Rub it out. From the ProSlide® Waterslide Maintenance Manual: “If mild cleaners can’t remove stains, chalking or other discolorations, it’s time to use a rubbing compound.”
But which one? These compounds come in a variety of grits from very coarse to very fine; in most cases, very fine to fine grits are all that is needed. Remember to work a small area at a time (3 ft2/1 m2), and if you’re using a buffer keep the RPMs between 1,700 and 3,000 and use only light pressure to avoid scratching, pitting, gouging and swirl marks.
Sand it out. If the rubbing compound does not bring back the finish or repair minor scratches, try wet sanding the affected area. Be sure to keep the sandpaper wet at all times so you don’t gouge the surface. Start with 600 grit waterproof sandpaper and work up through 800 and 1,000 grit in ascending order.
Once you’ve rubbed or sanded out the stain, apply wax to the fiberglass surface.
Want to learn more ways to keep your slides stain-free?