Warping lumber

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Forum topic by TonyInGuam posted 01-03-2013 02:42 AM 1558 views 0 times favorited 9 replies Add to Favorites Watch
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22 posts in 2272 days

01-03-2013 02:42 AM

Happy New Year Everyone,
I’m incurring some warping problems with my store bought lumber. I generally work with 1x lumber to make signs for my wife’s business, pine and poplar. Recently, I purchased some poplar from a hardware store and I scrutinized each board, nice and straight. A couple of days later I cut, routed the boards to final dimensions and stacked them on top of each other in my outside storage closet. A few days later, I removed some boards for sanding and noticed that several of the boards on the top of each stack had warped/twisted a little. Not a huge deal because of the finished product, but I’m curious on how to prevent in the future when I’m more critical of the warping. I’ve read some of the articles on the site and think that not using spacers in between the boards might be the culprit, but really unsure. I live in Guam where it’s hot and humid daily, thanks for any advice/recommendations. Tony

-- Tony

9 replies so far

View Madwood's profile


68 posts in 3291 days

#1 posted 01-03-2013 02:56 AM

Tony, I would let your lumber acclimate to your shop for a little more than a couple days. This way, with the humidity, it will absorb moisture more evenly…before you cut anything. Also, stacking them as you did, without any stickers between, allows uneven moisture absorbtion, causing the warping.
HTH, John

-- In the shop making chaos out of order

View WDHLT15's profile


1797 posts in 2716 days

#2 posted 01-03-2013 04:53 AM

I agree. The warping is occurring because the moisture content of the wood is changing.

-- Danny Located in Perry, GA. Forester. Wood-Mizer LT40HD35 Sawmill. Nyle L53 Dehumidification Kiln.

View tenontim's profile


2131 posts in 3984 days

#3 posted 01-03-2013 03:56 PM

Tony, as I remember my days in Guam, the relative humidity was just a couple of percent short of raining. All the lumber in Guam is imported, so you will have to give it time to soak up all of that moisture. If the hardware store had the lumber inside, it’ll stay fairly straight, until you store it outside. Stack it outside for about a week, then you can mill it straight again. Hope you have a jointer, since a lot of that lumber is going to twist.

View bondogaposis's profile


5153 posts in 2591 days

#4 posted 01-03-2013 04:52 PM

I think it warped because the the boards are adjusting to the humidity differentially. That is the outside surface of the top board is picking up moisture faster than the underside. Stickering will help a lot so that the humidity has a chance work equally on both sides of the board at the same time and same rate.

-- Bondo Gaposis

View TonyInGuam's profile


22 posts in 2272 days

#5 posted 01-05-2013 12:02 AM

Thanks guys for all of the info and advice

-- Tony

View Harry Montana's profile

Harry Montana

46 posts in 2235 days

#6 posted 01-18-2013 09:14 PM

here is a complete checklist that will be very usefull for you, it is about storage and acclimating: acclimating wood.htm

-- With regards from Harry Montana

View Purrmaster's profile


915 posts in 2333 days

#7 posted 01-28-2013 05:13 AM

One thing that someone suggested to me: If the board has cupped, store it upright with the cup facing away from you. Basically, it will cup in the other direction and straighten out (more or less) at some point. It’s not perfect, it takes a long time, and can be iffy. But I’ve had it work a few times. Worked best with thinner lumber.

View TCCcabinetmaker's profile


932 posts in 2594 days

#8 posted 01-28-2013 05:27 AM

Another thing you could do is get a moistuer meter and test the lumber in the store before buying it.

-- The mark of a good carpenter is not how few mistakes he makes, but rather how well he fixes them.

View MonteCristo's profile


2099 posts in 2428 days

#9 posted 01-28-2013 08:27 PM

If the wood was milled from poor stock, eg a tree with a good lean on it, it will move in nasty ways every time the humidity changes. Sometimes they can screw things up in the kiln as well and embed stress in the lumber that will reek havoc later on. Also, boards with complex grain patterns tend to be more unstable.

You might want to look for a different supplier . . .

-- Dwight - "Free legal advice available - contact Dewey, Cheetam & Howe""

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