Wood movement and cupped boards

Thanks for all of the advice. Very helpful. I'll give the boards a
few months indoors and then mill them down. The really badly cupped
ones I'll split into 6" planks and then edge glue if I need the extra
width.

BTW, I should have said that I have an old set of nicked planer blades
that I have been saving for just this kind of job (at least for the
first few passes). It sometimes pays to never throw anything away.

Lars




On 2005-03-13 11:55:48 -0600, Lars S <[email protected]> said:

> I recently acquired over a dozen 42"x12"x1-3/4" white oak stair treads
> from a rennovation site of a 100-year-old greystone. This would be a
> gloat, except I already spent a day getting them from the construciton
> site, pulling nails, and cleaning them off. And, the biggest problem,
> most of them are significantly cupped from being exposed to a few onths
> of rain and melting snow. The cupping is about 1/2" to 3/4" across the
> 12" width of most of the treads.
>
> Here's my question. If I sticker the treads for a while (how long?)
> will the cupping reverse over time? If not, I can easily plane off
> 1/2" of material and make some very nice, flat 1-1/2" boards (I'm
> thinking two side tables and a matching coffee table), but I don't want
> the planks to reverse-cup once I've made a nice table top. I'm a bit
> impatient, so I would prefer not to wait a year to use the wood.
>
>

"Lars S" <[email protected]> wrote in message
news:2005031311554816807%larsstole@gsbuchicagoedu...
> I recently acquired over a dozen 42"x12"x1-3/4" white oak stair treads
> from a rennovation site of a 100-year-old greystone. This would be a
> gloat, except I already spent a day getting them from the construciton
> site, pulling nails, and cleaning them off. And, the biggest problem,
> most of them are significantly cupped from being exposed to a few onths
> of rain and melting snow. The cupping is about 1/2" to 3/4" across the
> 12" width of most of the treads.
>
> Here's my question. If I sticker the treads for a while (how long?)

Month or two. 1% per week is a reasonable rate for indoors equalization.

> will the cupping reverse over time?

Mostly. Some "set" might have taken place which is not reversable.

If not, I can easily plane off
> 1/2" of material and make some very nice, flat 1-1/2" boards (I'm
> thinking two side tables and a matching coffee table), but I don't want
> the planks to reverse-cup once I've made a nice table top. I'm a bit
> impatient, so I would prefer not to wait a year to use the wood.

About stair treads - they've got a buttload of sand and stuff ground into
the upper surface. If you can get that sanded off, I'm sure your planer
will thank you.

>
>
>

Lars S wrote:
>
....
> Here's my question. If I sticker the treads for a while (how long?)
> will the cupping reverse over time?

Not just by that....a steaming to provide a uniform moisture level
followed by controlled drying <might> help, but it's a shot in the
dark...

> If not, I can easily plane off
> 1/2" of material and make some very nice, flat 1-1/2" boards ...

You'll salvage a lot more nice material if you resaw them down to 6" or
so, joint the edges and reglue...if you keep the pieces together and
oriented properly you'll probably find it hard to tell where the joints
are when done...

> I'm a bit impatient, so I would prefer not to wait a year to use the wood.

Haste makes...what was that again, precisely?

"Joe Tylicki" <[email protected]> wrote in message
news:ZS%[email protected]...
> >your chances are not good.<
>
> I would have to agree. You could try exposing the opposite side to the
the
> elements and see if it evens out, much like flipping deck boards. You
could
> try it with just one piece first to see if it works. I believe the
cupping
> is caused by the wood fibers compressing and does not reverse upon drying.
>

For your edification :
http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.htm
Specifically, chapter 3.

"toller" <[email protected]> wrote in message
news:Ao%[email protected]...
> You are being too optimistic. If they are cupped 1/2", then you have to
> remove 1/2" from both sides, so you will wind up with 3/4" stock at most.
> Plus, if you put them in a planer, they may flatten them out prior to
> cutting, and never get the cupping out. There are work-arounds, but they
> are not easy; you really need a 12" jointer.
>

That must be one hell of a planer you've got that can flatten the crown on 1
1/2" oak.

"Phisherman" <[email protected]> wrote in message
news:[email protected]...
> First of all congrats on the treads--I wish I had such a find. The
> cupping probably won't reverse over time if stickered. However,
> here's a trick that may work:
>
> On a hot sunny day place the cupped boards on the grass on a hot sunny
> day. Place the boards in the orientation of "n" rather than "u."
> The warm moisture from the grass will expand the wood fibers and tend
> to make the boards less cupped. A moist heating pad might work just
> as well, although it would take longer to do so many boards.
>
> I learned this method from my father who used it to flatten warped
> doors. It looked like crazy thing to do then left me amazed how well
> it worked.
>

This works as well as it does for the same reason that stickering the pieces
which are now saturated one side works. Once the expanded fibers begin to
contract again, the wood returns to nearly the same configuration it held
prior to the first imbalance.

Once again, good information in Chapter two.
http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.htm

"Joe Tylicki" <[email protected]> wrote in message
news:iNh%[email protected]...
> George, from what I gathered, Chapter 3 related mainly to the movement of
> wood upon initial drying from its "green" stage. I did not see anything
> that relates to the instant case, i.e., seasoned lumber exposed to the
> elements causing repeated wetting and drying of one surface of the board.
> In this case, as in the case of your typical deck, it does not matter what
> direction the grain runs, as the cupping will occur in the direction of
the
> exposure to moisture. This is because the fibers on that side of the
board
> have been crushed by the expansion when wet, and upon drying, the surface
> area is now smaller than it was originally.
>
> Joe
>
>
Hysteresis is what you want to look at. The answer to whether or not it
will return to a semblance of its former configuration.

toller wrote:
> You are being too optimistic. If they are cupped 1/2", then you have to
> remove 1/2" from both sides, so you will wind up with 3/4" stock at most.
> Plus, if you put them in a planer, they may flatten them out prior to
> cutting, and never get the cupping out. There are work-arounds, but they
> are not easy; you really need a 12" jointer.
>
> By all means try letting them dry out and see what happens; but your chances
> are not good. A few months ought to be plenty.
>
>
True, but you could rip them in half, joint them flat on a 6" machine,
glue them back together, then plane them. You could probably salvage
5/4 or better...plenty for coffee table purposes.

You are being too optimistic. If they are cupped 1/2", then you have to
remove 1/2" from both sides, so you will wind up with 3/4" stock at most.
Plus, if you put them in a planer, they may flatten them out prior to
cutting, and never get the cupping out. There are work-arounds, but they
are not easy; you really need a 12" jointer.

By all means try letting them dry out and see what happens; but your chances
are not good. A few months ought to be plenty.

>
> You'll salvage a lot more nice material if you resaw them down to 6" or
> so, joint the edges and reglue...

That is a good suggestion; it will probably also be less work in the long
run.

>your chances are not good.<

I would have to agree. You could try exposing the opposite side to the the
elements and see if it evens out, much like flipping deck boards. You could
try it with just one piece first to see if it works. I believe the cupping
is caused by the wood fibers compressing and does not reverse upon drying.

Joe

George, from what I gathered, Chapter 3 related mainly to the movement of
wood upon initial drying from its "green" stage. I did not see anything
that relates to the instant case, i.e., seasoned lumber exposed to the
elements causing repeated wetting and drying of one surface of the board.
In this case, as in the case of your typical deck, it does not matter what
direction the grain runs, as the cupping will occur in the direction of the
exposure to moisture. This is because the fibers on that side of the board
have been crushed by the expansion when wet, and upon drying, the surface
area is now smaller than it was originally.

Joe


"George" <george@least> wrote in message
news:[email protected]...
>
> "Joe Tylicki" <[email protected]> wrote in message
> news:ZS%[email protected]...
>> >your chances are not good.<
>>
>> I would have to agree. You could try exposing the opposite side to the
> the
>> elements and see if it evens out, much like flipping deck boards. You
> could
>> try it with just one piece first to see if it works. I believe the
> cupping
>> is caused by the wood fibers compressing and does not reverse upon
>> drying.
>>
>
> For your edification :
> http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.htm
> Specifically, chapter 3.
>
>
>
>
>

I've had SOME luck in reversing the process--wetting the concave side to
expand the fibers, and aggressively drying the concave side. Reduces the
cupping, anyhow. The Furniture Doctor book recommended putting cupped
boards concave side down on the lawn for a few days. Let the moisture from
the earth hit the concave side and the sun bake the convex side.

Then you've got to sticker/anchor/weight the boards while they dry to
equilibrium so they don't jump back as they were. I don't know if that
induces some residual stresses that will show up when you use them.

It's a shame to waste all that fine wood, hope something works.

Another thought--is the convex side the bottom (unfinished) side of the
tread? Might be a chance of it flattening out when the unfinished side
dries to the same moisture content as the finished side.


Walt C



"Lars S" <[email protected]> wrote in message
news:2005031311554816807%larsstole@gsbuchicagoedu...
>I recently acquired over a dozen 42"x12"x1-3/4" white oak stair treads from
>a rennovation site of a 100-year-old greystone. This would be a gloat,
>except I already spent a day getting them from the construciton site,
>pulling nails, and cleaning them off. And, the biggest problem, most of
>them are significantly cupped from being exposed to a few onths of rain and
>melting snow. The cupping is about 1/2" to 3/4" across the 12" width of
>most of the treads.
>
> Here's my question. If I sticker the treads for a while (how long?) will
> the cupping reverse over time? If not, I can easily plane off 1/2" of
> material and make some very nice, flat 1-1/2" boards (I'm thinking two
> side tables and a matching coffee table), but I don't want the planks to
> reverse-cup once I've made a nice table top. I'm a bit impatient, so I
> would prefer not to wait a year to use the wood.
>
>
>

First of all congrats on the treads--I wish I had such a find. The
cupping probably won't reverse over time if stickered. However,
here's a trick that may work:

On a hot sunny day place the cupped boards on the grass on a hot sunny
day. Place the boards in the orientation of "n" rather than "u."
The warm moisture from the grass will expand the wood fibers and tend
to make the boards less cupped. A moist heating pad might work just
as well, although it would take longer to do so many boards.

I learned this method from my father who used it to flatten warped
doors. It looked like crazy thing to do then left me amazed how well
it worked.

You can plane the boards instead, although you will have thinner
boards. If your boads are damp, you will need to dry them and become
stable before working on them.


On Sun, 13 Mar 2005 11:55:48 -0600, Lars S
<[email protected]> wrote:

>I recently acquired over a dozen 42"x12"x1-3/4" white oak stair treads
>from a rennovation site of a 100-year-old greystone. This would be a
>gloat, except I already spent a day getting them from the construciton
>site, pulling nails, and cleaning them off. And, the biggest problem,
>most of them are significantly cupped from being exposed to a few onths
>of rain and melting snow. The cupping is about 1/2" to 3/4" across the
>12" width of most of the treads.
>
>Here's my question. If I sticker the treads for a while (how long?)
>will the cupping reverse over time? If not, I can easily plane off
>1/2" of material and make some very nice, flat 1-1/2" boards (I'm
>thinking two side tables and a matching coffee table), but I don't want
>the planks to reverse-cup once I've made a nice table top. I'm a bit
>impatient, so I would prefer not to wait a year to use the wood.
>
>

Lars S wrote:
> I recently acquired over a dozen 42"x12"x1-3/4" white oak stair treads
> from a rennovation site of a 100-year-old greystone. This would be a
> gloat, except I already spent a day getting them from the construciton
> site, pulling nails, and cleaning them off. And, the biggest problem,
> most of them are significantly cupped from being exposed to a few onths
> of rain and melting snow. The cupping is about 1/2" to 3/4" across the
> 12" width of most of the treads.
>
> Here's my question. If I sticker the treads for a while (how long?)
> will the cupping reverse over time? If not, I can easily plane off 1/2"
> of material and make some very nice, flat 1-1/2" boards (I'm thinking
> two side tables and a matching coffee table), but I don't want the
> planks to reverse-cup once I've made a nice table top. I'm a bit
> impatient, so I would prefer not to wait a year to use the wood.

Don't have a clue if you will ever get the cupping to reverse.

Maybe some, but probably not much.

A little tip.

After 100 years of service, who knows what has been ground into the
surface of those treads.

When it comes time to surface them, go to a commercial drum sanding house.

Save your jointer and planer blades.

It will not only be faster, but less costly in the long run.

Lew