drying 12/4 white oak

[Josko Catipovic]

I seem to be doing fine with 8/4 (and thinner) white oak, bit some of my 12/4 slabs are developing surface checks. I sticker freshly-sawn lumber in an outside shed for a year, and then move it into/near the shop which is ~70% RH in summer and typically 30+% in winter. There's ample air circulation and no direct sunlight in the outside shed. Most of the wood is ~12-14% when I move it. Clearly it's not working for 12/4, although 8/4 comes out nicely stress-free. Any suggestions welcome.

[David Mealey]

Hi Josko,

My first suggestion is to read Scott T Smith's sticky on this site re: drying wood. My limited experience over the last 3-4 years has taught me to be patient with the process, especially with larger, 12/4 slabs. I'm assuming you have end sealed the slabs before or shortly after milling. I don't know what part of the country your in but 1 year of air drying in the Pacific NW is to short. Typically slabs that size need 2 summers to get down to an appropriate mc and are ready for kiln drying. There are a lot of variables to consider but the ones I can control and suggest researching are proper stickering and good airflow. I'm also assuming that your doing plain (flat) sawing at that size. If I'm milling slabs for that thickness I try to get as much if not all heartwood in the piece. Even with good technique sometimes the wood just goes where it wants to.

[John TenEyck]

Most defects happen during the first stages of drying. If it's getting down to 12 - 14% MC in one year that's way too fast for 12/4 white oak, as David said. I think you need to take steps to slow down the drying until you get down to the FSP.

John

[Josko Catipovic]

Thanks guys, seems I need to slow down drying outdoors. I'm on Cape Cod, which is very humid (although cool) summertime, and was more worried about molds than drying too fast, I was letting the shed get pretty high, temp-wise, with passive solar gain, and ran a fan for ventilation. Maybe it's time to open up the shed and see what happens. Hopefully I can get some more 12/4 oak this season; not quite sure how to go about it, given all the closures and such.

[John TenEyck]

Well you're not really drying outside in the traditional sense since your wood is in a shed. So, yes, open the doors and turn off the fans. As long as air is free to circulate through the stack it shouldn't get moldy, but keep your eye on it. If your stacks are more than around 5' wide or free airflow is blocked, however, then you'll have to run the fans at least some of the time. Let the RH fluctuate as it wants, just like it would if truly outside, until the MC gets down to 28%; then you can go faster. And patience. 12/4 white oak takes years to air dry w/o serious defects.

John

[Scott T Smith]

Well you're not really drying outside in the traditional sense since your wood is in a shed. So, yes, open the doors and turn off the fans. As long as air is free to circulate through the stack it shouldn't get moldy, but keep your eye on it. If your stacks are more than around 5' wide or free airflow is blocked, however, then you'll have to run the fans at least some of the time. Let the RH fluctuate as it wants, just like it would if truly outside, until the MC gets down to 28%; then you can go faster. And patience. 12/4 white oak takes years to air dry w/o serious defects.

John

What John said.

Targeted daily MC% reduction for 12/4 WO is around .4 of a percent. You really need to take it slow. I would be highly surprised that 12/4 would air dry in a year w/o significant defects. What are you using to measure the MC%?

[Tom Bender]

A couple of my experiences;

Had a few pieces of Oak milled so I could bend them wet. The stack sat in the summer sun for a couple of hours. The top plank was ruined, full of surface racks. The rest was fine.

Had an Oak log milled into 8/4 and stickerd it in my garage for a year. Ends sealed but no forced airflow. Garage is dry and airy. No defects. Just lucky I guess.

I like John's advice and would add two points to even out the conditions within the stack;

- start your stack at least 6" off the floor

- cover the top of the stack with something flat