cupped boards
 

On 10 Oct 2004 02:23:48 GMT, (JMWEBER987) wrote:

Been air driying some red oak in the garage for a few months. . The boards are
just shy of being 4/4 and 6 to 9 inches wide. In the process of moving it to a
new area I noticed that many of the boards are cupped. was this caused by
uneven drying between the top and bottom of the boads? if so will the cupped
boards eventually stringhten our as they continue to dry? I'm assuming their
pretty dry now since they have been stickered for quite a while now.. Would it
help to go through the stack again and turn all the boards so the convex
(wetter) side it up? How about storing it unstickered now, would that help
un-cup them? Mike in Arkansas


I takes a year per inch of thickness, on the average, to become "air
dry." As wood dries, it cups, wanes, twists--that's just what
happens. It is difficult to tell if wood is dry without some kind of
test. I would probably turn the boards around to dry them as evenly
as possible, but there's no guarantee what will happen. Drying wood
is part science and part art.

Hi JM,
As wood dries it tends to cup toward the bark side. If you look at the end of a
log or board, as the wood dries the growth rings tend to straighten out. Obviously
if you quarter saw the log most of this will be negligible. Top does not matter so
flipping will not change anything. I keep mine stickered as long as possible
usually until I use the board or need the space. Cheers, JG

JMWEBER987 wrote:

Been air driying some red oak in the garage for a few months. . The boards are
just shy of being 4/4 and 6 to 9 inches wide. In the process of moving it to a
new area I noticed that many of the boards are cupped. was this caused by
uneven drying between the top and bottom of the boads? if so will the cupped
boards eventually stringhten our as they continue to dry? I'm assuming their
pretty dry now since they have been stickered for quite a while now.. Would it
help to go through the stack again and turn all the boards so the convex
(wetter) side it up? How about storing it unstickered now, would that help
un-cup them? Mike in Arkansas

I have found that the best chance of reducing cupping is when the wood is
still "wet", i.e. the first few months. So I am afraid there may not be much
that can be done for your wood now that it has "set". Force required to
straighten would likely end up with cracking the wood.

The ideal way to dry wood is with consistent stickers and lots of weight.
Wood at the bottom of my stacks always comes out better than at the top. I
use concrete cinder blocks on top, but have started using those nylon web
cargo straps as well to get more pressure on the top pieces. The worst
cupping will be the flatsawn pieces near the bark as JGS states. if you
look, you may find that ripping down the center or "pith line" will yeild
two pretty flat peices that won't require much jointing. This works best as
you work with cupped boards nearer the center of the tree. the edges will be
more quartersawn or riftsawn and as result will be nearly flat.

I have air dried quite a bit of wood (for hobby, not pro) over the last few
years, include two cherrybark logs about 23" in diameter. I get a lot of
satisfaction out of taking a live tree all the way to furniture. I get
others to do the sawmill work, but I'm always there to watch and help. Air
drying is a big investment in time and space. but after a few years, you end
up with a steady supply ready to work with. Watching the roughsawn peices
come out of the planer is like Christmas. The cost sounds real advantageous,
but it probably isn't unless you count your effort at zero cost and you have
plenty of space for stacks of wood, which I did. But a dollar per board ft
is typical. But by the time you add up all the wasted wood due to drying
defects and just plain undesirable parts, I have found there is usually 20%
waste on average. Cherry, walnut and Oak in that order are well behaved.
Cypress is great too and drys quick, but I've only found use for it in
outdoor funiture. Sycamore twists badly, and sweetgum is very cool but
twists with enormous force. I'm not sure what it would take to keep it flat.
I suffered maybe 50% loss on that, but I love the wood.

Anyway, enjoy and good luck. Where in Arkansas? I lived in Jonesboro the
past few years but have moved to St. Louis this past summer. Moving the shop
and wood was fun. . .not.

- Jeff

www.fourleavesworkshop.com

"JGS" wrote in message
...
Hi JM,
As wood dries it tends to cup toward the bark side. If you look at the end
of a
log or board, as the wood dries the growth rings tend to straighten out.
Obviously
if you quarter saw the log most of this will be negligible. Top does not
matter so
flipping will not change anything. I keep mine stickered as long as
possible
usually until I use the board or need the space. Cheers, JG

JMWEBER987 wrote:

Been air driying some red oak in the garage for a few months. . The
boards are
just shy of being 4/4 and 6 to 9 inches wide. In the process of moving it
to a
new area I noticed that many of the boards are cupped. was this caused
by
uneven drying between the top and bottom of the boads? if so will the
cupped
boards eventually stringhten our as they continue to dry? I'm assuming
their
pretty dry now since they have been stickered for quite a while now..
Would it
help to go through the stack again and turn all the boards so the convex
(wetter) side it up? How about storing it unstickered now, would that
help
un-cup them? Mike in Arkansas

Nope, turning will do no good. It's not present differential moisture but
past which causes cup and bow. Sapwood started with more than the
heartwood, so it loses more volume when drying.

The oft-referenced "inch per year" is valid for 17th century New England and
outdoor sheltered storage. If your garage has had the same conditions as
your home, your wood's probably good to use. If the house has lower
humidity due to air conditioning, bring the boards in, sticker for exchange,
and let them accommodate a couple of weeks before planing.

So much for my free advice. These guys know all the answers.
http://www.fpl.fs.fed.us/tmu/publications.htm
Pick the ones you're interested in.

"JMWEBER987" wrote in message
...
Been air driying some red oak in the garage for a few months. . The
boards are
just shy of being 4/4 and 6 to 9 inches wide. In the process of moving it
to a
new area I noticed that many of the boards are cupped. was this caused by
uneven drying between the top and bottom of the boads? if so will the
cupped
boards eventually stringhten our as they continue to dry? I'm assuming
their
pretty dry now since they have been stickered for quite a while now..
Would it
help to go through the stack again and turn all the boards so the convex
(wetter) side it up? How about storing it unstickered now, would that
help
un-cup them? Mike in Arkansas

Phisherman, JG, Jeff and George. Thanks for taking the time to help. Your
tips, and info are much appreciated.
Mike in Arkansas