Blistering paint

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Blistering paint

Postby mark48 on Sun Sep 23, 2018 12:10 pm


I completed my PocketShip (Puffin) two months ago and it has been moored in a local freshwater lake since then. The boat's exterior was prepped for painting per the manual, then painted with two coats of Interlux Pre-Kote primer, sanding between coats as directed, and sanding nearly all the primer off before moving directly to Interlux Brightsides paint. After sitting at it's mooring for 6 weeks or so, I now have a problem with blistering on the painted cockpit decking surface as shown in the two photos below.

The blistering is limited to the inner surface of one of the cockpit storage lockers (non sun-exposed) and the forward portion of the cockpit deck (i.e., not the seat-backs, or the hull exterior) at least so far. The larger blisters can be compressed with my thumbnail, and range in size from small "BB" to pin-prick in size. Portions of the forward part of the cockpit deck have a textured feel as though I had painted it with some non-skid product. During my painting, I tried to follow Interlux's directions to the letter including drying times; painting was done inside a garage with the roll-and-immediately-tip method using foam rollers and foam brushes, and when I had completed the boat and for at least the next several weeks, the painted surfaces in question looked "perfect."

Puffin blistering paint #1.JPG
Puffin blistering paint #1.JPG (63.19 KiB) Viewed 295 times

Puffin blistering paint #2.JPG
Puffin blistering paint #2.JPG (84.47 KiB) Viewed 294 times

So, fellow boat-builders (and CLC), what went wrong, what do I do about it, and how do I prevent the same thing from happening again?

I've been told by a professional boat-builder that "touching up" Brightsides is a fool's errand; that when it's time to repaint a Brightsides-painted boat, sand it all down and apply a new coat (or coats) to the entire hull; that one will always see a "touch-up job" no matter how carefully done. Despite this advice, I'm expecting I'll have to sand the cockpit decking surface down and start over on at least that part of the paint job. Any advice is deeply appreciated. (I'm also posting this same message on the general forum of CLC because that site gets more boatbuilders' traffic these days than the PS forum, and most everyone here is using Interlux Brightsides paint.)

Mark Nunlist
Lebanon, NH
Posts: 107
Joined: Fri Jun 28, 2013 9:55 pm

Re: Blistering paint

Postby Wayne G on Sun Sep 23, 2018 9:38 pm


That’s bad luck. I’ve attached a link to a WoodenBoat Forum thread from 2009 that discusses the same issue with this paint.
No real consensus but most suggestions are contamination causing gassing when exposed to heat and sun.

I think I would just sand down the areas in question with 400 grit sandpaper and paint over these rather than completely sanding and repainting. ... n-my-paint
Wayne Gray
Orlando Florida
Wayne G
Posts: 63
Joined: Thu Jul 14, 2016 11:19 am

Re: Blistering paint

Postby mark48 on Sun Sep 30, 2018 8:12 am

Greetings all PS builders and users of Interlux Brightsides paint,

I corresponded with the tech rep at Interlux, including one of the photos above. His response was that the paint had blistered because it had been covered with pooled rainwater, and that I should sand the blistered area and repaint. Other posters on the CLC main forum had suggested pooled water as a possible culprit, and I realized - after the fact - that my PS had been temporarily ballasted "down-at-the-bow" slightly when moored in quiet water. I've since corrected the ballast issue, but one cannot have pooled water standing on Brightsides paint without this happening. According to the tech rep, there shouldn't be an issue with Brightsides paint applied to the sides of the hull (which can get close to the waterline even for those using an anti-fouling bottom paint) but we'll see.

Posts: 107
Joined: Fri Jun 28, 2013 9:55 pm

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