9% moisture from Airdrying. Kiln needed?

[dirk martin]

I've got some knotty white pine, that I've been air drying for several months.
Here in north/central Wisconsin, we've had a significant, low humidity spell, and when I put my moisture meter on it (Lignomat), it's reading 8 and 9%.
Do I need to run this thu the kiln? Or will I be ok, making glueups with it?

[Randy Heinemann]

To answer your question directly, it's my opinion that there is no reason to kiln dry lumber that is already 9% moisture content. In the Midwest, there are fairly large swings in humidity. If the wood is truly at 9%, there shouldn't be any reason to do anything other than bring it into your workshop and let it sit for a week or two to acclimate to the shop. It seems unlikely that it will stay at 9%, but once it's acclimated to your workshop, I'd say just use it. I personally don't have a moisture meter, but I'd guess that most kiln dried wood I have used is above 9% just from sitting in either the lumber yard or my climate controlled basement shop. Someone can tell me I'm wrong about the exact numbers, but I still don't see any reason why you can't just use the wood.

[Mel Fulks]

Agree with Randy. Insistence on kiln drying came from groups making rules to protect companies from complaints about perceived natural
defects , like not being “space age plastic”. Nice reddish walnut becomes harder to work and loses color by being kiln dried.

[dirk martin]

Why the desire to acclimate it to the woodshop, when the woodshop isn't the final destination?

[dirk martin]

Agree with Randy. Insistence on kiln drying came from groups making rules to protect companies from complaints about perceived natural
defects , like not being “space age plastic”. Nice reddish walnut becomes harder to work and loses color by being kiln dried.

Interesting. I never knew this.

[Richard Coers]

As long as you don't mind having the pitch ooze out from not being set with heat, you'll be set to go.

[dirk martin]

As long as you don't mind having the pitch ooze out from not being set with heat, you'll be set to go.

Ouch!.....good point....

[Andrew Hughes]

As long as you don't mind having the pitch ooze out from not being set with heat, you'll be set to go.

The pitch should eventually set in about 40 years give or take 5. :)

[Steve Eure]

Air dried lumber may or may not contain bugs and/or larva. I know that those professional sawyers who kiln dry also run a cycle at the end to kill insects that may be lurking in the wood.

[Gary Petersen]

Why the desire to acclimate it to the woodshop, when the woodshop isn't the final destination?

Acclimating to the shop is done so the wood is at equilibrium in the environment where you'll work on it and isn't moving during the project. Or at least isn't moving different to other boards you're using that may have been in the shop longer.

[Warren Lake]

Gerry Metz stated Pine should be dried to 10-12 percent. Most of the other woods he specked at likely 6.5 - 7 percent. Ive used air dried on Facias and both air and kiln on many shop cabinets. The kiln stuff was down around 7 or lower and machining it sounded a bit different and almost felt a bit brittle compared to air dried.

[Mel Fulks]

Gerry Metz stated Pine should be dried to 10-12 percent. Most of the other woods he specked at likely 6.5 - 7 percent. Ive used air dried on Facias and both air and kiln on many shop cabinets. The kiln stuff was down around 7 or lower and machining it sounded a bit different and almost felt a bit brittle compared to air dried.

that’s cuz’ it IS more brittle . Apologies to all who are trying to “cut down on peanut brittle”. AND that’s why Robin Hood made all his bows
out of air dried wood. Story goes, that he when he made the first one he put it close to the fire to dry it …then he heard a voice yelling,
“YOU ARE KILNING MEEE !!” And that is probably what inspired James Dean in Rebel Without a Cause to do the “hand to face pull-down”
while moaning to his Dad , You are killing meee !!

[Tom Bussey]

Moisture content only effects size so I think that acclimating it to the shop is a waist off time. Wood will take on and loose moisture as the humidify changed. Here in Nashua Iowa air drying will only get you to about 10 per cent. And only after a very long dry spell. But it will bounce like a ball when the relative humify changed. The way it was explained to me is that kiln drying takes the moisture out of the cell of the wood. It will still grow and shrink but it does so at a much slower rates and not as much. Kiln drying also Kills anything that is in the wood. I got some hickory one tine that had powder beetles in it. It traveled from board to board. I try to stay with kiln dry wood because of the experience. I do not like to mix and match air dried and Kiln dried.

I have a fireplace insert that is rated at a 72,000 BTU furnace and I use it to help with the heating bills. When it is 20 below zero and the wind is blowing it feels mighty mice in the living room. It is a good idea to set a bowl of water out because it can get to dry. One just has to be a where of the fact that wood will move and there is nothing that one can do about it and build so that, not if but, when it moves.

I do have some air dried red oak at the present that I bought at an auction. I mention it because I wouldn't have any trouble using it in a frame and panel construction, for the frame, but I would prefer kiln dried for the glued up panel. But if the truth be told I would prefer the whole assembly be kiln dried. PS : the air dries is stored in a different place from my other wood.

In my opinion don't worry about wood moisture content or acclimating the wood and just enjoy the different processed that come with building. Build so the wood can move ( no cross grain gluing like Norm used to do) and go for it.

[Mel Fulks]

Interesting. I never knew this.

We used to be asked by suppliers if we wanted air dried , or kiln dried. So that tells me that not everyone would accept kiln dried.

[Randy Heinemann]

Acclimating the wood for a project to the workshop will bring it to the moisture and temperature level of the workshop. Letting it acclimate for a week (actually 2 weeks is probably best), will bring it to the moisture level in your shop. Since your moisture meter says your wood is at 9%, it seems likely to me that your wood will absorb some moisture from the shop, the end result being possibly a couple of percentage points higher. When wood absorbs moisture it moves and it's likely to change shape at least a little. You want that to happen before you joint and/or plane the board. If they are already jointed and planed, it's possible they might move at least some in the process. In the end, you want the wood to be completely stable before you cut it to size and square up your boards. The one thing you don't want is to get everything jointed, planed, and cut to size and have the wood cup or warp even slightly. In my opinion, spending a week or two letting the wood just lit in your shop is worth it. It might not move, but I don't usually take that chance.

You're right that the piece's final destination might make the parts move again, but that's something that should be thought through during the planning of cutting the boards to size, making drawers, making doors, etc. You really want to start with straight, stable wood if it's at all possible.

[Jim Dwight]

I have used constuction lumber at 20% moisture for furniture before and I try not to do that now. 20% is too high. But I've never had an issue with wood down around 10% moisture. It might get a little drier or wetter after you finish the project but the piece should be designed to accomidate that (at 20% it will definitely get drier and may warp or split as it does).

I do not acclimate wood I buy. I do like to do my initial cutting leaving the pieces a little oversize, however. The reason for that is the wood sometimes moves some when you cut it down so it's best to leave it oversize so you can flatten or straighten it again after it settles for a few days - if you can take the time. But acclimation doesn't make sense to me because the moisture level in my shop is rarely the same as the moisture level in my house and both change during the year. So how does it help anything to let the wood settle at the shop moisture? The piece has to be designed to accomidate the future moisture changes anyway. You should be talking about small changes in moisture.

[Don Stephan]

Original poster did not clarify if the moisture reading was consistent between boards and on the surface and the middle of a particular board.

I allow to acclimate to work area because seldom can I start and finish a project in just a couple days, and the wood may stabilize at a different moisture content (and move) after a couple weeks than what it was initially. Two weeks to acclimatize is just part of the planned project schedule.

[Tom Bussey]

I hear what you are saying but, This is how I work. I usually rough cut my parts, then I straighten the shop and get rid of all the strips and cut offs that are no longer usable, That takes time. Then I proceed. I am retired but I still work part time so I do not get to work in my shop 8-10 hours a day. if you are working, married and have Children you will you will be lucky to get an hour or two in a day in the shop, and because of school activities and so on, some times one is lucky to get in a full day in on Saturday. I build furniture, actually now I have been building custom work benches and with all the sawing ang gluing and so on and so on. Because of life getting in the way, a bench with a solid 4 inch top take about 2 -3 months to build. What difference is letting the wood set for a week or two going to make.

Because of work schedules and every thing, don't you think that by the time you get around to assembling and finishing, that the wood might have had time to acclimate? And Moisture can only pernitrate wood or be removed only so far in a given time so the wood doesn't change the farther it goes into the wood. In other wards the moisture of the wood 1/8 of an inch will not change much. It is like heat. The greater the temperature difference the faster the heat flows. If there is a 2 or 3 degree temperature difference, the change will not even be noticed. it

[Richard Coers]

Something to consider. There is kiln dried, and then there is proper kiln drying. Rush the loads with a higher heat schedule to meet demand and you can get brittle and stress filled lumber. Do it right with good equalization and conditioning cycles, then you get quality material. Not every board out of a kiln is trash, just like every board that is air dried is not infested. But you will see both if you work at it long enough.

[Kevin Jenness]

What difference is letting the wood set for a week or two going to make.


It depends. Stickering 4/4 lumber for two weeks in a shop at 65*F and 45% RH could drop the MC down two or three points, which might make the difference between a miter joint staying tight in service versus gaping open. Thicker material takes longer. If you have time on your side you can avoid moisture related problems. Some designs are more accommodating of wood movement than others. I try to keep my shop between 35% and 50% RH and get my lumber in as long as possible before use.

[Bradley Gray]

I have a gluing bench in my shop - 3X12" x 8'- when i am in the middle of a build I clamp the parts with stickers and clamps to this bench overnight or over the weekend so that parts I have jointed and planed stay flat.

Wood moves.

[Randy Heinemann]

While anything is possible, I really doubt that, with lumber starting at 9% moisture you will have problems. Would I let it acclimate to my shop for at least a week? Sure. Why not? You really don't have anything to lose. Chances are you aren't going to rush through the project anyway.

[Kevin Jenness]

One thing to remember when using a pin type (resistance) meter is that you are reading the electrical conductivity at the depth of the pin penetration. 1/4" pins in 4/4 material go only halfway to the core and may not give the full picture. Weighing a sample and comparing it to oven dry is definitive. Pins driven to the core can show a moisture gradient and pinless meters can give an average for a defined range of thickness.

If your pine truly is at 9% you probably will be fine.

[Tom Bussey]

I still think acclimation wood to the shop for a week or two is not worth doing. My reasoning is if you are a hobbyist it may well be a week before you can get back into the shop. I rough cut my parts oversize and I hang them on a close line in my shop. That way if or whatever stress that is in the wood can be released and the wood can go to a point of equalribeum. Others just stack it. By the time one gets around to cutting and surfacing things to size the wood will be acclimated

Today saws come with a riving knife. But a few years a go, some of the wood before riving knives, would move and clamp tight against the back of the blade and cause problems or open up and bow causing the board to come away from the fence. That is what I call stress for a lack of anything else to call it. If you need a part 3/4 X 2 1/2 by 46 inches It is much easier for the wood to acclimate if cut at lets say 2 3/4 wide than it is if it is left at 10 inches wide. If it is going to bow and twist it is better to let it happen after rough cutting, and after it has set a few days. then mill the wood to size. Are you not doing the same thing, than to let it set for two weeks and then cut it apart so that it can then move around. And letting it set for some more time until you can get back to it.

Either way again if a hobbies, the wood will be more than acclimated to your shop before the project is done. Moisture only effect size And once it leaves the shop and goes into a home that is either heated or airconditioned everything changes again. If you are a professional then you probably aren't reading this forum and don't really need advise.