How to prevent warping

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Forum topic by DTOLAR posted 08-08-2015 03:16 PM 990 views 0 times favorited 11 replies Add to Favorites Watch
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28 posts in 1050 days

08-08-2015 03:16 PM

I make a lot of things using large slabs of wood. Tables and such. I just got two pieces of bookmatched walnut that are 96” long and 18”wide, about 3” thick. I usually dont have much trouble with those, but here lately I’ve been getting lots of requests for Pecan cutting boards. I made a few on request, then a few more, and now I have 22 pending orders.

I have a source to get these big pecan slabs, live edge of both sides, 8ft long, 12-16” wide, and 2” thick. WEll the Pecan really likes to cup and check and get bumpy as it cures, these slabs were cut green and sticker stacked. They were cut back in February, and it rained almost every day until June, but has bene dry since. They are kept outside, but under a tarp.

This last slab I got, I took to a guy who has a huge 24” planer, looks like a Zamboni, and he planed them out flat for me. took them down to about 1.5” thick, then I took them home and cut out a dozen cutting board blanks or so. Ive had them stacked up in my garage and have been working though these orders since June 29th.

I noticed yesterday that most of what I have remaining have cupped really bad, to the point that I probably cant use them. a few probably have a 1 inch cup on a board 12” wide. If I planed it out, theyd be less than a half inch thick. I dont mind a little cup, I just put that side down, these are raw cutting boards so they don’t have to be perfect.

So what can I do to prevent this cupping? Do I need to start keeping the blanks inside, out of the heat? I figured since they are mostly dry, the heat wouldnt be an issue, they’ve been outside since it was cut.

11 replies so far

View upinflames's profile


217 posts in 2189 days

#1 posted 08-08-2015 08:11 PM

Pecan is one of the worst when drying to buckle, crack, warp, turn inside out, you get the point. The good thing is once it’s dry it is stable, just that initial shock of twists and turns….

View AandCstyle's profile


3075 posts in 2284 days

#2 posted 08-08-2015 09:15 PM

DTolar, do you have the blanks stickered? Were the slabs planed about equally on both sides? Does the sun ever shine directly on them? You might be able to get them flat by applying moisture to the concave side and letting the sun shine on the convex side. HTH

-- Art

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28 posts in 1050 days

#3 posted 08-08-2015 09:23 PM

I do not have the blanks stickered. I figured once they were cut that small it wouldn’t be necessary

Yes they were planed out evenly, not totally planed down perfectly flat, there was still a little cup in some places, but no more than an 1/8th inch. No direct sunlight on them. Theyre were literally just stacked on top of each other in the corner of my shop.

Ill try the water and sun trick, I have done similar things before with dimensional lumber, and weights, but I didn’t think it would work with pieces this thick, and hard.

View AandCstyle's profile


3075 posts in 2284 days

#4 posted 08-08-2015 10:01 PM

I think that the issue was exacerbated by not stickering the blanks. The wood will expand and contract no matter how thick it is. I have learned to always sticker newly surfaced wood and a fan isn’t a bad thing if possible.

-- Art

View rwe2156's profile


2967 posts in 1508 days

#5 posted 08-08-2015 11:46 PM

You cut the blanks too soon.

After they were planed you should have re stickeed the board for at least a month before cutting the blanks.

By cutting the blanks too soon you opened up the end grain and they dried too quickly.

If the cup is over 3/8” they are probably toast for 1” thick boards.

I think your options are seal the ends with paraffin (or whatever you like) to stop the “bleeding” and:

1. Sticker them and forget them for,a couple months.
2. Stack them to dry differentially by deliberately exposing the concave surface to air. Moving air maybe even better.

-- Everything is a prototype thats why its one of a kind!!

View DTOLAR's profile


28 posts in 1050 days

#6 posted 08-08-2015 11:55 PM

That makes sense….I was just hoping that since these slabs were 6 months old, that they were pretty dry. They started off over 2” thick. And we planed off about 1/4” off each side. It’s a huge 24” planer that cuts top and bottom in the same pass, huge in feed and out feed rollers, no snipe, it’s nice.

I’m about to be doing a bunch more that are now 8 months old, and have been in this 100+ heat for over a month. Since they will also be planed, do I need to still sticker them after they get planed for a bit?

View WDHLT15's profile


1748 posts in 2503 days

#7 posted 08-09-2015 12:20 AM

Your slabs are not close to being dry. That is why they are cupping. One side is losing moisture faster than the other. 8/4 pecan will take about a year to dry down to 15% if you air dry them outside in Georgia. May take longer depending on your climate. They need to be below 10% to use inside, so you either need to kiln dry them or cut them into smaller pieces and bring the pieces inside and sticker them for a couple of months after they are fully air dry.

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

View DTOLAR's profile


28 posts in 1050 days

#8 posted 08-09-2015 12:29 AM

Oh wow, I though they would dry much faster than that.

Sadly here in East Texas, our ambient humidity it’s about 35% at best, makes it tough to dry wood. I may get a meter to keep in the house.

View a1Jim's profile


117126 posts in 3604 days

#9 posted 08-09-2015 12:58 AM

Many of the previous statements are true. When woodworking many folks don’t know about the basics of what to do with wood before you build with it ,Make sure it’s dry enough(7-10%), rough cut wood and let it acclimate(adjust to your shops atmosphere) in your shop,while storing wood,store it so there is even air flow around all sides of your material(use stickers) use wood the most stable wood possible.

-- wood crafting & woodworking classes

View Yonak's profile


986 posts in 1548 days

#10 posted 08-09-2015 04:21 AM

Helpfull information…

thank you :)

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View DTOLAR's profile


28 posts in 1050 days

#11 posted 08-09-2015 04:22 AM

I flagged both of those earlier

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