Can You Stain a Fiberglass Deck?

Why Choose Fiberglass

• Fiberglass decks provide a weatherproof surface, but they still require sealing to keep the porous surface from staining. Walking across such decks barefoot does not come with the hazard of splinters in your feet. The smooth surface feels like the inside of a shower stall because the two are made of the same materials. Once installed, a fiberglass deck requires little maintenance, making it ideal for busy boat or homeowners.

Why a Fiberglass Deck Stains

• The surface of fiberglass is not completely solid. Microscopic holes create a porous surface. Unless the surface is coated with a protective coating to seal these pores, stains can happen. Stains occur when rust or a liquid penetrates the pores in a fiberglass deck. To remove the stain, you must get down into these pores to lift the stain out.

Removing Stains From Fiberglass

• Although muriatic acid is certainly effective at removing stains from fiberglass, it can damage the coating if used excessively, says Dan Dickinson, author of "Powerboat Reports Guide to Powerboat Gear: Take the Guesswork Out of Gear Buying." To be safe, opt for specialty fiberglass stain-remover products, which contain less-caustic acids than muriatic acid. For stains other than rust, a simple all-purpose cleaner will work to clean the fiberglass, especially if you catch the stain before it dries and sets.

Preventing Stains

• To prevent stains on a fiberglass deck, you must seal it. For best results use a synthetic polymer polish instead of a natural wax. The polymer polish will penetrate deeper into the fiberglass, creating a tighter seal on the surface. To ensure you cover the entire deck with the polish, William M. Burr in "Boat Maintenance: The Essential Guide to Cleaning, Painting, and Cosmetics" suggests wearing polarized sunglasses. Uncovered areas will stand out more when you're wearing the glasses.