Posted by LeeG on May 28, 2005

It's still an issue but not as severe. Rapid increases of temperature while the epoxy is curing on sealed wood can still cause problems,,fewer of them but still enough to not assume that one wet-out or sealing coat can eliminate the preference for stable temps. For example,,if you were to apply a sealing coat or wet-out coat on porous okoume then increased the temps 15 degrees you're pretty much guranteed to get 1000's of tiny bubbles. When they cure you're left with a pockmarked surface with 1000's of tiny air channels,,that may or may not be sealed into the wood. So let's say you apply a wet-out coat and squeegee the epoxy to make a homogenously even application of glass cloth. It may look totally sealed but there's tiny little spots that aren't. If you were to apply a fill coat and the temps raised up as would occur from a 60 degree shop to a 80 tent the wood will still outgas. Sure it'll be less but there's no way around it,,it's like putting a bottle in hot car,,the pressure will increase. So instead of a 1000 tiny bubbles you get a dozen. That's a lot less, but it's a dozen you wouldn't get if the temps were stable. A good example is the last s&g kayak I made where the panels were pre-sealed before wiring and multiple applications of epoxy occured throughout the construction. There were two wire holes I didn't seal up well and since all the construction was during the winter in a cold shop there were many temp swings I kept finding a bubble at those two wire holes. The wood was well sealed,,,it was just two wire stitching holes that developed a bubble after the second fill coats. They didn't show up in the wet-out and first fill coats because the temps were constant. In subsequent glassing the temp was raised during the glassing and the two bubbles appeared at the wire holes.

In Response to: Re: epoxie temperature by Peter on May 27, 2005