Boards are checking, still usable?

Set up my first drying operation. I've got a smattering of boards I just had sawed up: some black walnut, white oak, hackberry, hard maple. I sealed the end grain with paint, and they've been drying for about two weeks. I spaced them with stickers, painted the end grain to prevent checking, but even so, some of the 8/4 and 12/4 boards are checking. Is there a way to slow down the checking, and when the wood is dry will I be able to use the boards that have checked for anything? I expected my first homemade drying operation to have a couple hitches but I'd really like to put all of the wood, checked or not, to good use. Thoughts?

You have to let them freak out and release the stress. You'll have better more stable lumber in the end.

When you get ready to use the wood, trim the ends off, give a solid rap on the bench, if they still split, keep cutting. Once you get a solid piece of wood, I usually cut off another at least another inch or so. Because once the wood is milled, the check can continue as the wood dries out more.

What is your drying set up?

I've got the wood stacked with stickers in my mudroom. It's about 10 degrees warmer and a bit more humid than the outside temperature. The wood is not under direct sunlight, is shielded from rain, and the airflow comes from two windows in the mudroom. I have two fans that I use from time to time to move air around in the room. I'm not allowed to dry the wood in my building's shared backyard area, so I felt that the mudroom is the best option. Thanks for the response, by the way!

Walnut and maple are pretty forgiving, but white oak isn't, and none of them are at 12/4. 8/4 white oak has a maximum drying rate of 1%/day; 12/4 must be well less than 0.5%/day but I'm not sure. Where are you located? More specifically, what's the RH in your mudroom? You need very high RH at the beginning of the drying cycle for wood that thick. Those fans may be a problem. Also, unless the ends of the boards were painted within the first 3 days after the logs were cut to length it does no good. Wax emulsion or aluminum roof coating is best, but paint will work if heavily applied soon after the logs are cut to length.

John

Robert, are you experiencing end checking or face checking? There are different causes for each.

John, I'm in Northern Illinois. As for the RH, I'm going to buy a hygrometer, as I only found out about their existence recently when reading a book by Bruce Hoadley. I painted on a solution of wood glue and water before milling, then, after I began to notice a bit of checking, I slapped on some paint just in case.

Scott, Some of the boards have minor face checking, but the problem here is mostly end checking.

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Originally Posted by Benjamin Levin

John, I'm in Northern Illinois. As for the RH, I'm going to buy a hygrometer, as I only found out about their existence recently when reading a book by Bruce Hoadley. I painted on a solution of wood glue and water before milling, then, after I began to notice a bit of checking, I slapped on some paint just in case.

Scott, Some of the boards have minor face checking, but the problem here is mostly end checking.

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It's not painting the ends of the logs before milling that matters, it's how long after the tree was bucked into logs. After 3 days painting the ends does little good; the checking has already begun and the only way to stop it is to cut the end of the log off until you see no more checks. At this point you would have to cut your boards back beyond the end checks and then seal the ends. I rarely do that however, if the checks are very deep because you lose too much valuable wood. I let it go and work around the checks after drying, hoping to get the most useable wood out of the board as possible.

John

Ah, I see. Thank you for the insights. Fortunately, I sealed the ends of the logs no more than 24 hours after they'd been procured.

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Originally Posted by Benjamin Levin

Ah, I see. Thank you for the insights. Fortunately, I sealed the ends of the logs no more than 24 hours after they'd been procured.

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If that's true and you are getting end checking then the stuff you used to seal them isn't doing a good job or you are leaving the logs in the sun. Some checking may still occur no matter what you do.

John

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Originally Posted by Benjamin Levin

Ah, I see. Thank you for the insights. Fortunately, I sealed the ends of the logs no more than 24 hours after they'd been procured.

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Procurement is one thing - the real issue is when were they felled and bucked to length. That's when the three day clock starts.

The simple solution is to end trim to the point where the trimmings come off in one piece, and the re-apply end sealer. This does not prevent all end checks though.

A classic problem is black walnut yard trees. They tend to grow quickly, and thus have a wide sapwood band around the heart wood. Although the sapwood shrinks at the same percentage as the heart wood, it shrinks more quickly, and thus if your boards have a lot of sapwood on the perimeter they may split heavily.

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Originally Posted by Scott T Smith

Procurement is one thing - the real issue is when were they felled and bucked to length. That's when the three day clock starts.

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Benjamin,

I like to apply AnchorSeal to the ends of the logs "as soon as possible" after they are felled, within 10 minutes for some species. Then saw as soon as possible. I've tried several methods of sealing and I think AnchorSeal is the best - it's dries to form a coat of wax that slows down the drying. As mentioned, you can cut away existing end checks down to the unchecked wood then seal. To make sure you've cut past the invisible checks, take a thin slice and bend it to see if it breaks easily. Once the checks start it's hard to keep them from getting deeper since moisture can more easily leave the ends from deeper inside causing more shrinkage.

The thicker and wider the wood the more likely it is to end check.

Something to keep in mind for the future is the season. Hot summer can cause more loss from checking. If trees are cut and logs sawn in the late fall the boards can and get rid of a lot of the water while the temperatures are cool. Starting the air drying when it's not hot can also reduce fungal growth in wet wood for less chance of sticker stain and general discoloration in some light-colored woods. Holly, for example, may actually stay white if cut in the winter.

I see John T mentioned keeping the stack out of the sun. I sometimes use overhanging old metal roofing at my sawmill to make sure the ends are shaded. Too much wind can be a problem too depending on the humidity. Expert Gene Wengert warns that some relatively cool spring days with low RH and high wind can cause a lot of checking. (Search the woodweb for lots of discussion about drying wood.)

I assume you realize how much time it takes to air dry thick planks of some species. The old "rule of thumb" says to allow one year per inch plus a year. This is pretty rough - some takes longer and some much quicker. A good moisture meter is helpful.

What to do with thick planks that with deep checks on the end? If there is enough solid wood between deep end grain cracks I cut spindle turning blanks for the lathe. In fact, much of the thicker planks I saw are processed into woodturning blanks. I sticker and air dry outside for a while then saw the wood into pieces and/or bowl blanks, reseal the end grain, and finish air drying indoors in a heated/cooled space. (I check dryness with a pinless moisture meter and by periodically weighing representative blanks.) Some of my turning stock has been drying for for 15 years now.

JKJ

I bought some Engleman spruce from a sawmill in southern British Columbia; The tree was felled about 4 days previous, the pieces were about 24 inches long, and split into quarters. He split it for me before I picked them up that day, about the 3rd week of October last fall. I drove back to Edmonton the following day and immediately de-barked the logs when I arrived; the wood was sopping wet under the bark. I troweled PL premium glue on the end grain to seal it up, and after running out of glue, I painted the ends with some old oil paint I had.

These logs wintered inside an unheated building. They didn't check much at all until I put a few pieces outside in the sun in June. After a few minutes I heard loud pops from the wood, so I immediately brought them back into the building, where they continue to dry.

I think it's best to dry the wood nice and slow; keep them in a cool place with minimum air movement allowing them to slowly dry.