Gel-coat is the most common finish for recreational and commercial fiberglass boats. It accomplishes two important roles on boats:
First, it looks good! It is available in many colors and provides a smooth, attractive finish.
It also provides important protection for the fiberglass laminate structure beneath. Sunlight and water are destructive to fiberglass over a long period of time. The finish provides an excellent barrier between the fiberglass and the elements.
This finish is available in liquid or paste form. It is a two-part polyester mixture that hardens when catalyzed. It does not cure when in contact with air, so special application techniques must be used. In new boat construction it is often sprayed on female hull molds prior to the application of fiberglass and cloth. In repairs, this method is seldom applicable. Instead, the material is applied to the repair and then covered with plastic or a barrier coat of polyvinyl alcohol (PVA). Some manufacturers offer an additive that rises to the surface after application, removing the need for PVA. After curing, this additive can be washed away with soap and water.
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