Planks (a light wood?) that make up the top of a small table are weather warped. "Cupped" upward.
This isn't meant to be a centerpiece of the home, but it would be nice to make it presentable again.
What's the usual repair recommended for such a condition?
Tools available: the usual drills and hand tools; table saw; router; belt sander; palm sander; paint gun and compressor.
Suggestions welcome.
Thanks.
Replace the boards. And put them so if they cup they will cup with the center up. Fasten in the center and keep painted/varnished. _____________
Well, you could ....
a) plane down the boards to make them flat on the surface
b) if thin/narrow enough, bend them down and fasten
c) if not thin enough, remove and rip one or more kerfs on underside, put glue in kerfs, bend flat.
Depends on the amount of cup and the edges of the table. My wife inherited an attractive elm claw foot from her mom. It had a similar problem and one of the glue joints had failed too. I removed it from the legs, removed the edge trim, sawed through the failed glue joint and glued it back together. Before gluing I took a thin pass through a thickness planer to level the top out again. Came out looking good. If you don't have a planer, search around for a friend or school that does.
RonB
Very hard to say how I would address it without seeing a picture. Can you post a pic somwhere? Be careful if you plan to try and address it with a planer because depending on the defect the planer rollers can sometimes just hold it flat while it planes it, then aftewards it rools right back into it's curl and you have a nice flat but curled surface still.
I like to start this type of conversation by saying, "you're not happy with it the way it is now, are you?" or "it doesn't work now, does it?". I guess we can't hurt too bad.
I would remove the top. On a nice spring day I would lay it on the grass with the humped side up. Let it sit there a day preferably with some sunshine. The piece has probably gotten wet at some point and the top dried quicker and pulled the warp. I am suggesting you try to equalize the moisture throughout the piece. I'm thinking you will see some substantial improvement after a day of absorbing ground moisture on the shrunken side and air/sun drying on the top side. I would them give it lots of weight on a flat table surface, not on the concrete patio or garage floor. After a week, see what you have.
I like your suggestions. The lawn and sunshine are readily available. But the only large flat surface is the garage floor. And weight? Hmm... 2 front wheels of the Toyota come to mind...
Thanks.
Find someone with a planer and have them smooth it out for you into a flat surface.
I thought his suggestion ingenious as well. How about that Toyota, an appropriately-sized sheet of 3/4" plywood (make a sandwich of your "moistened" top) and a piece of 2x10 as a caul?
Just a note - cupping takes place towards the moisture not away from it.
Just to clarify: the concave side is moist, and the convex side is dry?
Table top looks like a U (not as drastic I hope). Top got wet while the underside remained drier. When it dried out the compressed fibers (caused be the dry side restricting even swelling of the wet side) distort it... according to the books :)
As mentioned, a possible sollution is to wet it all down lay it on stickers and put weight on it to dry.
The "proper" method for an antique is to router out the underside and replace with hardboard. That leaves the original top surface while providing a flat base for it. Something I probably would not have the nerve to do.
Mike
Not necessarily ... and AAMOF, and depending upon the grain and the way the wood was cut off the tree, it more likely to be just the opposite of what you stated ... the concave side being the dry side, and the convex the moist. :)
There are indeed some exception with certain grain patterns due to the way the wood was cut from the log (plain sawn, rift sawn, etc.), or if laminated, but mostly wood cups and checks parallel to the grain and to the drier side.
Excellent example is the cupping of hardwood floors, which "cup" (concave side up) when wet from the underneath ... dry on the top, wet on bottom ... one of the main reasons why a moisture barrier is always used _beneath_ a hardwood floor.
Another hole in your balloon ... leaving a board to dry out in the sun, The concave side is drier from exposure to the sun and heat, and, once again, the board generally cups toward the dry side.
Try this by laying a board on wet grass before the morning sun hits on sunny day, check it out by noon. :)
Here is indeed, "according to the books":
Wood warmed by the sun experiences a virtual RH far below the ambient RH. The surface dries faster than the rest of the lumber. This is why cupping and checking often occur on decking boards; the top surface is much drier than the rest of the board. Shrinkage of the top surface commensurate with this dryness causes cupping and checking parallel to the grain
What are "stickers"?
On 2/22/2012 11:58 AM, Paul Conners wrote: ...
goatheads, sandburs, wavy thistle, ... :)
Sorry, couldn't help it.
Sorry but I believe what I said to still be right.
While grain of course will have effects the cupping will take place towards the moist side (or away from the compression pressure might also be a way to say it). Take a look at porches or decks, do you seen any cupped down? Fave you ever found a table top that cupped down?
Your wood floor - is it cupping because it is moist underneath or because of the mopping and drying taking place above? as for the board on the lawn - don't know, would have to try it.
Your quote - Is it indeed the sun causing the surface to dry faster or is it in fact that the problem is not visual until the surface dries?
I will explain it as one of the books due (please recall I said this was according to the books - not neccessarily the truth - I believe much of the things "known" are not the truth of what is happening, but only what we as humans can guess at/or comprehend with our limited knowledge).
Wood cells normally want to swell and then shrink back to their normal shape and size. When something restricts this the swelling continues on uncompressed sides (i.e. the bottom of the board, or anywhere else it is not wet/or drier). This forces the cells into more of an oval shape instead of their original shape. When they shrink from drying this shape is not shanged so the compressed sides of the cell (we will call it the width) ends up smaller than it used to be. As this is repeated we end up with cupping/warping/checks/etc..
I can never recall seeing a board that was cupped in any direction except on the side effected by changes in moisture.
Mike
Sticker A sticker is a type of a piece of paper or plastic, adhesive, sticky on one side, and usually with a design on the other.
Stickers, Bumper Stickers - Sticker Giant Stickers made easy. 26,000 bumper sticker designs in stock. Custom sticker
Stickers - Shop for a new Custom Stickers Political stickers, art stickers, funny stickers and millions more! Highest
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123stickers.com - Custom vinyl stickers | Custom Banners ... Custom Vinyl Stickers | Custom T-shirts | Custom Banners. Low minimum customThen I tried "sticker wood" and got this and the like:
There comes a point where the flaming of "Don't you use Google?" is worth it...
Sticks of wood (lumber). Usually they are used in stacked lumber to keep the wood separated for air flow - and flat.
I did not mention that you would want a flat surface under the stickers.
Mike
Did you bother to even read the supporting evidence I provided disproving your unequivocal contention, first above?
It is indeed "not necessarily the truth", as I clearly outlined above, complete with a cite as to the an explanation for why your statement is not necessarily the case.
By all means, offer a cite that supports your contention to the contrary.
Yes, and as a result, that attitude arguably insures that your knowledge in this regard will remain limited.
The above is either so poorly worded as to be useless in defining your contention, or the result of a total misunderstanding of the effects of moisture and humidity on the dimensional instability of wood.
It's really impossible to tell which?
Again, too loosely worded to be of much use in defining the problem ... and your admission that you have "never recalled" seeing that, is certainly no proof of your argument.
Yes, it is indeed this _differential_ in moisture content between opposite faces that causes the phenomenon of cupping, but not necessarily for the reason you unequivocally stated first above.
Simply put, cupping is most often the result of the opposite (convex) side being moist, and the cupped (concave) side being drier ... the exact opposite of your unequivocal statement.
IOW, your understanding is mostly backwards of the actual effect of moisture on wood, with the exceptions I noted above. You will certainly want to do your homework, and provide some supporting evidence to the contrary, if you want to continue a reasonable discussion of the issue.
Just 2 mor cents...
Grain of course plays a part is how the reaction takes place, but as you said "but mostly wood cups and checks parallel to the grain and to the drier side".
As my previous post metnions - never seen a floor/table/deck cup down.
But I don't want to argue it. As said - I am simply repeating it from information I have read. I doubt anyone knows for sure the real reasons for it all. Mike
Ok. Whatever you would like to make it. I have no need to argue. I think my sentences were clear enough.
You also call into question whether or not I even undestand moisture - and that I will not be able to learn (if I don't).
I do believe for some reason you feel offended and seem to have a chip - but that is fine too.
You have decided what you will take for the answer - nothing I say or do will change it.
Mike
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