Wood and Weather after Final Dimensioning

[derek labian]

I am building a pair of exterior doors out of rift sawn white oak. Last weekend I fully dimensioned all the parts but was unable to finish the the point of a glue up. I have not cut grooves or mortises yet. I planned to finish this weekend. Over the last week, the weather got cooler; today the wood is no longer strait, small amounts of twisting and cupping.

Other than crying a bit, any ideas on how I can salvage this disaster?

My plans for 5" x 1 3/4" rails. They were already dimensioned to this. Styles are similarly dimensioned.

It seems like all I can do is reduce the width and thickness of the rails and styles to get them strait again. I assume there's no chance of it warming up / humidity returning and the wood straightening back up again is there?

[derek labian]

Has anyone had any success with clamping the boards and letting them sit for 72~ hours in an environment with comparable humidity to when they were originally cut?

If I do have to reduce the thickness, is there any practical difference in a door that is 1 5/8" vs 1 3/4"?

[Bruce Lowekamp]

Partially I think it depends on whether what you’re seeing is from the weather changes or if it’s more because there were stresses in the wood (either from the tree or b/c it was dried too quickly) that shifted the wood a little after it was cut. Doesn’t hurt to try to clamp it with higher humidity but I wouldn’t bet a lot of money on it.

Too late now, but as someone who also goes a week (or longer) between steps in a project, I try to rough dimension everything in one session and leave the final dimensioning to be done the same day I’m doing assembly. Most of the time it doesn’t matter (and I have a dehumidifier in my shop) but not unusual to need to straighten out a board just a little after it’s sat there a week. Every once in awhile I have one that shifts enough that I can’t use it. Glad I found it...

Bruce

[derek labian]

Thanks Bruce. I was expecting to finish the project the same weekend but something came up. I also have a mini-split I need to manage climate, but haven't gotten to it yet. I've clamped the rails and i'll let them sit for 72h just to see if it makes any difference. If not, I'll replace the worst board and re-dimension to 1 5/8" for the rest at time of assembly :/

[Lisa Starr]

Were they sticker-ed while they were sitting all week? If they weren't, try sitting them on a narrow edge on a sticker and letting them sit another week. The Wood Whisperer has an interesting video that shows the effects of wood drying unevenly due to storage methods. As they equalize them may return to something close to your original shape. Just as a "for next time", like Bruce said, mill part way, let them acclimate for several days and then finish mill.

[derek labian]

Were they sticker-ed while they were sitting all week? If they weren't, try sitting them on a narrow edge on a sticker and letting them sit another week. The Wood Whisperer has an interesting video that shows the effects of wood drying unevenly due to storage methods. As they equalize them may return to something close to your original shape. Just as a "for next time", like Bruce said, mill part way, let them acclimate for several days and then finish mill.

I didn't Sticker these because I planned to work on them. The 4 rails were stacked on their face on a pair of kregg benches.

Right now i have them clamped together in a semi-strait fashion and brought indoors to increase the humidity (there was a cold snap). I was going to leave them like that for 72 hours and see what I got.

If that doesn't work, I can stack them vertically with stickers. Do you think I have a better chance with them being stacked on their faces with stickers or using the clamp method?

[Lisa Starr]

My inclination is that they would have the best chance of returning to original configuration sitting on several stickers on their edges with space between the flat faces. Clamped may well just be continuing the uneven drying. Of course, wood is wood, nothing is guaranteed work. But I'd give them at least a week sitting on their edges, not faces to see if that will help.

[Mel Fulks]

I agree with Lisa. Was that white oak kiln dried? Many won’t stack milled pieces without a plywood cover with a little weight on it.

[derek labian]

I agree with Lisa. Was that white oak kiln dried? Many won’t stack milled pieces without a plywood cover with a little weight on it.

Yes. It had 6% moisture, it had been sitting stored for about a month as well before milling.

[derek labian]

Hi Lisa,

Thanks for the advice. I switched them to vertical and will let them set for a week. I added a fan for circulation.

[Warren Lake]

moisture content, how you machine it, how you store it. Its wood not in a panel its going to live in the wild so doing in an extra step is better. Used to see about 15 percent or more move after a first machining and set so it can move. If you want to use that material and keep your same thickness or go thicker then resaw and make them stave core.

[derek labian]

moisture content, how you machine it, how you store it. Its wood not in a panel its going to live in the wild so doing in an extra step is better. Used to see about 15 percent or more move after a first machining and set so it can move. If you want to use that material and keep your same thickness or go thicker then resaw and make them stave core.

I looked into this quiet a bit, and decided 8/4 white oak was fine without going stave core. I still think if i had assembled right away it would have been fine. 1/4 Rails moved quiet a bit. Maybe a blessing in disguise to replace that one board.

My current doors, knotty alder, move quiet a bit depending on the time of year.

[Don Stephan]

Might have been Bruce Hoadley's Understanding Wood that suggested an approach that has worked for me. The explanation in his book is that, since wood is always absorbing or giving off moisture depending on the humidity of the surrounding air, the moisture content across the thickness of a board is likely not uniform. For example, let's assume the middle is higher moisture content than the surfaces, and the board is twisted. When it is flattened, more wood is taken off one pair of opposing corners than the opposing corners, on each side. Stickered, over several days the surface moisture content will become uniform as the interior moisture content adjusts, which may cause some additional warping. For several years my approach is to flatten and straighten, sticker for at least a week, and flatten and straighten a second time. if more than two light passes over the jointer was needed to flatten the first face, after planing the opposite parallel the board is stacked and stickered for another week and then flattened and straightened a third time. If more than two light passes are needed yet again I consider the board unstable and don't use it in critical locations. Boards that have been flattened and straighted twice and seem stable are kept stacked and stickered until incorporated in the project. Tabletops and similar glued assemblies are either stickered until attached to the rest of the project, or leaned against a vertical surface so that ambient air has access to all sides. Not saying this approach will work for everyone, or that everyone should use this approach, just sharing what has worked for me.

[derek labian]

Might have been Bruce Hoadley's Understanding Wood that suggested an approach that has worked for me. The explanation in his book is that, since wood is always absorbing or giving off moisture depending on the humidity of the surrounding air, the moisture content across the thickness of a board is likely not uniform. For example, let's assume the middle is higher moisture content than the surfaces, and the board is twisted. When it is flattened, more wood is taken off one pair of opposing corners than the opposing corners, on each side. Stickered, over several days the surface moisture content will become uniform as the interior moisture content adjusts, which may cause some additional warping. For several years my approach is to flatten and straighten, sticker for at least a week, and flatten and straighten a second time. if more than two light passes over the jointer was needed to flatten the first face, after planing the opposite parallel the board is stacked and stickered for another week and then flattened and straightened a third time. If more than two light passes are needed yet again I consider the board unstable and don't use it in critical locations. Boards that have been flattened and straighted twice and seem stable are kept stacked and stickered until incorporated in the project. Tabletops and similar glued assemblies are either stickered until attached to the rest of the project, or leaned against a vertical surface so that ambient air has access to all sides. Not saying this approach will work for everyone, or that everyone should use this approach, just sharing what has worked for me.

Good information Don.

What I was having trouble wrapping my head around is, even if wood is stable in the assembly location, when a door is installed, its going to be directly subjected to two different moisture levels etc, hence using quarter or rift sawn wood. In a climate like Houston that has huge humidity swings, even if its stable after two weeks and two passes, is that going to mean its stable once subjected to its final environment?

[Alan Gage]

So which way did they cup?

Wet wood will cup up (concave shape) if left on a flat bench as the exposed face will dry and shrink more than the bottom. The ends will often curl up as well (I usually finds the ends curl before it cups)

Presumably dry wood in the same situation, if it gains moisture as it sits, would cup/curl down as the exposed face swelled.

If this was consistent across the pieces it might tell you if moisture was the cause or if it was more likely stress in the wood.

If I see a board that was flat on a surface cupping/curling due to moisture after a day or two I'll flip it over often times it will react the opposite direction to help cancel it out.

Not sure what you're using for a moisture meter. Were you checking the moisture in the center of the boards or just on the surface?

Alan

[derek labian]

I'm not sure how it cupped because I didn't realize the issue until I started moving them around. 3 boards were very lightly cupped or twisted, maybe a 32nd of an inch. One board cupped heavily, 1/8 or more of an inch. I guess that would be one of Don's "unstable" boards. Maybe it's a bit of luck, if I had assembled with that board, the results would maybe not be so great. I purchased two more 8/4 boards with strait grain to replace that one. So far I'm not sure they have reverted at all, so I may just re-dimension them slightly smaller right before assembly and hope for best.

[Don Stephan]

Bruce Hoadley covers this in detail, working through an example of moving wood from one ambient himidity level to a different one.

Wood expands and contracts at a different rate along the growth rings than across them. Hence flat sawn boards may show cupping or flattening out with hunidity changes. Quarter sawn wood should not cup with humidity changes. But it will get wider or narrower to some extent. All depends on the amount of humidity change in the ambient air.

I don't believe any finish completely blocks moisture movement, but most if not all will show the rate of moisture movement. This may be the reason it is always recommended to apply the same finish to all surfaces, so the rate of moisture movement is similarly decreased.

Every few months I have to re-read portions of Understanding Wood but it is an excellent reference book for any woodworker. A similar book is Cut & Dried​ by Richard Jones.

[Tom Bender]

A solid wood door might not be a good choice as an exterior door in Houston, especially if it gets wet.

[derek labian]

Partially I think it depends on whether what you’re seeing is from the weather changes or if it’s more because there were stresses in the wood (either from the tree or b/c it was dried too quickly) that shifted the wood a little after it was cut. Doesn’t hurt to try to clamp it with higher humidity but I wouldn’t bet a lot of money on it.

Too late now, but as someone who also goes a week (or longer) between steps in a project, I try to rough dimension everything in one session and leave the final dimensioning to be done the same day I’m doing assembly.

Yeah, a good lesson for future projects.

These doors have 48 parts that have to be final dimensioned.. so it takes a substantial amount of time to final dimension before a glue-up. In any event, I bought two more pieces of 8/4 and I think the project will be fine. The biggest challenge will blue gluing everything up before it sets.

The final result of my attempts to un-cup and twist the wood were failure. No meaningful difference.