How to Repaint Gelcoat

Lead Image
  • 2-50 hours
  • Intermediate
  • 0-1,000
What You'll Need
Painter's tape
Gelcoat spray gun
Methyl ethyl ketone peroxide (hardener)
Fine grit sandpaper
Palm sander

Gelcoat is a material made of polyester resin used on industrial pipes, pools, showers, and boats. It is the same material used to build the hull of boats with the exception that it does not contain fiberglass. Gelcoats typically contain additives and pigments for protection against harmful UV rays. It also has good waterproofing and anti-abrasive properties. Gelcoat is the preferred material for painting fiberglass since it offers good protection.

Over time, gelcoat’s colors fade. If an area has become dull and cannot be repaired by buffing and chemical cleaning—a repainting job is in order. Because of their thick consistency, gelcoats require spray guns during application. Gelcoat and related application materials are readily and widely available in marine supply stores.

Step 1 - Prepare Area

using a spray paint gun

Preparation of the area is as important as painting itself. The quality of the final product will not only depend on the painting skills of the laborer, but also on the extent and thoroughness of the preparation.

Prepare the area for painting by stripping the old coat. Put on a respirator mask. Sand the area using a fine grit sandpaper and palm sander; sand thoroughly until the surface becomes dull, leaving little or no trace of the old gelcoat. Remove excess grease or fine particles off of the area by running a rag soaked in acetone over it. Make sure to leave no traces of grease since it can cause gelcoat to bubble and not stick properly later on.

Protect areas that do not need repainting, such as edges, with tape. For large areas, cover them with thin plastic sheets; use a tape, the ones used during painting, to hold them in place. Remove detachable parts that will not be involved in the repainting.

Step 2 - Apply Initial Coating

Following the manufacturer’s recommendations, put the hardener and gelcoat in the spray gun. The gelcoat gun will bind the gelcoat with the hardener during spraying. The first coat is important as this will serve as a base coat for the second and final coating. Spray a heavy coat of the mixture on the surface. Make sure the coat is consistent and even. Next, allow the gelcoat to cure and harden before proceeding to the final coating.

Step 3 - Apply Final Coating

For the final coating, apply a heavy coat making sure that all areas are fully coated; apply a consistent and even coat to prevent paint runs. Allow paint to harden and cure.

A good gelcoat repaint job can restore fiberglass products such as boats to its original condition. Care should be taken when applying gelcoat, as it is highly hazardous to one’s health. Make sure to wear the appropriate protective clothing such as goggles and respirators to keep you safe while doing the whole repainting process.