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How to Apply Antifouling Paint

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How to Apply Antifouling Paint

Most antifouling paints are chosen based on their performance characteristics. For this reason, it is very important to accurately prepare and apply the antifouling paint to your boat. If you take the correct steps in applying these paints, you will get the performance and desired effect out of the paint. The paint will also last longer and work more effectively if the proper steps are taken. The following steps are general suggestions for applying Antifouling bottom coat paint. You should always follow the manufactures suggestions when applying any paint to your boat.


The first step in any painting endeavor is to clean the surface of any grit and grime. This should start with a simple wash. The easiest time to clean your boat of the slime and grime is directly after you pull your boat out of the water. Right after you have removed your boat from the water, the dirt that has formed on your boat will be wet and easy to remove. If you let the gunk dry on the surface of your boat, you will have to scratch and rub for hours to remove the build up. A pressure washer is a great option to remove grime and any loose paint at the end of the season. After you have washed down the boat, you should strip and sand the surface.

Strip & Sand

The second step in the painting process in stripping and sanding your surface. The adhesion of the new paint will not be good if the paint underneath is peeling and failing. You need to take your favorite knife or chisel and chip off all of the paint that is flaking. Once you have scraped all of the excess paint off of the bottom, you need to wipe paint thinner over the hull. The paint thinner will remove any left over dirt, loose paint, and grease from your surface. After you have finished with the thinner, you should lightly sand your surface with 80 grit sandpaper and remove any sanding residue with fresh clean water. (If you are not aware of the previous bottom paint that was applied you should apply a bottom coat primer to ensure adhesion)

You should keep in mind that Antifouling paints contain toxic materials. You should wear a mask over your nose and mouth so that you do not inhale the residue after you sand your surface. You should also protect your eyes and ski to prevent any possible skin irritation.


Once the surface has been prepped it is time for the third step, stirring. Most antifouling paints contain large amounts of cuprous oxide. Cuprous Oxide is a high-density pigment that will settle on the bottom of the can. For this reason, it is extremely important to mix Antifouling paint vigorously. You will have to use good old fashion elbow grease. Pour the paint into a mixing bucket so that you will not slosh the contents onto the ground. At this point, stir those sediments off of the bottom of the can until your stir stick feels clean. Continue to stir until you have a uniform consistency and color in your paint. It can take up to 20 minutes to accurately stir your antifouling paint. Make sure that your paint is precisely stirred so that you get the protection you need.


Painters often see the high price of antifouling paint and want to stretch it as much as possible. Adding a thinner to antifouling paint is strongly discouraged. Antifouling paints are supposed to be applied as they are in the can. For difficult application conditions, small amounts of thinner may be needed. This should be done with extreme caution! Thinners can create and inadequate thickness which could lead to paint failure.


The fourth step in the painting process is applying the paint to the surface. Rolling is the easiest method to apply antifouling paint. To make your job a lot easier grab an extension handle from your local hardware. You should also wear long sleeves and gloves that can be discarded to protect your skin. First, you should tape your waterline so that your paint will be applied straight and even. Next, you should pour your paint into a tray. You can now dip your roller into the pan and apply your paint up and down (From the waterline to the Keel.). When you replenish your paint make sure you stir it to make sure the copper is evenly distributed. By the time you get around your boat the paint should be dried. If the manufacture suggests a second coat then go for it. Your paint will last longer with added protection. There is no prep work needed for second or third coats.

Congratulations! You are now finished! You can now clean up and relax on your freshly painted vessel.

All information was taken and modified from Pettit and Interlux product manuals.