How to Refinish a Gel Coat on Fiberglass

How to Refinish a Gel Coat on Fiberglass

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Gelcoat is polyester resin that is pigmented. It comes in many colors, and in most cases it has additives that make it resistant to ultraviolet rays. It can also contain wax to give it a marble-like finish. Gelcoat is used for a protective layer over the fiberglass but also doubles as paint. Gelcoats are used for many fiberglass applications including boats, tanks, air scrubbers, duct work, and bathtubs.

Items you will need

  • Fine-grit sandpaper

  • Electric palm sander

  • Painters' tape

  • Rags

  • Paint roller

  • Disposable paint bucket

  • Stir sticks

  • Acetone

  • Gelcoat

  • Gelcoat hardner

  • Detergent or liquid soap

Use fine grit sandpaper and an electric palm sander to prepare the area that you are refinishing. Smooth out all the cracks and fractures in the gelcoat. A palm sander significantly speeds up this process.

Wipe area down with clean rags and acetone. Clean any oil or residue from the surface.

Wash with soap and water to ensure the piece is acetone free. Let dry.

Use painters' tape or masking tape to protect areas you don't want to be covered with gelcoat. Remove the tape before the gelcoat hardens. If left until after the gelcoat hardens it can be a hassle to get off.

Mix your gelcoat with the hardener as directed on the container. Apply the first coat. let it cure, and then add the second. Two coats are usually standard. Let gelcoat cure for at least one to two hours.

Wax your gelcoat with standard boat wax. Apply generously with a clean rag in circular motions and let dry. Buff out with a fresh rag until it shines. Wax is not just for looks it also protects the gelcoat.


  • Always wear a respirator when working with fiberglass materials. If you have any cuts on your hands, wear rubber gloves when using acetone. Work in a well-ventilated area when gelcoating.


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