On May 28, 4:39*pm, Kenneth wrote:
On Wed, 28 May 2008 15:37:56 -0700 (PDT), whit3rd

wrote:
(the pressure on a plane
blade can collapse the little cellulose tubes, and they
won't wick up the glue if they're not open).

It seems to me that the comment would make sense only for
end grain, so I suspect I am missing something.

The runup to D-day saw a massive effort to glue up plywood
into gliders, and the early batches didn't hold very well. The
trouble was traced to the platen presses (that held the
plies together to make loose bits into solid plywood).

(from _The New Science of Strong Materials_, J. E. Gordon)
"... a proportion of aircraft plywood was ungluable. The joints
in such plywood, made with all due care, looked like
any other joints but had no strength..."

The effect is sometimes called case-hardening, and is
due to microscopic damage that prevents the glue from
penetrating into the wood to make contact with
the subsurface (strong, intact) wood fibers.

Sandpaper is a good treatment for the problem.

On Wed, 28 May 2008 18:19:12 -0700 (PDT), whit3rd
wrote:

On May 28, 4:39*pm, Kenneth wrote:
On Wed, 28 May 2008 15:37:56 -0700 (PDT), whit3rd

wrote:
(the pressure on a plane
blade can collapse the little cellulose tubes, and they
won't wick up the glue if they're not open).

It seems to me that the comment would make sense only for
end grain, so I suspect I am missing something.

The runup to D-day saw a massive effort to glue up plywood
into gliders, and the early batches didn't hold very well. The
trouble was traced to the platen presses (that held the
plies together to make loose bits into solid plywood).

(from _The New Science of Strong Materials_, J. E. Gordon)
"... a proportion of aircraft plywood was ungluable. The joints
in such plywood, made with all due care, looked like
any other joints but had no strength..."

The effect is sometimes called case-hardening, and is
due to microscopic damage that prevents the glue from
penetrating into the wood to make contact with
the subsurface (strong, intact) wood fibers.

Sandpaper is a good treatment for the problem.

Howdy,

Thanks for that interesting comment...

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

In article bWR_j.5654$u7.3933@trnddc07,
says...
What am I doing wrong?

Hard to say but it is obvious that either your glue is no good or the wood
surfaces being glued were "dirty". I suspect the latter.

Was the "kindling pile" inside or outside? Did you machine or sand the wood
surfaces to be glued so that you had nice fresh, dry, unoxidized,
unweathered wood for the glue?


My first thought at that sort of spectacular glue failure would
be 'wet wood'. Wet is not always obvious, but wood above a
certain moisture content does not seem to bond well with any
waterbased glues that I've used (I haven't used titebond, since
it's not commonly sold in these parts; but I understand it to
be a member of the 'white glue'/pva/aliphatic family, also).

-P.

--
=========================================
firstname dot lastname at gmail fullstop com

Peter Huebner wrote:
In article bWR_j.5654$u7.3933@trnddc07,
says...
What am I doing wrong?
Hard to say but it is obvious that either your glue is no good or the wood
surfaces being glued were "dirty". I suspect the latter.

Was the "kindling pile" inside or outside? Did you machine or sand the wood
surfaces to be glued so that you had nice fresh, dry, unoxidized,
unweathered wood for the glue?


My first thought at that sort of spectacular glue failure would
be 'wet wood'. Wet is not always obvious, but wood above a
certain moisture content does not seem to bond well with any
waterbased glues that I've used (I haven't used titebond, since
it's not commonly sold in these parts; but I understand it to
be a member of the 'white glue'/pva/aliphatic family, also).

-P.


It is in that family. And I'd tend to agree, but this wood was tinder
dry. I"m still not sure what the issue was here. I've not had a chance
to glue anymore of it, but will let you guys know when I do.

Tanus