lumber goes across a 16 foot Irvington Moore end
trimmer to end trim lumber even lengths with nothing
shorter than 6 feet. From end trimmer goes direct to
our 6 foot Irvington Moore automatic chain arm
lumber stacker. From automatic stacker it goes to
our air drying buildings.
Lumber is air dried under air drying buildings
for about 45 days before going into dry kilns.
We have double brick kilns with apex roof line
which are computer controlled two different ways
along with hand held monitors in kiln chamber so as
to closely monitor drying process. Usually takes
about 2 weeks to kiln dry hardwood lumber.
Anytime you start kiln drying lumber you have to
figure out what is the start up moisture content as
if you start the drying cycle off at too high a
temperature it will destroy the usability of it.
When lumber is dried to fast the fiber is pulled
apart with lumber looking like a honey comb. About 2
percent moisture lost per day is ideal.
You take about 3 algebra formulas to figure out
the start up moisture content by weighing samples &
drying samples in a small oven. You can then monitor
moisture being lost as lumber is being dried.
Usually on air dried lumber you start out at about
110 degrees & finish the charge at about 180
degrees. It's not really the heat that dries lumber.
It's the depression between the dry heat & wet
(humidity) heat that pulls moisture out of lumber.
WE CONDITION (STRESS RELIEVE) all our dry kilned
lumber. We feel if the lumber isn't stress relieved
then we are doing our customers a disservice.
Usually takes about 12 hours to cool down dry kiln
chambers then another 12 hours of pumping raw steam
into the dry kiln chambers to force moisture back in
to relax the lumber.
For those unfamiliar with condition (stress
relieve) you have to do this at the end of the dry
kiln charge to relax the lumber. As you force
moisture out of lumber by the end of the charge it's
laying there stressed.
Perfect example is when you use your table saw to
split a wide board or cut part of it off. If the saw
is pinched where it's hard to get the board to go
through the saw then the lumber IS NOT stress
To resolve this problem you condition the lumber
or force moisture back into the lumber at the end of
the drying process to relax the lumber. You do this
on most all hardwoods. Softwoods or Poplar you don't
have to condition. Even though Poplar is a hardwood
it's so open poured that it doesn't need
conditioning. This makes the lumber more user