When fabricating and repairing products reinforced with fiberglass, the most common coating for its surface is gel coat. Gel coat is a unique formulation using two-part polyester resin as the first layer of resin applied to a mold. It is commonly used for making a vinyl ester or polyester composite part. The purpose of this layer is to develop an opaque surface that will not show through like glass. Gel coats and other polyester resins are UV resistant. When they are properly cured, they can be safely submerged in water
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The composite parts are made in a female mold, with the gel coat applied to the surface and backed with several layers of fiberglass reinforcement and more resin. This part, when removed from the mold, would form the exterior surface of the parts. The different colors are achieved by using a colored gel coat. Most boats are made from gel coats with fiberglass and polyester resin.
What is a gel coat?
A gel coat is a special coating applied over the fiberglass surface on a boat. It is made from epoxy, polyester resin, and a catalyst, among other chemicals in its composition. In its natural state, the gel coat does not have any structural value. But when combined with fiberglass, it provides a durable and smooth surface that will prevent the hull from weakening quickly due to ultraviolet light and water intrusion.
The coating is the first material applied to the mold of the fiberglass hull of a boat, creating the exterior surface of the hull. Usually, the manufacturer also introduces pigments to give the gel coat the desired color. However, many manufacturers produce gel coats in a wide range of colors so that users do not have to add pigments to the base.
Gel coat coverage
The coating’s coverage varies based on the desired thickness and application techniques when applying gel coat, such as boat gel coat paint. Typically, it is thinly applied. Usually, a gallon of gel coat covers between 40 to 80 square feet (12.2 and 24.4 meters) at a thickness of 20 to 25 miles (0.508 to 0.635 mm).
Gel coat paint
Gel coats come in a wide range of colors. Thus, it is easy to find a color that will match what’s painted on your vehicle for repair. There will be no tell-tale sign that the vehicle is painted over or repaired. Although gel coat is sometimes called gel coating because it looks like paint, it is a resin layer. Therefore, it is easier to restore the gel coat than get another paint job.
Gel coat for coating or repair
The primary purpose of gel coat is for in-mold applications. However, you can also use gel coats for secondary application, like a coating. When used in this manner, the gel coat needs an air inhibitor to cure correctly. An air inhibitor could be styrene wax, PVA release film, or a high-gloss coat additive. The latter is often used for the boat’s hull that is above the waterline.
When using gel coat as a coating or repair material, there are several requirements, so read the manufacturer’s instructions carefully.
