Fiberglass is frequently used for bathtub and shower surround surfaces. This cost-effective material is long-lasting and requires only basic care and maintenance to keep it looking good. If you have hard water, stains will slowly build up on the surface of your fiberglass bathtub. Even if the bathtub is in otherwise clean condition, white film and crusty flakes caused by hard water leave the tub looking dirty. Remove hard water stains and prevent them from returning with the use of simple supplies found around the home.
Fill a spray bottle with undiluted white vinegar.
Spray the undiluted vinegar over the surface of the fiberglass tub. Allow it to sit on the hard water stains for 10 minutes to loosen the stains.
Soak paper towels with the vinegar spray and wrap them around the faucet of the bathtub to loosen hard water stains and mineral deposits. Leave the vinegar-soaked paper towels in place for 10 minutes, then discard them.
Pour white vinegar over a clean sponge to wet it. Sprinkle baking soda onto one side of the sponge. Scrub the hard water stained areas of the bathtub. Use the vinegar and baking soda combination to clean the rest of the tub, too.
Rinse the bathtub with water to wash away the stains and baking soda residue. Dry the fiberglass surface with a clean cloth.
Buff the sides of the fiberglass surface with olive oil to prevent hard water stains from forming again. Use a dry cloth to wipe off excess oil so the tub isn't slippery.
Substitute lemon juice for white vinegar to remove hard water stains, if desired.