9% moisture from Airdrying. Kiln needed?

[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.