How to Fix Weathered Fiberglass

Pour 1 cup of detergent into 1 gallon of warm water. Clean the old, dulled gelcoat off the fiberglass using a sponge soaked in this solution. Adding 1 cup of household bleach to your solution removes mildew if necessary. Rinse the fiberglass thoroughly with water and let it dry.

Remove oil and grease buildup from the fiberglass surface by wiping a clean rag soaked in either acetone or MEK. Completely remove grease and oil from the gelcoat surface for polish or wax to work. Using detergent alone to remove oil and grease often leaves reside in the gelcoat's porous surface.

Apply wax to the fiberglass with a clean, foam pad or cloth using circular motions. Let the wax dry to a haze, and then buff the excess with an old towel or other clean, soft cloth. The wax fills in microscopic pitting in the fiberglass surface resulting in a smooth, reflective surface.

Polish the fiberglass. Using a soft cloth, a apply the polish to small areas at a time in circular motion. Polish each section until it becomes glassy. The polish works as an extremely fine, liquid sandpaper used to remove the pitted surface. Apply another coat of wax for appearance and protection purposes.

Use a rubbing compound if shine is not restored from polish. Rubbing compound is a highly abrasive cleaner applied to fiberglass in the same circular method as polish. Removing all wax in the same-direction sweeping motion avoids uneven compound distribution. Polish the fiberglass and buff it with wax following compound application.