warpage - completely preventable?

[Will Blick]

On another forum, there was some discussion about larger cabinet doors warping. This is something I have always been curious about.


We all know hardwood expands / contracts on its width (cross grain). We must account for this movement when designing a cabinet door. We all realize we must start with well dimensioned boards which are flat, square and parallel. We all know that applying a good finish is critical to slow down the woods ability to be effected swings in humidity. However....


When making large cabinet doors, say 4'+, you select the right wood, accurate milling, quality finish, etc. .... what are the chances that cabinet door will be FLAT in 5 years?


I have seen some large cabinet doors dead flat after 5 years, and other times, I have seem some warped enough whereas they warrant a re-do. Yet, no difference in the wood, finish or assembly.... Is there just an inherent risk factor in using hardwood for large cabinet doors, and no matter how good the craftsman technique is, he runs the risk of the door NOT being flat in the future? Does wood always have this unpredictable factor?


Since I don't install cabinets for a living, I have not seen enough of these larger doors over time to get a feel for risk factor here ? Is the risk factor 2%? 10%? Any particular woods more/less prone to this warping?


Of course, in smaller doors, their is much less risk, as the warping is not exaggerated by length, hence why I am asking about larger cabinet doors....

[Loren Hedahl]

I had the good fortune (or bad, depending on your perspective) to purchase a large pallet load of number 3 common ash directly from the mill.

I did all the good things to season it, and it has seasoned for 5 - 6 years. However, as you can imagine, this wood has a lot of "character". I've grown to love working with it, but warpage is an issue!

So, for anything where warpage can't be taken out or accommodated, I plane a bit thick, resaw, rotate the boards, glue and re-plane. That way the warpage of the one half board is resolved by the warpage of the other half board.

[Will Blick]

Loren, confirmation is nice.... and I like the term "character"...of course, many of us would use different words to describe warpage :-)


> That way the warpage of the one half board is resolved by the warpage of the other half board.


If I am understanding this.....you re-saw in half, flip one board 180 degrees on its width, than glue to return to the intended size. The premise is..... one board will try to warp in one direction, the other board will try to warp in the opposite direction....if the glue holds, you have contained the warping?

If am understanding this correctly...., I must admit, that is quite a clever trick.... how successful is it? Is this a widely used / accepted concept ? Very interesting....!

[Chris Friesen]

If I am understanding this.....you re-saw in half, flip one board 180 degrees on its width, than glue to return to the intended size. The premise is..... one board will try to warp in one direction, the other board will try to warp in the opposite direction....if the glue holds, you have contained the warping?

I've used this technique to prevent cupping on large laminations (bed and workbench legs, moving vise jaw, etc.). It won't protect against twisting.

To maximise the chances of doors staying flat, use quartersawn wood for the rails/styles. Panels are usually flat-sawn because the grain is more interesting, which means they'll want to cup. A thinner panel will exert less bending force than a thicker one.

[Loren Hedahl]

Loren, confirmation is nice.... and I like the term "character"...of course, many of us would use different words to describe warpage :-)


> That way the warpage of the one half board is resolved by the warpage of the other half board.


If I am understanding this.....you re-saw in half, flip one board 180 degrees on its width, than glue to return to the intended size. The premise is..... one board will try to warp in one direction, the other board will try to warp in the opposite direction....if the glue holds, you have contained the warping?

If am understanding this correctly...., I must admit, that is quite a clever trick.... how successful is it? Is this a widely used / accepted concept ? Very interesting....!


I must admit - I've thought of some other words not exactly fit for a family newspaper when dealing with this.

You've got the process correct, I believe.

As to it being successful / widely used / accepted - no way. It takes extra time, leaves a seam in the middle that can be seen . . . . . . Of course using straight grain quarter sawn wood is the best. Even better might be structural plastic or some other maximally homogeneous material.

But that is just the point. Those limitations and imperfections are my challenge to create something functional as well as unique and beautiful in the eyes and minds of those who might appreciate such.

As to the twists and turns and gnarls and knots - my wood stove consumes the worst and I just deal with the rest. One of my most used power tools is a Makita power plane. Plan to upgrade to a Bosch or Festool soon, mostly to contain the copious spray of shavings.

I've got two projects going now. A very small bathroom that I integrate wood, set in like tile, and ceramic/porcelain tile on the walls is almost complete. I prefinish the wood with clear polyurethane floor varnish so the grout wipes clean just like on the tile. The second is a small fiberglass Scamp trailer. These projects are just for me. I couldn't charge 1/10th of my labor to someone else. What this translates to is - most reasonable persons consider me mostly harmless but sort of eccentric and very slow.

I love it!

[Howard Acheson]

Wood is wood and wood moves when it's equilibrium moisture content changes. Some woods a less stable than others. Also, while wood expands/contracts across its width, whether the board is flatsawn or quartersawn, will make a big difference. The rate of movement is greatest across a flatsawn or tangential cut board. And, the board is most likely to cup as it moves. The most stable boards are those that are quartersawn or radial to the grain.

So, understanding that, boards that are cut quartersawn and then glued up will have the best chance of staying flat even with changes is size due to changes in their EMC.

Another thing that many oldtimers knew was that doors should never be closed on an enclosure until the item has fully acclimated in its final location. Leave the doors open for a couple of weeks or else you may cause unequal moisture on the two surfaces of the doors. It's also a good practice to design some ventilation in an enclosure. This is particularly important if the enclosure will contain electronic equipment.

[Chris Padilla]

Wood: a fickle medium!

The only way to minimize movement is to NOT use solid wood. Use plywood or MDF and apply veneers. Now I realize this isn't always possible nor does this guarantee a lifetime of flatness but it is something to consider.

[Tony Bilello]

1)you must start with flat boards that have been 'properly' dried and kept in an environment similar to a normal indoor envirment. Well, we know this is not practical but we can come close. Where you buy your lumber has a lot to do with this.
2) Unfortunately, the most stable boards have the least interesting grain pattern. To get around this, find a pretty wood with a pretty grain but still a fairly straight grain. Red oak fits the bill here in the south and not surprisingly, it is a very popular cabinet grade.
3) Use plywood as much as you can, where you can. Your design will dictate when and where you can use plywood.
4) if you have something with a really interesting grain pattern, more than likely it will move (warp) on you. If you want to use it, try to find an area not too large and use it as an accent piece.

I have seen some of my furniture and cabinetry 20 years later with no warping problem. Stay away from the BORG and find a hardwood specialty yard. You will pay more, but you wont be posting here in a negative reply.

Keep in mind that in the era of heating and air conditioning homes are more environmentally regulated and that should help. Air drying alone, normally will not be as good as kiln dried.

Tony B

[Peter Quinn]

Roll Da Dice, each and every time. I've been working a few years in a shop that makes cabinets, millwork and passage doors among other things. i have seen what appeared to be perfectly stable pattern grade mahogany get up and dance several weeks after the doors were assembled and finished. I'm talking one or two out of 40, just went wild like spring break in FLA. Leaves you scratching your head.

When you start with common you sort of anticipate that sort of thing given all the knots and inherent tension involved, but all wood can move. Verticle grain, correct moisture content, flatten/plane/rest/reflatten/replane, aclimate to the shop, climate control the shop; you do what you can and use all your best tricks. Its still wood.

Roll Da dice, cross your fingers, don't let it bother you. Thats my take.

[Will Blick]

Loren.... I appreciate that tip.... when in doubt, its probably a good safety measure... yeah, not for high volume shops, but a good hobbiest tip. I am quite surprised glue can hold-off woods desire to move with such strong opposing forces. This says something about how good glues are today....

Howie, as usual, great post..... I should have mentioned using quartersawn..... even so, I would think 7' cabinet doors are still vulnerable to a bit of warping.... again, not extreme, but enough to have the bottom corner touch the face frame when closed, and the top corner NOT touching.... in reality, that represents very little warping..... but still ruins the clean look of your work.

Good tips Tony.... yep, often the most interesting grain patterns are the ones that will cost you the most in warping... such is life. Hence the populatiry of veneers :-) And i fully agree, when possible, use ply or MDF to keep the project stable in the largest areas.

[Will Blick]

Great summary Peter! :-)

That was the point of the thread.... sometimes it's just out of your control.... you do everything right, and you still get burnt. BTW, your 1 or 2 out of 40 is about what I suspected.... under 10%.... maybe closer to 5%

[Neal Clayton]

Wood is wood and wood moves when it's equilibrium moisture content changes. Some woods a less stable than others. Also, while wood expands/contracts across its width, whether the board is flatsawn or quartersawn, will make a big difference. The rate of movement is greatest across a flatsawn or tangential cut board. And, the board is most likely to cup as it moves. The most stable boards are those that are quartersawn or radial to the grain.

So, understanding that, boards that are cut quartersawn and then glued up will have the best chance of staying flat even with changes is size due to changes in their EMC.

Another thing that many oldtimers knew was that doors should never be closed on an enclosure until the item has fully acclimated in its final location. Leave the doors open for a couple of weeks or else you may cause unequal moisture on the two surfaces of the doors. It's also a good practice to design some ventilation in an enclosure. This is particularly important if the enclosure will contain electronic equipment.

i always find it odd that no one questions the attempt these days to build air tight structures. those same old timers also knew that a structure which could co-exist with its natural environment, rather than trying to keep that environment out with layers of plastic and foam, would last much longer.

[Chris Padilla]

Neal, most houses are built that way! ;) haha

[Chris Friesen]

i always find it odd that no one questions the attempt these days to build air tight structures. those same old timers also knew that a structure which could co-exist with its natural environment, rather than trying to keep that environment out with layers of plastic and foam, would last much longer.

Up here in Saskatchewan, the difference between an airtight structure and one that "breathes" is probably several thousand dollars a year in heating bills, especially since we just got a 20% increase in natural gas prices.