Air dried walnut ready to use?

[Mike Cutler]

Seven years ago I went in half with a fellow Creeker on some walnut logs. It was quite the endeavor to move them.
The logs were band milled to 2” thick slabs and they are about 11’ long and up to 24” wide. I stickered and banded them to a torsion frame, and left them in a Shelter Logic bldg., and in the loft of my garage.
This past week, for the first time, I milled two of the “ junkier” slabs to kind of get an idea of what I had. And to get some material for a sewing machine table top.
Enough of the back story. My question is, how necessary is it to run these boards through a kiln? I can see no visible bug infestation, or any evidence of infestation, in the boards, or the stickered stacks.
Is it okay to use this material for a sewing machine table top? It’s not a fine furniture piece, more utilitarian in nature. I just need a big surface.
Here are photos of the boards laid out on my table saws.
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[John TenEyck]

I don't see any worm holes so it doesn't look bugs are an issue. That leaves moisture content. I would take a small specimen, something that weighs a few hundred grams, dry it in an oven at 220F until the weight is constant, and determine the moisture content. If it's +/- 1 - 2% with the EMC of your shop or, even better, the location the finished piece will reside it's good to go. You can use a moisture meter as long as you probe across the thickness to get a good average, but the oven dry method is foolproof.

John

[Mel Fulks]

John is certainly right . But I would not kiln dry it . The modern kiln drying cooks wood brittle and often changes the color, with loss of
red-ness. Compare the way air dried works to the kiln dried. Air dried is much nicer to work ,especially with hand tools.

[Mike Cutler]

Thank you gentleman
It is a pretty wood. Much nicer than I thought it would be. For a “yard tree” it seems okay.
The grain on those 4 boards runs straight, and the end grain shows all q-sawn to riftsawn. It should make a “stable” surface.
Moisture content right now is whatever the ambient humidity level would be in Connecticut. I expect it will be 20-25% right now.
The sewing machine is in my basement, and there is always either a dehumidifier running, or the woodstove. I think I’ll bring those 4 boards into the basement for a month or two, and then finish the milling and sizing.
I’ve been watching this walnut for quite a few years now. Hopefully the rest is as usable as these boards seem to be. I probably have 700-800bd/ft of it. Milled will Probably yield 450-500 usable bd/ ft if I’m lucky.
I’m actually stunned at just how flat all of it stayed over the years.
Mel, you are dead on about the hand tool use. I have some junky Stanley’s I keep around, and used one of them to get rid of the band mill marks. It was really easy to plane.
I like the oven trick John. I’ll cut a few test pieces tonight.

[John TenEyck]

Mike, I think you will find the MC to be more like 12 - 14% if it was stored outside, and no more than 10 - 12% if it's been inside.

John

[Mike Cutler]

We’ll, that MC is much better than I expected. Thank you for the good news.
I bought this wood for two reason. First to teach myself to steam bend wood, and secondly because it worked out to less than 50 cents per bd/ft. I had toyed around with live edge for awhile, but it’s just turned out to not be my thing, so the wood sat stacked until this week.

[Scott T Smith]

Hi Mike. I'm a kiln operator. Let me start by proving some insight into kiln drying.

There are four different types of kilns in use in the USA. They are 1 - conventional (steam), 2 - dehumidification, 3 - vacuum, and 4 - solar. Of these four, the only one that will change the color of black walnut is a conventional kiln that uses wet steam. The others won't change the color (nor will a conventional kiln that uses dry steam). Vacuum kilns fall into two categories - deep vacuum that requires either RF or heat transfer plates in-between the wood layers, or shallow vacuum such as the iDry system that use convected heat.

Wood brittleness usually occurs if a conventional or DH kiln dries the lumber below 6%. With a careful kiln operator brittleness should not be a problem.

Of all the native US species, black walnut heart wood is toxic to most bugs and not usually susceptible to insects. There are exceptions (I've personally seen termites in dry stacked green BW slabs), but for the most part - if there are not signs of bug infestation in the sapwood you should be good to go w/o kiln drying / sterilizing it.

Usually in the NE air dried lumber won't get below 10% -12% MC if stored outdoors, but if you bring it into a heated / humidity controlled shop it should eventually equalize around 8% - 9% MC, which would be fine for most woodworking projects.

Best of success to you.

Scott

[Mike Cutler]

Scott

Thank you for the information.
There is a lot that goes into processing wood before it ever hits the racks in a lumber yard. More than I realized. I've been lucky so far with respect to wood movement, but I always pay attention to that part of woodworking,i as part of the project. This particular walnut came from a stack I have outside, protected from the elements. I have two more stacks in the loft of my garage that have seen at least 135 deg F during the summers for past 5 years. ( The gable vent fan kicks on at 135 deg, and sometimes it runs continuously during the summer.)
Based on John's input I cut three blocks of wood approximately 150 grams each, and cooked one in the oven, to get an idea of moisture content. They're in the basement now with the walnut for the table top. Once the blocks reach equilibrium, the walnut should be ready to go. Probably about the Thanksgiving time frame.
It's comforting to know that walnut has a natural bug resistance property.

[John TenEyck]

Mike, what moisture content did you find your wood to be?

John

[Mike Cutler]

John

If I did it correctly, it was about 13-14%.
The three test blocks weighed between 155 and 160!grams. After the wood was cooked, they were in the 133-138 gram range.
The two cooked blocks and the uncooked block, are sitting on the work bench in the basement.
One of the cooked blocks is in an Ohaus, Triple Beam scale. It’s been picking up about .2 Grams per day in weight. The uncooked block is slower to lose weight.
If the internet info from the forestry department is correct, it’s supposed to take up to 800 hours to reach equilibrium.
I tried microwaving a block of walnut. That got sketchy!! You could see the steam coming out of the ends, and that block was HOT! The two in the oven got hot, but it was different. Maybe because more time was involved.

[John TenEyck]

The average of your data is 157.5/ 135.5 = 16.2%. That could be as air dry as it will get, depending upon the RH where you live. In any case, I would feel comfortable bringing it into your shop to acclimate. It's going to take awhile though before it gets down in the 8% range.

FYI, I would stick with the conventional oven when measuring moisture content. A microwave may be cooking out more than just water.

John

[Mike Cutler]

John

The microwave was a “ for fun” test. I stopped as soon as it started to smell.
We have a parrot, 2 cats, and my Vizsla. Walnut is a known toxin to just about every pet in the house. As soon as it put out a distinctive odor, it was stopped!
The wood is in the basement right now, where the sewing machine is located. If it takes a bit, it takes a bit. I’ve got time.
I haven’t started the woodstove just yet, but the dehumidifier runs continuously. That will bring the RH in the basement down, once it starts.
I have the week of Thanksgiving off, as well as the next, and will make the table top then. I also brought in some extra lumber to make drop leaves.
It should be a fun project. It won’t take long, but should be easy and fun.
Thank you for all of the help. I’ve never done much with domestic hardwoods, and air dried, is a new path for me.
Other than home/ house repairs, this is the first woodworking project I’ve done in a few years.