Whether fiberglass, porcelain or acrylic, bathtubs inevitably become contaminated with grime that makes them unappealing. Each time you bathe, you shed dead skin, dirt particles and oils, which consolidate into scummy grime on tub surfaces. This grime becomes more attached to tub surfaces over time, causing otherwise shiny fiberglass, porcelain or acrylic to become dull. Dirty, dull bathtubs are unpleasant to use and look upon. Fortunately, basic solutions are capable of making any bathtub shiny again.
Squirt 1/4 tsp. of regular, mild dishwashing liquid into a 1-gallon bucket. Fill the bucket with water, and then thoroughly mix the solution.
Drench a cleaning rag with the dishwashing solution. Wipe the tub's surface to dislodge grime buildup and stains.
Continue wiping the tub's surface with the solution until all buildup and stains are gone. Frequently rinse the rag under the tub's faucet as you clean.
Saturate another rag with water. Wipe the tub's soapy surface to rinse away the solution.
Buff the tub's surface with a soft towel. Leave no moisture on the tub's surface.
Inspect the tub for shine. If the tub's surface isn't as shiny as you would prefer, apply car wax to another rag.
Wipe the tub walls (but not the bottom of the tub) with the wax, distributing it thinly and evenly. Let the thin coat of wax fully dry.
Buff the tub walls with a fresh rag, removing the excess wax buildup. Continue buffing the tub walls until they shine.