Drying freshly milled black walnut boards

[Dan Borello]

I am in the process of building a grandfather clock, and excited to get started. I hit several local stores, but wasn't really able to find the material I wanted.

However, I hit the craigslist jackpot today. Someone mentioned they had some black walnut, and I took a trip to their property. They had tons of logs, and had milled 6 boards that are prefect for my use: http://i.imgur.com/11nv0SDl.jpg

The facts:

Aged 2+ years in block form
Milled today
Up to 1 1/2" thick
Moisture content in the middle of the face ~25%
Stickered in my garage in Oregon
Polyurethane applied to the ends


Obviously, I am eager to get started on this wood. However, I don't want to be foolish.


What moisture content should I target prior to squaring and building?
Approximately how long will it take to reach this moisture content air drying?
Would a ghetto-kiln be advised? Some 2x4s, plastic, a fan, and a dehumidifier. How long will it take under these conditions?


I appreciate any two cents you might have.

[Andrew Hughes]

I think you should wait until they are down to 12mc or lower.I also would leave them just as they are.That spot looks perfect to me.
Sometime in the fall I would pull a board out of the middle cut it in half and check the mc in the middle.
You know the longer you wait the better,Congats on the wood score nice looking stuff.Aj

[Dan Borello]

I think you should wait until they are down to 12mc or lower.I also would leave them just as they are.That spot looks perfect to me.
Sometime in the fall I would pull a board out of the middle cut it in half and check the mc in the middle.
You know the longer you wait the better,Congats on the wood score nice looking stuff.Aj

Alright, 12% is the target.

I know the longer I wait the better.... I"ll just have to be patient.

I got very fortunate with the wood. I ran in to two nice gentleman, and it was a steal. $200 for the whole lot, just over $2/BF based on gross dimensions.

[Ed Aumiller]

At 12% MC you will have more shrinkage and possibly warping/bowing when you have them in your house...
In most homes the wood will eventually reach about 8% MC.
Most air dried lumber settles out at 12% unless in a heated & A/C conditioned room (i.e. in your house)..

If you use them at 12%, find a moisture calculator to determine amount of shrinkage..
(http://www.woodweb.com/Resources/RSCalculatorsWoodShrinkage.html)

The good news is that flatsawn walnut has a relatively low shrinkage and is very forgiving..

Also be sure the CENTER or heart of the wood is 12%, not just the outside of it..
If it is in a heated area with a little air flow you should be ok in about 6 months

There is a discussion on moisture meters in this same forum just down the page..

[Danny Hamsley]

If you take two cheap box fans oriented parallel to the stack blowing air alongside the stack on the long axis, the increased air flow will pull the water vapor from the stack and speed up your drying. Locate each one about 1/3rd from each end, and have them blowing in the same direction. I would estimate about 60 to 90 days to get fully air dry to 12%. Then, you can bring them inside your house for a couple of weeks, and they will get into equilibrium with your inside space.

This not recommended for all species, particularly oak, but walnut dried well and can handle the extra air flow. Even if you run them part time, they will help.

[Cody Colston]

I would also dry the lumber to the EMC inside your home, especially for something as nice as a grandfather clock. The attached link has a calculator to determine EMC. Be aware that the thicker the lumber, the longer it will take to reach EMC.

http://www.csgnetwork.com/emctablecalc.html

[Brad Seubert]

I built a small kiln in my basement, holds about 300 bf and works awesome. The tough part about drying with a kiln is figuring out the correct drying rate so your wood doesn't dry to fast and end up with a bunch of defects.Since yours is already close to 20% you wouldn't have to worry much about that. Could probably get that pile down to 12% in a few weeks.

My kiln is just an insulated box I built with an attic fan, dehumidifier, and some 100 watt light bulbs for heat. Depending on where your located and the temp you could get by with just some plastic, a couple fans, and a dehumidifier.

[James Zhu]

Well, I think you should move the propane tank outside, it is extremely dangerous to leave it indoors if there is a leak.

[Dan Borello]

At 12% MC you will have more shrinkage and possibly warping/bowing when you have them in your house...
In most homes the wood will eventually reach about 8% MC.
Most air dried lumber settles out at 12% unless in a heated & A/C conditioned room (i.e. in your house)..

If you use them at 12%, find a moisture calculator to determine amount of shrinkage..
(http://www.woodweb.com/Resources/RSCalculatorsWoodShrinkage.html)

The good news is that flatsawn walnut has a relatively low shrinkage and is very forgiving..

Also be sure the CENTER or heart of the wood is 12%, not just the outside of it..
If it is in a heated area with a little air flow you should be ok in about 6 months

There is a discussion on moisture meters in this same forum just down the page..

Thanks for the information. I don't want to rush this and get a lot of movement. Based on my weather station the house is currently at 74F and 51% humidity. Therefore, the EMC is 9.3%. I am sure this varies, but it seems like a good target.

I am glad to hear walnut is well behaved.

[Dan Borello]

I built a small kiln in my basement, holds about 300 bf and works awesome. The tough part about drying with a kiln is figuring out the correct drying rate so your wood doesn't dry to fast and end up with a bunch of defects.Since yours is already close to 20% you wouldn't have to worry much about that. Could probably get that pile down to 12% in a few weeks.

My kiln is just an insulated box I built with an attic fan, dehumidifier, and some 100 watt light bulbs for heat. Depending on where your located and the temp you could get by with just some plastic, a couple fans, and a dehumidifier.

This is tempting. Have any pictures of the setup?

[Jeff Ramsey]

Dan, I am about finished with a walnut project. This is only my opinion on using walnut, but I try to work boards in with both heart and sap wood. The contrast, in my opinion, is quite handsome. In the case of your clock, I'd consider resawing and bookmatching the sides with a blend of heart/sap wood. Just a suggestion to consider, for what it's worth.

You're right to be concerned about moisture content. I've resawn boards that I thought were seasoned and dry, only to watch them cup or twist in a few days after being resawn.

Good luck with your project; it's a good one.

[Dan Borello]

Dan, I am about finished with a walnut project. This is only my opinion on using walnut, but I try to work boards in with both heart and sap wood. The contrast, in my opinion, is quite handsome. In the case of your clock, I'd consider resawing and bookmatching the sides with a blend of heart/sap wood. Just a suggestion to consider, for what it's worth.

You're right to be concerned about moisture content. I've resawn boards that I thought were seasoned and dry, only to watch them cup or twist in a few days after being resawn.

Good luck with your project; it's a good one.

Hi Jeff,

Unfortunately, I don't have the capability to resaw the boards. However, since I assume they were cut from the same log, wouldn't two pieces have to be book matched already?

I am no expert on walnut, but I really like the grain pattern. Attached is a quick shot I took. It looks like it might include some sap wood as well:

http://i.imgur.com/zqcVLYyl.jpg

[Howard Acheson]

Polyurethane is a poor end sealer. It does not resist moisture well. The material to use is called Anchorseal. However it should be applied immediately after the boards are cut to length. You want to immediately start preventing moisture from leaving the boards through the end grain.

Finally, you should use some sort of moisture resistant material between the cement floor and the beginning of your stack. Plastic drop cloths work well.

Your target Equilibrium Moisture Content should be 8-12%.

[Jeff Ramsey]

Hi Jeff,

Unfortunately, I don't have the capability to resaw the boards. However, since I assume they were cut from the same log, wouldn't two pieces have to be book matched already?

I am no expert on walnut, but I really like the grain pattern. Attached is a quick shot I took. It looks like it might include some sap wood as well:


Yes, adjacent boards will look book matched if oriented properly. Walnut is pretty, isn't it? Wait until you get a good finish on it. Experiment with different finishes before you do final finish. It'll look rich when you're done.

Walnut is also one of my favorite species to mill because of its fragrance.

[Robert LaPlaca]

Air dried Walnut is a treat to work with it carves so beautifully, Walnut is my favorite species to work..Even better that you have lumber all sawn from the same log, cannot get a better color and grain match then that.

I was lucky enough to run into a deal like you found, bought 300 bd ft of the most beautiful air dried 5/4 Walnut that was all clear, 13" to 16 " wide and figured. The only down side of the lumber is it was only 8'-9' long lengths. Built two Queen Anne highboys from the lumber

[Dan Borello]

Polyurethane is a poor end sealer. It does not resist moisture well. The material to use is called Anchorseal. However it should be applied immediately after the boards are cut to length. You want to immediately start preventing moisture from leaving the boards through the end grain.

Finally, you should use some sort of moisture resistant material between the cement floor and the beginning of your stack. Plastic drop cloths work well.

Your target Equilibrium Moisture Content should be 8-12%.

Unfortunately I wasn't able to Anchorseal at home depot. I picked up some rustoleum rubber sealant that will hopefully do the trick.

I have the bottom board on sticks. Should I still be concerned about moisture from the concrete?

[Larry Copas]

End sealer should be applied within a few days after the tree is cut while still in the log. In your case end sealer will do little if any good.

In my area, especially this time of year water will condense on the cool concrete. I would get your lumber off the floor. Forget about the paint cans for weight, as you don't have enough to do any good.

Walnut is one of the easiest woods to dry, I'm sure you will be fine. Get the fans on it.

[Larry Copas]

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