Suggestions on Acclimatizing Lumber

[John Crawford]

Hi folks:

I'm wondering if any of you could offer some tips on getting lumber acclimatized. I feel like I loose way too much to end checking, as well as to splits developing in the middle of the wood.

I work in my basement. In the summer, humidity is around 55 percent; in the winter it dips down to 40 or so (the heater is down there).

Let's say I get some 4/4 kiln dried lumber from the local sawmill, which keeps it in an unheated warehouse. I bring it into my basement, paint the end grain with latex paint, and sticker it. After 4-5 days I often get some serious checking, and boards often split from the center as well. I hate sitting there and watching it self-destruct....

Seems to me like I am losing moisture too fast. Would you have any suggestions on how to control things better?

Thanks for the help!

[ernest dubois]

That can be a big adjustment for the wood, coming into a heated room like that. Still, the description you give is pretty general so it's hard to say, though I also know the sounds of pings and pops wood makes along the way. Keep the wood in your shop in the furthest corner from any heating source for one. Did you ever try to ease the transition by, say keeping the wood in the garage or some place not directly heated like on the porch or in the mud-room for some weeks prior to bringing into the heated space? All the same, some (tropical)woods are just very sensitive. And finally, try reducing your use of kiln dried wood. I have found that the more of the process I can control the better result in the end I get which even includes making sure that the initial lengths are enough to account for some expected loss from checking even when the proper precautions have been taken.

[Kevin Jenness]

Here in VT we often have to bring kd lumber that has been stored in open sheds and rebounded to 11-13% MC into our heated shop. In a commercial shop, we are usually trying to get the lumber into use as soon as possible, so we are trying to speed up moisture loss. To that end, we rack the lumber on stickers up high, or put it in a small DH kiln. We have issues with excess movement and distortion if we try to rush the process and use the wood too soon, but rarely have I seen the kind of degrade you are talking about in domestic woods. It makes me wonder about the kiln drying process employed by the mill you patronize. Do you monitor the MC of lumber when you purchase it, and have you checked the MC of material fresh out of their kilns? Are you having problems with particularly hard to dry species like oak, or with all woods? I also wonder whether your shop is drier than you think? Where are you located? In the NE, RH in an uncontrolled heated space can get down below 20% quite easily on a cold midwinter day.

In any case, it seems you need to slow down the moisture loss in your lumber. If you have a a space available for storage with intermediate conditions between the mill and your shop, say a slightly heated garage, keep your lumber there a while. Use a more effective end sealer like Anchorseal to retard end grain moisture transfer. Consider using a humidifier in your shop in the winter (and a dehumidifier in the summer). When you bring damp lumber into the shop, keep it in the coolest area for a while. If you don't have a moisture meter, get one and use it.

[Jim Matthews]

I have a similar set up, in a basement that gets very damp in Summer.
I buy air dried lumber, and have none of the problems you describe.

A few questions, please:

What species check?
How much waste is generated?
Are all equally effected?

How quickly is the lumber dried in the commercial kiln?

Do you have access to "seasoned" lumber,
that has been stickered for longer periods?

[Steve Baumgartner]

I'm also inclined to be suspicious of the drying at the sawmill. If they were too aggressive or didn't really dry the wood completely, that could contribute to the problem.

[John Crawford]

Thanks for the suggestions everyone. Sounds like it may be time for (a) a moisture meter, and (b) a new samill....

In answer to some questions: this happens with soft woods (pine), but I just had similar experiences with 8/4 oak (prompting my rage!). Most get some end checking, perhaps 1/5 develop problems in the middle of the boards. I keep a hygrometer on top of my pile, but the moisture level in the room is artifical, in the sense that in the summer I'm running a dehumidifier, and in the winter I'm running a humidifier.

I like the idea of trying some intermediate spaces before bringing it downstairs. I have an unheated garage, and an office that is used by me (and not used by my sweetheart), so some lumber could hang around in there for some time....

[Howard Acheson]

>>>> paint the end grain with latex paint

Couple of points about that. End checking only occurs if the ends of board are not sealed within 2-3 days from the tree being bucked into rough lumber. If your lumber has been kiln dried, you will not get the situation that causes end checking. Next, latex paint is a very poor end sealing method. You seal the ends so that the ends do not rapidly lose their moisture. Latex paint is formulated to allow air to pass through it to prevent bubbling It does not provide the moisture block that is necessary to prevent end checking. The professionals all use a wax based end sealing product like Anchorseal.

But, all this said, end sealing is only necessary and effective for newly felled lumber. If lumber has been properly kiln dried, you should not have end checking or splitting. My lumber is stored about the same as yours and I never have the problems you have related.

[John TenEyck]

The best advise I can give has already been given, but it bears repeating. Get a moisture meter. You have to know what it is you are buying in order to know 1) if it's worth buying and 2) if any precautions are needed when you get it into your shop. My basement shop has just about the same Summer/Winter RH range as yours. I don't have any issues with checking after I bring wood into it, even wood from uncontrolled warehouses in the middle of Winter. Pine has to be one of the most forgiving woods, so if you're having trouble with it something is really out of whack.

John

[Kevin Jenness]

Since you are tempering and monitoring your workspace, the problem must be with the lumber. The defects you are seeing are typically caused early in the drying cycle. Oak is especially susceptible to end and surface checking if subjected to an overaggressive kiln schedule. I suspect you are seeing problems reemerge after redrying in your shop of poorly dried wood. The fact that your lumber supplier doesn't seal the ends prior to kiln drying is not a sign of quality, and there may be more issues as well.

[ernest dubois]

There is always the old reliable tip to go by when buying wood. Buy it thick and long.

I've never had a moisture meter since starting full-time woodworking in 1996, wouldn't know how to reliably use one even.

[Kevin Jenness]

If you use air dried lumber that is acclimatized to your shop, and your shop conditions are well aligned with the conditions in service of your products, you don't need a moisture meter. Otherwise, it's a very useful if not essential part of the kit.

[John Crawford]

Thanks again everyone.

Today was my one bit of free time to go get a few boards for a new project, so the comments all came in handy. I searched around and found a different mill. This one is more of a family affair that has been around for 50 years, so it was fun to go out there. I expect I'll get better results with all your help.

[Scott T Smith]

Since you are tempering and monitoring your workspace, the problem must be with the lumber. The defects you are seeing are typically caused early in the drying cycle. Oak is especially susceptible to end and surface checking if subjected to an overaggressive kiln schedule. I suspect you are seeing problems reemerge after redrying in your shop of poorly dried wood. The fact that your lumber supplier doesn't seal the ends prior to kiln drying is not a sign of quality, and there may be more issues as well.

^^^ This.

The problems that you are describing sound like improper drying. Just about all drying related defects (end and surface checks, etc) develop when the wood is dried from green down to 35% MC. However, often times these defects do not become visible until the lumber has dried below 25% (even though they developed at a higher MC%).

You should not need to end seal dry lumber (even if it is 15% MC). End sealer is primarily effective when the lumber is at higher MC%'s.

[ernest dubois]

Yes, this is often overlooked, when the damage begins and to what extent. The damage begins early on. Slabbing on a sunny windy day working outside, end checking can begin immediately and the end grain cannot be coated early enough, better had that work not been done then. And then, those checks extend beyond the point where they seem to end by some 10s of mm.