Kirby's Marine Primer | first-time user's question

Selected Kirby's Topside Hull & Deck alkyds for my Waterlust project, with their primer going on first before finish coats inside & out.

Applied first coat to well-scuffed (wet ScotchBrite) epoxified cockpit yesterday, wondering now when it'll be hard-cured enough for wet sanding before second coat.

It was 72° / 53% RH when I applied it w/ 3" foam roller, later reached 80° / 54% RH overnight. 15 hours later it's dry to the touch but still seems soft, but as this is my first use I'm curious just how long I need to wait until I can sand then re-coat. Information on label doesn't cover this so rather than call Kirby's I thought I'd ask the folks here who've used this stuff themselves.

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RE: Kirby's Marine Primer | first-time user's question

I haven't used Kirby's so I can't answer directly, but your reference to wet sanding primer is ringing an alarm bell for me. All the marine primers I've used have been high build primers with talc. Wet sanding those would be a bad idea. Some folks here, Dick Dowell and his Peeler Skiff come to mind, have had problems with high build primers absorbing water. If you haven't previously wet sanded Kirby's and their literature doesn't tell you to wet sand it, you might want to check with them before you do.



RE: Kirby's Marine Primer | first-time user's question

Interesting perspective, thanks.

Talc's one of the 'filler' ingredients listed on the label, along with titanium dioxide and zinc oxide.

No I haven't yet begun to sand yet - wet or dry - but was about to begin.

So your suggestion to contact Kirby's for their recommendation is a good one. I'll call tomorrow. I'll be leave water out of the process until after I hear what they recommend.


RE: Kirby's Marine Primer | first-time user's question

   I would be interested in Kirby's response to your question.   I will be applying some of their primer soon.



Keith H

RE: Kirby's Marine Primer | first-time user's question

I use Kirby's paint on my Skerry, but I did not use their primer.  My understanding was that the high build primer is useful for helping to acheive a smooth surface, but was not necessary for good adhesion.  15 years of use on my boat has proved that to be true - I've never had an issue with the paint.

RE: Kirby's Marine Primer | first-time user's question

Good info Bob, thanks for posting that!

I'm more for using their primer on the cockpit for its 'fill-in' capability; it was much trickier keeping epoxy under control than on the hull's exterior. Sanding epoxy's not something I look forward to and trying for smooth, level surfaces in the interior makes it an even more unattractive a proposition. If their primer aids in providing a more uniform surface for the finish coats to me it's worth the effort. I don't want to compromise the bond though if water's not something that should get on the primer prior to finish coating.

RE: Kirby's Marine Primer | first-time user's question

   I used the Interlux PreKote primer under Brightsides on the outside of my Skerry for the reason that I had a number of irregularities in the surface that I felt I couldn't get sanded out.  I should have tried harder.  I wound up leaving too much of the PreKote on the surface and it's soft compared to the Brightsides so the finish as a whole has not been as hard as I wished.  Also, I was painting in the spring and didn't get the finish coats on fast, so the Prekote absorbed humidity and I had some adhesion issues.  Sand, repaint.  Grr.

I used the Brightsides right on the epoxy in the interior, and it's harder and while my finish is still a bit lumpy, it is still ok from 10 feet away.  For that reason, I wouldn't use a high fill primer over epoxy again unless I did a better job of sanding and fairing, so there was very little primer left after sanding.  I'm using Prekote on my kaholo, but the big flat surfaces mean that the sanding is easier than the skerry, and I've used epoxy/phenolic microballoon fairing mix to deal with the remaining dips and not relying on the primer.

Years ago I used Kirby paints on a CLC canoe project for my nephew.  They have some different colors, and my young (at the time) nephew chose some fun colors for his:  Bright orange exterior and cream interior.  Named, of course, the "Creamsicle".

They were very traditional paints and they take quite a while to fully harden, especially on epoxy where they aren't soaking into bare wood.  I would give it 2-3 weeks anyway before using.  And sanding (dry sanding) resulted in balls of gummy paint if I didn't give it at least 3 days.  No wet sanding, and be very patient with the drying time, if these are the same base paints as I used.  That said they spread beautifully with a brush and don't require as many coats as Brightsides, which goes on very thin (if you know what's good for you).

RE: Kirby's Marine Primer | first-time user's question

+1 on what Mummichog says about fairing with fairing compound instead of primer. Epoxy/microballoon mix does a better job filling large and medium scale irregularities than high build primers. Save those for pinhead sized holes.

On one boat I used microballoons, followed by System Three 2 part Yacht Primer followed by System Three 2 part linear polyurethane paint with a cross linked last coat. This had the advantage that System Three's epoxies would bond to the primer, as well as the other way around. That was very handy when I found that I had missed a spot when fairing. I didn't notice it before priming, but after priming it was really obvious - it looked like an irregular gouge nearly 1/4 inch deep. I was able to leave the primer on, glop some microballoon fairing compound onto it and sand it smooth, then prime and paint it. My point with all this is that rather than mixing and matching paints, primers, fillers and epoxies, sometimes there's a real advantage to considering it as a finishing system and having the manufacturer's compatibility working for you.



RE: Kirby's Marine Primer | first-time user's question

Called Kirby's last Tuesday, got George K. on the line. Put question to him, he replied he doesn't see why there'd be any problem with wet-sanding their primer. So I did a small trial Tuesday evening with some black 3M 220 W/D, used first dry and then with water to lubricate during sanding.

Used dry the dust was quick to accumulate. This primer, once dry, is still relatively soft, easy to sand. Need to wear a respirator, vacuum often.

Done wet the dust becomes a slurry, sanding action’s faster. Mopping up the slurry residue's easy enough using microfiber cloths than can be rinsed & re-used, or maybe a sponge. Wet-sanded surface is smoother to the touch than what had been sanded dry.

Before I began I did note areas where primer had been left a bit thick could be easily scratched with a fingernail, to the point the primer could be gouged away. This after drying for over 48 hours. Now after five days those areas are much more resistant, harder to get anything off. Good to remember when re-coating that the drips & heavier coverage will take longer to dry to full hardness.

Glad I posted my question here, good stuff coming back from Forum members in response.

I agree with Laszlo's comments on choosing finishing components carefully for the desired end result. It's good that we have so many choices for what we want to achieve, and that we can take advantage of the experiences of others here about what their experiences have been as we look to chooe what to use for ourselves.


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