Often fiberglass tub refinishing is needed because the tub itself was not supported well from below when it was installed. Surface cracks and even splits can develop from uneven pressure on the tub floor. In other cases, accumulated wear can abrade the smooth finish, allowing dirt and soap scum to build up in areas without visible cracks.
To fix cracks up to several inches in length, get a fiberglass tub repair kit. It includes a Dremel tool for sanding and refining the edge of the crack so that fresh fiberglass will adhere to it. Also included is support to install under the cracked area so it will sustain more pressure. Once you have smoothed the edge of the crack and installed the subsurface support, you can sand the surface and apply the new fiberglass layer. If you prefer, you can then sand and refinish the entire tub interior, then recoat it with a fiberglass refinishing spray. This process will make the repaired crack much less apparent, and the sprays are available in several colors.
If your fiberglass tub interior has no visible cracking, but just looks unsightly due to accumulated dirt and soap scum in tiny rough crevices, you can restore the surface with an effective surface cleaner. This three-part process includes two surface cleaners to remove hard-water mineral deposits and stains, and a polymer resurfacing coating that restores the gleam of a new fiberglass surface on your tub. The surface coating seals the tub interior to reduce the rate of new stain formation. Once you have restored your tub surface with this product, avoid using abrasive cleansers on your tub. They will break through the new coating and allow soap scum and dirt to build up again.
Rigid Bathtub Floor Inlay
If the center floor of your bathtub is the only area showing stains or cracks, line your bathtub with a rigid fiberglass floor inlay. They are bonded into place with a waterproof epoxy and are nearly invisible in a white tub.
Acrylic Polymer Refinishing
This method, although time-consuming and smelly due to the chemicals in the bonding primer and refinishing paint, works well. Most companies guarantee the results of these refinishes for at least two years. You need to sand the tub thoroughly, then apply two coats of surface primer. Allow 15 minutes for it to dry, then spray the first coat of the color-matched acrylic polymer, or update your tub to glistening white. Put on three coats altogether, and let the acrylic polymer dry for 30 minutes between each coating. You will be able to use your tub again within 48 hours.
The most expensive solution for refinishing your fiberglass tub is a bathtub refitting. Unfortunately, this is not a do-it-yourself project. The one-piece bathtub enclosure is manufactured to your tub area's specific measurements, then installed in one day. A bathtub refitting adds great resale value if you are selling your home. Most refits are guaranteed for 15 to 25 years.