How To Clean Fiberglass Tub That Has Yellowed?

White vinegar, baking soda, lemon juice, salt, shampoo, and soft drinks effectively eradicate the yellow stains of your fiberglass tub and make it spark white. 

However, you have to properly apply the remedy, follow the right process, and rinse the tub to get a magical cleaning. Otherwise, you may not get a clyster clear white bathtub as you expect. 

Don’t worry; in this post, we’ll share 7 natural, non-toxic, and pet-safe homemade remedies, and 3 commercial cleaners to deep clean the fiberglass tub. You hardly need 15 minutes and a little elbow grease to follow the instructions. 

So, without further beating the bush, let’s get started. 

Table of Contents

Why Is My Fiberglass Tub Turning Yellow?

Fiberglass Tub Turning Yellow

Using hot water during showers, soap scum, wrong usage, hard water, and rusty water for old fixtures are the main culprits to turning your white fiberglass tub yellow. 

Fiberglass genuinely looks snow-like white, which is great for decorating a bathroom to give an aesthetic appearance. Moreover, a fiberglass tub is more reasonable than porcelain, acrylic and ceramics. 

But the irritating thing is it becomes dirty quickly. If it won’t be maintained for some days, it turns yellow, even black stuff. 

Before knowing the cleaning methods, it’s wise to learn what makes it yellow. 

Wrong Using

A bathtub is designed to use for bathing. But, it is too large and can hold a lot of water. Many people use it as a pond or aquarium. So, having water all the time in the tub is enough to turn it yellow even within 3-4 days. 

Using Hot Water

Especially in the winter season, you might use lukewarm water for showers. Water Hotshots on the tub surface will fade the shine of fiberglass. So it looks pale and yellowish. 

Soap & Shampoo Scum

Usually, you use soap or shampoo each time you use the tub for a shower. 

That’s no problem. 

But, if you don’t have a habit of properly rinsing the tub before leaving the bathroom after a shower. Soap and shampoo scum will remain in the tub.

When a lot of scum is stored on the tub surface, it eventually turns yellow. 

Hard Water

Getting a supply of hard water in your bathroom from the municipality is a curse for all USA homeowners. 

In most cases, you may also be the victim of this. This hard water contains a huge amount of calcium and magnesium. The fiberglass tub turns yellow due to high mineral content. 

Old Fixtures

You often use a stainless steel faucet, shower, and other fittings for durability. But, over time, rust and corrosion affect the fittings. 

When rust and corrode affects the fixture microscopic deposits mix with water. That creates a layer on the white bathtub. So you find your tub yellow. 

Debris Buildup

Caulking is used to properly install the tub’s fittings and ensure no water leakage. But, when many years have passed, these caulking may loosen from the exact space. The caulking dirt and debris are also another reason for the yellow bathtub. 

See also  How to Clean Plastic Shower Floor and Tile Grout: Guide!

These are the reasons that turn your white fiberglass tub yellow within a few days or years. Now, it’s time to look forward to its cleaning methods. 

How To Clean Fiberglass Tub That Has Yellowed

How To Clean Fiberglass Tub That Has Yellowed

There are various, especially homemade, ways to clean the tub. Some are effective for regular cleaning, and others for deep cleaning. 

Many homeowners also love to use store-bought commercial cleaners, as they can’t manage time for making these homemade solutions for their hectic schedules. Or won’t have patience. 

However, no matter which group you align with. We discuss the process in 2 sections. 

Section A shows you the easiest, fastest, and simplest homemade remedies. And in section B, we’ll mention 3 commercial bathtub cleaners that are effective but affordable.

Section A: Homemade Fiberglass Tub Cleaner

Homemade means 100% homemade. You’ll need some kitchen ingredients or food items that are available at your home most of the time and can avoid the hassle of buying anything extra for this. 

Remedy 1: White Vinegar & Water (Good For Soap & Shampoo Scum)

If your tub becomes yellow due to regular soap and shampoo scum, vinegar and water combination is excellent for removing these discolorations.

You’ll Need 

  • 1:1 ratio of white vinegar and water
  • A spray bottle
  • A scrubber pad
  • A towel


  • Fill half the spray bottle with white vinegar and half with water to avoid the hassle of liquid measurement. 
  • Properly mix the ingredients. 
  • Spray the solution on the tub surface and wait 5 minutes to work the vinegar acid on the dirt. 
  • Gently scrub the tub with the scrubber pad to remove the stains.
  • Open the faucet and rinse the tub thoroughly. 
  • Wipe the tub with a dry towel to dry it. 

Remedy 2: White Vinegar & Baking Soda (Good For Old Fixtures Rust)

If the tub is too yellow for passing rusty water, only vinegar won’t be effective. Here comes baking soda to strengthen the solution. You can use this solution to remove rusty water tough stains.

You’ll Need 

  • 1:1:1 ratio of white vinegar, lukewarm water, and liquid dish soap
  • 2 cups baking soda
  • A small glass bowl 
  • A putty knife 
  • A scrubber sponge
  • A towel


  • One by one, pour white vinegar, lukewarm water, and liquid dish soap into the glass bowl. 
  • Add baking soda to the liquid and slowly but continuously stir with the putty knife until it forms a paste-like pancake batter. 
  • Apply the paste on the specific area where the stains are stubborn and need deep cleaning. 
  • Let the paste sit on the surface for a few minutes. At that time, vinegar, baking soda, and soap soften the stubborn stains. 
  • Then scrub the tub with the sponge. 
  • Rinse the tub and see a clear, white, stain-free bathtub. 

Remedy 3: Sliced Lemon or Juice (Light Cleaning)

Who doesn’t love to get a fresh fragrance from the bathroom during a shower? 

See also  5 Easy Steps To Clean Bathtub Naturally without Chemical

Everybody loves you too. 

Our third remedy is lemon, which is good for your health and lightly cleans your fiberglass tubs with a fresh smell. 

You’ll Need

  • A lemon 
  • A spray bottle 
  • A scrubber sponge
  • A towel


  • Cut the lemon in half, and bring out its juice by squeezing both pieces. 
  • Now, fill the juice into a spray bottle.
  • Spray the juice on the tub surface where necessary. 
  • The acidic acid of the lemon juice will react with fiberglass to remove yellow stains. 
  • Gently scrub the tub. If you find the tub is filthy in some spaces, rub it with lemon slices. 
  • Rinse with lukewarm water. 
  • Make it dry wiping with the towel 

Remedy 4: Salty Water (Good For Hot Water Spot)

Cleaning fiberglass with salty water is helpful if your bathtub turns yellow for using hot water or its age. Because salt is naturally very abrasive, mixing it with water also makes it abrasive. So it works to remove water hot spots and year-round dirt and grime. 

You’ll Need

  • 1 cup water
  • 1 tablespoon salt
  • A spray bottle 
  • A scrubber sponge
  • A towel


  • Pour water into the spray bottle and add salt to it. 
  • Shake the bottle to mix water and salt properly. 
  • Spray the salty water on your fiberglass tub and let it sit for a few minutes. 
  • Gently rub the tub to clean stains that turn it yellow. 
  • Finally, rinse the tub with clean water and wipe. 

Remedy 5: Shampoo (Good For Light Cleaning)

Shampoo not only cleans your hair to make it look shiny, but it is also great to shine your bathtub. 

Amazing, right?

As it is already available in your bathroom, so you won’t arrange anything extra. 

You’ll Need

  • 1 tablespoon shampoo 
  • ½ cup water
  • A spray bottle 
  • A scrubber sponge
  • A towel


  • Pour ½ cup water into the bottle and add shampoo. 
  • Shake the bottle, so the shampoo distills the water and makes a good liquid cleaner. 
  • Spray cleaner on the tub, scrub with a sponge and rinse with clean water. 
  • Finally make the tub dry.

Remedy 6: Soft Drink (Good For Removing Water Spot )

Soft drinks, like coca cola and Pepsi, have Phosphoric Acid. You can use soft drinks to clean the tub, as this Phosphoric Acid will chemically react to remove the dirt and debris. 

You’ll Need

  • A bottle of Coke or Pepsi 
  • A scrubber sponge
  • A towel


  • Pour soft drinks clinging to the tub’s walls and wait for 10 minutes. 
  • During this time, the acid’s chemical reactions will soften the fiberglass’s stains. 
  • Gently scrub the space, and rinse with clean water to remove the stains, even a watermark spot. 
  • Wipe and dry the tub. 

Remedy 7: Borax (Good For Hard Water)

Have you supplied hard water in your bathroom? 

Thinking about how to clean the hard water stains… 

Here Borax comes to sparkle clean your fiberglass bathtub.  

You’ll Need

  • 1:1:1 ratio of Borax, dish soap, and lukewarm water
  • A putty knife 
  • A glass bowl 
  • A scrubber sponge
  • A towel


  • Add equal amounts of Borax, dish soap, and lukewarm water into the bowl. 
  • Make a paste by stirring them. 
  • Apply the paste to the bathtub and leave it for 30 minutes to 1 hour. 
  • Scrub the tub to remove softened grime. 
  • Rinse and wipe the tub. 
See also  How To Restore Shine To Fiberglass Shower?

Section B – Commercial Fiberglass Cleaner

Fiberglass isn’t only used for making tubs. Instead, hot tubs, water tanks, boats, etc., are also made with fiberglass. So, many companies that produce cleaning products supply fiberglass cleaners. You can use any of them. Here is a list of 3 products. 

1. Bio-Kleen Fiberglass Cleaner

It comes in gel form in a spray bottle to make it handy. The cleaner dissolves within seconds and works more rapidly than homemade remedies. Once you apply this cleaner, you’ll get the sparkling clean tub you wish to have. 

On top, it’s flexible and versatile to use on fiberglass tubs, boats, RVs, sinks, bowls, and even ceramic tiles. 

2. Bring It On Cleaner Hard Water Stain Remover

When the hard water stains make your fiberglass tub yellow with its mineral content and rust stains. You can go with Bring It On Cleaner Hard Water Stain Remover, as it is specially formulated to serve this purpose.

Besides cleaning the tub, it releases a fresh mint scent as it has mint as one of its ingredients. It’s non-toxic because any harsh chemical isn’t used.

3. Bio-Clean Eco-Friendly Hard Water Stain Remover

If you love a biodegradable fiberglass cleaner, this Bio Clean Eco-Friendly stain remover is a nice choice. 

No matter which strains (water spot soap scum, mineral deposits, lime scale), make your tub yellow. This all-purpose cleaner will magically clean all these and turn your tub white like new ones. 

Since it is non-scratchy and eco-friendly, there is no concern about scratching the tub or polluting the environment.

Note: To use your commercial cleaner to clean your fiberglass yellow bathtub, follow the company instructions. 

Tips To Avoid Quickly Yellowing Your Tub & Look Shiny

  • Wipe the tub to dry after each time you use it. Or keep the bathroom door open for some time to allow air to circulate; that will help dry the tub faster. 
  • Routinely clean the tub at least once a week. So the soap and shampoo scum won’t accumulate on the tub and make a yellow layer. 
  • Never adversely scrub the tub when cleaning, as it may scratch the fiberglass and look odd. 
  • If your tub is too old, you can use fiberglass makeover wax to reglaze its shine. Even applying this wax also limits the yellowing percentage of the tub.

Clean & Shine Fiberglass Tub

Using your home products, you can effortlessly sparkle and clean the tub as you love to look at it all the time. 

But, if you are a mom of toddlers, a corporate lady, or a senior person with back pain. It’s wise to make a lot of remedies at once, and store them for future use. So when needed, you can instantly use it. 

Or go with any of our suggested cleaners, that you find nice for you. 

The main thing is, fine tune your tub to look it white again and all the time even after using it for many years. 


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