# Question About Drying Times



## SFLTim (Apr 19, 2013)

I opened a green log of Pecan about 3 months ago and re sawed several boards for drying. I weighed the sections which are roughly 18” x 8” x 2” at the start of the process. The beginning weight for each section was 9.2 lbs. I recorded the weight and continued to do so each month on the same day of the month to track the change. 

The pieces lost a significant amount of weight the first month, a total of 2 lbs the first month ( -22% ). The second and third month however, the change in weight has been negligible, only 0.1 lbs each month.

I don’t own a moisture meter yet, and my obvious question would be is there a correlation between when the weight of a piece flattens out to a corresponding %MC? Three months obviously doesn’t seem to be enough time for a 2” thick fresh piece of wood. This has been simply air drying inside my air-conditioned house with relatively low humidity ( I do live in Florida however....). If anyone knows of a decent correlation like this I would be obliged if you could provide a link. Thanks.


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## Kevin (Apr 19, 2013)

Hardwood will hit a plateau once it gets to a certain point. The rapid weight loss you saw was the wood losing the free water - the moisture between the cells. Now it is losing the bound water *in* the cells, and since you aren't forcing the bound water out it's going to come out slowly, which in the case of Pecan this is what you want, unless you had a kiln and could get it out under a controlled schedule designed for Pecan. 

Pecan weighs 62 lb/ft³ green and only 45 lb/ft³ at 20%MC if you want to do the math you can get pretty close as to where it's close to right now. Your piece is about .17 ft³ if my math is right so you can use 7 pounds and to get it close.


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## SFLTim (Apr 19, 2013)

Kevin said:


> Hardwood will hit a plateau once it gets to a certain point. The rapid weight loss you saw was the wood losing the free water - the moisture between the cells. Now it is losing the bound water *in* the cells, and since you aren't forcing the bound water out it's going to come out slowly, which in the case of Pecan this is what you want, unless you had a kiln and could get it out under a controlled schedule designed for Pecan.
> 
> Pecan weighs 62 lb/ft³ green and only 45 lb/ft³ at 20%MC if you want to do the math you can get pretty close as to where it's close to right now. Your piece is about .17 ft³ if my math is right so you can use 7 pounds and to get it close.



Thanks. I appreciate the lesson. It makes sense regarding the free water, etc. It’s been sealed since day one with Anchorseal, so I’m sure it still has a long way to go, although by the info you provided of 45 lb/ft3 x 0.17 ft3 it would indicate that the wood should be near 20% MC at 7.65 lbs. I’m at 7.0 lbs now, but I just have a gut feeling it’s wetter than that. I know, I know, must get that good moisture meter and put an end to all of this. Just don’t have the funds for a really nice one yet, and I read bad reviews of some of the cheaper pin types. Just don’t want to throw away my money. Thanks for your help.


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## Kevin (Apr 19, 2013)

20% is the ballpark where the plateau is hit for nearly every species, so it sounds close enough to me. Even though weighing is more accurate than even the most accurate meter, a good meter is indispensable.

.


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## jimmyjames (Apr 19, 2013)

All of the big lumber kilns use the weight calculations that Kevin mentioned, its the most accurate way to test the moisture content of wood, what they do is take test cuts of a board from the stack, weigh it and then bake it in an oven for x amount t of time and then weigh it again, that will tell you your moisture content of the lumber. Depending on if your log was dead or alive when you milled it will have an effect on drying time, it may very well be at 20%, 20%mc isn't hard to achieve and doesn't take very long, now going lower then 20% takes much longer especially with 2" thick lumber. If you have enough to spare cut off a chunk , weigh it and then bake it and then weigh it again, I'm not sure on the bake temp or time needed, that info could be found on the net somewhere, but that will tell you the dryweight of the wood and then you could do more accurate calculations.


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## SFLTim (Apr 19, 2013)

Thanks guys. Good information. Sounds like most species hit 20% rather quickly then it’s a long slow grind to get down to 10 - 12%.


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## davidgiul (Apr 19, 2013)

A good source of information for drying is David Martin of GVWP. He has a rather extensive wood operation. A couple of years ago, I purchased 5 k bd ft of 4/ 4 kd Black Walnut from him and I was very happy with the results. He is a member of this forum.


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## jimmyjames (Apr 19, 2013)

davidgiul said:


> A good source of information for drying is David Martin of GVWP. He has a rather extensive wood operation. A couple of years ago, I purchased 5 k bd ft of 4/ 4 kd Black Walnut from him and I was very happy with the results. He is a member of this forum.




+1 on this advice, David has boatloads of useful information on drying lumber, he's usually rather helpful when questions like this arise


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