Drying black walnut????

[Martin Siebert]

Is there something about black walnut that causes it to dry differently??? By that I mean sometimes fast and sometimes slower?? I have some now that has been sticker stacked in my shop {heated and air conditioned} with a dehumidifier running to keep the humidity to 50% or less for the last year and it has only gotten down to 19%.
The last batch I had went to around 8% in the same time frame. I have also had other wood in the shop {cherry and maple}, not a lot, but some that have gotten down to like 9% or better in the same time frame. The wood in question was cut in the winter time so the sap should have been down and it did not seem like it was very wet at the time. I have cut some white oak that had water literally running out of it when the blade went thru and it dried faster than this.
Thank you for any information, it is greatly appreciated.

[Tom Hogard]

Same thickness? Double the thickness and you increase drying time 2.5 to 3 times.

[Martin Siebert]

Yes sir, and I had some that is 5/4 and some 12/4. The last batch seemed to take the typical time it usually does which was about the same as all the other hardwoods done at the time. I was always told that porous wood, that with open grain like walnut, would dry sooner than say cherry or maple, but not this time. Nothing else has really changed and that is what is confusing. The woods I have played with that always took the longest was black locust and hickory.
Don't get me wrong, I don't want it to dry real fast...I had some black cherry slabs that for some reason seemed to lose moisture real fast and of course they all cupped too. I don't know, it is just strange that walnut dries normally in one batch and the next seems to just sit there and hold it when the humidity level is low and constant. As always thanks for the info, it is greatly appreciated.

[John TenEyck]

You mean you put green lumber straight into an environment at 50% RH? That would a recipe for checking, cupping, all kinds of defects. It's normal to air dry green lumber outside until it's down below the fiber saturation point (about 29% moisture) before bringing it indoors for final drying. In any case, I can only guess that the lumber that dried "normally" had a much lower moisture content than your current batch, or the conditions in your shop are not as dry now.

John

[Martin Siebert]

You mean you put green lumber straight into an environment at 50% RH? That would a recipe for checking, cupping, all kinds of defects. It's normal to air dry green lumber outside until it's down below the fiber saturation point (about 29% moisture) before bringing it indoors for final drying. In any case, I can only guess that the lumber that dried "normally" had a much lower moisture content than your current batch, or the conditions in your shop are not as dry now.

John

Sorry for the delay...I was on a dive trip. I should have relayed that it was in fact right around 24-25% before I brought it in. The initial outdoor dry I always do first and I sticker it outside right off the mill and cover the pile with a section of roofing metal. That time depends of course on what time of year it is and how hot it can get during the day. Maybe I didn't get a good read with my meter, but the initial time seemed like it was typical to get it to the 25%. I know open grain woods can sometimes lose or gain moisture very quickly, I just never seen it do it like this before. Thanks for the reply and info!!!

[Tom Bender]

Could it be that it is already dry and your measurements are off?

[John K Jordan]

Martin,

I just saw this. I have different types of walnut that varies widely in properties, some from the same tree.

Could it be your moisture measuring method? I didn't see if it was mentioned, but what meter are you using? I have walnut that varies widely in density. I have a pinless Wagner meter which relies on setting the proper wood density - they provide a species chart. However, the chart doesn't account for differences in density. A dense piece of walnut I have tricks the meter into showing a higher moisture content.

If you do use a pinless meter you might measure a small piece cut with square sides and calculate the density.

Regardless of the meter, you can check the absolute moisture content of a sample regardless of the wood type or density by using the oven dry method. If not familiar with it, I wrote up something a while back.
https://sawmillcreek.org/showthread....ven-dry-method

(Just ignore posts #3, 4, and 5. Someone confused oven-dry moisture testing with drying bowls with a microwave.)

The oven-dry test is the most accurate moisture measurement but it is destructive and a bit of trouble. I generally use the weight method, fairly easy with the woodturning blanks I process but still possible with a board: weigh the piece and record the weight. Wait some time and reweigh. When the weight no longer changes, the board is at EMC, as dry as it's going to get in that environment. For pieces 3" or larger I generally wait 1 to 2 months between weighing.

JKJ

Is there something about black walnut that causes it to dry differently??? By that I mean sometimes fast and sometimes slower?? I have some now that has been sticker stacked in my shop {heated and air conditioned} with a dehumidifier running to keep the humidity to 50% or less for the last year and it has only gotten down to 19%.
The last batch I had went to around 8% in the same time frame. I have also had other wood in the shop {cherry and maple}, not a lot, but some that have gotten down to like 9% or better in the same time frame. The wood in question was cut in the winter time so the sap should have been down and it did not seem like it was very wet at the time. I have cut some white oak that had water literally running out of it when the blade went thru and it dried faster than this.
Thank you for any information, it is greatly appreciated.

[Martin Siebert]

Thanks fellas for the replies...yes, it very well could be that my moisture measurements are off. I use a pin type meter and the battery does have some time on it. I am going to do the oven method and try to confirm what is going on. This week I flattened a slab that was reading 18%, I checked it again two days later and it read 10%.....I'd like to think I can dry slabs that quick!!! But, I know it is wishful thinking and something has to be off. I will let you guys know what I find. Thanks again for the replies!!!

[Kevin Beitz]

I found that when drying that the out side skin when taken out
of the kiln will show a number. Let it set for a few days and the
water in the middle of the wood will creep to the outer skin and
give you a different number...

[Martin Siebert]

I found that when drying that the out side skin when taken out
of the kiln will show a number. Let it set for a few days and the
water in the middle of the wood will creep to the outer skin and
give you a different number...

Can you tell us what the numbers looked like??? Guessing you kiln dried the wood down to like 6-8% and in a few days of being out of the kiln the outer surface came up how much?? And how much do you think the ambient humidity affected it as opposed to just continuing to dry???

[Jim Andrew]

Think you can just cut a few inches off the end of a board, then test for a somewhat accurate measurement, depending on how good your tester is. Cheap tester, not too accurate, expensive tester, pretty good.