SleepNpilot,

CLC provides a pretty thorough guide for painting with polyurethanes. My only additions would be emphasize the warning about humidity and Pre-Kote and to remind you that high fill primers like Pre-Kote are much softer than paint. Their purpose is to fill imperfections and it is expected that you will sand most of primer off, ultimately leaving it only in the low spots it is filling. Brightsides bonds to sanded epoxy resin just fine.

When we painted my Peeler Skiff, we only wet sanded the final coat. Brightsides, but not all other types of polyurethanes, can be buffed with an automotive buffer and very fime buffing compound after the final coat. Looks like gelcoat if you've done a good job filling imperfections.

Cheers,

Dick

I read CLC's instructions about painting and priming.  They left how how many coats.  It seems only one.  The manufacturer mentions more than one if needed.  That's where my question comes into play.  What am I looking for to make the dicision to add more layers of primer?   I am sorry I didn't comprehend your sentence about buffing with an automotive buffer.  I have read over and over that you can't do that with brightsides.  So you are sharing that you can?  You also said you only wet sanded the last coat.  What grit did you use between (before your final coat) and I guess then you dry sanded in between the coats prior?  What grit with those coats?

The primer fills in the tiny imperfections in the glass.  If the surface looks smooth and is free of imperfections/pinholes to your satisfaction, then you have enough primer.  Keep in mind that the mirror smooth surface of Brightsides will highlight any imperfections in the surface.

I did two coats of primer, then about 4 coats of Brightsides.  I wet sanded with 400 between coats of Brightsides.  My goal was a good looking boat from 10' away, and I exceeded that goal.  If you are looking for show quality, definately more primer, more sanding and more paint!

SleepNpilot,

Mark answered the primer coats question perfectly. Just remember that Pre-Kote is soft (like chalk). You'll need to sand most of it off after each coat. It's just to fill imperfections --- otherwise the Brightsides will not have a solid foundation.

Many polyurethanes (linear polyurethanes) should not be buffed. Brightsides is not one of them. Remember that one-part polyurethanes should be given plenty of time to cure (at least a week in 70-degree weather) before buffing.

I used 220 grit between coats. In my opinion, anything finer before tha last coat is wasted effort. You're trying to take down tiny bumps and high spots between coats and improve adhesion. The next coat just covers up anything more.

Regards,

Dick

   Once you have sanded the primer to your satisfaction, how do you clean all the dust off? Water is out of the question, do you just vacuum the hull?

Put on a coat of primer, let it dry. Either scribble all over it with a pencil, dust it with a cottonball dipped in graphite or lightly spray it with black spray lacquer so that it ends up mostly primer colored with speckles of paint.

Now sand it with a longboard and stop when you start getting down into the epoxy. You'll have spots that are wood-colored (high), primer-colored (medium) and speckled primer-colored (low). Put primer only on the low spots, let it dry. Put a complete coat of primer on the boat and go back to the first paragraph.

Stop when you have no more low spots (or are sick of priming and sanding).

Good luck,

Laszlo

HikeAZ,

I used Festool sanders with a Festool HEPA Mini-Vac. Best tool investment I ever made. No dust at all. Otherwise, I'd work in a well-ventilated area with a filter mask. The dust from Pre-Kote is very dangerous and will cover everything. After sanding, I'd vacuum the sanded surfaces and then wipe them down with a tack cloth very slightly moistened with the same paint thinner that your going to use with Brightsides. I used Interlux 333 Brushing Liquid.

Hope this helps,

Dick

Additional comments:

1. Pre-Kote is a high build primer. That means that it doesn't take that much Pre-Kote to fill imperfections. The downside is that it is very soft and also attracts moisture from the air. Unless the weave of the glass was not filled with resin, or you have other deep imperfections, one coat will probably suffice. If you have large or deep surface depressions to fill, perhaps you should a filler such as a marine "bondo" before priming.
2. Brightsides will adhere to sanded epoxy resen better than it will adhere to Pre-Kote. The only reason to use Pre-Kote is to fill surface imperfections. Too much Pre-Kote left on the hull will actually weaken Brightsides' bond to the hull.
3. Your bare hand is an excellent tool for finding roughness and imperfections on a surface.
4. Shining a light at a shallow angle to a surface will help discover unfainess in the surface. A primer cannot fix an unfair surface.

Cheers,

Dick

   This is a great discussion because it makes me question the use of primers. If the primer coat is soft, won't the finish coat on top of the primer be softer than it otherwise would be? So the end result is a really pretty coat of paint that doesn't hold up as well as it could? Why not skip the primer and be satisfied with a more durable finish?

Birch2,

I tend to agree with you. Especially because I was trying for a utilitarian, not a boat show, finish. I was not impressed with Pre-Kote. Were I to do it again, I'd probably have used additional coats of epoxy resin, with serious sanding between coats, instead of Pre-Kote. Of course, Pre-Kote does sand much more easily than epoxy, is lighter, and is much less expensive.

On the other hand, having used Pre-Kote, my Peeler Skiff has been used for three saltwater seasons and still looks like it did when I launched it. I've touched up a few scrapes on the bottom strakes with Brightsides and that's the only maintenance, aside from an occaisonal hose and wet sponge and an annual coat of automotive paste wax, the exterior finish has gotten.

Cheers,

Dick

Dick

Great information, thanks.

Mike