bottom paint

erbinsky

Canoeist/Builder
I am building a 16 ft. Sassafrass lapstrake canoe and after reading tons of material on paints and primers I'm more confused than when I started.I've glassed the bottom 4 planks with 6 oz. cloth and the entire outside of the hull with west system epoxy.It's sanded smooth and if it was one of my cedar strip canoes I would varnish it and be done.My question is do I have to prime the sanded epoxy before I paint it or can I paint right over the epoxy.Also the question of 1 part or 2 part paints comes into play.Any advice would be greatly appreciated. Thanks Jeff.
 
Over WEST epoxy that's been sanded smooth, I don't think you'll find that primer adds anything to the equation except another fairly soft layer which needs to be sanded smooth before you can apply the real paint. I've done a number of sail boats and canoes (and even a small portion of my garage's exterior) with marine enamel (Interlux Brightside) over sanded WEST epoxy and it's always worked out great. The only one I ever did with primer annoyed the hell out of me when I had to re-sand the entire boat first, just to get back to a smooth surface to put the paint on and it didn't hold-up any better. In their book, the Gougeon Brothers also stated that there didn't seem to be any advantage to priming properly prepared epoxy, so that's good enough for me.

Most one-part enamels won't tolerate sitting in the water for more than day-trip-type excursions (they'll peel if, for example, you leave the boat in the water for several days on a mooring) but for typical canoe use this isn't a problem. Two-part paints are certainly tougher, but are more expensive, more toxic to apply, very thin - so they show surface irregularities more and the application is somewhat more tricky. On a canoe, I doubt I'd bother with them. In any case, if you drag the boat over a rocky beach or hit anything they probably aren't going to hold up much better than regular enamel.

Also be careful about prepping or washing the surface with solvents before painting. It can be done, but sometimes adding another chemical to the mix just seems to cause future adhesion problems. Unless you believe that spots have been contaminated, a rubdown using plain water and a Scotchbrite pad seems to be the best way to be sure you have a clean, amine-blush-free surface that's ready to paint (let it dry first...).
 
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