Paint Problems


Rolf Warncke
Last time I had the boat in the water it developed some "pimples" in the paint. It was the first time the canoe has been in the water for any length of time sine I finished the restoration on it. We did some paddling while we were up in the Adirondacks. The "pimples" are no bigger than the head of an eraser and many of them are smaller. testing a few of them by cutting them off I found that the paint separated from what looks like the primer layer and there was moisture in the bubble. My suspicion is that these might be spots where I sanded through the primer and put paint directly on filler, but I'm not sure. Is this something anyone else has ever come across? I confess not using "expensive" paint, but I did use Rustoleum Marine Enamel topcoat and Primer. Thought it would do the trick. I'm looking for any thoughts or suggestions.

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the most common problem for the cause of blistering is not letting the oil base filler cure long enough before painting. If that's the case then its oil inside the blisters and not water moisture. With such small amounts of liquid that you can pull from the tiny blisters its hard to tell the difference. If thats the case it best to use the boat as much as you like, just ignore the blisters for the first year or so to allow the oil to work its way out and then do a good repainting job.

If the blisters are water moisture it could because the paint, primer and oil base filler are not as compatible as one would like! With so many different formulas for grades of paint its impossible to determine what exactly is comptable with what. Again the answer is just give the canoe some use and over time and it will normally go away and then you can repaint.

The bad new is that some blistering never goes away. It may not be as noticeable but it may come back with the temperature and moisture conditions are just right. Thats why most builders figure out a system that works for the paints and oils that they use and then stick to it.

The blisters are normally just in the surface of the paint and not into the filler. This makes it just a cosmetic problem and not a structural problem. If you can bare to live with the blisters for a bit and let the hull age for a bit you should be able to do a reasonable repaint for next year without any problems.

Thanks for the detailed answer to my question. If you would tolerate a little more info and my idea for a plan I would appreciate your thoughts. This was my first restore. I used only the best filler and canvas...yours. Very satisfied with the results. Let the thing cure for 10 weeks primed and painted. I took it out on the lake once and put it in the rack in the garage. It's been there for two years while I've been doing an addition on the house. The blisters did not appear until after using the boat two weeks ago while we were camping up near assembly. What I'm thinking to do, and have started is to scrape and sand the places where the blisters are and then put it back into storage until next spring, then I'll scuff sand and repaint. How does that sound. I want to get this right. I bought a set of your Morris plans at assembly that I plan on using with my son in his wood shop class this year. I should say our class as I am the teacher. I'd hate to see this happen when he gets his done so I want to work the bugs out in my head and on mine before he gets to paint.
Well, the curing of the filler should certainly not be the problem!
There must me something in the paint that is causing the problem. I have had blistering problems with Primers before which is why I don't use them any more. I just go straight to using the finish coat. Its impossible for me to determine exactly what is going on but ageing the paint will normally cure the problem. I would say your approach right now would be correct and then hope for the best!