Acrylic Tubs and Showers need special attention:

The major advancements in plumbing fixture variety and selection occurred with the use of fiberglass and acrylic plastic. These materials allow manufacturers to create an unlimited variety of shapes and sizes.

These units also offered freedom from the use of ceramic tile on the walls of shower stalls and bathtubs. This was a major step forward in making tub and shower areas easier to maintain.

The acrylic and fiberglass units do have their weak points, however. The finish on the products is not as hard as porcelain.  These products are extremely sensitive with respect to the type of cleaners that must be used.  Absolutely never use an abrasive cleaner on these products. Use the mildest soap, like regular dish soap DAWN (not dishwashing machine soap, these have abrasives in them!), that you can find. . Certain soaps and cleaners can actually fade the color of units. Some soaps contain alkalies that will actually cause cracks to appear in the finishes as well. You must use very mild soaps and clean often! Remember that these fixtures have a softer finish than cast iron products. This means that you MUST use softer cleaning instruments!! The best thing to use is simply a wash rag. Scouring pads of any type will, in all likelihood, leave tiny scratches.