Will Alumetron harm new paint?

Skipper October 29, 2014 Ask The Skipper

Daniel G Spielbusch Asked:

I will be cleaning my fresh water badly algae overgrown aluminum pontoons with Algex when I pull it out soon. I will be painting the logs below the water line with a bottom paint for aluminum, because they are badly pitted/rough from years of not cleaning off the algae. I am planning on using 4 coats VS721 on the paint next spring and Alumetron above the waterline. Do I need to keep the Alumetron off the new bottom paint?

My goal is to restore the logs to a smooth/slick surface so the algae won’t grow so badly next year,use less gas and increase speed. It is stored on a lift trailer so I can access the full surface of the logs.

Answer:

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You can not apply VS721 over antifouling bottom paint. Also, it’s difficult to get paint to attach to aluminum unless you use some pretty aggressive primers, which are usually only available commercially or to the military. The other problem with paint below the waterline is that refinishing it is going to be an annual ritual. Sanding, scraping, repainting etc.

If the pontoons are a little rough, you may want to consider buffing them out with Alumabuff and a Linear Buffer. This will brighten the pontoons and help to smooth them out a bit. It will not do anything for the pits but will make the entire pontoon brighter and more like new. Just make sure that the corrosion is not all the way through the aluminum. If that’s the case you will need to weld them and grind the area smooth. Next coat the entire log with Alumetron. This will seal the surface and although it’s quite a thin coating it will help fill in the pits and at least seal them. You can then protect the area below the waterline with VS721. VS721 can be applied over Alumetron, once it cures. The pits will be below the waterline and not visible when the boat is in the water and the top will be nice and shiny silver.

If you can wipe the slime off the pontoons from time to time, you will not get any growth and the only maintenance you will need is to reapply the VS721 in the spring.

Thanks for your question,

Captain Aurora
Richard Kittar