How to Remove Stains From Fiberglass Bathtubs and Shower Stalls

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Removing stains from fiberglass tubs and shower enclosures requires the right cleaning solutions and careful application to avoid damaging the finish. Fiberglass bathtubs and showers may develop stains from hard water or mold and may be marred by paint and adhesives. Fiberglass scratches easily, so full stain removal with gentle methods may take more than one attempt.


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Use Castile Soap

Try using a mild soap to remove stains on fiberglass tubs without scratching the surface.

  1. Apply a mild liquid soap to the stained area of the fiberglass with a sponge or soft cloth. A thick liquid soap such as Castile works well on shower walls.
  2. Leave the soap on the stain for 15 minutes, or up to an hour for a tough stain. When you return, rub the soap over the stain in a circular motion before rinsing.
  3. Rinse the soap away thoroughly with warm water. If any sign of the stain remains, repeat the procedure or try the next method.


Make a Scrubbing Paste

If Castile soap doesn't work, you can try making an abrasive paste.

  1. Mix baking soda with a small amount of water, such as 1 tablespoon of baking soda to 1 teaspoon of water, to create a thick paste.
  2. Dip a moist sponge or soft cloth into the baking soda mixture. Rub this mild abrasive on the stain to remove it without scratching the fiberglass.
  3. Rinse the baking soda off with warm water and wipe the surface with a dry soft cloth.


Try a Solvent-Based Cleaner

You can also try a solvent-based cleaner by applying it and letting it set on the stain for an hour before scrubbing the stain.

  1. Open the bathroom window and turn on the fan if there is one. Apply a quarter-size amount of nail polish remover or turpentine to a sponge or soft cloth. Always test a product like acetone or turpentine on an unobtrusive area of the fiberglass surface to make sure it doesn't affect the color before you apply it to a larger area.
  2. Moisten the stained area with the solvent. Apply more if needed and rub it in well. If the stain includes paint or adhesive, you'll need enough solvent to penetrate the materials that are adhering to the fiberglass.
  3. Allow the solvent to soak in for an hour. Scrub the stain with a a soft nylon brush. Dip a sponge of soft cloth in hot water and rub the area again if the stain is stubborn. Remove the residue with a clean, damp sponge or cloth. Wipe solvent off before you rinse the stain to keep the solvent from going down the drain. Don't get solvent on plastic, such as drain covers.