Gel coat is a polyester resin based paint that is pigmented with color and infused with different additives for extra strength and protection. Gel coat requires a catalyst which is methyl ethyl ketone peroxide, or MEKP, in order to harden. Gel coat can be applied three different ways: brushed on, rolled on or sprayed on. Applying the gel coat with a brush or a roller can have setbacks such as lines or brush strokes in the finish. To get a smooth professional finish like you see on new fiberglass boats, spray application is the only way to go.
Prepare the surface that you will be gel coating by sanding it completely smooth using 300 grit sandpaper. In order for the gel coat to bond properly the entire surface must be thoroughly scuffed.
Blow the dust off of the surface and wipe the entire surface down with a rag damp with acetone. Let the surface dry completely.
Put on a pair of rubber gloves and fill a small bucket with gel coat. Add one to two percent catalyst and thoroughly stir it in using a paint stir. The more you add the faster the gel coat will harden. Generally after the gel coat is catalyzed it will begin to gel up after 20 to 30 minutes.
Paint the surface by dipping your roller or brush into the gel coat and applying the gel coat to the surface. Gel coat is relatively thick and should cover in one to two coats. Clean the brushes and rollers with acetone when you are done applying the gel coat.
Fill the spray gun with the catalyzed gel coat and apply the first coat in a heavy mist. Let the first coat begin to jell up and apply a second heavier coat. If needed apply a third heavy coat to completely cover the surface. Let the gel coat harden.
- Always protect your skin from catalyst to avoid chemical burns.
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