Yes, indeed, the companies that supply the chemicals for dipping wood do
have tests for the presence their chemicals. Each chemical dip will have a different test procedure, so when buying
from several mills, it will be tough to
test for dipping unless they’re all using
the same chemical for dipping.
QI have some lumber that is cupped quite a bit after it has been kiln dried. Is
there a way to flatten this
lumber by putting water on one face?
AIf you can flatten a cupped piece of lumber or a small cutting from this lumber, you are indeed quite lucky.
Indeed, flattening cupped lumber is
almost impossible to do. The water techniques are not terribly effective.
The best chance at flattening can
be achieved by quickly rewetting the
convex side. Use hot water. It will try
and expand, but it cannot do so. As
a result, it will develop what is called
compression set. (In brief, some of
the cells that are trying to expand will
squish.) Do not let water go beyond
the surface (maybe 1/4 inch) on this
In other words, do not wet for more
than an hour at most. Remove the
water and then let this convex side dry
(but do not dry too fast, such as using
a heater). As this side dries, it will
shrink and hopefully the amount of
shrinkage will be enough to result in a
The problem with this technique
is that it is hit and miss as far as how
much water to add. Often, two treat-
ments are no better than one. Further,
flatness is not permanent; the piece
will cup if rewetted.
An alternative method is to steam
the piece, getting it "soaking wet"
throughout as well as hot. Then bend
it flat and then dry it while holding it
flat. This again is not totally perma-
nent and is hard to do. ;
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