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PostPosted: September 18th, 2019, 8:01 pm 
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So just finished laying up the inside football on my cedar strip canoe - main inside layer yet to come. It's my first build, and I filled the staple holes in the outside before glassing, as (despite everything I read) I thought I could camouflage them a bit. While I now have sort of beige staple hole marks instead of resin colored ones, the difference is pretty marginal so I decided I would not bother filling them when I did the inside. Seems that was a mistake, as I got lots of outgassing around many of the staple holes on the inside (I assumed that since they were already filled under the exterior coat I would be covered for this, but apparently not), leaving a bunch of small bubbles under the glass here and there. Squeegeed most of them out before everything set up, but still quite a few left.

I just did a base coat over the rest of the inside to head off more bubbles when I lay the full inside glass, so I think I will be covered there. But is there anything I can do to get rid of them under the football glass before I put on the main layer? There are maybe 20-30 scattered around the hull - none are very big, and the football overall is solidly glassed. I can live with them but if there's is a quick fix before I go any further with the glass (eg some "surgical" sanding that won't be obvious once the next fibreglass layer is on) I would appreciate anyone's thoughts/experience in this.

Thanks all


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PostPosted: September 19th, 2019, 11:41 am 
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Joined: February 26th, 2009, 11:13 am
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Location: Eganville, ON
Making sure you glass while temps are dropping helps keep bubbles inside the wood.

A base coat should eliminate the problem though.


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PostPosted: September 20th, 2019, 8:10 am 
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Location: Waterloo, ON
There was a regular contributor to Wooden Boat Magazine who would crank the heat up in his shop. let the boat warm up, and the turn off the heat and let the boat cool while he was fibreglassing specifically with the goal of having the cooling wood suck in/absorb more epoxy for a better bond. He couldn't be entirely sure it made a difference, but it didn't hurt.

I don't recall having an issue with bubbling from staple holes, but I've only built a couple of boats. If nothing else, doing that first coat while the hull is cooling can't hurt.

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PostPosted: September 20th, 2019, 2:15 pm 
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Joined: February 12th, 2008, 6:01 pm
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Location: North Bay, Ontario
I got pinholes in the epoxy-glass layer only once, and that time I used a slightly faster hardener. Don't know if that was the cause, but the correlation was there. Maybe the faster hardener heats up more, causing bubbles to form? In any event it was a royal pain because I had to find them all and fill them.

Kinguq.


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PostPosted: September 25th, 2019, 5:07 pm 
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Joined: August 26th, 2019, 7:00 am
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Was using West System 207 hardener, which is rated as a slow hardener. Am now in the process of cutting out and refilling the worst ones - some of those continued to bubble even after the original glass was cut out and refilled! Major pain in the arse. Seems out of the ordinary based on comments here and elsewhere, and no clue why it is happening - pre-coated, kept a close eye on the shop temperature, making sure it dropped after application, so at a bit of a loss as to why. Have kept them down this time by watching closely for a couple of hours after glassing. The only thing I can think of is I did plug the staple holes on the outside before flipping it over (no real bubbling issues for the outside)'using a Lepages wood filler - didn't do it when I glassed the interior and maybe there was some reaction with the filler? Anyway, a definite pain but important lessons learned for next time. Thanks for the feedback.


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