HELP! Who know about drying wood?

I wouldn’t seal them up – Even though it’s hot, it’s also pretty humid – no? I would think that you’d need to cut these, stack, sticker and cover them, and let them air dry to acclimate to your evironment’s equilibrium moisture (dictated by relative humidity and tempature primarily). I don’t think a 24” diameter log would dry in a month. I would imagine that these logs still have a high percentage of water in them…

After stabilizing to the outdoor environment you’d probably want to bring them in to the indoor environment and let them acclimate to that too. A moisture meter could help you know what’s going on.

Are you planning on cutting boards/slabs? Are you open to cracking if left in the log form?

-- Dorje (pronounced "door-jay"), Seattle, WA

to add to…. building furniture out of barn wood and the study in hand made chairs i did some yrs back the A/C
in my experiance acts as a dehumidifier pulling any moisture out fairly rapidly enough to be a factor with wood making the transition from outside to inside barnwood being roughly 12 to 15% (air dried) even for 50yrs {this is a 1” board im talking about} unless i dry it to 8 to 10% she’ll bust wide open any hint of a check and when thats in the middle of a table thats bad news now this is just about the moisture and AC
as to the moisture blushing i was once told by a high quality musical grade lumber producer when looking for 4”walnut that” 4”lumber would not be dry enough in 10 yrs to build a table out of if not kiln dried and that would take so long that nobody could afford it” ,
i realise youre speaking of just epoxing some benches but at rhe risk of echoing Dorje- dont seal em up, yet
sounds as if you might need to introduce them to some dry heat some how, mabey 120 degrees for a couple three weeks, i know on small boards you can weigh the board then use the oven a 220 degrees for twenty min, let cool then weigh again repeating untill you reach a balance thus ending with a kitchen kiln dry method but these seem to big for that ….mabey some improvision would work ,,

-- "when you think youre going to slow, slow down just a little bit more" .... Pop's

More to add, in Florida the humidity in the hot season is so high not much drying goes on, winter is best for drying (the dry months). Also the rule of thumb is one year per inch of thickness. I would cut stack and sticker where there is plenty of ventilation. Heat is not necessarily what draws the moisture out, it is low humidity and air circulation that will remove moisture. The AC drying theory sounds good, maybe drying indoors might work in your location. Here is some basic information on Air Drying.

-- Ron, Twain Harte, Ca. Portable on site Sawmill Service http://westcoastlands.net/Sawmill.html http://westcoastlands.net/SawBucks2/phpBB3

More of my thoughts on Kiln drying. I air dry all my lumber and it gets down to around 7% during the summer months where I live in the Sierra’s. I have had some lumber dried by a friend with a dehumidification kiln and lost about 50% of the value (Walnut and Oak) to serious checking and warping. After that I have had a hard time validating a kiln.

During the drying process the outside of the lumber will always dry first and faster than the center of the wood. This will cause the cells on the outside of the wood to shrink (this is called cellular collapse) at a faster rate than the cells located in the center. This different rate of shrinkage is what causes checking, cracking and warping.

The big difference between the two methods of drying is that dehumidification constantly draws moisture from the wood non stop; this is what causes most problems. Air or solar drying will draw moisture from the lumber during the day and at night this process slows to a stop and gives the moisture in the center of the wood time to equalize with the outside. This will lessen the stress of drying the out side faster than the inside. This daily cycle of letting the lumber dry in a more equal fashion between the center and the outside will produce less damage to the cellular structure of the wood.

To Summarize; Unequal drying between the center and outside of the lumber is what causes damage from shrinkage. Air drying draws away moisture during the day through higher temperatures and lower humidity. At night these conditions change to lower temperatures and humidity giving the center and outside of the lumber an equalization period that reduces cellular collapse thus causing less damage to the wood.

I am now working on a solar kiln that uses the same principal as air drying, it is just a little faster than plane air drying.

-- Ron, Twain Harte, Ca. Portable on site Sawmill Service http://westcoastlands.net/Sawmill.html http://westcoastlands.net/SawBucks2/phpBB3

I live in Mississippi and have only recently started buying “green” lumber. I have a guy that I know who has set up a lumber mill. He used to be a cabinet and finish carpenter and knows what good lumber is. He gave me some cherry this past summer that we cut to 5/4. In our 100% humidity summers we have here it took about 5 to 6 months to get to around 10%, down from 25%+. I just had some 12/4 and more 5/4 milled by him and i’m guessing that the 12/4 will be a year or longer drying.
Now when it comes to whole logs, even though there only a couple of feet long, will take forever to dry. I had a friend who had a walnut tree that blew down during Hurricane Katrina, milled. He’s going to use it for turning blanks and left alot of it between 8 and 10” thick. It had been laying in a field for almost 2 1/2 years and after I checked it with my meter, it was still over 25%.
I do agree with natural air drying. I think it’s better for the wood.

-- Joey, Magee, Ms http://woodnwaresms.com

I am going to have to disagree with Treebones here. A properly ran D/H kiln is much easier on the wood. You are not pulling moisture out of it like you are wringing a sponge. It is a slow and steady process, at lower temps and higher humidity than a solar kiln. The constant “cycling” of a solar kiln can cause stress. The high temps the wet wood is exposed to is the reason for case hardening and checking.
Not trying to pick a fight or anything. I am just siting my experience on the subject. I prefer D/H, simple safe, and easy.

-- Urban logger, http://nelsonwoodworks.biz/

Daren, Ive got to ask (not picking a fight but want to find more answers), what is the humidity in your D/H kiln and is this a higher humidity than found in a natural air drying setting? My experience with a D/H kiln is with someone els running the kiln and I understand that operator experience has a lot to do with this. Also if D/H is a slow steady process does this make it slower than air drying?

I supply some walnut to quality gun stockers and other high end woodworkers who wont touch kiln dried material and wont start there projects until at least ten years air dried, just a note.

Here is some good information by; James E. Reeb, Wood Products and Utilization Specialist

Dehumidification Dry Kiln

Dehumidifiers can be viewed as a type of low temperature wood dryer although temperatures can reach as high as 160°F. Dry kilns that operate at these temperatures are capable of drying most wood species at maximum drying rates. Dehumidification kilns can dry wood to a low MC of 5 or 6%. Dehumidification kilns operate in the following manner:

1. humidity (moisture in the kiln) is removed by condensation on the cold coils of a heat pump dehumidifier;
2. liquid Freon® is evaporated in the coils and then cools;
3. water is condensed from the moist air drawn across these evaporation coils;
4. the evaporated Freon® gas is compressed and the pressurized gas attains temperatures as high as 245°F;
5. dehumidified air is passed over the hot coils to provide useful energy for drying the lumber.

Vents are not needed in dehumidification kilns, as they are in steam kilns. Vents can be used as an extra control, especially to help control temperatures in the drying cycle.

Solar Dry Kiln

In Kentucky, solar dry kilns offer a relatively inexpensive way for the woodworker or hobbyist to dry small quantities of wood. Drying times depend on the weather, and electricity is needed to run kiln fans. The heat energy necessary for drying comes from a solar collector. Depending on the chosen design, moist air can be removed through vents or condensed on the cold solar collector at night. Solar drying can result in high quality lumber, primarily because the moisture gradients in the lumber are allowed to equalize at night when drying is not taking place. Drying times vary and are relatively long.

Water and Wood

A commonly mistaken belief about lumber is that once dried it is permanently seasoned in its final dimension. A dry piece of wood will exchange water molecules with the surrounding air according to the level of atmospheric relative humidity. Loss or gain of moisture in wood products may cause such troublesome results as shrinking or swelling, interference with paint adhesion, and increased susceptibility to decay and stain.

Water is found in wood in three forms. Free water is found in its liquid state in the cell cavities or lumens of wood. Water vapor may also be present in the air within cell lumens. Bound water is found as a part of the cell wall materials. As wet wood dries, free water leaves the lumens before bound water. Water can be removed from wood fairly easily up to the point where wood reaches its fiber saturation point (FSP). The FSP is defined as that MC where the cell wall is completely saturated with (bound) water, but no liquid water is present in the cell lumens.

Wood does not start to shrink until it has dried below its FSP. FSP for most wood species falls in the range of 25 to 30% MC. It becomes increasingly hard to remove water from wood after reaching the FSP. Remember, it is only after water begins to leave the cell walls that the wood begins to shrink and its strength begins to increase.

Stress Relief

As stated earlier, free water is removed from wood until the FSP is reached. After reaching FSP, the bound water starts to move to the surface of the wood. When this occurs, the wood cells start to deform, and the wood begins to shrink. The surface shrinks faster than the core, causing stresses in the wood. In addition, shrinkage occurs at different rates with regard to orientation of the grain. The difference in shrinkage can result in bow, crook, cup, or twist (see the Glossary for definitions of these terms).

When stresses are severe enough that checks occur on the wood surface, commercial operators stress relieve the lumber. This is typically done by rewetting the surface with wet steam for hardwoods such as oaks. In the case of faster drying hardwoods and most softwoods, water is used. In either case, the lumber surface will swell slightly, relieving the stress. For some end uses, such as construction lumber where appearances are not important, surface checks are not a problem. Sometimes kiln-dried lumber can absorb enough moisture when stored in a warehouse to remove stress.

-- Ron, Twain Harte, Ca. Portable on site Sawmill Service http://westcoastlands.net/Sawmill.html http://westcoastlands.net/SawBucks2/phpBB3

Well, you have been doing your reading….but you said you are air drying, not kiln drying (can’t believe everything you read either). I am kiln drying. Yep, gunstock makers do not want kiln dried wood, I too sell to them. The reason they don’t want it is because of old traditions/wives tales, and bad experience with improperly dried hardwood. We are talking 2 1/2” stock with those guys, which is harder to dry. 4/4” is childs play.

And your big commercial units I do not have any experience with running…but I did used to take my wood to a kiln drier and a small % loss is “acceptable” to them, heck it was not their wood. It was not cool with me, you’ve been to my site. I sell $15 bft wood, any loss was too much, so I built my own. I am not going into all the mechanics of my kiln here. I have been down this road. Mine is a small kiln for “hobby use” I dry 300 bft at a time, all year long (which I could never do with solar in my area. We can go 2 weeks without the sun even shining…in that time I have another 300 bft dried in my d/h)

I will be honest I only scanned through you “facts” you found on the subject. If I miss anything in this reply sorry. My d/h runs at 100 degrees in the dry cycle (then after the wood is dry and stable I can bring up the heat to kill powder post beetles if necessary). I most often air dry first, to be honest that is the tricky part. If you can get wood to under 20% without degrade it’s kinda hard to screw it up after that.

Having said that, I do dry fresh sawn. You asked if it was slower than air dry because of the humid environment. No the humid environment is water that is coming from the wood (being forced out mechanically in a steady fashion by the heat the d/h makes) It is faster and safer than air drying where you cannot control the humidity. “Slow and steady” was in comparison to a solar kiln which literally bakes the water out of the wood and exhausts it.

I appreciate your wanting to discuss this more, and know that is why you are asking questions. It’s an interesting subject, and more woodworkers should be drying their own wood (and know more about wood in general like the other stuff you stated about re absorption and EMC)

I have been d/h drying wood with a $200 (yes $200) homemade kiln for 3 years now. Drying stuff like 24”wide curly maple slabs. I am not talking out of my hat here. I am a newish member here, and don’t want to sound weird when I say this but I got dragged into this conversation (kilns and how mine works) at another forum (WoodWeb, if you are curious) 2 years ago. I spent HOURS a week helping people make kilns, just being a good guy. Here comes the sob story and the reason for me not wanting to get dragged into it again. One of the guys I met over there was a real inquisitive guy, man he picked my brain for every scrap of knowledge I had gained running my kiln for a little over a year….a month later he was selling MY kiln plans on eBay. No joke, he copy pasted my emails and printed them like a manual and was presenting himself as a kiln dry expert (he had kiln dried 200 bft of 1/4 sawn oak that was already air dried) He ran 1 load, saw how easy it was and ripped my off. I am not greedy, like I said I gave 50 of the plans away before this one guy. But that one guy ruined it for everyone. I don’t discuss it anymore, I sell the plans myself.

I still stand by my statement d/h is safer than solar. I have been in this business awhile, and have talked to many who have built solar…and for the first few loads they were running “cheap wood” trying to get it dialed in. I am not totally knocking solar drying. Just for me it is 30 degrees here today and the sun is not out…but I still have 300 bft of 20” wide walnut drying in my d/h. Your highlighted part about the night letting the wood rest from the stresses placed on it during the day kinda makes my point more than yours. It proves the heat puts stress into the wood like I said. My d/h does not stress the wood. I personally (after well over 10,000 bft for personal use/to sell as kiln dried) have never had to condition a single stick. Not one customer has ever mentioned stress, and I have not ruined a single bft in the kiln. Sure I have had some stuff blow up (crotches, weird stuff that was going to no matter what) that is what you get drying funky wood. Straight grain (or curly for that matter) wood always comes out nice and flat, free from checks etc.

EDIT: I am adding part of a p.m. I sent to Treebones, should have typed it in this too in the first place.
The info you copy/pasted from those other sources is OK…but not all kilns are the same. Information from one source is not wholey true for all kilns and should not be taken as “everything you need to know”. Just like not all air dry conditions are the same. You said you can get wood 7% in your area, I know alot of guys in the arid parts of the country who can. Here in Illinois 12% is as dry as it will ever get.

I should have stayed out of this conversation. I just wanted to add my $.02 that in my opinion a properly set up d/h beats solar hands down on many levels. Convenience, quality of lumber…That’s all I have to say.

-- Urban logger, http://nelsonwoodworks.biz/

Daren, Thanks for your experienced knowledge and information. I have seen the plans you mentioned on eBay and understand your frustration, I would be furious. I will be building my solar kiln this year and will find out first hand how it goes here where we have plenty of sun and the low humidity. I have looked into the many pros and cons of the different types of drying and still like the advantages of the equalization or rest period and look forward to my project here.

-- Ron, Twain Harte, Ca. Portable on site Sawmill Service http://westcoastlands.net/Sawmill.html http://westcoastlands.net/SawBucks2/phpBB3