How to Whiten Plastic or Fiberglass Tubs & Showers

Well-used acrylic plastic and fiberglass tub surrounds and shower stalls seldom retain their pristine appearance. Things that fade the original white color to an unappealing, dull yellow include surface grime, dyes in soap or shampoo, and hard water deposits. If the stall or tub surround wasn't expensive, however, a certain amount of the discoloration may be caused by changes in the plastic or fiberglass itself. While you can clean yellow stains -- and even some dyes -- you can only restore chemically faded plastic or fiberglass by repainting it.

Cleaning Stains

You may not know what is causing the yellowing, but if it isn't uniform, it's probably exterior staining. The non-abrasive cleaners that may remove these stains include:

  • Dishwashing detergent. Mix an ounce in a gallon of water and scrub with a sponge or plastic scrubbing pad.
  • All-purpose household or bathroom cleaner. Use this in the same way as you would use dish detergent. You can also use shampoo or body soap.
  • Baking soda. Make a paste with water and scrub the stall with a sponge or plastic applicator.
  • White distilled vinegar. Spray the vinegar full-strength on the stains; let it stay there for a few minutes, and then scrub it off.
  • Acetone or turpentine. Wipe these solvents on the plastic with a soft cloth to remove stains caused by dye, paint or pigments.

Help for Hard Water Deposits

Because it contains acetic acid, which dissolves the salts in hard water, vinegar is an effective treatment for mineral deposits that can yellow a fiberglass or acrylic bathroom fixture. It works best if allowed to stay on the deposits for minutes or even hours, but if you spray or wipe it on a vertical surface, it quickly runs off or evaporates. To prevent runoff, mix vinegar with borax to make a paste; spread the paste liberally on the discoloration and scrub it off after an hour or so. You may need to spray the paste periodically with more vinegar to keep it wet.

Restoring Chemically Faded Plastic

If age has turned the color of your shower stall or tub surround to a uniform insipid yellow, you probably won't be able to restore the color with a cleaner. Instead, purchase a tub and shower refinishing kit from a hardware store or building supply outlet. The kit contains paint specially designed for use on acrylic and fiberglass as well as chemicals to prepare the plastic. Follow the instructions in the container when using one of these products. It's important to wear a respirator and provide ventilation in the space in which you're working, because the chemicals are volatile and noxious.