Ask WWGOA: How to Stop Wood from Warping


Cabinet Warping ProblemQuestion:
I built a kitchen for my nephew from the ground up and it didn’t turn out too shabby–for a beginner. The top is white hard maple and the rest is red oak. (See attached photo.) These have been installed in his kitchen since June 09. A problem has developed on the cabinet side at the end of the long “L”. The panel is solid oak, not the cabinet grade plywood. It has warped inward about 3/16″. No other warping has occurred in any of the other cabinets. What could have caused this to happen? The panel was pieced together from two pieces and is 3/4″ thick.”

Submitted by ggleixner

Answer:

That’s a very impressive job. Nice work!

When you refer to an end panel, I don’t know if you mean a base cabinet or upper. If you glued two boards together to make a 24″ wide base cabinet end panel, the problem is that the boards you put together were too wide to use this way. It’s best if the boards in your glue-up are 4″-6″ wide, so two boards for a 12″ wide upper would work.

A couple things can lead to a glued up panel warping. It’s possible that the material wasn’t dried correctly. This is often called case hardening, and leads to the outside surfaces being at a different moisture content than the core of the piece. If you planed the wood, did you remove the same amount from both faces? If a lot of planing is done and more material comes off one face than the other, the board can warp. Did the wood have plenty of time to acclimate to your shop before you used it? I’m in Wisconsin and in the winter, I make sure my material is in the shop 2-3 days before I plan on using it. If your shop is a separate building, are you controlling heat and humidity there? It’s best if the conditions in which you build the project are the same as the conditions in which it’ll live. For me, this meant adding a humidifier to my shop in the winter, because everyone up here humidifies their houses all winter long. And, of course, I’ve got heat in the shop. How about the location of that specific panel? Is it near a dishwasher or other steam source? Excessive ambient humidity could make a panel warp.

If all the material you used came from the same source, and you’re not seeing warping anywhere else, you could simply have a couple of hinky boards. Plenty of woodworkers recommend alternating the direction of the annual rings to make certain movement of each board counteracts its neighbor. If I have followed all the guidelines above, I don’t worry about alternating the ring pattern. However, on future glue ups, if you want a little extra stability insurance, take the extra step of alternating the rings.

George


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Discussion
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21 Responses to “Ask WWGOA: How to Stop Wood from Warping”
  1. Roger

    My wife and I make maple/walnut cutting boards in the shape of states. The problem is when we glue three boards together to make the UP of MI they start warping once we bring them inside the house. I have been told to bring the boards in the house before I glue them to let them acclimate to the house temperature. The maple has been kiln dried but stored in an uncontrolled climate in my pole barn. What do you suggest?

    Reply
    • WWGOA Team

      My hunch is that your problem is related more to moisture imbalance than temperature. I’d suggesting getting a moisture meter and checking the moisture content of your lumber where it is stored. Then bring a board into the shop, and another one into your house. Lean them against a wall for a month or so in each place, then check the moisture of each of those boards. I’m guessing that you will probably see a moisture drop a few % in each case. If the board in the house is approximately the same as the one in the shop, then you can just acclimate the boards to your shop. If you see a MC difference between the house and the shop, then you should acclimate the wood to your house before working with it. Typically you would be fine to bring the wood into your shop until it reaches moisture equilibrium, but it is worth testing the difference between house and shop as well, since that is also a potential culprit.
      In my area (MN), if I store lumber in a non controlled environment it will drop to about 12% moisture content. When I bring it into my shop, it will drop to about 8%. If I use it in a project when it is still at 12%, it is almost certain that I will experience a problem, including distortion and/or joint failure.

      Reply
  2. Sarah

    I refinished an antique dresser last summer and finished it with a nice glossy paint. The original top was warped so we used a wet blanket and blocks to straighten it out before re-screwing/attaching to the base. It is now peeling up on the corners. Does anyone have any suggestions on how to stop this without having to ruin my new paint job???? This is so frustrating.

    Reply
    • Customer Service

      Hi Sarah. I’d suggest waiting a few months to let the moisture equalize, and at that point you can better assess whether you can do a touch-up paint job or if more aggressive measures are needed. I’d suggest removing the top for this period if you can, to better allow the top to achieve moisture equilibrium.

      Reply
  3. Tom

    A few months back I made a chess board out of 1/2″ plywood. Just the other day I took a look at it and it warped. I plan on making another one to replace it. If I seal it with say for example with Thompson deck sealer before painting it, will that prevent it from warping?

    Reply
    • Customer Service

      Hi Tom,

      I wouldn’t suggest using a deck sealer on your chess board. To minimize warping on your project, some of this will come down to construction technique and the rest to finishing. If you are applying veneer to the top of the plywood, be sure that you apply the same thickness of veneer to the top and bottom. When finishing, be sure that you apply your finish evenly, same number and thickness of coats, to the top and bottom.

      Happy Woodworking!
      Kate
      WWGOA

      Reply
  4. Nyaline Sugent

    a wet cloth was set on my dresser,I caught it quickly but can tell it started to do something to the surface. Can I use furniture oil on it to keep it from getting bad?

    Reply
    • Customer Service

      Hi Nyaline. As long as you let the effected area dry thoroughly it should not get any worse than it is now. Furniture oil might make it look somewhat better. Also, try a product called “Restor-a-finish” from Howard products, as that can be very effective for hiding a water stain, particularly on dark woods.
      Thanks
      Paul-WWGOA

      Reply
  5. jillian

    I was trying to reproduce a table for a client at a different height. I had my carpenter make the round table top 40″ diameter, 1.5″ thick poplar wood. It was flat when we picked it up from the carpenter and then the faux finisher finished the product and brought it to my office and I laid it on top of another table and could immediately tell that it was over 1/2″ warped. Looked twisted. Faux finisher said that she did it in her studio which has central air. It sat standing up on its side for a while and then it sat flat on 2 paint buckets when she finished it. I don’t know if any of that caused the issue or if it sat in an unairconditioned space for a long period that I was not told about. I am having to remake out of pocket and want to avoid the same thing happening again. Any suggestions?

    Reply
    • Customer Service

      Hello Jillian,

      There are a couple of common culprits that can lead to this situation.  First, the wood might not have been stable to begin with.  It is possible that it was not completely dry, or acclimated to the shop environment when it was built.  Sometimes if the wood is not quite at equilibrium, and there is more wood planed off of one side than the other, it can tend to move a fair amount after planing.  I’m guessing that this was not the case here because it was flat when you picked it up, and normally you would see signs of movement fairly soon after milling it; most likely by the next day.  Another common culprit happens at finishing time.  If an uneven amount of finish is applied to the top versus the bottom, it can lead to problems exactly as you are experiencing.  The general rule in finishing a table top is this; whatever you do to one side, do the same thing to the other side.  Many woodworkers will put a single coat of finish on the bottom of the table, and numerous coats on the top.  This will cause the panel to cup in a concave fashion because the bottom of the table will let in more moisture than the top, causing the bottom to expand at a faster rate than the top.  If that is what happened here, you might be able to save it but applying more coats of finish to bottom, and applying some weights or clamping pressure to encourage the top to flatten out. 
      To avoid this in the future, be very patient when building the top.  Let the wood acclimate in your shop for a couple weeks before doing any machining on it, then let it sit for another day or two after planing and before assembling.  That is probably slightly overkill, but if you have the time it is worth being extra cautious.  Use a moisture meter to determine that the wood is sufficiently dry and is no longer fluctuating.   

      Thanks,
      Paul WWGOA Video Membership

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      Reply
  6. Sharon trout

    We just recently had a arbor constructed and the 4in x 6in x 10 ft rafters are warping on the ends, is there anything we can do to stop it. Thank you

    Reply
    • Customer Service

      Hi Sharon. This can be difficult to control unless you know what the root cause of the warping is. My guess is that the wood was not fully dried to equilibrium prior to construction, and if that is the case, it is going to find it’s equilibrium and then it will be done with this major movement. If you can somehow brace the rafters while they are drying, that can hold them in their straight position until the wood is done drying and then they are less likely to warp after that. It that is not root cause, then it is potentially getting some exposure to moisture now that is causing this, but you would probably see signs of water penetration of this were the case.
      Thanks
      Paul-WWGOA

      Reply
  7. Hoyt

    I have left-over long leaf pine boards averaging 5 1/2 x 96 inches. We had these cut from lightning damaged trees on the farm. I have a lot of left-overs now that have been in my unairconditioned barn here in SE Alabama (hot, humid summers). I would like to make some shop cabinets using these boards. I now have a table saw, bandsaw, jointer, and planer, so I can do a lot to even up these boards. The shop cabinets have to remain in the barn, the same barn where the lumber is. My question is whether there are precautions to use to prevent warping and movement of the glue-up’ed boards if I make panels out of them?

    Reply
    • Hoyt

      I forgot to state that this wood is now 18 months out from cutting, and was kiln dried first. We used a lot to refloor my grandfather’s house, in which we live. That floor is doing well so far (nearly a year old).

      Reply
      • Customer Service

        That sounds like some great timber! That wood should be stabilized by now, but it is always a good idea to check it with a moisture meter. In terms of tips to prevent warping and wood movement, just follow normal woodworking practices; Don’t constrain movement in your wood, and apply the same number of coats of finish on both sides of your panels.
        -Paul

        Reply
        • Kevin

          I am building a backgammon board and using wood inlays for the long diamonds in the base board. I am using a maple board with exotic wood as inlays. The problem I am having is after I glue the inlays the board warps once it dry’s. I started trying to work with thicker wood 1/2 and then gluing the inlay which is 1/16 thick. Once dry, I then planned it down to a 1/4. This helped but the board still warps. I am using wood glue. I wood temperature is stable. The thinner the wood I use the more it warps.

          Any help would be appreciated.

          Reply
  8. Brenda

    Hello, I have walnut circles fresh cut pieces that I want to make table tops out of. They are 30″-22″3″ . How can I finish these so they don’t warp? I hear soaking them in a solution that helps to stop cracking or splitting such as Peg a polyethylene glycol stabilizer. Is this a good idea.? I just had them planed and fine sanded. The circles were just cut 3 weeks ago. Thank you for any help. Brenda

    Reply
  9. Betsy

    Hi. I am lucky enough to be moving into a new townhouse, and I am watching the build as it progresses. I noticed that some vertical boards in the structure of the closet are warped. Will they continue to warp more? Is this a problem that should be changed? Will it become a problem later? Thanks!

    Reply
    • Customer Service

      Hi Betsy. You can ask the builder about it, but some amount of warping in your framing material is normal and you probably don’t need to worry about it. Wood will typically stop warping after it is completely dry, and once the drywall is attached you will probably never have any problems with it.
      Thanks
      Paul-WWGOA

      Reply