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How do I fix a Veneered chessboard that's backing "cupped"

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Forum topic by souichiro posted 04-02-2009 02:03 PM 2111 views 0 times favorited 12 replies Add to Favorites Watch
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souichiro

369 posts in 2001 days


04-02-2009 02:03 PM

Topic tags/keywords: veneer chess bow cupped cup backing board

I am working on this chessboard with a veneer surface. I made the face a one large panel and glued it onto a pine plank as a backing. I had planned on then gluing a solid maple veneer face on the back to stabilize it. However, when the face dried overnight…... it bowed or “cupped” the backing board. Perhaps 1/8” or so. Does anyone with experience in this have any suggestions for me to correct the issue? I am happy with the colors of the board and feel like it works. I’d love to be able to correct it before I work on the edging.

I also have a blog entry about this here)

Any ideas would be greatly appreciated.

Regards,
-Dale

-- Dale, Oregon


12 replies so far

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Damian Penney

1140 posts in 2647 days


#1 posted 04-02-2009 09:06 PM

You could try pressing it flat when you apply the backer (vacuum press?)

-- I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso

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TopamaxSurvivor

14750 posts in 2331 days


#2 posted 04-03-2009 12:23 AM

I wonder if it will dry back down in time?? Or maybe a solar kiln to see what happens? Seems like that grain should move again as it dries. BTW, beautiful job on the board!!

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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Waldschrat

505 posts in 2091 days


#3 posted 04-05-2009 08:11 PM

Dale,

I looked at your stuff and I first want to say, well done, the chess board looks great!

Ok at risk at stating the obvious, rule number one of veneering anything, and I mean everything, chessboard, panel, door, whatever is always use a symetrical build up of the layers. Ok, the only exception is well, ok there are probably two i can think of… is when you have a chessboard, root burl, or some sort of intarsien, and the second is when you have a vapor barrier on a door. That is why your board warped.

How to fix it? that is much more difficult. A important factor is what kind of glue did you use to veneer the chessboard to the core wood? If you used white/yellow glue (PVA or PVC), than it will make everything to repaird your problem a bit easier.

You could try using a veneer that is exactly the same thickness of what you have on the side you veneered, put it in the press and us a duroplast adheasive, so a Urea-Resin Glue (plastic resin adheasive)... an example out of the trusty “pocket ref” is the “DAP Weldwood Plastic Resin Glue”, I have never personaly used this one, as we do not have this brand here. but it is the type of glue that is important. Make sure that the grain of the backing veneer is perpendicular to the core wood!

That should straighten everything out, but I can not promise. Normally when workingwith solid wood cores there is a “locking”veneer, approx 1mm thick then comes the final veneer. These veneers should always be layed so that every layer is perpendicular to each other and symetrical (excecpt chessboards, etc… ) Then you will have garanenteed a flat board.

-- Nicholas, Cabinet/Furniture Maker, Blue Hill, Maine

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TopamaxSurvivor

14750 posts in 2331 days


#4 posted 04-06-2009 02:04 AM

Waldschrat,

Why won’t the backing flatten when it dries back out?

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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Waldschrat

505 posts in 2091 days


#5 posted 04-06-2009 02:12 PM

TopamaxSurvivor,

Well, I am not saying that it will not flatten out (its possible, but I think that is not the problem), but more than likely, at least from what it looks in the pic on the blog link, that it looks like it it had a higher moister content when the wood was pressed with the veneer, and I will tell you why I think that: I think the opposite is true. We need moisture to flatten this board out and when we do it is still a temporary fix until some sort of backing veneer is put on, to stabilize this panel.

The board is curved upwards (towards the veneer), which I would believe is caused by either one, or both of two thing.

A) the wood was moister when pressed, dried from the heat from pressing or by itself from less moisture in the air and shrunk, since one side is bound fest/fast by the glue and the veneer layer (which locks the wood from moving (at least mostly but not all movement) thus the side which is free to the air, dried quicker plus is more free to movement because lack of the backing veneer, shrunk, and the other side did not/could not, thus we have the bow in the wood.

B) the other think to cause this because it does have a solid wood core is the simple fact of what happens to wood when you leave a board sitting on a workbench over night, usually it will cup upwards because the air will will dry out the side exposed , and not the side which is sitting on the benchtop. To counter this simply lay the board the other direction and it will go straight again and if left long enough it will cup the other way. I doubt though that this is the problem, although you see why in most shops that I know, man made veneered boards are usually stored upright for this reason— on edge, especially when they are freshly veneered, and are still cooling down, it is very important that the just veneered panels are cooled evenly and depending on the type of adheasive (namely Thermoplast or Duroplast) if it should be stacked with muntins/sticks to allow air to circulate all around (so with thermoplasts, PVC or PVA /white, yellow glues) or completely covered with each panel stacked on top of each other with a scrap panel on top to stop air circulation and allow slow cooling (the Durplast kinds).

The only way to make this panel flat for permanent is to make a backing veneer of similiar wood type and thickness to keep this panel from going curved again, not the problem is, once I have thought of it is to see how to get the moisture back to where it was at when it was originally pressed, then at that specific moisture content, press the backing veneer on, so it will stay straight.

-- Nicholas, Cabinet/Furniture Maker, Blue Hill, Maine

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Waldschrat

505 posts in 2091 days


#6 posted 04-06-2009 02:13 PM

TopamaxSurvivor,

by the way cool expression “Debt is nothing more than the 21st Century’s form of slavery” very true when one thinks of it, interesting!

-- Nicholas, Cabinet/Furniture Maker, Blue Hill, Maine

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TopamaxSurvivor

14750 posts in 2331 days


#7 posted 04-06-2009 05:54 PM

Waldschrat,

The debt saying is an idea I got listening to Thom Hartman on the radio. You can google him and listen on the web.

Back to the wood; could this small of a project be made just using plain old plywod as a backer? Maybe 1/2 or 5/8”.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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souichiro

369 posts in 2001 days


#8 posted 04-07-2009 05:29 AM

Waldschrat,
Thanks so much for all of this infomation!! I am thinking that it is how you are saying….. the wood core was dry having been purchased at a “big-box” store as a glued plank. It had actually been stored in my shop for about 6 months, and so I think it was well aclimated. It must have been the moisture in the water-based glue and the veneer only on one side.

So I should glue a equal veneer perpendicular to the core grain on the back using a plastic resin glue, right?

(The original glue was yellow glue. The board was placed in the house after glued, and it “cupped” overnight.)

A few quick questions if possible….

1- Should I stop using yellow glue for larger veneer panels do you think?

2- Did I read this correctly for future applications…... If using a solid wood core, glue a veneer on front and back both perpendicular grain to the core. And then glue my final veneer panel on the now stabalized core?

TopamaxSurvivor,
I would think so. I have glued things very similar in size (20×20 inches) to plywood in the past without issue. And I have heard that you can use MDF board as well. Can’t speak for that, but I know that I’ve always used plywood before. I guess I was sort of thinking that I would try something “nicer” than plywood. LOL. Serves me right, eh.

-- Dale, Oregon

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Waldschrat

505 posts in 2091 days


#9 posted 04-07-2009 04:00 PM

in sequencial order:

TopamaxSurvivor:

Yes, you are correct, Using an already made plywood is WAY easier, and actually how the Profi´s do it. Nobody messes around making thier own panels in the business I know. BUT I have heard of it… The only time I have ever heard of making your own solid wood core panels by your self is in a old book from Fritz Spannagel called “Der Möbelbau” from 1940! He has a good points in the book refering to the lack of quality solid-wood core man-made-panels/boards, one should make them for himself to assure the highest quality (you see here how seriously germans and thier handworkers take quality—a bit too far sometimes—- and nobody really does that now-a-days anyway…

Souichiro: I would not say “serves me right” usually the highest quality stuff (expensive) is made not to unsimiliar to what you have made with your solid core, we just get it from the factory with the locking veneer already on it in 2×5 metre panels, so you are on the right path, although an expensive one. (unless you have the time of course)

Yes, you should try gluing a backing veneer to the back. Like I said, I can not promise perfect results, but I think this is you best shot. You might want to set it back in your shop for at least a couple of days. By the way an important question…. When or what time of year did you veneer the board? It matters because (well by us in the mountians) in the winter its is drier and summer moister. You will probably have most success if you can reproduce approx the moisture that occured in the air at the time of original veneer pressing.

Its good that you used yellow glue, that means it can be softend with heat, so when you press the backing veneer on the panel, it should then be flexible enough to allow the panel to go flat again.

Souichiro, answers to your quick questions:

1) You can continue using white or yellow glue, (it depends how quick you are) (I use white glue too for small stuff, especially before I mix a bucket of the Urea glue together. this is also depending on how big, or how many things I have to press), you just have to keep in mind that, and this is very important when pressing larger or many things, that the open time of white/yellow glues is on a summer day, can be as short as 1 minute or so. In the winter, when its colder and the water does not evaporate out of the glue so fast it can be up up 12 min or so. This also dependings on the relative humidity. So you can just imagine, doing a larger piece, you have to be quick to get it into the press.

This is one of the real advantages of using the duroplast urea based, or as you called plastic resin glue. The open time is simply longer and it cannot be softened again by heat, once its sets up, it sets up. Not to mention you can cut it with flour to thicken the glue a bit so it does not come through the pores of large pored woods such as oak, ash, or sometimes walnut or cherry.

2) Yes, you read correctly! Always use a “locking” veneer layer, just as you wrote, and always remember the grain of each succeeding layer should be turned to be perpendicular or 90 degrees to the layer under it. That all there is to plywood, and thats how you will keep your selfmade boards straight. If you do it like this you will save your self alot of heartache and work trying to repair it later.

and you are right MDF, chipboard, hardboard, all of them, can be veneered no matter how thin… just keeping in mind that if it is a homogeneous material like MDF it does not matter the grain direction. If it is 3, 5 or 7, ply plywood or something like multiplex (I do know how you call it in english) then always veneer (or the final veneer) perpendicular to the grain underneath it (Generaly the same direction of the core veneer) and always make sure of a symetrical buildup of the layers.

-- Nicholas, Cabinet/Furniture Maker, Blue Hill, Maine

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souichiro

369 posts in 2001 days


#10 posted 04-07-2009 05:56 PM

Nicholas,

I just wanted to say thank you so much for all of this information! I can not tell you how much I appreciate it. I will glue the backing as you say and hope for the best. :)

But more importantly, I have now learned some very valuable things. I feel as if I have a better way to visualize this now. One more step in a wonderful hobby!

Again, thank you for your time, and thanks for your valuable insight.

Regards,
-Dale

-- Dale, Oregon

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TopamaxSurvivor

14750 posts in 2331 days


#11 posted 04-09-2009 07:30 AM

Nicholas, I’d like to add my thanks too. I haven’t done this yet, but intend to when i have time. I had no idea white/ yellow glue’s open time could be as short as a minute!!

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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moshel

864 posts in 2339 days


#12 posted 04-09-2009 08:57 AM

i had a similar problem (http://lumberjocks.com/projects/12700) and the backing was plywood… I am still fighting this. would love to hear if the backing fixed your problem.

-- The woods are lovely, dark and deep, but I have promises to keep...

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