First Time Fiberglass = Not So Great



Enthusiastic about Wooden Canoes
Quick update here. The area that had the white bubbles / pin holes was one of the spots where the resin was pretty heavy. So I knew I could safely sand down a bit more. I did so, and the pin holes started to disappear. I'll keep you guys looped in to the organized mess that has become this first canoe build of mine. Onward to victory!! And disaster management!!


Enthusiastic about Wooden Canoes
Hey Everyone -

So, after sanding off the excess epoxy (without damaging the cloth beneath) I finally got around to applying an additional, very thin coat (2 coats actually) with a foam roller designed for epoxy application. The roller left behind small bubbles on the very top surface, which I think will disappear when I sand again in preparation for the application of UV repelling varnish.

A different issue revealed itself that I don't recall having seen before, and it doesn't seem there will be a reasonable way to address it. There is a definite "discoloration" that I'm thinking is related to the insufficient squeegeeing. What is interesting is that the discoloration is most evident when looking along the canoe from the bow. Walking towards the stern, the discoloration begins to disappear - which I would guess is indicative of the issue being with the glass cloth itself not being thoroughly pressed onto the wood surface. The glass catches light differently at different angles.

Anyway, my rookie speculation aside, I wanted to post some pics to get your thoughts. Seems to be yet another issue that I will simply need to make peace with and take the lesson on to my next attempt. Thanks.



Todd Bradshaw

I don't know for certain by any means, but it reminds me of instances I have seen where the sizing got washed off of the cloth before use. In order for fiberglass cloth to absorb resin and saturate well, it is treated during the finishing process with a chemical sizing (Volan, Silane, etc.). Most of these treatments are water soluble, so exposing your cloth to water, even in the form of really high humidity before installing it can cause a problem and areas that may not saturate well.

In possible scenario #2, it might be the result of pushing the application of a batch of resin beyond the point where it should have been used when applying the cloth. Resin starts hardening and thickening as soon as you mix it. Fiberglass takes time to absorb the resin. If a particular batch of resin has reached the end of its pot life it may already be getting too thick to saturate properly and the cloth may not have enough time to fully absorb resin before everything stops being workable.

There are other possibilities, but those two come to mind.

Jim Dodd

LOVES Wooden Canoes
I agree with Todd, about the resin kicking over in the cup ! If you have it in a cup, and you start feeling it get warm, you might see discolored runs in the cloth. As you have shown in the pic.
Get the resin on the hull as soon as possible !
The runs seem to fade in time. Let us know in a week or two !


Rod Tait (Orca Boats)

I have also seen lines like this when the builder takes more time than they should in getting the whole boat wet. When doing a canoe if working alone, one does a bit on one side, moves to the other and then works back and forth. If you stay on one side too long the next batch of resin does not blend with the last leaving evidence of where you left off. Always best to get the whole project wet as fast as you can and then go back and clean up drips, runs, excess, etc. And on a good size canoe, it really helps if at least two people are applying resin.