LumberJocks

Wet vs. Green vs. Dry

  • Advertise with us

« back to Wood & Lumber forum

Forum topic by careforapint posted 07-29-2011 07:26 PM 1046 views 0 times favorited 7 replies Add to Favorites Watch
View careforapint's profile

careforapint

15 posts in 1151 days


07-29-2011 07:26 PM

Topic tags/keywords: wet green dry turning sapling

Hi All-
Quick question…

I’m cutting down a few saplings in my back yard and want to use the trunks for small turning projects. I just cut one down and pieced it up so the wood is still really wet. I was hoping to make a little goblet, so I tried to glue up a wet chunk (3” dia x 5”) to a waste block mounted to my face plate and to no surprise on my end, the glue failed on the wet wood. (I don’t yet own a chuck or a screw mount for my midi lathe. I know, I could probably turn it on centers, make a jam chuck and try that way to hollow out the bowl, but I wanted to try this first.)

I know it depends on size, environmental conditions, political affiliations, moon phases, etc…, but generally how long does it usually take before “wet” is considered “green” and then considered “dry”?

(I know a moisture meter would be a key tool in this, but alas, I don’t own one and only have my eyes and fingers to help with that.)

-- Christopher - Virgina


7 replies so far

View rance's profile

rance

4132 posts in 1817 days


#1 posted 07-29-2011 07:33 PM

1” per year for air drying. For what you have, google “Drying Methods” Microwave. You can probably reduce that to a week or less. HTH. Oh, and you pretty much figured out the mounting on the lathe options that will work.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

View Scsmith42's profile

Scsmith42

125 posts in 1333 days


#2 posted 07-31-2011 01:54 AM

Christopher, I operate a kiln. Maximum safe daily drying rate is dependant upon the species and thickness. The terms “green” and “wet” refer to the same thing; it “wet” wood is green wood.

As an example the maximum safe daily drying rate for 1” thick oak is 3.5%. 1” black walnut is around 5%, 1” thick southern yellow pine is about 15%, and so on. AS a comparison, 2” thick oak is 1.4% per day.

Rate of drying is reduced exponentially by the thickness of the board.

Unfortunately, the “1 year per inch” rule is incorrect and simply won’t go away, and in many instances adhering to this rule will cause excessive degrade.

The most critical phase of drying is from green down to 25% moisture content.

-- Scott, North Carolina, www.quartersawnoak.com

View careforapint's profile

careforapint

15 posts in 1151 days


#3 posted 07-31-2011 02:09 AM

Scsmith42 – thanks, that’s helpful.

I guess what I mean between “wet” and “green” is that when I first cut that sapling down and clamped up those blocks, the wood actually dripped with moisture. “Green” wood is what I’d refer to that in between stage from wet and “seasoned” or “dry”.

I’ve done some more reading online and it looks like there should be a moisture meter in my toolbox in the near future.

-- Christopher - Virgina

View TopamaxSurvivor's profile

TopamaxSurvivor

14752 posts in 2332 days


#4 posted 07-31-2011 02:21 AM

Scsmith42 the “1 year per inch” rule… will cause excessive degrade.

Can you elaborate? Any good rule to thumb to replace it?

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View rance's profile

rance

4132 posts in 1817 days


#5 posted 07-31-2011 03:12 AM

Scott, you’ve piqued my interest. :) That looks like a good subject for a blog. Would you mind sharing the insight you have? When I say “air drying”, I’m referring to stacked and stickered with a covering to keep the rain off. I realize there are all kinds of factors that can affect that though. In a dense forest vs. in the middle of a Kansas wheat field.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

View Scsmith42's profile

Scsmith42

125 posts in 1333 days


#6 posted 07-31-2011 05:18 PM

Rance and Topomax, ask and ye shall receive!

Knowledgeable lumber professionals have been trying to kill the “1 year per inch rule of thumb” for a long time, because it is so grossly misleading.

Actual drying time depends upon species, thickness, and local environmental conditions.

In the CONUS, probably 75% of all wood species dry at a rate significantly faster than “1” per year”. In fact, in most locations and for most species (slow drying species such as white Oak excepted) 4/4 lumber is well air dried within a couple of months, and six months for 8/4.

Lumber can and will start to degrade if air dried too long in an uncontrolled environment. Whenever lumber dries and then regains moisture, damage can and will occur (which happens frequently when AD outside and exposed to extreme humidity changes. Typical defects that result from excessive air drying are increased checking; warp, discoloration, etc, due from excessive cycles of rain and sun. If you’re a professional operation air drying in specialized drying sheds, you have more fudge room.

Here is a link to a US Forest Products Library publication that provides information about air drying tests performed in various parts of the U.S.

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr121.pdf

The information on page 4 is especially insightful about differences in air drying rates due to temperature and humidity. As an example, 4/4 oak stacked and stickered in early January required almost 5 months to dry down to 20% MC, yet similar species/thickness stacked and stickered on June 1 only requires 2 months.

One of the take-aways from this information is with respect to when to harvest and air dry. Due to the slower air drying rate for lumber stacked/stickered in the fall, if you’re going to dry a slow drying wood such as 12/4 oak then it would be best to mill, stack and sticker around October 1st in order to minimize defects.

When planning to air dry lumber, unfortunately there is no single hard and fast “rule of thumb. Rather, it is best if you first determine the species, thickness and associated maximum safe daily drying rate for your lumber. Step 2 would be to either mill, stack and sticker at the appropriate time (if a slow drying species), or to use the USFPL information as a reference to get an idea based upon the time of year and your location. Step 3 is to use a quality moisture meter to record actual MC% (once you are below 30% – meters are not accurate above that).

It’s really not that hard, it just requires a little more homework time up front.

-- Scott, North Carolina, www.quartersawnoak.com

View rance's profile

rance

4132 posts in 1817 days


#7 posted 08-01-2011 02:41 AM

Thanks Scott. :) I’ve only dabbled in drying some very short pieces of offcuts from my yard. I’ve ruined a LOT of Holly in the process too. I’ve had marginal success, but mostly with pen-blank size pieces and maybe a few small bowl blanks. I can easilly see how so many factors can affect the drying. I think you’ve successfully convinced me that (for me), building one of those back yard kilns is simply out of the question. I’d rather trade any large logs I come across to a mill for some already dried immediately usable lumber. Thanks for the details.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com

Latest Projects | Latest Blog Entries | Latest Forum Topics

GardenTenders.com :: gardening showcase