How to remove tough stains from fiberglass tub

Fiberglass tubs are a popular choice for bathrooms due to their durability, easy maintenance, and sleek, modern appearance. However, even the toughest fiberglass tubs can fall victim to stubborn stains over time. Whether it’s hard water buildup, soap scum, or the aftermath of a particularly messy bath bomb, getting a fiberglass tub back to looking brand new can be a real challenge.

In this comprehensive guide, we’ll cover the most effective methods for removing even the most stubborn stains from your fiberglass tub. From everyday cleaning tips to heavy-duty stain removal techniques, you’ll learn everything you need to know to restore your tub to its former glory. By the end, you’ll be equipped with the knowledge and tools to tackle any fiberglass tub stain that comes your way.

remove tough stains from fiberglass tub

The Importance of Proper Fiberglass Tub Maintenance

Before we dive into the stain removal strategies, it’s important to understand the importance of regular fiberglass tub maintenance. Proactive cleaning and care can go a long way in preventing tough stains from forming in the first place.

Fiberglass is a durable material, but it’s not indestructible. Over time, exposure to harsh chemicals, hard water, and general wear and tear can lead to discoloration, scratches, and the buildup of unsightly stains. Neglecting your fiberglass tub can quickly turn a once-pristine surface into a dingy, stained eyesore.

Regular cleaning and maintenance is key to keeping your fiberglass tub looking its best. Ideally, you should be wiping down your tub after each use to prevent soap scum, hard water, and other residues from building up. A quick wipe-down with a damp cloth or sponge can work wonders in keeping your tub clean and fresh.

Additionally, you should be giving your fiberglass tub a more thorough cleaning on a weekly or bi-weekly basis. This involves using a mild abrasive cleaner or tub and tile cleaner specifically formulated for fiberglass surfaces. Gently scrubbing the tub with a soft-bristled brush or sponge can help lift away any accumulated grime or stains before they have a chance to set in.

By staying on top of your fiberglass tub’s maintenance, you can help prevent the development of tough, stubborn stains in the first place. However, even the most diligent of tub cleaners can occasionally encounter a stain that just won’t budge. That’s where the specialized stain removal techniques we’ll cover next come into play.

Common Fiberglass Tub Stains and Their Causes

Before we delve into the stain removal methods, it’s helpful to understand the most common types of stains that can affect fiberglass tubs, as well as what causes them.

Hard Water Stains

Hard water is a common culprit when it comes to stubborn fiberglass tub stains. As water evaporates, it leaves behind mineral deposits that can cling to the tub’s surface, creating unsightly white or cloudy stains. These stains are particularly problematic in areas with high mineral content in the water supply.

Soap Scum

Soap scum is another common stain that plagues fiberglass tubs. As soap and shampoo residue mix with hard water minerals, they can form a sticky, grimy buildup on the tub’s surface. Soap scum stains often appear as a dull, hazy film or discolored patches.

Rust Stains

If your fiberglass tub is positioned near any metal fixtures, such as faucets or drains, rust stains can be a real problem. Metal components can corrode over time, leaving behind reddish-brown stains that are notoriously difficult to remove.

Makeup and Beauty Product Stains

Cosmetics, hair products, and other beauty items can also leave their mark on fiberglass tubs. Mascara, foundation, hair dye, and even toothpaste can all contribute to unsightly stains if not cleaned up promptly.

Mildew and Mold

Damp, humid bathroom environments can foster the growth of mildew and mold, which can lead to greenish-black stains on fiberglass tub surfaces. These stains are not only unsightly, but they can also pose health hazards if left unchecked.

Understanding the common culprits behind fiberglass tub stains is the first step in developing an effective removal strategy. Now, let’s dive into the various methods you can use to tackle even the toughest of stains.

Everyday Fiberglass Tub Cleaning Tips

For routine maintenance and the removal of light stains, there are a few everyday cleaning tips you can employ to keep your fiberglass tub looking its best.

Baking Soda and Vinegar

A simple mixture of baking soda and white vinegar can be an effective and eco-friendly way to tackle light stains and general grime. Start by sprinkling a generous amount of baking soda over the affected area, then spray or pour white vinegar over the top. Allow the mixture to fizz and sit for a few minutes before scrubbing with a soft-bristled brush or sponge. Rinse thoroughly with clean water.

Dish Soap and Water

A mild dish soap diluted in warm water can also be a great go-to for everyday fiberglass tub cleaning. Squirt a small amount of dish soap into a bucket of warm water, then use a soft sponge or cloth to gently scrub the tub’s surface. This method is particularly effective for removing soap scum and light stains.

Microfiber Cloths

Invest in some high-quality microfiber cloths to use when wiping down your fiberglass tub. The small fibers in microfiber cloths are effective at trapping and lifting away dirt, grime, and residue without scratching the tub’s surface.

Preventative Measures

In addition to regular cleaning, there are a few preventative measures you can take to help keep your fiberglass tub stain-free:

  • Wipe down the tub after each use to prevent soap scum and water stains from forming.
  • Use a squeegee to remove excess water from the tub’s surface after bathing.
  • Avoid using abrasive cleaners, scouring pads, or steel wool, as these can scratch the fiberglass.
  • Apply a protective sealant or polish to the tub’s surface every few months to create a barrier against stains.

By incorporating these everyday cleaning tips and preventative measures into your routine, you can help keep your fiberglass tub looking its best and make deeper stain removal easier when the need arises.

Heavy-Duty Stain Removal Techniques

For those stubborn, set-in stains that just won’t budge with everyday cleaning methods, there are some more heavy-duty stain removal techniques you can try.

Baking Soda and Hydrogen Peroxide

A paste made from baking soda and hydrogen peroxide can be an incredibly effective stain remover for fiberglass tubs. Start by creating a thick paste by mixing equal parts baking soda and hydrogen peroxide. Spread the paste over the affected area and let it sit for 15-20 minutes before scrubbing with a soft-bristled brush or sponge. Rinse thoroughly.

The combination of baking soda’s gentle abrasiveness and the oxidizing power of hydrogen peroxide makes this a potent stain-fighting duo. Just be sure to use caution, as hydrogen peroxide can be harsh on skin and eyes.

Lemon Juice and Salt

Another natural stain-fighting combination is lemon juice and salt. The citric acid in lemon juice helps break down and lift away stubborn stains, while the abrasive nature of salt provides extra scrubbing power.

To use this method, simply sprinkle a generous amount of salt over the stained area, then squeeze fresh lemon juice directly over the salt. Let the mixture sit for 10-15 minutes before scrubbing and rinsing. You may need to repeat this process a few times for particularly tough stains.

Fiberglass Tub Cleaner

If natural remedies aren’t cutting it, you may need to reach for a commercially-made fiberglass tub cleaner. Look for products specifically formulated to tackle tough stains on fiberglass, porcelain, and acrylic surfaces.

These cleaners often contain a blend of mild abrasives, degreasers, and stain-fighting agents that are designed to safely and effectively remove built-up grime, soap scum, hard water deposits, and other stubborn stains. Always follow the product’s instructions carefully, and test it on a small, inconspicuous area of the tub first.

Here are a few top-rated fiberglass tub cleaners to consider:

Zep Tub and Tile Cleaner– Powerful formula removes soap scum, hard water stains, and mildew
– Safe for use on fiberglass, porcelain, and acrylic surfaces
– Non-abrasive, won’t scratch or dull surfaces
Bar Keepers Friend Fiberglass Cleaner– Specially formulated for fiberglass and acrylic tubs and showers
– Removes tough stains and buildup without scratching
– Contains oxalic acid to dissolve and lift away stains
Clorox Tilex Mold and Mildew Remover– Kills 99.9% of mold and mildew on contact
– Effectively removes stains caused by mold and mildew
– Safe for use on fiberglass, ceramic, and porcelain surfaces

Chemical Stripper

In extreme cases, you may need to enlist the help of a chemical stripper to remove deeply embedded stains. Chemical strippers contain powerful solvents that can break down and lift away even the toughest of fiberglass tub stains.

However, it’s important to exercise extreme caution when using chemical strippers, as they can be harsh on both the tub surface and your skin. Ensure the area is well-ventilated, wear gloves and eye protection, and follow the manufacturer’s instructions to the letter. You may also want to consider hiring a professional cleaning service if you’re not comfortable handling harsh chemicals.

Depending on the severity of the stains, you may need to try a combination of these heavy-duty techniques to fully restore your fiberglass tub. Be patient, work methodically, and don’t be afraid to repeat the process if necessary.

Preventing Future Fiberglass Tub Stains

Once you’ve put in the hard work to remove those stubborn stains, the next step is to focus on prevention. Implementing a few simple strategies can help keep your fiberglass tub looking its best for years to come.

Establish a Consistent Cleaning Routine

As mentioned earlier, regular maintenance is key to preventing tough stains from forming in the first place. Commit to a consistent cleaning routine, whether that’s wiping down the tub after each use or giving it a thorough scrub on a weekly or bi-weekly basis.

Use the Right Cleaning Products

Stick to mild, non-abrasive cleaners specifically formulated for fiberglass surfaces. Avoid harsh chemicals, acidic cleaners, and anything containing bleach, as these can damage the tub’s finish over time.

Apply a Protective Sealant

Consider applying a clear, protective sealant or polish to your fiberglass tub every few months. This creates a barrier that helps repel water, soap scum, and other stain-causing substances. Reapply the sealant as directed to maintain its effectiveness.

Here are some top-rated fiberglass tub sealants to consider:

Gel-Gloss Fiberglass Tub & Shower Restoration Kit– Complete kit includes cleaner, sealant, and applicator
– Restores shine and protects against future stains
– Safe for use on fiberglass, acrylic, and porcelain
Granite Gold Tub & Tile Cleaner– Gentle, pH-balanced formula won’t damage surfaces
– Helps create a protective barrier against stains
– Safe for use on fiberglass, ceramic, and stone
Meguiar’s Mirror Glaze Fiberglass Restorer– Restores shine and luster to dull, oxidized fiberglass
– Fills in micro-scratches for a smooth, glossy finish
– Long-lasting protection against future stains and discoloration

Address Problems Promptly

If you notice the early signs of a stain or buildup, don’t wait to address it. The sooner you can tackle the issue, the easier it will be to remove. Act quickly to wipe away residue and prevent the stain from setting in.

Maintain Good Bathroom Ventilation

Poor bathroom ventilation can lead to the growth of mildew and mold, which can cause unsightly stains on fiberglass tubs. Ensure your bathroom has adequate airflow and consider using a dehumidifier to keep moisture levels in check.

By following these preventative measures, you can help keep your fiberglass tub looking its best and minimize the need for intensive stain removal in the future.


Removing tough stains from fiberglass tubs can be a challenging task, but with the right techniques and a bit of elbow grease, it’s certainly an achievable goal. From everyday cleaning tips to heavy-duty stain removal methods, you now have a comprehensive toolkit to tackle even the most stubborn of fiberglass tub blemishes.

Remember, proactive maintenance is key to keeping your tub stain-free. Establish a consistent cleaning routine, use the right products, and apply a protective sealant to create a barrier against future stains. And if you do encounter a particularly stubborn stain, don’t hesitate to try the specialized techniques outlined in this guide.

With a little patience and persistence, you can restore your fiberglass tub to its former glory and enjoy a gleaming, stain-free surface for years to come. Happy cleaning!

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As the founder of Clean It Spotless, I am Melissa Walker, a leading expert in removing tough stains from fabrics, carpets, and upholstery. With over 10 years of experience in the cleaning industry, I have developed my own natural, non-toxic stain-fighting formulas that lift stains while preserving the integrity of the underlying material. My stain removal tutorials are widely read online, and I have appeared on local TV segments demonstrating my techniques. I also present popular stain removal workshops at community centers and schools.