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Tips On How To Fix A Crack In Fiberglass Tub


How To Fix A Crack In Fiberglass Tub

Fiberglass bathtubs are a sturdy, long-lasting, and affordable alternative to regular metallic or ceramic bathtubs. However, fiberglass tubs can develop tiny cracks due to stress from insufficient support and wear and tear from consistent use.

These tiny cracks can deteriorate into more profound fractures or openings within the tub walls or floor. Fortunately, you can fix the cracks on your bathtub and prevent further damage. This article explains how you can fix hairline cracks on your fiberglass.

How To Fix A Crack In Fiberglass Tub 

Materials required:

You’ll need the following materials to fix a crack in a fiberglass bathtub:

  • household cleaner,
  • a cleaning sponge,
  • scissors,
  • a small paintbrush,
  • fine-grit sandpaper or emery cloth,
  • rubber gloves,
  • a dry lint-free piece of fabric, and
  • a fiberglass tub cracks repair kit. 

Ensure there’s sufficient ventilation in the room before you proceed.

You can now repair the fiberglass crack using the steps below when you have the required materials.

Clean the crack and allow it to dry:

Scrub off any dirt and debris around the damage using a sponge and your household cleaner. Rinse with water and dry it using a lint-free cloth.

Sand crack area for a somewhat rough texture:

Sand the crack area using sandpaper to get a slightly rough surface. You can also use an emery cloth in the absence of sandpaper. 

You can easily add adhesives and other components from the repair kit with a rough texture. Brush off the remaining dirt from the sanding with clothing or even a brush.

Apply the adhesive:

The repair kit should contain an adhesive or binding agent with preparation instructions. Prepare the adhesive accordingly and apply it to the sanded area using the brush in the repair kit or any paintbrush.

Ensure the adhesive covers the area around the crack (not less than an inch away). In addition, ensure that the adhesive penetrates deeply into the crack to allow for sufficient saturation. Allow some time to pass to enable the bond to dry.

Fill the crack:

The next thing to do when the adhesive dries is to fill the crack with the fiberglass filler from the repair kit. Use a knife to ensure the filler completely penetrates the crack. Wipe off any excess filler and allow it to dry.

Sand the filled crack area:

Sand the crack area again with sandpaper paper or emery cloth to level the crack area with the surrounding area. Be careful not to dig into the filler and undo the repair.

Coat the crack area with epoxy:

Make an epoxy mixture according to the instructions on the epoxy resin in the fiberglass kit. Make a substantial amount of the mix because you’ll use it beyond this stage. Apply the mixture to the crack area, extending by at least 2 inches to the surrounding area.

Add fiberglass clothing:

Your repair kit also contains fiberglass clothing. Cut out some fiberglass clothing according to the size of the area of the epoxy mixture. 

Place the cloth over the crack and press firmly before the mixture dries. Run a putty knife over the fabric to eliminate air bubbles.

Apply more epoxy mixture:

You’ll be needing the epoxy mixture again. This time, apply enough epoxy mixture around the clothing with a paintbrush.

Apply the epoxy mixture over and around the fiberglass clothing using the paintbrush. Apply a generous but reasonable coat of the epoxy mixture in this stage. 

Seal the area:

The final step is to seal your repair efforts. Using the sealer in your fiberglass kit, cover the layers of repair materials on the cracked site to prevent water from penetrating and damaging the area.

Allow the sealer to dry before using your bathtub again. The area you just repaired would likely have lost its glossy finish. Apply a buffing compound to restore the glossing. 

A fiberglass bathtub crack is never a pretty sight. It spoils the overall look of the bathtub. But what causes cracks in fiberglass bathtubs? 

Why Do Fiberglass Bathtubs Crack?

Fiberglass bathtubs may crack due to one or more of the following reasons.

Improper installation:

Fiberglass is a flexible material and can bend to weight. A fiberglass tub, therefore, requires appropriate support to endure repeated usage. A plumber should support the bathtub with a sturdy concrete mixture. If your bathtub has numerous fractures, there’s probably a problem with the installation. A wrong installation can cause a fiberglass tub to crack from undue pressure. 

Heavy objects:

Dropping heavy objects on a fiberglass bathtub can cause it to crack. If you drop shampoo bottles, they are unlikely to cause significant harm. Cracks can form when plumbers drop heavy tools during installation or when kids play with toys in the bathtub.

Abrasive cleaners:

Harsh cleaners may diminish the tub’s luster and degrade the finish. Instead, choose a gentle bathroom cleaner that you may leave on for five minutes before wiping away with a washcloth.

Cleaning is essential in maintaining your fiberglass tub. However, you have to use suitable materials to preserve its sheen and prevent cracks. Continue reading to get valuable tips for cleaning your fiberglass tub. 

Fiberglass Tub Cleaning Tips

You don’t need harsh chemicals to clean your fiberglass tub. These cleaners can degrade the surface and, after some time, create cracks on the tub.

There are several natural and gentle cleaning alternatives for fiberglass tubs. They’re not only soft on your tubs, but they also don’t give off strong smells that aren’t good for you.

Your regular dish soap or laundry detergent:

A simple soap and water combination is one of the most accessible cleaning options for your bathtub cleaner any day. They’re practical, affordable, and readily accessible.

Laundry detergent or dish soap will quickly remove dirt and grease and keep your tub fresh and clean. However, use only cleaning agents that have no fragrance or bleaching agents.

Fill a bucket with warm water. Add some drops of liquid soap. Soak up the mixture with a sponge and clean your tub’s surface or floor. Leave the soapy mixture on the fiberglass surface for at least an hour and then rinse with water. Then, dry the remaining fluid with a towel to avoid watermarks.

Use Vinegar:

Another fantastic DIY fiberglass cleaner uses natural materials like vinegar and baking soda to cut through stubborn spots and mildew. When these ingredients are combined, an all-purpose bathroom cleaner is created, which you can use to clean your tub, shower stall, tiles, and even your tub faucet.

Hard water causes stains and mineral buildup, which you can remove with this simple DIY cleaning solution.

To clean a hot tub with vinegar, begin by mixing the solution and applying it to any stains or water sports in the tub. After allowing the paste to settle for at least one minute, scrub with a washcloth or sponge.

Use a mild scrub brush or a Magic Eraser to remove dirt and grime from tough stains. Rinse and dry the tub once you’ve finished, and for persistent stains, multiple applications or a different cleaning solution may be necessary.

Vinegar alternatives:

Lemon juice is an excellent alternative to vinegar for cleaning your fiberglass shower or tub. You can use lemon in several ways. 

You can use it as a spray bottle to saturate your tub surface. Cleaning the glass shower doors is also another idea with lemon juice. Sprinkle some salt on a half lemon if you have one lemon and not enough juice to rinse the tub. 

You can also use a lemon can as a makeshift scrubber to remove stubborn water stains. To avoid scratching the tub surface, use only a tiny amount of salt.

Another disinfectant, hydrogen peroxide, is a good substitute for vinegar. This approach is efficient on stubborn stains that vinegar and baking soda cannot remove.

Begin by covering the stain with multiple layers of white clothes. Allow the hydrogen peroxide to seep for several hours, preferably overnight, for the hydrogen peroxide to seep into the fabrics. Rinse the hydrogen peroxide away and dry with a clean cloth after sitting for a while.

Use Borax:

Another excellent cleanser for your fiberglass tub is Borax. You may also use it on most bathroom surfaces, including tile floors and grout. You only need a small amount of Borax to produce a significant effect when using a cleaning solution.

Combine the contents in a small bucket and transfer them to a spray bottle for more accessible application. Spray the tub’s surface with the cleaning solution and allow one hour. Next, use a soft sponge to brush away any residual cleanser before rinsing with clean water. To avoid the emergence of watermarks, always dry the tub after cleaning.


Fiberglass bathtubs are a sturdy, long-lasting, and affordable alternative to regular metallic or ceramic bathtubs. However, fiberglass tubs can develop tiny cracks due to stress from insufficient support and wear and tear from consistent use.

These tiny cracks can deteriorate into more profound fractures or openings within the tub walls or floor. You can clean these cracks by following the steps provided in this article.

Improper installation, using abrasive cleaners can cause cracks in your fiberglass. Safe cleaning solutions include soap or laundry detergent and water, vinegar, lemon, and Borax. Use soap that has no fragrance or bleaching agents.

Jacob Lindsey

Jacob is a home remodeling guru having worked over 15 years in construction in Reno, NV, mainly focused on home renovations. He likes taking ideas from his clients and making them a reality.

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