Lumber- How dry is dry enough?

[Dave Carteret]

I have around 150bd-ft of Ash that I had milled about 2-1/2 years ago. It's been sitting since then, stickered, in my garage. Well, I recently un-stickered & stacked it. My garage is somewhat climate controlled. It's heavily insulated and it never gets below 40 in the winter & never over the 80s in the summer. Certainly no humidity control though.

I bought a moisture meter recently and when I checked those boards, they're at 10%-11% MC. I also checked some of the Oak furniture in my house and it's at about 6%

Is that wood dry enough to use for projects? I can't see it getting any MORE dry in the environment it's been sitting in. I don't have anywhere inside the house for 16' long boards (or boards of any appreciable size) if that's the answer.

Thanks!
Dave

[Bill Davis]

I have around 150bd-ft of Ash that I had milled about 2-1/2 years ago. It's been sitting since then, stickered, in my garage. Well, I recently un-stickered & stacked it. My garage is somewhat climate controlled. It's heavily insulated and it never gets below 40 in the winter & never over the 80s in the summer. Certainly no humidity control though. The temperature is not really important it's the humidity that determines whether the woods MC goes up or down.

I bought a moisture meter Good on you for getting a moisture meter. It has been said that 90% of the problems with wood are caused by moisture. At least you can check the MC. recently and when I checked those boards, they're at 10%-11% MC. That is the MC that 55 to 60% humidity would give. I also checked some of the Oak furniture in my house and it's at about 6% 6-8 %MC is what you would expect for inside wood MC caused by RH of 30-45%.

Is that wood dry enough to use for projects? It depends on the design of what you are making. Ash has approx an 8% tangential shrinkage vs a 5% radial shrinkage so you could have some problems if you build a project with 11%MC wood then take it into a 6%MC environment. There will be some shrinkage that could cause a problem. But maybe not. If you warmed the garage it would reduce the RH and that would dry the wood further. I can't see it getting any MORE dry in the environment it's been sitting in. I don't have anywhere inside the house for 16' long boards (or boards of any appreciable size) if that's the answer.

Thanks!
Dave

If your project is designed/layed out such that shrinking and swelling won't stress joints or make things swell and stick you might be close enough in MC to not have difficulties.

[Curt Harms]

I don't know where you are, Dave but I'd guess it's not an arid climate. Check your same oak furniture again in July or August if you have the windows open. I'll bet it's not 6%:). I have lumber storage & shop in a (dry) basement. It's 6% right now but it'll be 10-12% in the summer. Just the nature of the beast. There is a debate about whether kiln dried lumber is more stable than properly air dried lumber. Hardwoods, my vote is no. Kiln drying is much faster and it kills any bugs but done improperly-too fast- it can also cause case hardening. I can see commercial operators only using kiln dried hardwoods. They don't want to spend the time dinking around with boards from different sources that have been dried differently, they want as uniform stock as they can get. This is less an issue for me as a hobbyist, I can vary construction to account for wood that is likely to expand(if it's dry now) or shrink (if it's humid now). That'd be a pain for a factory. I have heard that pitchy softwoods benefit from being heated to about 160* to "set the sap" so it doesn't bleed through any finish. My opinion and worth what you paid for it.

[Danny Hamsley]

I use wood of that M% here in GA for furniture, but I design in the ability of the wood to move due to seasonal changes in humidity. However, the climate here may be more humid in general and your climate may be different to where the wood needs to be a little drier.

[Rick Christopherson]

Contrary to the often repeated statement, finished wood projects do not experience a significant change with season in climate controlled homes. Once they are stabilized, they remain stabilized. When the differential in moisture is small, the process of absorption and expulsion is slow. An analogy to this is to take two blocks of ice and put one in the refrigerator and the other on the counter, and compare how long it takes them to melt. When the temperature differential is low, it takes a lot longer for the ice to melt. Same with moisture in wood.

The reason why many woodworkers perceive dramatic changes is most likely due to the initial changes they see when the project was first completed, coupled with the higher MC of the project when it was built. Most woodworker's workshops are in their garage and open to outside air changes. The humidity in the garage will generally be much higher than in the house.

The fact that your garage never gets above 80 degrees in the summer is actually hurting you in terms of wood storage. An elevated storage temperature for outdoor storage will have a lower relative humidity than the ambient air. In effect, it would be a low temperature kiln.

[Harvey Pascoe]

I would say that is dry enough EXCEPT for using wide boards where I like to see it down to 7, if possible. Species vary considerably, so what I do is cut off a six inch piece, resaw it in half and let it sit for a week, with the non resawm side down on something non absorbent like wax paper or formica and see how much warpage occurs. If it stays flat, its definitely okay. If it goes convex to the upside, its likely still giving up moisture, but could also be stress in the wood.

I agree with Rick on the finishing point but for one thing. Oils offer zero moisture barrier protection while varnish is the highest and acrylic somewhere in the middle.

[Dave Carteret]

Thanks guys. I'm in SE Michigan, so we see our fair share of temp & humidity swings. I've been figuring that after 2+ years, this stuff isn't going to get any more dry than it is now. Btw, these are 4/4 boards about 8" wide & 16' long. Same MC in the middle as the ends.

[Dave Carteret]

If your project is designed/layed out such that shrinking and swelling won't stress joints or make things swell and stick you might be close enough in MC to not have difficulties.
Thanks Bill,
I put a hygrometer out in the garage and it was 50/50 out there. 50 deg, 50% humidity. So I'm guessing that what I'm seeing in the wood is at equilibrium for those conditions. Wonder if I can get it any more dry out there...

[Mike Mastin]

If you wanted to build a tent around your stack of wood with heavy plastic and insert a dehumidifier in the tent, it would slow bring down the MC. Many people have built drying boxes and stuck dehumidifers in them and they work well for this purpose. White Oak with its tanins will eat the coils out of one if you are trying to dry it from a heavily green state, but with what you are doing, I think it would last more than a few drying cycles. Just need to make provisions to easily drain the dehumdifier without opening up your sealed tent/box too much. I would check it once a week and see what your MC is if you try this method.

[Scott T Smith]

Dave, it's pretty much equalized with your environment. If you want to get it lower, put a dehumidifier in your garage set for about 40% RH, or as Mike suggested stack and sticker the lumber with a tent around it and a dehumidifier under the tent. If you warm it up a bit to 70 degrees or higher it will dry out faster.

[John TenEyck]

Contrary to the often repeated statement, finished wood projects do not experience a significant change with season in climate controlled homes. Once they are stabilized, they remain stabilized. When the differential in moisture is small, the process of absorption and expulsion is slow.


This is true as stated, but note that the key is "climate controlled". Wood only remains stable if the RH remains in a narrow range, which means the home in which it placed must have good control of the RH. In reality, few do without both humidifiers for raising the RH in the winter and dehumidifiers to lower it in summer. Where I live the RH in my house is 35 - 40% much of the time in the winter and 60 - 75% much of the summer, which means wood placed there will change in MC from something like 6% to around 12 - 14%. And contrary to what many think, MC changes pretty quickly as the RH changes, regardless of what finish is on/around the wood. I've watched it with a moisture meter and observed it as doors stick as the RH goes up, and then swing freely again a couple of days after I turn on the AC.

So, what to do? My strategy is to just make sure the wood is in equilibrium with it's environment when you build with it. In the OP's case, that means getting the wood into your workshop and leaving it there until it's MC is appropriate for the RH there. If you do that your furniture will be fine as long as you design for the expansion/contraction that will occur due to seasonal changes in RH.

[Danny Hamsley]

On March 4, I stickered some 13/16" planed red oak in a corner of the living room behind a chair. My Wagoner moisture meter said the beginning moisture content was about 12.8%, typical of well air-dried lumber in Middle Georgia. Today, March 12, eight days later, the moisture content is 11.4%, which is a 1.5% drop. I tested an oak drawer front in the kitchen that has been there for 30 years, and it tested 9.4%.

[Dave Carteret]

On March 4, I stickered some 13/16" planed red oak in a corner of the living room behind a chair. My Wagoner moisture meter said the beginning moisture content was about 12.8%, typical of well air-dried lumber in Middle Georgia. Today, March 12, eight days later, the moisture content is 11.4%, which is a 1.5% drop. I tested an oak drawer front in the kitchen that has been there for 30 years, and it tested 9.4%.
Thanks for the info Danny. I've wondered how quickly the wood would acclimate if I brought enough inside for a project. I certainly don't have enough room to bring all of it in, but for a specific project, I could probably find the room.

I've also wondered..... how good would a kitchen oven be as a kiln? While cutting firewood, I found a Red Oak log that's very nicely burled. But it's ~25% MC. Wonder if I could dry it in the oven at 130-150deg for a few days.

[Scott T Smith]

I've also wondered..... how good would a kitchen oven be as a kiln? While cutting firewood, I found a Red Oak log that's very nicely burled. But it's ~25% MC. Wonder if I could dry it in the oven at 130-150deg for a few days.

Dave, I would not suggest drying a log in this manner, as most likely you will create extensive honeycomb within the wood. Wood dries very poorly in log form, and the drying schedule for red oak is very, very slow.

Your best bet would be to slab the log into approximate thickness that are usable, and then stack and sticker them and let them air dry for a while.

Drying oak successfully requires either a lot of time (air drying), or the ability to closely manage the temperature, RH%, and air flow around your lumber. Even though successfully drying wood when it's below 25% MC is not as challenging as when it is above 25%, the problems with attempting to use a kitchen oven to dry is that it is difficult to regulate the heat down low (100 - 130F range), you have no way of controlling the RH inside of the oven, and there is no airflow.