Oren wrote:
On Sat, 23 Jun 2007 14:53:55 -0500, dpb wrote:

Although it won't make any long term difference in strength because of
the end grain, I'd use Type III glue or this is a place where even
urethane glues have a place for the waterproof nature as a moisture seal
to prevent mostly water wicking into the end grain.

Can't the glued bond be stronger than the actual wood?

I may need my myth busted

Not on end grain. Glue joints rely on long grain to long grain
orientation for their strength. (*) End grain fibers can't form the
bond. It may hold for a little while as a mechanical bond, but even new
it won't have much strength and will certainly fail in the long run. As
noted, I use the glue for such applications as a moisture preventative,
not as a bonding agent. Pre-painting the end grain accomplishes much
the same objective but the glue is usually a little more convenient at
the time one is in the "putting it together" phase and wet paint is just
a lot more messy to use it at that time instead of glue. Dries more
quickly, too, in general, although the urethanes are pretty slow...

(*) Doesn't have to be parallel, but does have to be long grain. That
is, a cross-lap joint is fine whether the boards are joined end-ways or
at 90-degrees. Or the tenon cheek against the mortise side. But,
similarly to here, the tenon rail sides (top and bottom) even though
snug fitting, the glue surface there to the end grain in the mortise
don't contribute except for resisting racking forces and that only
mechanically.

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