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Preview: How to Use Epoxy, Part 2 – Getting a Smooth Finish for Paint or Varnish

March 24, 2016

Eric Blake continues his walkthrough on how to use epoxy to get a smooth finish for paint or varnish at the Brooklin Boat Yard.

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– We’re back in the shop here and gonna have a look at our epoxied, clear-coat panels. These first couple panels were just a clear-coat, one with a fast-cure epoxy, and one with a clear-coat epoxy. But they were just rolled, and left right off the roller. So kind of, two coats, just applied. This third panel was rolled and tipped out, and you can see the difference between these. There’s a little dust in this, but it’s a much flatter, smoother surface. With epoxy, you know these drools that you get, you get what you get. It looks how you leave it. So that is just hardened, thickened epoxy that is much higher off the surface than this here. So it’s very important when you’re laying epoxy to do many thin coats, and take the time to tip it out with a brush. Always good to wear a dust mask, a paper mask is fine. You know cured epoxy is FDA approved. You can kind of eat off of it, but not something you wanna breath. Carcinogenic just like any nuisance dust, wood dust. Always have a dust mask. So I’m just gonna grab a foam block with some 80 grit. And what I wanna show you is with this first panel, I’m sure anyone who’s used epoxy before knows about amine blush. Amine blush is a byproduct of epoxy and it actually is a very thin wax that comes to the surface when the epoxy cures. Some epoxies are a lower blush than others. This clear coating epoxy that we used is a lower blush formula. But you see that as you sand that epoxy, if you’re very close to the next day it’ll kinda ball up. But it just clogs your paper, and your get these kind of dobs of wax that will shorten the life of your paper. One way to get rid of that amine wax is a very quick scuff with Scotch-Brite and some warm water they say. And that will just kind of wash that residue off the surface, and certainly extend the life of your sandpaper. I’m gonna block this out for a coat of primer, and we’ll see what all these panels look like with a little paint on them. Certainly the key to sanding out epoxy is using, sanding in general, is using a sanding block. This is just a piece of Styrofoam, I have these other sanding blocks. You can see, as I sand, there are areas that are higher and lower. And that’s just a product of not getting the epoxy rolled out evenly enough. And a lot of people’s big problems with coating with epoxy is they don’t spend the time to get it laid out nice and evenly. You end up with these highs and lows. You’re not sanding with a sanding block. You end up burning through the low spots and the high spots are left as epoxy. As you sand through, the wood under is softer than the epoxy, and you get this incredibly mottled surface which is just a nightmare to put any paint on going forward, and have it look good. I’m not gonna spend lots of time here, but just coming through here I wanna show you this spot which was kind of haphazardly coated. And as you start to sand that– There’s nothing nice about that. That is just a really bad application process. This is much higher than the surrounding area. And you really created a very unfair surface out off a nice flat sheet of plywood. So over here, where we’ve rolled and tipped– Less the dust particles, it’s very easy to get a completely flat and epoxy sealed surface. I just took the tops off of the dust particles that were in there, with 80 grit, and now I’ll use a 120 on a soft block. So that’s kind of it right there in a nutshell. The more evenly applied and tipped out the epoxy is, you end up with a surface that is very very fair, and incredibly flat. And when you put a coat of primer or varnish on that it’s just gonna look like the grain is filled and it’s beautifully finished. A sloppy epoxy job, or just something right off the roller, if you plan to paint or varnish over it, you can create a lot of work for yourself, and you see that here. You don’t wanna put paint or varnish, or anything over epoxy that is still glossy like this. Now there’s two rules of thumb here. I have taken time to roll and tip out a nice smooth coat. This would be a panel in a cockpit, a door panel, something that I wanted a quick build-up that was gonna be a glossy finish whether it’s varnish or paint. So a lot of time was taken in the application of that. In the bilge of a boat, you may just wanna roll a couple coats of epoxy on, and you’re never gonna see it again. It’s under the sole boards. Typically, what I will do in areas that I want a good epoxy seal, but I don’t necessarily care about the finish, is take the tops off of that like this, and then grab some Scotch-Brite to leave as much of the epoxy barrier on the surface as possible. I’ll simply take a Scotch-Brite pad, and you can see that Scotch-Brite de-glosses that epoxy very quickly, and that is all you would need to do to that surface for a quick and dirty paint. This is leaving maximum epoxy barrier on, and giving you something you could throw a coat of white bilge paint on. We’ve got these paint trays at the boat yard, and instead of going through lots and lots of disposable tray liners we just have a big roll of, kind of a kitchen size aluminum foil that we peel off and line our tray liners with. We’ve got our surfaces prepped and I just wanna throw some primer and some sealer at some of these, so you get a feel for what they look like, with some finish on them. Typically if you’re gonna paint something, I would go with a primer coat, as just a good tie coat before paint. One coat of primer and then go to paint. Primer’s gonna show up any defects, any pinholes, anything that needs body work. White on wood is definitely, if it’s gonna be painted, that first coat of primer is what’s really gonna give you a visual of body work going forward. Otherwise, I’m just gonna show you what a section of this looks like with some sealer. So I’ve just got a three-inch roller, some primer. And our first panel here, where it’s in the bilge, I’m just gonna roll it and not tip it at all and give you a look at what a quick and dirty finish will look like. This is just primer right out of the can. It’s nice, it kinda gives you an eggshell texture. We’re not even gonna mess with our improperly prepped surface. But here I wanna show ya primer, and then some sealer next to it. Then I’m gonna roll and tip out, like we did with the epoxy. And then next to it I’m just gonna put some 1026 sealer to show you how beautiful that can be finished clear, if properly prepped. These surfaces will dry very smooth. Be ready for coats of gloss, paint or varnish to create a beautiful water-proof surface without a lot of time investment that last well, with very low maintenance. Next we’ll get into laying fiberglass cloth and Dynel.


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