Gelcoat Spray Gun: The Right Tool for a Great Job

Ask any handyman and they’ll be the first to tell you that a professionally done job requires only the best tools. Spraying a boat with gelcoat is no different. If you use the wrong tools, or the wrong thinners and nozzles, your job will be far less effective and aesthetically pleasing.

Gelcoats are preferred by many fiberglass boat owners because they are very visually pleasing and provide a good amount of protection over time. Gelcoats are almost always included on fiberglass boats new from the factory. Gelcoats can last up to a decade, but they require annual (sometimes more) polishing to maintain the integrity of the gelcoat.

Gelcoat is commonly applied using a spray gun. A spray gun connects to a supply of compressed air that pushes the pigment out from the nozzle onto a surface. The painter presses on a trigger to make the spray paint exit through the nozzle of the gun.

Spray guns have several dials that allow you to adjust the flow of the paint. Most spray guns have two dials, known as the “fan control” and “fluid control”. The fan control dial controls how wide the swath of paint is when it exits the gun. You should aim for your swath to be about as wide as the length of your hand (7-8 inches). Your fluid control simply controls how much paint is released into the nozzle. Most spray guns require 2 twists of the fluid control nozzle, and this will suffice for the amount of paint flowing from the nozzle.

The spray gun also has a pressure regulator and dial which tells you what “PSI” you’re spraying at. The higher the PSI, the more quickly the pigment will exit the spray gun. The PSI you need to use with your gun depends on the brand of gelcoat, and this will typically come with the instructions provided by the gelcoat manufacturer. When spraying in hotter temperatures, you will typically use a lower PSI to avoid a “sandy” look to your gelcoat.

Gelcoat Spray Gun

Gelcoat Spray Gun

When spraying the gelcoat, you should place the gun about 7-8 inches from the surface of your boat. As you swipe from one side to another, you should aim for 40-50% overlapping of the layers as you move across the surface of your boat. You also need to ensure you spray any crevices that aren’t covered by your initial coat.

When spraying gelcoat, you will need several spray nozzle tips. Using a larger nozzle tip in the initial coats of gelcoat will allow you to thin the gelcoat less and still be able to spray it onto the boat. For the initial coats, a good size nozzle tip is a 2.2 to 2.5 mm tip. For the final finish, a 1 mm tip will work because you will have thinned the gelcoat sufficiently with your surfacing wax and patch booster.

The amount of layers and the thickness of these layers should be provided by the gelcoat manufacturer, as well as the sanding requirement for your boat in between coats. When done properly, a sprayed gelcoat can save you application time and ensure optimum coverage over your hull.

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