Black walnut slab stability

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Forum topic by Allwoodsmatter posted 10-25-2016 08:18 PM 551 views 0 times favorited 3 replies Add to Favorites Watch
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1 post in 725 days

10-25-2016 08:18 PM

I was recently commissioned to make two replicas of a coffee table that a customer lost in the fire. For the tops, I’m going to use a slab of walnut that they have had in the family for about 50 years. It was 19×42 and 4in thick. I split the piece on a Woodmizer to make two, 2 inch thick pieces.

I would like to flatten and dimension the full slabs to 1 1/2 inch thick 18×40”. My only concern is whether a walnut table top of those dimension would be stable or, whether it is likely to warp (particularly because the pieces were cut from a board that dried at 4 inches thick.)

My moisture meter is showing 6%

If anyone has knowledge or information, I would appreciate the advice.


3 replies so far

View sawdustdad's profile


364 posts in 1029 days

#1 posted 10-25-2016 08:52 PM

A lot depends on the board. Is it flatsawn or quartersawn? If it’s quarter saw through the pith, it might be pretty stable. If it’s flatsawn, it will warp some. I think a quick chat with the client regarding the importance of preserving the boards vs. having a flat table top is in order.

OK, so what are the options? Of course using the full slabs would be easiest, but most likely to warp, especially if flatsawn. If it’s that old, it is probably pretty much at equilibrium but the fact that you resawed it exposes the inside to the atmosphere. It’s impossible to predict the outcome of the whole boards, so I think i’d do a couple things. First, I’d stack the two thinner boards in the shop for a couple months to see how they react to the new dimensions. Then, depending on how much they warp, I’d rip them into boards about 6 to 10 inches wide, and after carefully matching the grain, reglue them into a top. That will stabilize the top considerably. If the construction allows it, add cleats to the undersides of the tables to restrain them.

Here’s another, though more radical, approach. Cut the lumber into veneer and build an MDF cored top, with solid wood edges and a veneered top and bottom. That’ll stay flat.

It all depends on how important a seriously flat top is to the customer. One thing I tell people is that “It’s wood, a living, breathing material. It will move. It’s in it’s nature to do so. Accept that, appreciate that. If you can’t or won’t be satisfied with the possibility of some wood movement, then let’s talk about plastic or metal…”

-- Murphy's Carpentry Corollary #3: Half of all boards cut to a specific length will be too short.

View Chris208's profile


239 posts in 2414 days

#2 posted 10-26-2016 02:01 AM

if they go wonky, rip them along the straight grain on the edges, mill the 3 subsequent parts, and reglue them. The glue line will disappear entirely if you get it right.

View WDHLT15's profile


1776 posts in 2620 days

#3 posted 10-26-2016 02:06 AM

If the slabs are dry and in equilibrium with the in use environment, they will be stable and not move. If they are really at 6% moisture content, then they will be fine for indoor use as a table. If they were stored outside in a shed or barn, i would be suspicious of the 6% moisture reading. Slabs in that environment usually dry down to about 15% moisture content. Make sure your moisture content is correct.

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

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