How dry is dry enough, really

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Forum topic by DaneJ posted 09-03-2009 04:44 PM 1578 views 0 times favorited 11 replies Add to Favorites Watch
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56 posts in 3380 days

09-03-2009 04:44 PM

Topic tags/keywords: drying milling lumber question

I have nearly 300bd ft of lumber (maple, cherry & walnut) that I milled up about 18 months ago. I sealed the ends, and stickered as soon as it was milled. Other than some crotches and figure there isn’t much end splitting, so I must have sealed the ends correctly. Some of it has been stickered inside with a dehumidifier for the last 6 months.

I was thinking that it must be getting close to use so I bought a moisture meter a few months ago in order to monitor it scientifically. I have been monitoring, and recording, the MC since. So much for science… I am thinking of reverting to logic and common sense. Here is why, everything I read says that wood should be between 7-10% MC to ensure workability and stability. But mine is 10-12%, and has not decreased by more than a percent.

Exasperated I kept searching for answers to find out what I am doing wrong. Somewhere I read that the actual MC is not as important as being stable, and the suggestion was that when the MC of your lumber matches scrap in the same shop then the lumber is ready. So I took the MC readings of some cutoffs in my shop, all were between 9-14%, so I am thinking that the lumber that my lumber at 12% is ready.

So much for the long story, here is my question, am I crazy, lazy or just impatient if I start using the lumber that is at %12??

Any comments would be welcome, thanks in advance.

-- Dane, Fairview Pk, OH. The large print giveth and the small print taketh away... Tom Waits

11 replies so far

View Roper's profile


1389 posts in 3885 days

#1 posted 09-03-2009 04:51 PM

seeing as you are in ohio i would think that getting your MC anywhere between 8 and 12% should be fine. out here in colorado that would come down a little bit more. i would try using one piece to make a box or some small furniture piece and see how much it moves during milling. just remember the longer you wait the more stable it will become.have fun.

-- Roper - Master of sawdust-

View WibblyPig's profile


172 posts in 3446 days

#2 posted 09-03-2009 05:16 PM

How thick is it? If it’s 4/4, you should be good to go. The rule of thumb is one year per inch.

-- Steve, Webster Groves, MO "A society grows great when old men plant trees whose shade they know they shall never sit in."

View sw_iowa_sawyer's profile


39 posts in 3549 days

#3 posted 09-03-2009 05:34 PM

I have two solar kilns that I use to dry my lumber and when I take it out it is between 6-8%. I then store it in my garage until such time that I need it. Depending on the wood type it will go back up to 8-11% give or take. When I am ready to build something I put it in my shop and it takes time to build whatever doing it on nights, and weekends and I have so far never had a issue with using lumber in that range of readings.
A kiln is used to dry lumber first but also to kill any wood borne insects as well so it serves a dual role. In my application I air dry the wood in a barn to around 12ish and then kiln dry it the rest of the way. When I have put fresh green lumber in the kiln the first part of drying is pretty quick but it takes a while to force the last part of the moisture out of the wood. It has to do with how the wood holds it water content and is interesting I guess but not really that important. In your application your wood will never dry down to anything lower the the conditions of the area it is stored in. It will reach a equilibrium to the surrounding area and then stop drying.
I have tested this several times using fresh cut basswood sticks in my basement. I put in a couple of sticks in the basement in the winter and it will dry down to whatever the other wood in my basement is because of the heated air from the furnace. It is a slow process though and a kiln just speeds it up. I believe much of what people call wood movement twisting, warping, cupping has to do with how it was cut in the milling process I have found defective logs produce defects in the final lumber. As an example a log with a off center pith has internal stress in it that will show up in the finished lumber. Sometimes when you cut a log you can watch the wood curl, twist, bow, as you are cutting the board off the log. If you use that board you are bound to have some possible issues with whatever you are building.
Bottom line…
I believe that as long as you allow for normal expansion you would be fine using that material.
All that antique furniture was built using wood that was dried in such a fashion and much of it is still around today because it was built using quality construction that allowed for expansion/contraction.

Wow that was long winded wasn’t it
Probably worth what you paid for it….

Good Luck

View DaneJ's profile


56 posts in 3380 days

#4 posted 09-03-2009 06:01 PM

Thanks everyone…

Roper—I guess it may be time to convert the rough sawn to surfaced then a project.

WibblyPig—All of the lumber is 4/4 or 6/4, I started with the rule-of-thumb but though that, being an engineer, that there was a need to be more precise.

swiowasawyer—I am interested in the soalr kiln, did you use plans or just wing it? Ive seen plans on the forrestry service web site and thought of scaling it down with a Maloof style ari-dry bin next to it for early stages of drying…

-- Dane, Fairview Pk, OH. The large print giveth and the small print taketh away... Tom Waits

View Kjuly's profile


311 posts in 3457 days

#5 posted 09-03-2009 07:14 PM

Hi Dane,
SW-Iowa-Sawyer covered it very well. I would like to add one more thing… where and how you check the wood will have an effect on the reading. To get a accurate reading I cut 6” off the end of the board and check the middle of the fresh cut. The next time you are checking moisture run this little test… check your board in several places and make note of the different readings that you will get around knots and areas where the grain runs at a steep angle to the face of the board. Then cut off 6” and see what that reads.
I built a solar kiln from plans that I got from Fine Woodworking. The article was written by
John Wilson. Sorry I could not find the issue number but it was about 10 years ago. The kiln worked well here in Michigan.

-- Keith, Charlotte, MI

View DaneJ's profile


56 posts in 3380 days

#6 posted 09-03-2009 09:21 PM



My standard procedure, I’m kinda new to measuring MC but… 3-4 areas on the board, middle and about 9” from each end, I read with the grain and across the grain, if they differ I will try 3” away and then take the highest. I may try the cut and measure to see if there is any difference.

BTW—I am using a Lignomat E/D.

I will search for the FWW article on solar kiln. I may build one in the future but it will have to be a passive solar because I lack power that far from the house and I don’t want to burry a cable across the yard and field.

-- Dane, Fairview Pk, OH. The large print giveth and the small print taketh away... Tom Waits

View huff's profile


2828 posts in 3457 days

#7 posted 09-04-2009 02:18 AM

Dane, I think everyone has covered it pretty well for you. Like SW stated. You can kiln dry it to 6-8%, but once you bring it to your enviroment it will restablize to an average MC for your area. We usually figure 9 -11% for the average here in the Carolina’s. I think you’re real close to being able to use.
I would suggest that you plane your lumber that you want to use close to the final dimension, restack and give it a few days to restablelize.

-- John @

View sw_iowa_sawyer's profile


39 posts in 3549 days

#8 posted 09-04-2009 06:27 PM

I used the plan I found here
It has worked real well, you could use solar powered fans to keep it completely self controlled but they are kinda expensive I think when they say “Go Green” they mean the money flying out of your pocket to buy the stuff but if you could afford it it would use not power except what the sun provided.;

View DaneJ's profile


56 posts in 3380 days

#9 posted 09-04-2009 08:13 PM

SW thanks for the link from it, I followed:
these instructions reference solar powered fans, that may help with the operational cost, but the fans seem to require a pretty big up-front investment.
I wonder if there is a way to change baffles, or whatever, to tke advantage of passive airflow?

I’ll let ya’ll know what I find…

-- Dane, Fairview Pk, OH. The large print giveth and the small print taketh away... Tom Waits

View WIwoodworker's profile


65 posts in 3870 days

#10 posted 09-05-2009 05:36 PM

You’ll be fine with the MC you have. Commercial kiln drying accomplishes several things which are important for mass production and manufacturing.

1) Speed to market…kiln drying significantly reduces the time needed to dry wood.
2) Reduced degrade…controlled drying schedules reduce degrade especially in species like maple and oak.
3) Kills insects.
4) Provides standards for better manufacturing. A manufacturer can produce a more consistent product if the materials they use have the same MC.

For woodworkers these things can be important but many people still use air dried wood with excellent results. Good luck with your projects.

-- Allen, Milwaukee, WI

View DaneJ's profile


56 posts in 3380 days

#11 posted 09-05-2009 09:53 PM


Regarding “speed to market”...
with 300bdft ready to go and as much more ready to be taken down and milled, I should be good for a while.


-- Dane, Fairview Pk, OH. The large print giveth and the small print taketh away... Tom Waits

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