Epoxy paint then assemble, or paint after?

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ditherer
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Epoxy paint then assemble, or paint after?

Post by ditherer »

I know the rule is to give 2 (or 3?) coats of epoxy prior to putting all the bits together… and if you do each new coat while the previous one is tacky, you get some nice chemical bonding (rather than having to rely on mechanical bonding after sanding), but why not assemble, glue/fillet, then do the 2-3 coats? Isn’t that easier?

I know it’s harder to get around, but better than trying to manage a pile of painted bits & pieces, let alone trying to do recoats-while-tacky… isn’t it?
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Heimfried
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Re: Epoxy paint then assemble, or paint after?

Post by Heimfried »

To my knowledge there is a so called "open time" for any sort of epoxy which should be between 24 and 72 hours. I'm building a different boat and used this open time (in my case 24 h) to put on the next epoxi coat or laminate with glass and did so for more than 4 years without any problems. And it is no more tacky after 6 to 10 h. It is far easier to coat an even surface than most parts of a existing boat.
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dsimonson
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Re: Epoxy paint then assemble, or paint after?

Post by dsimonson »

I was building in Camp 1, we didn't pre-coat anything, and I did several "hot-coats" once assembled. It was really a mix of some sanding between coats, and some hot-coating, depending on sequence, timing, and where in the boat at what time. Lots of sanding... in small spaces! I think getting a few coats on pieces before assembly would be a bit easier, if you've got the space to do it.
Peter E
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Re: Epoxy paint then assemble, or paint after?

Post by Peter E »

I pre coated all my parts before assembling. The epoxy I used I didn't have to worry about blush. I coated the pieces in the eve so the temperature dropped after I was done. This seemed to eliminate most off gassing bubbles. I spread the epoxy with spatulas used in auto body shops. Depending on the size of the piece the size of the spatula. The most important thing is to go slow less bubbles. One coat a day. Don't forget the edges if water is going to damage the ply this is the weak point.
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Re: Epoxy paint then assemble, or paint after?

Post by pocketyacht »

First off. Don't pre coat parts with epoxy before assembly!!

Second time your coats when you do apply so you can coat while the epoxy is still green (soft).

First coat on, within 36 hours take a utility razor blade and like a windshield wiper scrape away until the out gas roughness is gone, apply a second coat, within 36 hours give it a light sand as needed to smooth any drips, rough spots, etc and coat again. Done.

Do this procedure with a 4" foam roller followed by a slightly wet foam brush, roll and tip method.
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