I have a custom built dinning room table which has begun to warp in the last two years. The table is about ten years old. The table top is about 1″ thick, the surface 1/2″ is solid black walnut, the bottom half is oak plywood. The walnut is obviously drying out and contracting, so far with no surface cracks. How can I get moisture back into the wood, straighten out the warp, and prevent this from happening again.
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Other than the fact that it is bad voodoo to laminate solid wood to plywood, you should look into whole house humidity control. Both are common problems, but you can do something about the latter.
<edit> While you haven't mentioned where you are from, I have to go psychic and assume that you are coming out of a heating season. Give details on where you live and what you have for a heating system so you might get some real advice. There is no magic to warping, it is a matter of moisture, and you have been lucky you haven't had any cracking up to now.
Edited 4/4/2002 12:22:06 AM ET by Qtrmeg
I'm curious - any idea why it was built this way instead of solid walnut?
I don't know about ply on solid wood, it's a really bad thing to do.
If it were me, I'd take off the top and get the wood/ply separated any way I could..........clean up the walnut then try to get the cup out........wet down the cupped side ....as it swells and straightens use some kind of edging (think countertop) .........reattach to legs/etc. in a way that will keep the thing level. A little bit of creativity and you can save it. (crossed fingers)...............all fails, make a new top using either solid wood or walnut ply, but don't mix the two.
Humbug, Someone was sold a load of humbug ten years ago. Your table top was doomed to failure from the moment that that construction technique was proposed and then employed. Breaking all the rules is alright if you know what the rules are, but the 'craftsman' that made this either didn't know them, saw £ signs, or $ signs, or didn't care. Your table top is, well,.... firewood. Sorry to be the bearer of bad news.
I could speak plainly on the topic if you'd prefer.
http://forums.taunton.com/n/mb/message.asp?webtag=tp-knots&msg=5690.1
The above is a link to a similar discussion between us limp wristed, pinky extending, tea drinking effeminates over at Knots. Slainte, RJ.
Some people are born a couple of nips under par. I'm not one of them.
Edited 4/5/2002 2:39:59 AM ET by Sgian Dubh
Edited 4/5/2002 2:46:14 AM ET by Sgian Dubh
Edited 4/5/2002 2:55:47 AM ET by Sgian Dubh
While I agree that the rules have all been broken and so has your faith in the original builder, I assume that, given the amt of money you have invested in this table is enough to make you want to "save" it and that you will try.
Therefore, I am suggesting this method, untested, out of the dark recesses of my imagination, as a practical substitute for letting the limp wristed one from turning your table into birdhouses or firewood. He will, undoubtably, be sitting back with a cup of tea, his pinkie appropriately extended, and enjoying a good chuckle while prophesying gloom and doom and inwardly praying to the walnut spirits for blessings on his warning.
The main principle ignored was that both sides of the wood need to have exposure to breathe equally. If you stain and seal one side only, or in this case, cover with plywood on one side, you have made it possible to allow one side to expand and contract with changes in humidity at a greater or lesser rate than the other side. My behaviour changes when I am hot and wet on one side only too.
So the solution is to allow air to get to the walnut on the bottom too. I would turn the table upside down on a padded surface or remove the top and do the same with it (If the guy knew what he was doing at all it will be easy to remove the top from the leg frame) and then proceed to remove much of the plywood backing. One method would be to start at the center with a plunge router set to just get to the joint between walnut and plywood and carefully work the stuff out. Another might be to use a forstner type bit to plunge cut several hundred holes honeycombed into the plywood. Then re-mount bracing and stabilizers.
All you loose with this experiment is a few hours of time. It will take some time for it to return to normal if at all, but I'm betting it will stop it from ghetting worse.
But the original builder owes you unless you knew he was doing this on a DIY amature basis and it didn't cost you much.
Cheers.
I don't think that your analysis of the cause is correct.
Yes, if you suddenly move the table from a area with one mositure level to another moisture level there will be warping due to the uneven mositure levels in the different parts of the top.
However, from everything that I have read from Hoadley (sp?) and the Wood Product Labratory indicates that within a few weeks or a couple of months the whole top will be back in equalibrium. And in a typical house the mositure level does not change that quickly.
I believe that what is happening is that the equalibrum moisture level has changed from whatever it was when it was built and the walnut wants to move differently than the base and thus the warp.
The only way that I know to fix it would be to cut some groves in the base so that it was not solid and then add cleats (with sloted mounting holes) to make up for the lack of support. Or maybe add extra supporting pieces to the table apron.
Not knowing all of the details of the construction I don't know if any of this practical or not.
Now if the grooves were made 1/2" wide by a router every 2" for the length of the top, both theories would be satisfied.
I'm supposing that yours would be right if the ply and the walnut were at different moisture levels to begin with. Good points!
And I'm more a builder than a scientific woodworker so I've got more disclaimers than titles after my name.
Excellence is its own reward!
The table is ten years old, the warping has been an issue for two, the walnut seems to be contracting more than the ply. How to get moisture back into the wood and prevent warping again.
While it would be nice to know where humbug lived, in my area (humid NE) the table would be fine around August. By the next heating season install a humidifier and leave the table alone. Can you MacGyver the table to minimize the stability issues? Will the design of the table withstand some of the fixes? I dunno, but I’m looking at this as a symptom of a more widespread problem.
Oops, this should have been to all...
Edited 4/9/2002 10:08:55 AM ET by Qtrmeg
"his pinkie appropriately extended."
The table top is probably toast piffin, except that you might at great expense separate the 'veneer' from the ground, cut it up lengthwise, reflatten it, and re-attach it to similarly grained timber of the same species, but of visually uninteresting stuff, and then treat it as a solid timber top. The problem, simplistically is that the veneer--1/2" thick-- is attached to man made board, and the two are not a very good marriage. They are grounds for divorce prior to the marriage vows even being exchanged.
1/2" thick timber is a plank of solid timber, and behaves as such, and man made board is not, and doesn't behave like solid timber. Therefore the marriage is always a fight. Can anyone say flat plywood with a straight face?
However, the idea that someone came up with of running a series of grooves along the length might help---faceted flats might be acceptable, and it might just avoid the need to repolish. Still, the 'veneering' job was a rather half baked idea in the first place, and really would have been best if not mentioned at all before the client agreed to it. Slainte, RJ.
Pass the Prozac--------pass the Viagra. I've always wondered what it's like to be a dozy stiff.
Edited 4/10/2002 3:49:31 AM ET by Sgian Dubh
Agreed.
I hope you didn't take my comments about your tea drinking pinkie badly. I was just taking off on your first comments and was in a jovial mood at the time.
You are right of course about the table top but my instinct is that this owner will try to do "something" and that seemed like an inexpensive attempt to facilitate.
BTW, we have a president who might be your cousin or other relation. Some folks call him "Dubh-yah"Excellence is its own reward!
piffin, I am seldom offended by anything anyone says about me, or to me in a forum, and you most certainly have never got up my nose. I use such terms as pinkie pointing, and effeminate to distinguish us, well,.... pinkie lifting, effeminate wood 'artistes' from the wood hackers that habituate this bicycle front wheel parking bum crack exposing group largely masdfe up of wood whackers, ha, ha.
Bubb'ya is also known as Pretzel Shrub, but the pretzel was probably smarter.
The table top is toast as it is. I've seen the same problem too often to conclude otherwise. But it could probably be fixed if someone was prepared to throw very large amounts of skill, time, and money at it. Slainte, RJ.
Pass the Prozac--------pass the Viagra. I've always wondered what it's like to be a dozy stiff.
Edited 4/11/2002 2:39:06 AM ET by Sgian Dubh
Edited 4/11/2002 2:40:13 AM ET by Sgian Dubh