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    Oh no Warped Wood

    Last weekend I started a new project with some Poplar boards. I planed and cut them to size on Wednesday and during the holiday weekend cut dovetails and dados. The wood is being kept in the unfinished room over my garage where there is no HVAC. Some of the wood is now greatly warped. Last week there was a slight warp but I figured that would ease out.

    Am I doomed or is there a quick fix? I've generally avoided warped wood all these years so I never really learned what the solutions were apart from planing it down, which is too late for a piece that has already been dimensioned.

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    Re: Oh no Warped Wood

    I found this after posting the thread:

    http://www.craftsmanslegacy.com/lega...en-Warped-Wood

    Anyone done this? It sounds like something that would work, meaning the glue application part and that glue feeding into the wood through capillary action.

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    Re: Oh no Warped Wood

    Were the poplar boards air dried or kiln dried? How thick are they and where were they stored before you started planing them? Did you sticker the boards again after dimensioning them and storing them in the attic for the last week?

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    Re: Oh no Warped Wood

    I have not tried the technique in the link, (the glue part) so have no idea if that would work. I have had some luck with the method of applying water to the inside of the bow, but it does not make them perfect. Realize that when wood warps, it is not only the moisture in the cells that changes, it also compresses some of the cells, so they seldom return to the full "normal" status when re-wetted. That may get you straight enough so you can assemble and clamp until dry. The downside is that the wood may crack later as it acclimates.

    If the wood was fairly dry when you worked it, and then warped when putting in the upstairs, I would first put them on edge or with spacers in between to let them fully dry out. They may have been subjected to uneven moisture when in the attic area, and may return to what you had before when they dry.

    If you have had the wood for a few days before working it, it is curious that they would warp after that much time unless they were really wet and green when you started (which could easily be the case if it is freshly re-sawn or you planed quite a bit off them).). That is why I would first try just letting them dry. If its not a large volume, maybe you could move them into the house for a bit.

    That sure is a bummer.

    Go
    Last edited by Gofor; 12-01-2018 at 11:55 AM.
    Practicing at practical woodworking

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    Re: Oh no Warped Wood

    I would set them outside in the sun with the convex side up. Works best in the summer but still should work now, just taking longer

  6. #6
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    Re: Oh no Warped Wood

    Save for quartersawn lumber (which only change in length, width, and thickness, but not shape), boards (particularly flatsawn) are never going to remain stable in an unconditioned room where the humidity is constantly changing. Temperature is of little concern other than for the short-term relationship between relative humidity and temperature, but the relative humidity versus the current moisture content of the wood is what drives wood to move one way or the other, and the endgrain and facegrain patterns of each piece of lumber will always tell the story of how the board is going to move in relation to gaining or losing moisture. This is part of the reason why it is said that wood is best thought if and treated as a living breathing creation as it will continue to react to moisture changes for as long as it exists — you can’t really force it after the fact, you can only modify your processes to minimize unwanted change and modify your designs to better cope with the forces created by these changes.

    Boards that are warped today may well be flat, or even warped in the opposite manner, a month, or six months, from now when the air is wetter or drier than today as the wood is forever moving.

    But in your case what has likely happened (I’m guessing here as you did not state your process, but this is the typical progression of events) is that you ran some lumber that was not yet acclimated to the present humidity level through-and-through (as in all the way through to the interior) through a thickness planer and took all, or most, of the wood thickness off just one side of the board. When you do this you have a board that on one side is more or less acclimated as it was exterior wood to begin with and on the other side you have suddenly exposed interior wood that had not previously acclimated to exterior conditions and now there is a sudden and dramatic difference in the moisture content on both sides of the board resulting in the warping or cupping condition.

    If you removed very much wood then it can take some time to acclimate, but that is further exacerbated by the fact that current conditions humidity wise are rather unstable this time of year until we get into the sustained cold at which point the air is more stably dry overall. This is why one should plane roughly even amounts of thickness off both sides of a board that has not fully acclimated to an even moisture content all the way through -- that way you have balanced stresses in both sides and avoid most of the unwanted movement. This also helps to keep balanced any physical characteristics within the board that would tend to drive warping or cupping.

    A better procedure, still, is to remove around 1/2 to 2/3 the desired thickness from a board during initial planing — removed evenly from both sides — and then let the board sit for a week or two to see how it responds. Then if it is still straight, plane the remaining thickness off, removing roughly equal amounts from both sides. But if it has warped or cupped, them first rejoint the wood to flatten one side, then rethickness it to final dimensions. This takes longer but it is far more forgiving of wood movement, especially for flatsawn lumber, and gives you a chance to save a board as once it has been thicknessed to final dimensions your options have vanished unless you can accept further reducing its thickness by rejointing the board flat and then thicknessing it to a final consistent thickness, but now you are left with far thinner boards than intended. Either way, to reduce the degree of thickness lost to the rejointing and thicknessing steps it helps to cut long boards down to something much closer to their target lengths and widths as such reduces how much thickness must be removed versus a longer board.

    So if you removed a significant amount of thickness then you are really better waiting awhile before proceeding as anything you would try to do to flatten things now is just as likely to create problems once the moisture content stabilizes — the issue may even self correct significantly once moisture content evens out (or it may not, there are no guarantees as it could even worsen with the changing humidity).

    It is important to understand that using tricks like wetting wood on one side to force it to warp or cup in a desired manner only makes it flat while that moisture content stays exactly the same, so once you screw or nail the wood into place you will have pent up stresses within the wood over time as the moisture content shifts that can warp or twist your final project if it is not strong enough to resist those forces (depending upon the degree of warping/cupping and the width of the board, those forces can become quite considerable). A little trickery can be fine if the warp, cup, or twist is very slight and the board will be secured to a frame strong enough to resist those forces, but often the end result is nails pulling out over time or glue joints pulling apart due to the forces generated in the wood if the problem was not either properly addressed or the project designed to be forgiving of such movement (that why panels in solid wood panel doors are floating, for example, as that allows the rails and stiles to move independently of the center panel since each moves at a different rate).

    If you want to keep your wood stable over time as well as control the humidity level at which your wood acclimated the a dehumidifier is a very good investment for the shop, plus it will largely eliminate rust in the workshop (so more time for woodworking and less committed to polishing tools and cast iron).

    Right now we are at the start of a season where humidity levels in unconditioned spaces will really begin to plunge as compared to the warmer months when humidity levels are typically quite high in much of our area, so this is the start of a season of significant wood movement as-is. If this is an item that is destined for the indoors you may find it helpful to store your boards indoors in your conditioned area so that they are exposed to your interior humidity levels and see how they respond in that environment.

    Best wishes on your project. We all know what you are experiencing right now as it is part of learning to work with wood rather than against it!

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    Re: Oh no Warped Wood

    I'm not sure if this would work for you or not but I once had a roughly 11" x 11" solid poplar drawer bottom and it had been air dried out side for years. I planed it by hand. I noticed it had a significant cup in it. So on the back side of the cup I used a spray bottle to mist the back to pull it the other way, then set it in the sun for a short amount of time. It pulled it back perfectly, and it never returned back to warped. I used the drawer bottom in a table I made. Not a very scientific fix but it worked I guess.

    But sometimes even when I: let the wood acclimate to shop, take milling in steps over a week or two and let the wood rest inbetween milling, and then square it up and thickness it again to final thickness, and take an even amount off both side of the workpiece, sometimes they still just slightly bow again. Some of my white oak components for a project did that to me.

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  10. #8
    User Richo B's Avatar
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    Re: Oh no Warped Wood

    Quote Originally Posted by ehpoole View Post

    But in your case what has likely happened (I’m guessing here as you did not state your process, but this is the typical progression of events) is that you ran some lumber that was not yet acclimated to the present humidity level through-and-through (as in all the way through to the interior) through a thickness planer and took all, or most, of the wood thickness off just one side of the board. When you do this you have a board that on one side is more or less acclimated as it was exterior wood to begin with and on the other side you have suddenly exposed interior wood that had not previously acclimated to exterior conditions and now there is a sudden and dramatic difference in the moisture content on both sides of the board resulting in the warping or cupping condition.
    Ethan - you have nailed it exactly!

    Here's what I did and you will see several steps where I obviously went wrong per your diagnosis. Most of the events occurred last week (week of Thanksgiving)

    1. Tuesday evening: I bought three 1" x 12" x 6' poplar boards from Lowes (yes I know this is probably the worst offense of the whole bit but I don't have the fancy hardwood stores everyone else in the state has and I'm not interested in getting wood from the two wood suppliers in the area for every single project). I have purchased poplar from Lowes before and not had a problem. I did inspect the boards thoroughly before purchasing.

    2. Wednesday evening: Planed the three boards down from 3/4" to 1/2" on planer at work. In most of my woodworking I only use hand tools but I wanted to plane the stuff on the planer in my lab because I knew I'd spend all weekend if I did it by hand. Additionally I only planed one side of the three pieces. After planing then I cut several of the pieces of the carcass to size using the table saw. The bottom board and two sides came from the same piece of wood for consistency with the dovetails. Later I discovered that one of the sides was actually tapered on one end and had come that way from the store. So I had to get another piece from a different board.

    3. Thursday morning (Thanksgiving): Began marking boards and cutting dovetails.

    4. Sunday afternoon: dovetails are already finished at this point and dados start getting done in the two sides. At the end of the day I discover that one of the end pieces has a nasty warp starting. Prior to that I had noticed a warp in the bottom piece and left it indoors to hope to settle down.

    5. Jump ahead to today (Saturday Dec. 1) I’ve kept all the pieces of poplar out in the “attic” space and the one side is really warped and the other side is also warped.

    6. Now I did try laying a wet towel over the cup of the worst piece today and it did settle the wood down nearly flat. But then of course it wanted to warp in the other direction. So for now both side pieces are residing in an indoor room for the next week.

    At this point I probably won’t be able to work on this project until the weekend of December 22 due to working the upcoming weekends at my job. So hopefully this off period will help the pieces acclimate.

    Normally when I do a project I buy the wood and start working it within a week. I’m not sure I’ve worked it as fast as I did this time, especially with using a machine planer to remove so much grain so fast.

    I'm copying and pasting your long reply into a document for future reference. Very good stuff in there and helpful for next time.
    Last edited by Richo B; 12-01-2018 at 10:22 PM.

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    Re: Oh no Warped Wood

    Ricoh, it sounds like your wood movement was primarily a result of only planing one face. There was a delta between the core and shell MC% on your lumber, and by only planing one face you ended up with a board that was drier on one face than the other.

    Always alternative board faces when you plane them so that you can remove an equal amount from each side.

    Ethan - great writeup - as always.

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  13. #10
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    Re: Oh no Warped Wood

    Once a board is planed to final thickness, there is no place to go to remove warps, bows, cups and twists. Nothing I have every tried I am confident to tell you will work.

    That said, you can try a few things:

    1. A cup might be alleviated by ripping the board, jointing and gluing. Depends on the width of the board and the degree of cup.
    2. Sticker the board bow up, place a weight (or clamp) in the middle. Check daily, see what happens. You can put a light or fan over it. Often times a bow due to unequal drying can be balanced out.

    3. ALWAYS do your milling in stages. In your case, going from 3/4 to 1/2" I would do in 3 stages 1/8" each time mostly because that lumber might have a high moisture content.

    4. I don't recommend putting boards in the sun as the drying can over shoot and you will have a bow in the opposite face (how do I know this ;-)


    I'll re-emphasize milling equally and in stages. Even if the lumber is dried to 8% & if for no other reason that tension might be released.

    Give some thought to how you sticker boards between millings. I keep lumber in stickers or sealed in plastic bags as the project progresses, especially things like panels. I usually put a heavy board on top or use clamps, especially on resawn wood. Keep the stack off the floor, away from fans and out of sunlight.

    If you have a climate controlled room, that is the best place to store lumber.

    IMO your best bet is probably start over with new lumber.

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    Re: Oh no Warped Wood

    Richo

    I don't quite understand why you don't get your lumber at Precision Molding. 4/4 or 5/4 poplar will probably be cheaper than the "guaranteed to warp" boards from Lowes, and you'll have the extra thickness you need to plane the wood correctly. As you know, I live 10 minutes from Lowes and 50 minutes from Precision. For me, it's a no brainer - Precision every time.
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    User Richo B's Avatar
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    Re: Oh no Warped Wood

    Well I've certainly learned my lesson concerning planing a board. That said, I'm going to wait and see what happens to the boards I have before going further. I won't have time to actually work this project for a couple weeks due to Christmas programming at work. I'd rather not buy new boards as I've already shelled out money for these. If I had paid more money for cherry like I was originally thinking of doing I'd really be in trouble. The two worst boards have been residing indoors since Saturday and are looking much better. If by the 22nd all the boards have not settled down I might see what Precision has or wait until next year to take this one on. The wife doesn't like to see wood come in the house too much because she knows it costs.

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    Re: Oh no Warped Wood

    Sorry to hear about your dilemma.

    Some good information in this thread, perhaps a few more pointers.

    What are you building and what is the joinery process?

    One thing to remember is that no matter how careful you are and what precautions you take, wood will always move to some extent. Wide 12 flat sawn boards will never stay flat and will cup to some extent. Depending on the design of the project and the joinery, you may be able to pull the cup straight during assembly.

    For example I have just resawn a bunch of 5/4 Beech for drawer boxes and planed them down to 1/2. They are in my conditioned shop and a few of them have cupped to almost 1/4 from flat. This is not an issue for me, as the drawer boxes are dovetailed and once a cupped board is clamped against the square end of the board it joints to (dovetail joint) the cup is pulled perfectly straight and square.

    In general though, personally I stay away from wide flat sawn stock. If I have to work with 12 flat sawn boards, I would rip them to 6 flip one board to change grain direction and edge joint. From the same stock the joint would not be easily noticed.
    Last edited by Willemjm; 12-04-2018 at 07:47 AM.

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  18. #14
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    Re: Oh no Warped Wood

    Its been a couple weeks since I noticed the warping wood. Most of the wood has straightened out since its now being kept indoors. I've kept some pieces under weight as suggested on this thread and also by my woodworking volunteer to whom I go for most of my WWing problems. A couple pieces may still be hesitant and I might just replace those pieces. The joinery of the carcass (dovetails much like on a Dutch Chest) will correct some of the warping as it has on other projects I've done without further cracking in the future.

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