Kaholo 12'6" blistering in the sun


I'm in the final stages of completing my Kaholo 12'6", and I was just admiring its finish in the midday sun when the fully cured (at least a week old) top epoxy coat(s) started to bubble. How do I avoid this and more importantly, how do I fix those bubbles? I threw some cold water on top to get rid of the heat as quickly as possible. There are 3 epoxy coats on the deck. 

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RE: Kaholo 12'6" blistering in the sun

Anybody have this experience? I could really use some guidance. 

RE: Kaholo 12'6" blistering in the sun

Not ignoring you, just never seen this before and have nothing intelligent to add.

Maybe you could post some pictures?



RE: Kaholo 12'6" blistering in the sun

I'm sorry Laszlo, I honestly can't figure out how to load a picture here. If you follow my project Instagram at skunkworks_leo I just posted a picture there. Thank you.    

RE: Kaholo 12'6" blistering in the sun

Like this. The instructions are on the forum front page.


I need to think about this before I can try giving you an answer. Maybe someone else will hop in here in the meantime.



RE: Kaholo 12'6" blistering in the sun




RE: Kaholo 12'6" blistering in the sun

Back to the blisters. What makes this different from anything else I've seen is that the epoxy was fully-cured and that only the top of 3 coats was blistering. That pretty much eliminates outgassing from the wood as the cause.

What was the weather like that day? Hot or cold? Humid or dry? What was it like the night before?

When you cooled it off, did the blisters collapse on their own or did you push them down?

Is there any chance that some contamination got on the previous coat of epoxy?

This really is a puzzler.



RE: Kaholo 12'6" blistering in the sun

i've experienced blisterring before on one of my builds and it was incredibly frustrating.

in my case, the blistering was traced back to a bad batch of epoxy that was never really fully cured.  by that i mean, while it was never sticky, if you pushed your fingernail into it, you could always dent it..even when the hull was cool.  i concluded the epoxy had never fully hardened....and the consequences of it did not show up or become apparent until the heat of the sun...and it did something similar to your pictures...and the blisterring was only in the soft areas.

with respect to the fix....not a lot to offer.  i made tactical fixes and pulled most of the soft area off and re-finished....and you can only tell there was a fix if you closely inspect it.   to identify the problem area, with the boat cool,  i basically probed the entire hull with a dull nail and was able to identify the area of soft epoxy and pulled it up and replaced that section.       i have had other boats in the hot sun.....if the epoxy is properly cured....i have not seen anything like this.



RE: Kaholo 12'6" blistering in the sun

Thank you so much for your thoughts Laszlo and Hspira (and sorry for not knowing how to post those pictures!) What I ended up doing just now is cutting out the white spots with a blade and a sharp chisel. I then added a smooth layer of epoxy with a roller but the elevation change in the holes was too pronounced, so I deliberately added a "thick" layer that I'll go back and sand down before a couple more uniform layers of epoxy to finish it off. I'll paint over it if it remains visually painful to look at, but it doesn't look nearly as bad as it did a little while ago with the white spots. At least the paint will be smooth if I go that route. 

To answer your questions Lazslo, Friday afternoon was pretty hot and the sun was full blast (medium humidity, pleasant compared to Saturday). This is the only area that it happened in but it literally was a matter of 6-7 minutes. The bubbles faded a little bit when I cooled it off, but even pressing my finger down on it didn't dissipate whatever air or gas had formed them in the first place. Even after pricking them they still remained.

Thanks again, 


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