtub, you must call a professional because only welding can fix it. You need the right equipment and skills for this.

For a porcelain bathtub, you can use porcelain enamel paint or caulk if the cracks are not big. Porcelain is quite fragile so the area where you have made the repair will remain a weak point.

How can a bathtub get a crack?

Old tubs were made of cast iron which was then coated with porcelain, or made of stainless steel. Today the predominant material for building bathtubs is fiberglass and then comes acrylic. Bathtubs made with synthetic materials make them more affordable and long-lasting. But after using it for years, it is quite usual for them to develop cracks or fissures. 

There are a few different possibilities that can damage a tub. The most common ones are:

  • Improper installation. This means the tub was not properly installed. While installing a bathtub, it is important to check that it gets adequate support from below. Otherwise, the lack of unequal distribution of weight adds surplus pressure when a person gets in it. As a result, the added pressure affects certain points and causes hairline fissures. These fissures grow into more visible cracks. 
  • Heavy object. The second most common reason is the force with which a heavy object falls on the tub. Even a big bottle of soap or shampoo creates a lot of noise if it slips into an empty tub. When a heavy object falls, the power can cause fissures and dents on the tub’s surface. Don’t hang a shampoo rack above the tub as things can fall off it.
  • Abrasive cleaners. Most households use cleaners like bleach which makes the tub more damage-prone by corroding the coated finish. When the finish gets damaged, the acrylic or fiberglass gets exposed to water. This makes the material weak and gradually cracks start appearing in the bathtub.

Any one of the above reasons is enough to damage a bathtub. And a combination of these factors can prove fatal for it. Plastic tubs are most susceptible to damage. 

DIY tips on how to fix a crack in a bathtub

It is better to repair a crack in your bathtub as soon as you notice it. Otherwise, the damage is going to worsen because the crack is going to become larger. The following tips will help you fix a crack in most kinds of bathtubs. In addition, your bathtub will look almost new, and you will stop any mold growth or water damage that can affect the floor underneath your tub. 

Prepping is important

Before you repair the cracked surface and apply epoxy, you must clean it properly. You can skip cleaning the entire tub and clean the area where the chip or crack is. Use an abrasive cleaner to remove any residue like soap scum and then do the sanding. After doing this, you should again clean the area using cotton swabs to rub alcohol. 

Choose the correct refinishing kit

Most home-improvement stores epoxy bathtub repair kits which have two components. You should check and see which one is suitable for your bathtub. There are different epoxy repair kits for different surface materials like acrylic, ceramic, enamel, fiberglass, and porcelain. Additionally, you also need to get the correct shade of cream or white to match your bathroom. 

Use sandpaper carefully

Before refinishing the bathtub, you should sand the area which you will repair. This is to make the refinishing or patching compound hold on to the surface. While doing this, you must also take care not to sand any area other than the crack. Or the sandpaper will end up scratching other parts of the tub. Then you will have to patch the scratched area too. Pick fine sandpaper as some of them can be too rough.

Follow the instructions given on the epoxy kit

The two-component epoxy kit that you will buy for refinishing your tub will have instructions on them. It will tell you how to mix the components using a tray and a stick before patching. Some kits come with a small stirring stick and a mixing tray. You can use any small tray which you are ready to dispose of. If the pack doesn’t provide a disposable stick, you can use a toothpick, matchstick, or craft stick.

Put the tray on a steady surface for mixing the components so that there is no spillage. Now with the small stick or a spatula, smoothly apply the mixed epoxy into the chip or crack. Remember to apply in thin layers while you fill in the damaged area. Also, apply the layers in one direction. It is difficult to remove excess epoxy, so apply in a small quantity and add layers as needed. 

Give the patch time to dry

The instructions given on the package will also tell you how much time the patch will take to dry. Follow the recommendation and let it dry for the given duration. Either you have to let it dry for a couple of hours, or a whole day.

In some instances, you will have to smooth things out. Once the patch has become dry, use 400 or 600 grit sandpaper to sand the patch. Do this until the patched area becomes smooth like the rest of the tub’s surface. 

Touch the patched area after sanding. If you can still feel the crack or chip, it means that you haven’t done a great patching job. Unfortunately, the crack has not been filled in properly. Thankfully, you can always add another layer of epoxy mix to fill in the damage. 

Wait for the patch to dry. Your bathtub will become as good as new and ready to use.

It is annoying when something falls on your bath and creates a dent or crack. Luckily there are some kits that can help you to patch these. Don’t expect miracles from them but they can fill in some small holes. It makes it quite easy to repair the bath.