The phenomena can be caused by a severe moisture gradient,
growth stress in the tree or longitudinal (lengthwise)
casehardening. We can eliminate a severe gradient, as you
indicated that you checked the MC with a pin meter using
insulated needles. We can eliminate growth stresses because the
strips were straight when you ripped them. So, it is
longitudinal casehardening (also called drying stress).
With basswood and a few other species, there are wood cells
that shrink lengthwise or try to shrink longitudinally during
drying. They are restrained by the rest of the wood fibers in
the piece, so this drying stress develops. Normally, we would
relieve such stresses by using a conditioning period in the
kiln -- rapid rewetting of the wood at 180F. I would have to
look at the kiln temperature records to determine if
conditioning were used, if the temperature was high enough and
if the RH was high enough within two hours. Have the kiln
operator check the appropriate material in the Drying Hardwood
Incidentally, the prong test you refer to only measures
across the grain stress, not longitudinal casehardening. For
longitudinal casehardening, take an 8-inch-wide piece of
lumber, cut a 30-inch-long sample, rip the piece into two
4-inch-wide pieces, and put the two pieces back together. If
there is a gap at the ends or in the center more than the
thickness of a dollar bill, there is longitudinal casehardening
that may cause problems for some manufacturing schemes.
Q: We are having a problem with shrinkage. We make furniture, but someone else sells and delivers it. This person claims he did everything correctly, including opening the furniture wrapping (we wrapped the furniture with shrink-wrap and it was fairly well sealed) and letting it acclimate to the house climate. When the customer moved in, they said the furniture looked really wonderful, but within a week, it started to warp, open joints and crack in a few places. We are so careful to keep our plant at 40 percent RH and check the MC of the lumber. This is frustrating! Can you help?
Sycamore and wormy maple ranked highest in customer rankings of underutilized species.
Understand the differences in appearance, behavior and price
Understanding wood density can be a factor in
The latest news bites from the industry.
Why wood colors vary and what it means to you
Just how glue savvy are you?
--- Thank you for your patience ----
If you have any issues logging in or any other need feel free to contact us.