Epoxy seal coat or...

Epoxy seal coat or just apply the glass over the raw wood? Previously, I've just laid the glass fabric over well sanded wood and worked the epoxy into the weave. On a few occasions, I've encountered areas where the wood is thirstier than others, and when I've come back to check I've noticed a few white spots that I've had to scramble to correct. So I'm wondering: if I seal the wood with a coat of epoxy (which would have the added benefit of allowing me to sand very smoothly before applying the glass), would that overcome the problem of uneven absorbtion? Would the glass adhere just as well to an undercoat of epoxy, or am I better off with the initial glass-bonding coat of epoxy being able to penetrate into the wood fibers? The extra time of applying a seal coat is not an issue for me; the only question is: what will produce the better result? Any advice?


Jim Norman

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RE: Epoxy seal coat or...

I've done it both ways; on my first build I did a seal coat, on my second I didn't.  I did not notice a huge difference either way in adhesion or strength.  I think if you have conditions that could result in bubble formation or uneven resin absorption (working during warming temperatures, a strip-built boat, or, as I found, bubinga veneer) it may be worth the time to do a seal coat so you can sand out any problem areas and/or get even absorption before you apply the glass.  If you choose to go the seal coat way, make sure it's as thin as possible; use a plastic squeegee (the kind used to smooth bondo - very cheap at the auto parts store) to take off all the excess resin.  Sand lightly before applying glass to get good adhesion or put glass on just as seal coat loses its tack for chemical bonding to take place if there are no bubbles you need to sand out. 

RE: Epoxy seal coat or...

I've found a good reason to do a seal coat first (actually even before stitching) - if you work outdoors, the occasional rain that catches your boat unawares will not stain the wood. 


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