I bought some white oak lumber three weeks ago. I've just started
milling it for a project. I began with a piece 4/4 thick about
6 in. wide and 50 in. long. It was farily straight and flat.
I cut it into two pieces each 3 in wide. I jointed one face
and one edge so they were perfectly straight and flat. I
then resawed it with my bandsaw to reduce the thickness
to a little more than 3/4 in. But a minute later I noticed
that the smooth, jointed face was badly bowed (convex)! I
repeated the operation with the other 3 in. wide piece and
the same thing happened.
1) Why is this instant warping happening?
2) What can I do to avoid it? If this keeps happening I'll have to
throw out all the wood I bought.
A little more info:
The wood was dry when I bought it and has remained dry while
in my garage (3 weeks). My garage is dry and varies between 40
and 65 degrees F. I don't know how long since the wood was
cut for lumber. I don't notice anything unusual about the wood.
The jointed surfaces look very good.
: I bought some white oak lumber three weeks ago. I've just started
: milling it for a project. I began with a piece 4/4 thick about
: 6 in. wide and 50 in. long. It was farily straight and flat.
: I cut it into two pieces each 3 in wide. I jointed one face
: and one edge so they were perfectly straight and flat. I
: then resawed it with my bandsaw to reduce the thickness
: to a little more than 3/4 in. But a minute later I noticed
: that the smooth, jointed face was badly bowed (convex)! I
: repeated the operation with the other 3 in. wide piece and
: the same thing happened.
Sounds like case hardening, where the wood was dried too
fast. This makes the outside hard and dry, leaving
moisture inside. When you resawed, it exposed this
moister inner part, which then caused the warping (did it
warp toward the dry side)?
The other possibility is the wood had inherent internal stresses which
got released when you cut it, but I don't think white oak
has a problem with this.
Solution: buy your lumber from someone else, or at least find out if
your supplier is aware of this sort of problem.
-- Andy Barss
This sounds like case hardening. If wood is dried improperly, stresses
remain in the plank and when sawn, these stresses are released, warping the
I don't know of any way to know whether wood has case hardening other than
to cut it, but you may want to take this experience into account the next
time (if there is one) you buy from a particular lumberyard.
Telltale signs of case hardening is usually a multi-checkered end which may
be difficult to see on rough-sawn lumber when you're buying it. Take an
apron plane with you next time, take a slice off the end grain to freshen it
so you can see the fine cracks. Maybe run a pencil across the end-grain to
see the crazing. Take a swipe across one face near the end and look for the
same checking/crazing. Case hardening usually has many fine cracks so a
piece with a rather obvious checked end does not necessarily mean it's case
hardened - just dried quicker.
You should take the wood back to where you purchased it so he'll know he got
a bad batch. Depending on how reputable he is, you should get a refund and a
thank you for bringing it to his attention. If he's a butt-head and tells
you it's not his problem.... let your wallet do the talking next time. I
use a lumber supplier (Lakeshore Hardwoods near Pulaski, NY) that
guarantee's his wood and no hassle if you return it. Never had to exercise
that guarantee but nice to know it's there cause - stuff happens....
I can not offer any advice but I encountered a similar situation with
several pieces of 6 inch T&G pine boards. Within a few seconds of
ripping them, the boards curled right in front of my eyes. Three
pieces out of about 80 was not too bad but they were useless, even for
I've had this happen (instant warping/twisting) when ripping cheap pine
2x4s, but never with oak. I got a bunch of white oak from Lakeshore
Hardwoods also, and it was great quality - nothing weird as I milled
it. (BobS, where in CNY are you?)
I'll agree that you should call up the place where you got it, and if
they don't replace it, you should shop somewhere else.
Bob's not too far from you Andy. North Syracuse if I remember correctly.
We need to put together a CNY dorkers meeting at Dunkin' Donuts one of these
evenings. Looks like we've all spent some cash up at Lakeshore - great
place to get lumber. Great people.
As others have suggested, it is likely improperly dried, case hardened wood.
That said, it is not unusual to have one or two boards out a of batch that
show signs of being "reaction wood", or that have internal stresses that are
released when cut/milled.
When milling a batch of new lumber I can almost predict, after the first one
or two exhibit the behavior, which boards are going to be a problem ...
sometimes it is just the heft of the board, or a slight difference in color
and grain. Although these indicators aren't always a consistent predictor,
so you get fooled often, it is still worthwhile to pay attention and try to
anticipate the problem boards, particularly when ripping.
It boils down to a cost of doing business ... and, IME, another reason why a
prudent woodworker always adds a healthy 20% over his project needs to a
As others have said, improperly dried wood or just internal stress is
released but ripping.
When I have to rip heavier pieces (6/4 or 8/4+) that show sighs of warping
or twisting when ripping, I run them through the band saw first. This
relieves the stress and I can for the most part, re-rip or plane to size and
save most of the wood.
It may be improperly dried. It may also be that your garage is too
You shouldn't be resawing 4/4 stock to 3/4. Instead, take it down with
the planer, and try to take an equal amount from each face.
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