How to remove tough stains from fiberglass tub

How remove tough stains from fiberglass tubs can be a daunting task. Thankfully, there are several ways to go about it.

Taking care of your fiberglass tub is important in order to preserve its ACOC (advanced composite polyester) finish. Tough stains, grease, and acids can prematurely damage the finish. Here are three effective methods for removing tough stains from fiberglass tubs:

All three methods work well when used in combination with one another. You may want to try one or two of the methods before tackling the tougher stains with a more intensive approach.

remove tough stains from fiberglass tub

What Causes Fiberglass Tub Stains?

Although fiberglass tubs are touted for their durability and easy maintenance, they are not immune to staining. Stains can occur for a variety of reasons, including:

Hard water: This is perhaps the most common cause of staining on fiberglass tubs. Hard water contains minerals, like calcium and magnesium, which can leave behind unsightly deposits.

Soap scum: Soap scum is a mixture of soap and hard water minerals that can build up on the surface of your tub, causing stains.

Mold and mildew: These stubborn stains are usually the result of poor ventilation in your bathroom. When moisture isn’t properly ventilated, it can lead to the growth of mold and mildew.

Dirt and grime: Just like any other type of surface, fiberglass tubs can become stained with dirt and grime over time.

How to get tough stains out from fiberglass tub

There are a few different ways that you can remove tough stains from your fiberglass tub. You can use a commercial cleaner, or you can make your own cleaning solution with household items.

If you decide to use a commercial cleaner, be sure to read the labels and follow the instructions carefully. Some cleaners may require that you wear gloves or take other safety precautions.

If you prefer to make your own cleaning solution, you can mix together equal parts of vinegar and water. You can also add a few drops of dish soap to this mixture. Apply the solution to the stained area and scrub with a nylon brush. Rinse well with clean water.

Best way to clean a fiberglass tub

Set the controls on your washing machine for the delicate cycle and a warm water temperature. Place the stained articles of clothing in the washer, along with one cup of baking soda. Allow the clothes to soak in the baking soda and water solution for at least 30 minutes, then finish the cycle.

How to remove mildew from a fiberglass tub

Mildew can be a tough stain to remove, but with the right cleaners and some elbow grease, you can get rid of it for good. Here’s how to remove mildew from a fiberglass tub:

  • Start by mixing a solution of equal parts water and white vinegar in a spray bottle.
  • Spray the affected area with the Vinegar Solution and let it sit for 5-10 minutes.
  • While the solution is sitting, fill a bucket with warm soapy water.
  • After the Vinegar Solution has had a chance to work, scrub the area with a soft sponge or brush.
  • Rinse the area thoroughly with warm water and dry it off with a clean towel.

Clean with bleach

Bleach is one of the most effective cleaning agents available and can be used to clean a variety of surfaces, including fiberglass. However, bleach is also a harsh chemical that can damage your tub if it is not used correctly. When cleaning your fiberglass tub with bleach, always use a diluted solution and never leave the bleach on the surface for more than a few minutes.

To make a diluted bleach solution, mix one-part bleach with nine parts water. Once you have mixed the solution, wet a clean rag or sponge in the bleach water and use it to scrub the surface of your tub. Be sure to scrub all of the stained areas until they are no longer visible.

Once you have finished scrubbing, rinse the tub with clean water to remove any residual bleach. Dry the tub with a clean towel or let it air dry.

Clean with vinegar

To clean a fiberglass tub with vinegar, start by mixing 1 part vinegar with 4 parts water. Then, soak a clean cloth in the mixture and use it to scrub the entire surface of the tub. Once you’ve scrubbed the entire tub, rinse it clean with water.

Clean with baking soda

For light cleaning, mix 1/2 cup baking soda with a small amount of water to form a paste. Rub the paste onto the stained areas of the tub with a soft cloth. Rinse the tub with warm water. For tougher stains, add 1/4 cup white vinegar to the baking soda paste. Rub the mixture into the stain and let it sit for five minutes before rinsing with warm water.

Clean with dish soap

First, wet the tub with hot water and then squirt dish soap all over the surface of the tub. Use a sponge to work the dish soap into a lather, and then scrub the entire tub. Pay special attention to any areas that seem particularly dirty. Once you’ve scrubbed the entire tub, rinse it with hot water. Finish by wiping down the tub with a clean, dry towel.

Clean with a pumice stone

If you have a fiberglass tub that is starting to show its age, you may be wondering how to clean it. You may be tempted to just use a harsh cleaner and scrub away, but this can actually damage the tub and make it look worse.

A pumice stone is a natural way to clean a fiberglass tub without damaging it. The stone is simply rubbed over the stained area and the stain will start to come off. You may need to do this a few times to get the stain completely out, but it will not damage the tub as harsh chemicals can.

Tips for Preventing Fiberglass Tub Stains

There are a few simple tips you can follow to help prevent staining on your fiberglass tub. First, try to avoid using products that contain harsh chemicals or abrasives, as these can damage the surface of the tub. Instead, opt for gentle, non-abrasive cleaners. You should also avoid letting soap build up on the tub, as this can lead to staining. Be sure to rinse off any soap residue after each use, and wipe the tub down with a soft, dry cloth. Finally, try to avoid using hot water when cleaning the tub, as this can also cause staining.

Frequently Asked Questions

Here are some answers to some common questions about cleaning and maintaining a fiberglass tub:

Can I use bleach to clean my fiberglass tub?

While bleach can be an effective disinfectant, it can also be harsh and abrasive on fiberglass surfaces. It is best to avoid using bleach on a fiberglass tub as it can cause the surface to become dull and discolored. Instead, try using a cleaner specifically designed for fiberglass surfaces, or a mixture of water and vinegar.

How do I remove hard water stains from my fiberglass tub?

Hard water stains can be difficult to remove, but there are a few things you can try:

  • Use a commercial hard water stain remover or a mixture of equal parts vinegar and water. Apply the mixture to the stains and let it sit for several minutes before scrubbing with a soft-bristled brush.
  • Try using a pumice stone to gently scrub away the stains.
  • If the stains are still not coming off, you may need to use a stronger cleaning product like a hydrofluoric acid-based cleaner. Be sure to follow the instructions on the product carefully and test a small, inconspicuous area before applying it to the entire stain.

Can I use a power washer to clean my fiberglass tub?

While a power washer can be an effective tool for cleaning a variety of surfaces, it is not recommended for use on a fiberglass tub. The high-pressure water can cause damage to the surface of the tub and make it more prone to staining. It is best to stick to using a soft-bristled brush or sponge and a gentle cleaning solution.

How do I remove scratches from my fiberglass tub?

To remove scratches from a fiberglass tub, you can try using a fiberglass repair kit or fine-grit sandpaper. Follow the instructions provided with the repair kit or sand the scratches lightly with the sandpaper until they are less noticeable. You may need to apply a coat of fiberglass resin to complete the repair. If the scratches are deep or numerous, it may be best to call a professional to repair the tub.


If your fiberglass tub is looking stained and dingy, you can easily clean it with some common household ingredients. Vinegar, baking soda, and lemon juice are all great options for removing stains from fiberglass.

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Camilo Kawas is a seasoned entrepreneur and expert in the field of commercial cleaning, with a specific focus on clothes, carpet cleaning and floor care. With a profound understanding of the importance of selecting the right products for effective stain removal from clothes, Camilo has established himself as a trusted authority in the industry.