How long should I acclimate 10/4 thick wide walnut slabs for dining table?

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Forum topic by Liveedgewoodtables posted 02-08-2016 02:57 PM 1905 views 0 times favorited 12 replies Add to Favorites Watch
View Liveedgewoodtables's profile


8 posts in 1500 days

02-08-2016 02:57 PM

Topic tags/keywords: walnut


I just brought these slabs home from a custom drying kiln (Kiln been in business 40 yrs.) they dried it down to 12% MC. Before that, they had been air drying for 1.5 years and covered with tin and stickered. They have only been laying on the ground as pictured for about an hour.

As I have had problems in the past with cupping and cracking, I want to do it correctly this time. I am making a dining table from this bookmatched set.

As of now, it is acclimating in my home…laying flat and stickered.

My question is…how long should I let it acclimate before I join the slabs? I have heard two weeks and have heard 3 months??? Time is important…so the sooner the better.


12 replies so far

View a1Jim's profile


117328 posts in 3777 days

#1 posted 02-08-2016 03:04 PM

Usally you want to work with wood that is in the 6-8% .So the time it takes for your wood to dry to that percentage is arbitrary, according to the conditions in your shop.

-- wood crafting & woodworking classes

View SamuraiSaw's profile


515 posts in 2164 days

#2 posted 02-08-2016 03:41 PM

I’d been careful with MC that high, as Jim pointed out a 6-9% range is much better.

Time may be important, but rushing into the project will be even more expensive. I wouldn’t work it with more than 10% MC. Get a good meter and check it weekly.

-- Artisan Woodworks of Texas....

View Porchfish's profile


847 posts in 2732 days

#3 posted 02-08-2016 03:46 PM

I could dry those for you in my dining room to 8% +/- in about 15 years or so. Happy to help you out

-- The pig caught under the fence is always the one doing all the squealing !

View DrDirt's profile


4510 posts in 3942 days

#4 posted 02-08-2016 04:10 PM

Can also depend what you want to do. For the book match, are you going to rip away he sapwood from the center and try to get a tight glue line to look like a single wide board? Or are you going to keep both as a live edge slab.
12% seems still pretty high to me for kiln drying. I usually see less than 10% results.
The second is much easier, as you can build the base to accomodate the movement

-- “The two most important days in your life are the day you are born and the day you find out why.” Mark Twain

View Liveedgewoodtables's profile


8 posts in 1500 days

#5 posted 02-08-2016 04:45 PM

Thanks guys. When I picked up the slabs, I wasn’t too happy about the 12% MC either. He assured me it would be fine. I am purchasing a Delmhorst moisture meter in a few days and will check the moisture by inserting pins 1.25 inches in the center. If it is still at 12%...I will put a dehumidifier in the room.

I have a question…..if loss or gain of moisture causes these wide boards to cup….then what if my slabs were joined after being acclimated at 55% RH and then finished and shipped to an environment of 40% RH. What is to prevent if from cupping??? In all that I’ve read on here about cupping…this is never answered.

Any help is appreciated….I’m pulling my hair out on this (what I have left ).


View AandCstyle's profile


3178 posts in 2457 days

#6 posted 02-08-2016 11:25 PM

I have a question…..if loss or gain of moisture causes these wide boards to cup….then what if my slabs were joined after being acclimated at 55% RH and then finished and shipped to an environment of 40% RH. What is to prevent if from cupping??? In all that I ve read on here about cupping…this is never answered.

Any help is appreciated….I m pulling my hair out on this (what I have left ).

Bryan, cupping results when one side of the stock looses moisture faster than the other side such as when you plane one side and leave the opposite side untouched. The fresh side looses moisture faster than the other side. Finishing retards moisture gain and loss. The wood will still expand and contract across the grain, but cupping should not occur as long as both sides are exposed to the air and one side isn’t heated while the opposite side isn’t, think solar gain through a window. HTH

-- Art

View tturner's profile


63 posts in 2228 days

#7 posted 02-09-2016 01:15 AM

I think the time to acclimate is insignificant. As long as the material has changed to room temperature -being close to the same as the room it will reside- you will be fine. I did it. Took a live edge walnut slab and worked it in my shop, which took 2 weeks. That’s been 9 months ago and it’s been in my dining room since and hasn’t budged. If it’s reached optimal moisture content, it’s relatively stable. Avoid big changes in temperature and humidity levels from when you start the job until the finishing process. I risked a $950 walnut slab. The only problem is it doesn’t get enough dinners put on it.

-- I'm him

View pintodeluxe's profile


5798 posts in 3013 days

#8 posted 02-09-2016 01:37 AM

12+ inch wide slabs of flatsawn (insert species here) will probably cup or move to some degree. I shoot for 6-8% for dimensional hardwood 5/4 and thinner, but for natural slabs and thick stock I would allow a little leeway. Get it down to 10% with fans and a dehumidifier and you’ll be fine. Around 2-3 weeks under those conditions, depending on temperature.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View WDHLT15's profile


1792 posts in 2676 days

#9 posted 02-09-2016 01:47 AM

I would sticker them in the shop with air being able to circulate on all sides, and build the base FIRST. Most woodworkers rush to build the top first as that is the coolest part, but that is backwards. Make the base, then when you glue the top, you can attach it to the base very soon after completing the top, and that will help stabilize the top and minimize any future movement. Using table top fasteners is a good way to attach the top to the base. Holds the top tightly to the base, but allows for seasonal movement, preventing the top from cracking.

BTW, beautiful slabs. I assume that you are making a table.

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

View Liveedgewoodtables's profile


8 posts in 1500 days

#10 posted 02-09-2016 04:07 PM

Thanks guys…this is encouraging.

I would like to get your guys’ opinion on how I am attaching my top plate to my table. I always build steel welded bases. Of course the oval hole allow for my cross movement. Do you guys know of any other hardware to use?. I’m a stickler of stability and tightness. The tables will likely be shipped, so the owner would assemble the table and I am hoping they will not tighten screws to tight??

BTW…I think I will go with the 2-3 weeks to acclimate. It seems to me that whenever the tables cupped…it happened fairly quickly…within 2-3 days. My guess is that anything longer than two weeks may be wasting time.??


View JayGunn's profile


5 posts in 1198 days

#11 posted 02-10-2016 02:54 PM


This is a bit misleading, because it’s partially correct. Yes wood can cup if one face ends up at a different moisture content than the other.

But the main reason wood cups is that it shrinks and expands more in the tangential direction than the radial direction. So cupping is an issue with flatswan boards. When you look at the end grain, you see the curves in the growth rings spanning the width of the board. If those curves were straight lines then no cupping would occur. But since they generally are arcs, the wood WILL cup, away from the heart as it dries and toward the heart as it gains moisture.

Cupping will be least when the TR ratio is very small, like 1.2:1, and very pronounced when it’s 2:1 or ever worse. That’s one of the reasons that Honduras Mahogany is so forgiving and stable and hickory is not. Both the amount of movement and the ratio are significant. When the board is quartersawn, the growth ring lines span the narrow dimension of the board and don’t (typically) create the curves that are problematic.

</lecture> sorry, hope this helps.

View Aj2's profile


1873 posts in 1998 days

#12 posted 02-10-2016 10:11 PM

I think your going to be fine with 12 mc.Looking at your planks I see mostly quartered and rift.With a small cathedral grain down the middle.Your lumber guy or you picked out perfect slabs for a table top.Its got some character with proper grain running down the edges.
Plus walnut can be every bit as stable as mahogany or White oak.

-- Aj

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