Blistering paint


New Member
In June of 2003 I recanvased and filled my Otca. After spending four weeks curing in a hot garage, I applied the first two coats of paint to the Otca. Then, the Otca sat in another garage until June of this year, when I applied the final coat of paint and subsequently took the canoe on a twelve day trip in the Quetico. On about day four or five of the trip, the canoe began to develop a number of blisters - most much smaller than a centimeter in diameter. The blisters were filled with some sort of solvent. When the blisters were popped, the filler was exposed, which leads me to believe that the filler was not fully cured when I painted the Otca. Does that sound correct?

How long should I have waited for the filler to cure? (It no longer gave off the "curing odor" prior to the application of the first and second coats.)

Were the blisters caused by exposure to the sun or by exposure to the water?

Will the paint continue to blister or can I assume that the filler has fully cured by now?

Will I damage the canoe if I continue to paddle it in this condition?

What is the suggested method of repair?

Thank you,
Search on Blisters

Hi Jesse:

No one will touch this question with a 10 foot paddle huh? ;)

Search the forum for "Blisters" and you'll find a fair amount of information. Here is one thread:

It sounds like you could have let the filler dry more if you did find solvents in the bubbles. I've confessed my blister problems and find the hull interior getting soaked is the culprit. Water migrates through the filler and lifts the topsides enamel. If I let the canoe dry right side up the blisters dissapate.

Lately, I've been trying a primer but I haven't got any of these canoes soaked yet to complete the experiment. I had a blister problem on a recent trip (no primer, 4 coats of topsides enamel) and a buddy's canoe exposed to the same elements, for the same length of time, with primer and porch and deck enamel had no problems.

I suspect you may see the blisters again if you get the canoe thoroughly soaked.

I don't think you will damage the canoe. Just let it dry after use.

Maybe others will have some suggestions for repair. You could sand it thoroughly and try a different paint, but I think you would be better off using the canoe until it needs rehab or repainting and try that then.

So now to the important stuff. Please tell us about your trip!:D
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If you've varnished your canoe after canvassing and filling, then its quite likely that uncured varnish has wicked between the planking and settled into the canvas. The heat does its job on the varnish in the canvas, causing random blisters.

Since commiting to always finishing varnishing before canvassing, I haven't had this problem re-occur.

I should add that after awhile they will cure hard, and you can sand them out and repaint, or just leave them alone and they should pretty much go away.
Sounds like folks have pretty much covered your problem. I've had similar problems occur and it always follows getting the insides of my canoes wet. Usually any blisters have been quite small and go away.

Just returned from a 5 day trip on one of our Montana rivers and managed to swamp one of our canoes with my son in a set of rapids and wasn't able to retrieive it for several hundred yards. Thought it was a gonner but no damage. We did turn our two canoes over in the hot sun which I rarely do. This resulted in lifting some minute blisters which most have disappeared. Got to remember not to do that!