Painting my kayak - problem

[KevinB]

Hi everyone,

I made a canoe a few years ago. It's marine ply covered in fibreglass and epoxy resin.

In my ignorance, I painted it with ordinary house-paint gloss enamel. No primer, no undercoat. I've had a few problems with the paint not adhering: I've now got patches of no paint.

Now I want to paint properly. Is it OK to undercoat the whole thing or should I undercoat only the bare patches?

Any comments, suggestions or instructions will be most welcome.

Regards,

KevinB

[Chris Parks]

From my experience, been there etc, strip it all off and do it properly. I had no end of problems with one boat that kept losing the paint due to slack preparation and application.

[KevinB]

Thanks Chris, I've been thinking along these lines.

----Regards,
Kevin

[PAR]

Painting as you may know is 95% surface prep and 5% actual brush, roller or sprayer in hand time. Most issues can be traced back to the prep and you've pretty much identified the problem. Painting over the questionable prep with some primer, is just going to further test the previous coating's ability to stay stuck. Yeah it sucks, but you need to get back down to the surface and complete the prep properly, followed by sound coatings (varnish or primer and paint).

[KevinB]

Thanks for your reply PAR. I'm groaning about a complete sand-back and re-paint but I know once I get stuck into it I'll enjoy the job.

Regards,

KevinB

[Canoath]

I had to do similar back in 2013. Although I was trying to address a couple of areas where the epoxy was too thick and had cracked, I ended up stripping the lot including epoxy. I'm not suggesting you strip the epoxy but I had a hell of a time trying to remove just the exterior acrylic house paint. Despite trying anti-clog paper and some other types they'd all clog up quickly which was extremely frustrating. In the end a heat gun and scraper worked great though if you need to do the same you'll have to pay attention not to soften the epoxy too much underneath.

I roll and tipped White Knight Rust Guard epoxy enamel which worked well. It wet sands really well between coats. I used turps as a prepwash which was a mistake and lead to fisheyes. Final clean should've been with methylated spirits. My canoe spends it's time hull up facing the sun, mainly to test the paint and varnish on the gunwales. My paint went chalky after about 18months and I repainted after 2 and a half years earlier this year. That involved a quick wet sand followed by metho wash and wipe down for prep, then a single roll and tip coat. The sides and undersides of the gunwales were revarnished too. The canoe looked new again.

Anyway I'll post my refinishing thread. PAR was extremely helpful and you might find some good info in there. Page 2 is where the repaint occurs http://www.woodworkforums.com/f169/refinishing-eureka-177159/2

[labr@]

Plus 1 vote for wet sanding, both for between coats and for paint removal. It's messy but not dusty and the abrasive lasts a long time. Quieter than ROS too.

[PAR]

I use wet sanding for a few reasons, to control dust, which is important, but also so I can see what is happening with the surface. Feeling for a fair surface takes practice, but looking at the reflections in the wet areas during a sanding session can make seeing things a lot easier, compaired to dry sanding. Wet sanding produces a cleaner surface too, as the water washes away contaminates before the get ground into the surface. For finish coats, I always wet sand, but for bulk material removal, I'll usually dry sand, because the grits used are so coarse that you can suck it off with a dust extraction hood/blower.

Most of use develop methods to get things done. I've found when fairing a surface, I also am trying to smooth it too. Working a primer down until you've got it both fair and smooth, makes the top coats go down easier and the results much better to live with. Initial primer is dry sanded, because I'm filling low spots and knocking down high spots. Later in the process I'll wet sand, because I've filled and knocked down everything and am working on smoothing things up.