Acclimating lumber

Re: Acclimating lumber

Mark Mandell - Gone Round In New Jersey

I'd give it two weeks, depending on the humidity level in your shop

Re: Acclimating lumber

Yonak

JL, I don't wish to hijack your thread but, in a related question, do you-all acclimate your wood in the space where it will spent the rest of it's existence or in the shop where it will spend the next few weeks ? Is there a reason why either one is more valid ?

Re: Acclimating lumber

Virgil J

2 weeks to 29 years. 2 weeks for some I planed last night and some that is going on 29 years on the rack.

I don't fret this issue

Bill Tindall, E.Tn.

Our customers would typically begin working a delivery just after it came off the truck. I do the same. I think the whole issue of shop environment acclimation of KD lumber not something that needs to be worried about.

For those that are concerned, what is the concern?

Re: I don't fret this issue

paul in AZ

How about the ambient 2% relative humidity in the first half of the year in Az?

Re: Acclimating lumber

Mark Nowicki

About seven years, the average time it takes me to complete a project.

In my case the natural changes in climate are more of a concern.

Yes, my comment is meant to be facetious.

I agree with Bill.

LOL - all over the map then

JL

My usual procedure is to bring it into the shop, joint it and rough rip it. Then I start planing it. There usually is a couple of days between bringing it in and the start of working on it.

In this case, I have two other projects ahead of working it (finishing two benches and working on some chair parts) - so it will be two weeks or so.

Re: LOL - all over the map then

John K Jordan

I've heard it recommended to acclimate wood that will be physically restrained, like wood flooring.

JKJ

Re: Acclimating lumber

Don Stephan

No doubt I'll get ripped for saying what works for me.

I'll stack with stickers for two weeks before first flattening and straightening, then another two weeks stacked with stickers. I was having glued up panels warp as soon as the cauls and clamps were removed. Since I took this conservative approach eight or nine years ago glued panels seem to stay flat when unclamped, individual boards and loose bookshelves have stayed flat and straight for years. These are the results I want, and the process isn't objectionable for me.

Decide what works for you.

Re: Acclimating lumber

Barry Irby

NOFMA the National Oak Flooring Manufacturers Association requires Oak flooring be acclimated to the house for two weeks, I think, you can look it up.

The difference is they are considering you might install it in a room that is 12' wide or wider. 150 or 200" wide. If the overall accumulated change were just 1% that would be an inch or two. If it all occurred in one place it would be horrible. But, the flooring is divided into maybe fifty strips and each one moves a hundredth of an inch or two seasonally. So letting the flooring acclimate helps assure its as good as it can be.

You are not working with "pieces" 100" wide so you have much less concern.

Indeed, that is a good practice

What would be the problem?

Bill Tindall, E.Tn.

Lumber will have left the manufacturing site here in the East at a target value of 7% moisture content. It will arrive in sunny AZ at 7% two days later and move to some sort of storage, usually exposed to the outside. Some time later you buy some boards and take them home to your shop. What "bad" is going to happen if you begin working them at once?

If the received lumber is a different moisture content than what it will become in the shop, it is necessary to provide equal access to shop air on both sides of boards and panels in storage and assembly. It is differences in the rate of moisture loss or gain that cause panel warping, noted below by Don.

Uh, No

Mark Mandell - Gone Round In New Jersey

Memsahib has a strict rule:

"No storing lumber in the living spaces of the house."

Shame, too, as I'd have a lot more room in the shop.

Re: Acclimating lumber

Brian Holcombe

I have a broad range to this practice. Primarily it depends on what the lumber will end up being.

For shoji I buy softwoods and softwoods are not typically as dry as hardwoods when they're 'kiln dried'. At least in my experience. I like to buy them as soon as possible and sit on them as long as possible and will typically let them sit between phases of the work that require heavy removal of stock. I've developed this practice through experience.

Panels, all the same, though I like to resaw them ASAP if possible and let the re-sawn material sit for a good while (few days is typically all that is needed) with weight on them.

So I tend to wait between phases of work more so than I concern myself with working stock right from the yard, which is fairly common for me. This has resulted in both expedience and fewer bits of rework due to avoidable failures.

What!

Bill Tindall, E.Tn.

All that space behind the couch and under the bed wasted? Ideal for winter drying. But in the summer there are automobiles, which this time of year get to a dandy KD temperature for accelerated drying of parts, as needed.

Re: Acclimating lumber

Bill Tindall, E.Tn.

Framing is dried to 18% moisture content, soggy by our standards. General softwoods....I don't know. Hardwood lumber- the industry standard is 7%. You can count on any lumber leaving a modern drying facility whether for export or domestic, it will be over dried and brought back to 7%. This process results in a stable lumber somewhat resistant to dimension changes.

Nope

Mark Mandell - Gone Round In New Jersey

stated "You're not bringing that stuff into my house until it's got 3 topcoats and is useful for something other than collecting dust."

[aw, jeez, ma]

Re: Acclimating lumber

AZ in Colorado Springs

Here in C Springs the moisture content will settle at +/- 5%. (The lower limit of my moisture meter is 5% and many boards give no reading, and that's the case for every cutoff that has been sitting around for a while.) So I like to get wood a minimum of two months in advance of using it for a project.

The front room of my house is two stories to the ceiling, so the boards go in there, upright along the wall. Plenty sufficient for air circulation.

Again I ask......

Bill Tindall, E.Tn.

.....what is the problem of building with lumber that is not the same moisture content as it will be if left in the shop for XX days?

Re: Again I ask......

Barry Irby

OTOH, What would be the problem with acclimating the wood? Other than investing the time and storage space is there any disadvantage?

Re: Nope

Yonak

I guess it's a matter of : What's the purpose of acclimating the wood ?

If it's a question of, from one day to the next, will the joinery I cut yesterday still fit the same today ? ..Or is it a matter of, when I build a piece and then move it to it's home location, will the drawers work the same as in the environment in which I built them and will the lids close right or get stuck ? On the other hand, if you're building with all seasons accounted for, all should work smoothly no matter the humidity level, right?

Re: Again I ask......

AZ in Colorado Springs

As Don described above, glued up panels will warp. Then you're teaching a class, building a six board chest, and some of the panels are bowed. Very frustrating.

But if I wait , I can teach the students to flatten & square the boards and glue up panels that cooperate.

Dealing with panels warping, or not

Bill Tindall, E.Tn.

Two claims have been made that a thorough acclimation of lumber to shop environment is essential to prevent glued up panels from warping where otherwise they would warp. I will argue that if your panels are warping it is a result of improper handling of panels, that might be mitigated by acclimation, or might not if the shop humidity is not constant.

Presuming properly KD lumber to begin with, a panel will only warp if the moisture gain or loss from one side of the panel is different from the other side. Indeed, if the panel is handled carelessly after assembly and the moisture content of the panel is not equilibrated to the shop humidity, it will warp. The most common mishandling is storing a panel on a bench where there is free air circulation on the top and none on the bottom.

I store assembled panels on horses with sticks between the panels, or leaned against a wall with good air circulation all around.

The humidity in my shop, and some of your shops, changes in the course of a week. Acclimating the lumber to this situation is meaningless. I have to assemble and store panels in a way that ensures equal access of air to both sides. As an aside, I have a 20" panel I prepared some years ago. It has been stored in the shop where the humidity has ranged from 30 to 70% . It has stayed flat in spite of the fact that its moisture content has ranged widely over this time, as it will when you put it into furniture.

Suppose lumber is received of different moisture content than what it will become in your constant humidity shop situation. A panel is assembled from this lumber and stored with equal air access to each size. Why would this panel warp? In my shop panels don't warp and I have made hundreds of them with lumber of unknown moisture content relative to my shop humidity. Ditto for our former customers that made thousands of panels from lumber most assuredly not acclimated to their shop.

I will agree that if the shop humidity is constant and the lumber is acclimated to this humidity, it doesn't matter how panels are stored.

The above discussion presumes the lumber was properly KD to 7% MC to begin with. Other factors come into play if the lumber coming into the shop is only air dried to a moisture content significantly higher than what it will become in the shop.

Re: Dealing with panels warping, or not

Derek Cohen (in Perth, Australia)

Presuming properly KD lumber to begin with, a panel will only warp if the moisture gain or loss from one side of the panel is different from the other side. Indeed, if the panel is handled carelessly after assembly and the moisture content of the panel is not equilibrated to the shop humidity, it will warp. The most common mishandling is storing a panel on a bench where there is free air circulation on the top and none on the bottom.

Bill, I take the same precautions as you do. However, my concern goes further than merely the possibility of disequilibrium.

The question I have is whether internal tensions in the wood surface are a factor that we need to be aware of, and if we can deal with them? I have seen some boards begin to warp soon after re-sawing, and I have assumed that this is partially the result of disequilibrium of moisture. But not solely due to moisture. I had had boards warp as I cut them, some as badly as twisting into a pretzel as they come off the bandsaw.

I treat all freshly re-sawn boards by immediately stickering them as well as clamping them with cauls, which I will leave on until they are used. This works for me.

Regards from Perth

Derek