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Air drying wood chart, anyone?

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Forum topic by flipflop posted 01-23-2011 06:34 PM 6572 views 1 time favorited 6 replies Add to Favorites Watch
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flipflop

37 posts in 2881 days


01-23-2011 06:34 PM

Can someone please post up a chart or something that tells how long each species needs to air dry depending on thickness? I know humidity plays a part in this but just a guide would be great. Thank you so much.


6 replies so far

View Roper's profile

Roper

1370 posts in 3181 days


#1 posted 01-23-2011 06:46 PM

The general rule for air drying lumber is 1 year for each inch thick the wood is.And don’t forget to seal the ends so you don’t lose a bunch of wood.

-- Roper - Master of sawdust- www.roperwoodturning.com

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flipflop

37 posts in 2881 days


#2 posted 01-23-2011 07:10 PM

That’s what I have always gone by but red oak and white pine will breath different I would think.

View Daren Nelson's profile

Daren Nelson

767 posts in 3373 days


#3 posted 01-23-2011 08:29 PM

Table 1, page 4 http://nrs.fs.fed.us/pubs/rp/rp_nc228.pdf shows it depends on where it’s dried as much/more than species. Sure all species dry at a different rate in the same location. I don’t believe there is a chart that says X species will dry in X days…too many variables. Like in the desert obviously any wood will dry faster than in the marsh. On that chart from the link above you will see that the old “one year per inch” is not really true. I can dry hardwoods in 100 days in the summer here in central Illinois, softwoods much faster. In the winter, well they don’t dry much because they are frozen, that is kinda where the one year comes in I guess. And it’s only going to get so dry, depending on where you live. http://www.fpl.fs.fed.us/documnts/fplrn/fplrn268.pdf Like you said humidity (RH) and temp play a big part. http://www.csgnetwork.com/emctablecalc.html Obviously pine is going to dry faster than white oak, heck red oak dries faster than white oak, like I said too many variables in air drying.(location, species, time of year, thickness…) I’m just rambling, I’ll stop there, maybe someone has a better answer ?

View Bill Davis's profile

Bill Davis

226 posts in 3392 days


#4 posted 01-24-2011 12:44 AM

Here’s another good document on drying by a real guru on the subject Eugene M. Wengert et al.

A rule-of-thumb of time vs thickness is nortoriously inaccurate or just an approximation.
Drying is dependent upon the starting moisture content of the wood, the relative humidity of the air where it is being dried, the amount of air circulation over the wood, the specie of wood, the temperature and the moisture content you are trying to achieve. That is probably why we look for these rules of thumb – right? But it is a very interesting topic and quite helpful in understanding the relationship between wood and water which is helpful for us amateur woodworkers.
The reason for a kiln is mostly to speed up the process and minimize wood damage during the drying by controlling the rate of drying to ‘fast as possible’ but not ‘too fast’. Most damage to wood during drying occurs during while going from ‘green’ to about 2/3 green.

View Loren's profile

Loren

8315 posts in 3116 days


#5 posted 01-24-2011 02:19 AM

Check out the download version of the U.S. Forestry Service Wood Handbook:

http://woodworking.about.com/b/2007/10/31/download-the-wood-handbook.htm

Lots of useful information in that book. Free too.

View Sawmillnc's profile

Sawmillnc

150 posts in 2522 days


#6 posted 01-25-2011 03:33 AM

Daren,

Good reference. Again I have to try and dispel the rule of thumb. It is HIGHLY contingent upon things like species, thickness and LOCATION you are drying. Also whether it is in the open or in a covered environment.

Average woods like red oak and walnut in NC can be air dried after March in less than 100 days. Air dried is to around 14-15% MC

8/4 stock will take a minimum 140-180 days

-- Kyle Edwards, http://www.sawmillnc.com, Iron Station , NC (near Charlotte)

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