Posted by Fred, NC on May 13, 2003 at 18:06:42:
In Reply to: Re: How do I stain the frames, with epoxy ecapsulation? posted by Mark Bronkalla on May 07, 2003 at 12:07:40:
Ken - I built a Roustabout 20 years back, used air-dried white oak for all the longitudinals, dashboard, and as many structural members as I could. "White Oak" is the grandfather of boat-building lumber. I can't belive now they are finding it doesn't mix with epoxy cement or encapsulation? Says who? After 23 years of hard water-skiing use - never had a single failure. Of course the technology then was some epoxy, and a lot of Resourcinal glue. Frankly I worried more about the Glen L frame kit, of that time - it looks like it was made out of low level lumber - certainly not oak or any structural stuff. More like clear mahogoney. And the gussets were just 1/4" ply nailed in place. I build things with 200% overbuild - its an engineer's way! :)
I just remembered, the boat's "Lifting Strakes" were 100% white oak - encapsulated in epoxy and then painted over with several coats of epoxy paint (1979). They looked the same in 2001 as they did in 1979.
Fred, NC
: The oak will lighten slightly over time. The grain will become a bit less noticeable. I found this out when attempting to move some area rugs on the white oak floors at our old house. The varnish and epoxy will darken / yellow slightly over time as well.
: With the oak fully encapsulated in epoxy you should not have problems. I ran across the same questions when I started building and was afraid to go with the oak, but if I were to do it over again I would opt for the white oak, based on further research. With the oak fully encapsulated, and very little moisture migration as well as a lack of exposure to the air, I have a hard time imagine how the acid content would change.
: I have used white oak in a few of the boat parts (sheers and chines and a few other high tension spots along with furniture projects). I cannot see any lack of bonding performance. There was a LOT of clamping / bending pressure needed on the sheers at the bow.
: Conversely, the cycling of humidity in wooden airframe components is a significant issue (as they don't encapsulate due to weight allowances). In that case there is research done by the US Forest Products labs that point out the resourcinol glue is superior to epoxy for aircraft woods (primarily spruce), but the major blame for the failure is placed on the moisture content cycling. They did not test oak as it is not a favored wood for airframes (too dense).
: Unfortunately, I don't have any links or solid references to point to.