Thread: Epoxy coating or not?

Epoxy encapsulation will stabilize the wood from moisture content changes. A few thin coats of epoxy under paint will not appreciably improve the hardness or abrasion resistance of the Okoume. Since this is a glued lap build, you'd be wise to fully encapsulate the pieces. Encapsulation serves several functions, with moisture ingress and rot resistance being high on the list. The disadvantages are it's increase in build effort and cost.

Mike,

All my boats have been fully epoxy coated inside and out. In addition to moisture control and rot resistance it also provides an excellent base for paint or varnish, but yes, it is a lot more work.

I am at the stage of epoxy coating the interior of the Suffolk Beach Punt right now. On a boat that size it makes a hell of a lot of epoxy sanding, but I stand by the benefit from experience with the previous builds.

Others may disagree. This subject comes up a bit for discussion on other wooden boat forums and normally generates some vigorous debate..

cheers, Cameron.

The only debate is full encapsulation or just surface treatments, really. Those suggesting surface treatments, generally don't have a lot of repair and restoration experience, so . . .

Plywood in particular needs some protection, especially the end grain, so epoxy just makes sense. I'm of the opinion (which has changed in recent years) that epoxy coatings under clear finishes are less desirable then under paint. My logic is, under paint you need the extra protection, because you can't see what's going on with the wood, so the extra protection is beneficial. Under clear coats, it's lot more work and you have to worry about both the epoxy and clear coat materials. Again I'm calculating under clear it's less desirable, as you can see if there's a problem before it bubbles up the paint.

This said, there's a reasonable arguement to be made for the added protection epoxy under clear finishes can provide. For example if you drop a winch handle on a varnish over epoxy combing, you might not damage the wood, even if the varnish gets scratched. This level of protection is minimal (without fabrics), but worth considering.

Lastly, and of course in favor of complete epoxy encapsulation, is moisture control. Epoxy encapsulated surfaces (painted or other wise) are much more stable and predictable. This alone is enough to force your hand, though a considerable amount of effort and materials will be needed for this decision, it adds to the durability of the finishes.

Thanks for the valuable input. Opinion on the Wooden Boat Forum where I asked the same question seems to be not to bother due to the amount of work and the cost but I think I will go ahead and do it. I have a couple of weeks (at least) to finally make up my mind so I will do a couple of test pieces to gauge the amount of work. I already have the epoxy and considering the time that has gone into the boat so far a few more weeks or so wont hurt.

The WoodenBoat (magazine) forum has changed in the last few years. Once a good resource, now a place for a few diehard traditionalists and self appointed experts, that don't like to be told they're incorrect when they are. I've stopped posting there about 4 years ago and I know of several professionals, that have done the same previously and since my leaving the site. It's a sin really, it once was a good resource. So, it's understanding that those remaining contributors, couldn't be bothered with epoxy coatings on your project. It's still your call and I've tried to offer both sides of the debate for you to ponder.

If you do decide to epoxy coat the interior, use pre-coating. It is much faster and easier, and more economical, to pre-coat the surfaces of planks, etc before assembly. Doing it to a clinker boat once everything is assembled is a real PITA, and will cost you heaps in sandpaper alone.

I have decided to go ahead with epoxy encapsulation and have nearly completed the first coat on the inside. Had a couple of runs but used a scraper to get rid of those. What grit sand paper is recommended between coats of epoxy and before undercoat. Seafarer has good info in his thread about his new boat regarding sanding between paint coats but I could not find any info about how to treat the epoxy between coats and before paint and or varnish. Is it essential to get rid of any possible amine blush?

100 grit will do a nice job, if putting a building primer over it, smoother grits, up to 280 if clear finishing over epoxy. Removing amine blush is absolutely necessary. If you skip this step and have a blush under paint, the paint will literally peel off in huge sheets, because it doesn't stick the waxy blush. You can remove blush, which is water soluble, with a ScotchBrite pad and mild soapy water. The method kills two birds with one stone, as it scuffs up the surface as well as cleans the blush. Sand until you remove all the gloss.

Thanks PAR. I think I am all set to go now.