that you will glue?” The answer is
not the top of the teeth (which is
often the part that we sharpen),
but the instead it is the sides of
the teeth. For this reason, the rip
saws used, when gluing off of a
ripped edge, should be properly
“side-dressed.” Side dressing is
not always well done by every saw
The wood surfaces to be glued
must be chemically available,
called “active,” for attaching to
the glue. A quick test for the
activity of a surface is to put a
drop of water on the surface. On
a good, active surface, the drop
should disperse or soak into the
wood within a minute or two.
An inactive surface would let the
droplet remain on the surface
like a droplet on a freshly waxed
hood of a car.
For example, a surface
may be inactive due to aging
(oxidation), MC changes, dusty
environments, oil contamination
(from tools perhaps) or chemical
treatments of the surface. Some
wood composites use a bit of wax
in manufacturing; this makes
gluing very difficult. Hitting the
surface with one pass of sandpaper often restores activity. (Note
that damaged wood surfaces,
mentioned above as weak links
#4 and #5, will show up good in
this water drop test.)
QWe are seeing erratic oloring in our oak when finishing with
stains. We also re-
cently have seen this fuming too.
Will all the wood from one log
have the same color behavior?
What causes this stark variation?
AOne of the beauties of wood is its variation in color. I suspect in your case that you
are seeing color variation due to
a variation in the basic cellular
structure in the wood.
When a tree is put under
stress (wind blowing from the
same direction, struggling for
sunlight due to shade from
another tree, one tree leaning
against another, heavy branch,
etc.), the hardwood tree reacts
by forming tension wood cells,
rather than the standard or “
The tension wood cell typically has much more cellulose
(cotton is cellulose) and less lignin (the glue and stiffener chemical). So, tension wood cells are
very absorptive of stains and will
behave differently when heated.
Tension wood is often spread
over a wide area of the wood in a
tree stem. So, we will see variations from tree to tree, as well as
within an individual tree.
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