Basic Painting Questions

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Re: Basic Painting Questions

Postby marcusg » Tue Aug 24, 2021 9:09 pm

So I was just thinking about my floor, and about the spots that got delaminated. I sloppily expoxied most of them, but it’s not perfect and there definitely is wood showing…

Anyways, I just looked it up and apparently gelcoat only adheres to fiberglass? I got three quarts of this stuff in white:

https://www.iboats.com/shop/hi-bond-gel ... h-wax.html

…as well as the sprayable PVA stuff Greenlake recommended to help the stuff cure.

My question: since there are delamination spots on the floor, plus inconsistent spots where there’s paint or bondo or who knows what, do I need to just glass the whole dang floor to get this stuff to bond? I guess it wouldn’t be that expensive to buy a bunch of thin glass mat and enough s3 silvertip to do the whole floor…is that what’s needed?
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Re: Basic Painting Questions

Postby GreenLake » Wed Aug 25, 2021 2:16 am

SystemThree used to make a special SB epoxy that supposed worked well as a substrate for gelcoat. It was intended for surfboards that were then coated with gelcoat. There's this persistent story that gelcoat doesn't bond with epoxy, but closer reading seems to indicate that it's a matter of preparation (including getting the mix correct for the epoxy). Hence some of the special formulations.

I would expect that correctly mixed and cured SilverTip should work as well, just hunt around a bit to see whether there are some helpful tips for that applicaiton, like things to look out for other than getting the mix just right.
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Re: Basic Painting Questions

Postby marcusg » Wed Aug 25, 2021 11:18 am

So on your experiment with Gelcoating your floor, did you have to remove any and all traces of any sort of paint, leaving only pure epoxy-coated fiberglass/laminate?
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Re: Basic Painting Questions

Postby marcusg » Wed Aug 25, 2021 11:24 am

...and could I in theory skip on wetting out 40 sq ft or so of cloth and just make sure to coat the whole floor in a thin coat of epoxy?
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Re: Basic Painting Questions

Postby GreenLake » Wed Aug 25, 2021 12:04 pm

I had a mixture of paint. Some flaking, some adhering. And exposed laminate. Some of the exposed laminate I had given a coat of "neutral" gelcoat years ago. That's the transparent kind that they use for the really dark tints. When I put the gray gelcoat on, I scraped to get the flakes off, sanded a bit with a coarse disk and went from there. Gelcoat has held up well. It's now, what, a year? It's not smooth, because there was remaining texture and I inadvertently added some in places whether with small drips or ridges from the spreader I used to distribute it in the foot well. Even with all of that it still looks better than what was there before...
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Re: Basic Painting Questions

Postby marcusg » Wed Aug 25, 2021 4:35 pm

Ok cool, I’ll just patch up the exposed wood in a few spots with actual glass and then go for it. I was all ready to pull the trigger on a gallon and a half of s3 all purpose epoxy and a ton of 6oz cloth in case I needed to re-glass the whole thing before gelcoating, or in case gelcoating won’t work and I’d just re glass it then paint. Btw in planning to paint anyways with Pettit’s ezpoxy antiskid (“ez decks.”)

For now I’ll save $250 on panic buying more materials and just do a test on a patch when I get home. From what I’m reading the percentage of mekp catalyst can be tricky to get right for the stuff to harden in a reasonable time. Supposedly it’s about double or more of what they recommend. Although with the pva trick maybe that’s a mute point. Nervous as it’s a lot of new materials and I’ll need to figure out how to test them without starting a ticking time clock on when the can life of the different components runs out. Pretty sure I can pre-catalyze just a bit of gelcoat and not have to rush too bad with the rest of the can, but the spray pva I’m not sure.
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Re: Basic Painting Questions

Postby marcusg » Wed Aug 25, 2021 4:42 pm

(part of my panicked rush is to finish her with enough time to sail this year...as I've now got three years worth of repair experience, and about 10 hours of sailing experience...)
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Re: Basic Painting Questions

Postby marcusg » Wed Aug 25, 2021 4:54 pm

Oh...just realized...since there's going to be wax embedded in the gelcoat, does that mean I won't be able to paint it? I know prior to painting it's a big deal to remove wax with solvents. Or can I "wipe away" the wax with mineral spirits etc. same as on the hull and rest of the boat? -- EDIT: nevermind, looks like I can from a quick google
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Re: Basic Painting Questions

Postby GreenLake » Wed Aug 25, 2021 5:24 pm

Make sure to go sailing!

Looks like you have everything else in hand.
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Re: Basic Painting Questions

Postby marcusg » Thu Sep 02, 2021 10:31 pm

Going to test my Pettit easypoxy on a canoe I have first to gain confidence in rolling and tipping. To get canoe ready to paint, I faired gelcoat holes with Totalfair, then while experimenting with my waxed evercoat gelcoat, I realized it definitely does not bond to total fair. Which makes sense, since it's porous and I forgot to seal it with a coat of neat epoxy. Also it could've blushed I suppose.

notfair.jpg
notfair.jpg (85.57 KiB) Viewed 284155 times


Also did a test with the gelcoat on raw wood, laminated wood, and 3m filler'ed wood. The 3m filler bonded and cured the best, and the rest of it seemed to cure only if I laid it on thicker. The thinner spots didn't cure at all. But that wasn't the case on my previously-gelcoated canoe - everything seemed to cure except for the spots with fairing compound.

I have PVA and spray bottles but from what I read that's only for unwaxed gelcoat.

Tomorrow I'm going to do a test with gelcoat on:
-"dry" fiberglass (roughed up part of floor that doesn't look well-loaded with epoxy)
-epoxied glass on floor
-3m'ed floor
-totalfaired floor (after de-blushed and neat epoxied)
-primer'ed floor (old primer from sanding paint off, or maybe it's bondo who knows)

testspots.jpg
testspots.jpg (109.69 KiB) Viewed 284155 times


I ended up calling System three and they told me their epoxy doesn't bond to gelcoat, but I think they're just going on the assumption that epoxy never does, which is demonstrably untrue according to boatworks today video:
https://www.youtube.com/watch?v=kHAbygl ... b_imp_woyt

Good thread on the subject:
https://forums.sailinganarchy.com/index ... wont-cure/
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Re: Basic Painting Questions

Postby GreenLake » Sat Sep 04, 2021 12:06 am

Some gelcoats don't cure well in thin layers.
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Re: Basic Painting Questions

Postby marcusg » Tue Sep 07, 2021 6:22 pm

I’m still experimenting with the gelcoat. Now I’m trying rolling it on and seeing if I can get something more consistent that covers a wider area without using so much and having it be so unevenly distributed with a brush.

Today I primed my canoe with Pettits primer. They say you’re supposed to roll and tip it but in my experience there was no tipping it as soon as I tried tipping it it just smudged it around and I know you’re supposed to use the latest of pressure. I tried with both a foam brush and a tipping bristle brush with no luck. I did what I could to even it out with the roller but now that it’s dried it’s not the most even surface. I don’t necessarily need perfection for my canoe but the point here was to practice for the multi hundred dollar paint job on my sailstar, which I’m not any more confident on now. Pettit says I shouldn’t need to thin, especially considering I painted in 65 degrees in the shade with 65% humidity. What gives? I used a 1/8 system three foam roller…maybe too thin of coats? Took about 8 ounces of primer to cover the 12 foot canoe.
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Re: Basic Painting Questions

Postby tomodda » Tue Sep 07, 2021 6:56 pm

I don't think you can "Roll and tip" primer, it's meant to have a final sanding before the topcoat. Just brush. Lay the paint down starting a little away from last painted and draw it to the wet edge. Use a light hand, make sure not to "flick" the bristles as you come off the hull. The paint should flow like ink. Good practice for the top coat. Don't worry about holidays, sand them out later. Most important, try to maintain "wet on wet," if it dries too fast, then work in smaller patches. Don't thin the primer at all, let it do its thing, which is to build a nice surface for your topcoat.

Just my humble opinion. Learn good wet on wet technique, then roll and tip the top coats. In general, don't overthink it. The paint will "tell" you what to do and mistakes can always be sanded out. As I tell my (few remaining) friends, "When do you know it's done? When you're good and sick of sanding!" Stress less, sail more.
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Re: Basic Painting Questions

Postby marcusg » Sun Sep 12, 2021 9:48 pm

So on this "basic painting project" (ha!) I'm finally, after two years, getting really close to the fabled painting.

Question: Is there some order that makes more sense to paint than others? I'll be painting everything but the bottom (except for a couple repaired patches.) And I'll be using EZpoxy and EZdecks on all of it (plus EZ-prime,) which I've heard needs a good cure before messing with it.

I'm thinking maybe to do the hull topsides, then decks, then cockpit.
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Re: Basic Painting Questions

Postby tomodda » Mon Sep 13, 2021 12:34 pm

Sounds like a reasonable order of business. I painted in the reverse order to what you propose, but I flipped the boat to do the hull (I did bottom too). Two suggestions:

1) If you are trailersailing, not mooring the boat, then you don't need a different bottom paint below the waterline. My entire hull (from gunwales on down, anyway) is Kirby Green #3, with a nice red stripe at the waterline.

2) Use masking tape and plenty of it! Get the good stuff (Frogtape, for instance). For what it's worth, I taped up to the lines of where I wanted to paint, and taped newspaper on the other side, in other words, the same tape went to the paintline on one side and held a sheet of newspaper on the other. That way, I saved myself from the inevitable runs and paint drips. I also newspapered my seats when I was doing the cockpit and decks. Of course, if you are a better painter than I, then just cut in carefully (that's what the Pros do, masking tape is for amateurs, aka me!).

Tom
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