wood moisture content

[mclear6]

I recently purchased some air dried oak (4/4 6"x8' - $1 per bd ft). I check the moisture content and it ranges from 14-18%. I tried a "kiln dried" douglas fir 2x4 I just bought from HD and it came back 12%. I know everything out there says 8% is what you should use. I am planning to create a glassed door cabinet for the dining room. What are people's experiences with air dried oak and building furniture with it.

thanks


mike

[LCHIEN]

you may wish to read this wiki article on wood drying.

http://en.wikipedia.org/wiki/Wood_drying

It says that the wood will reach an equilibrium after drying for a while in which the moisture in the wood balances the humidty in the atmosphere. That point depends upon the air humidity and to a lesser degree the wood species and temperature.

Wood stored outdoors (in your garage or woodshed ) will differ than wood stored in a heated or airconditioned space.

Probably the low end for the latter case would be around 6-8%. Outdoor wood depends upon species, ambient humidity and temperature and might range from 10% in dry climates to 14-18% in humid locales.

The number you specify might be correct and be at equilibrium but You did not specify in your profile your location so that's no help.

Ideally if you're making furniture and it going to be inside the wood should be stored inside for a time period to reach its final indoor equilibrium before cutting and assembling - a luxury most of can't do.

[mclear6]

Loring, Don't you recognize the NJ Flag???

Thanks for the reply. I Live in Northern NJ.

[SARGE..g-47]

First.... excellent price on the air dried.. 14%-18% is on the high end of where you want to go. If I took my moisture meter down to my shop and got a reading of 12% on a 2 x 4 Doug fir piece... and then took a reading on a piece of 4/4 oak which read 14%-18% I wouldn't be concerned as both are actually around 12%. Doesn't make sense... huh?

PLease read your manual with your moisture meter. I have a Wagoner about 8 years old and was getting some reading I knew were not correct. But.. after reading the manual (why bother as we are all born experts on everything even if we have never used it ) it en-lightened me to the fact the Wagener is based on Doug fir. There is a chart in the manual that converts the reading to your species. On mine.. 14%-18% converts to around 11%-13% for white oak.

So.. each manufacturer of a moisture meter cannnot make one that is accurate on any species and has to gear the meter to one as different species have different densities. Keep in mind also that an end reading on a piece of stock will usually be drier than a center reading as moiture escapes quicker through end pore.

But.. if indeed your oak is 14% at end grain and 18% at center which I suspect is where you are getting those reading.. I would take a 1/32" pass off each size to bring the rough air dry down to 15/16" and then let is sit a few days. Severing the top sheath is going to expose new wood and allow moisture to either escape if your humidity is dry or get heavier if you have high humidity.

And I have done 8 major carcass pieces in the last 21 months using oak. The 8%-10% ideal is not a reality in Georgia in the summer. I shot for average 12% and will accept 14% in summer. And after you initially surface and let acclimate.. I would allow a few days more if you take it down again to say 3/4" as you have exposed new wood again. If you know you are going to use 3/4" to begin with.. you might as well take it there to save a step.

I am going to personally dis-agree about taking the wood inside the house. #1.. you probably don't have room and your wife won't allow it anyway. The point being that is ideal if once you decide to use it if.. if.. the machines you are goint to sever it on.. your work-bench and assembly-finish table are also inside. The reason... once it acclimates inside and you bring it back out to the shop to work.... you have just wasted your precious time as it will acclimate to your shop and it can do it over0night. So... what's the point"

Good luck and a tip.. if the wood is high in moisture and it is dry in Jersey.. work the joints tight... very tight as they will contract this winter in your heated house to some degree. If the wood is dry as in 8%-10%.. work the joints loose as they will expand at some point taken inside.

Have fun....

[mclear6]

Sarge.. Thanks that is exactly what I was looking for.

I went out recently and checked, it is about 14-15% at the ends and 18% in the middle.

I was planning on making a modified glass door bookcase found in the July 2009 Wood Magazine adding a third section for a wine rack for the dining room.

I'm teacher and off for the summer and it part of my "work" for the summer along with redoing the bathrooms and finishing the trim in the kitchem