Had a question regarding the ash slabs I cut. They are sitting in my garage, ends painted, stacked with 2x2s between them. They are 2" thick. How long should I let them air dry before I can pass them on to my brother and friends so they can plane and use them? I'm assuming air drying them will get them dry enough to let them work on, or do I need to look at a solar kiln since I won't be able to get down to the moisture levels dimension lumber is at.
O.K. here's some helpful hints. 1) They need airflow - get them out of your garage or keeps the doors open +/- a gentle fan. If they go outside, they need to be covered on top to keep rain/snow off but open on the sides to let the air flow. Also, keep them out of direct sunlight as much a possible. 2) 2x4's are too wide to use for stickers. Most people use about 7/8 x 1 1/8. At least you could rip the 2x4's down the center and be around 1.5 x 1.75. 3) The general rule of thumb is 1 year / inch thickness to reach equilibrium with air drying. However, this is highly dependent on species, temperature, humidity, wind, etc. The only way to really know is a moisture meter or doing a formal oven test. 4) Fully air-dried lumber in your region will vary between 12.6-14.9% (see page 4 here http://www.conradlumberco.com/pdfs/ch12_Drying_Control_of_Moisture.pdf). This will be fine for outdoor use, but for indoor use, you really need to get down around 8%. For that you need a kiln (slightly faster) or if you have the time, you can bring the air-dried pieces inside where the heat/AC will finish the drying and the wood will equilibrate to your house. If you use this method, you need to periodically check the MC or the weight of the wood and follow it until it stops dropping and levels out. I like to bring in air-dried wood and keep it in my shop with a dehumidifier set to 50%. This works for me. Be careful with this though. If you store lumber below grade without climate/humidity controls it will usually soak up the moisture from the air. The same is also true if you store kiln-dried lumber outside, it will go right back up to 12-15%.
Wow - thanks for the wealth of info! I'm using 2x2 (1.5"x1.5") now, I could rip some other lumber down to about an 1" if you think it's worth it. Bringing the wood indoors unfortunately won't work. But I could look at doing some type of solar kiln if that would be better to get them closer to that 8% Thanks again!
I'm not familiar with ash, but slabs take time, period. Even with a vaccume kiln slabs are tricky. I know with "most" woods letting it slow dry to a lower MC is generally critical. Sticker type can help prevent staining. If you put a slab in a kiln it will check it will split it will warp and bow. You can kiln it once it's down to a low mc to finish it and sterilize it. Generally you want to go slow and easy. I actually just flat stacked about 1500bft of red oak that has been sitting for a year in a relatively cool closed shed with no airflow. Most of it one inch It's at 12 percent. Some are 1.5 -2 inch slabs not sure on the interior mc.
LOL! It's probably drier right now than dimensional lumber you can buy at the store. Ash dries great - you are probably doing something seriously wrong if you can't get it dry. I store all of mine in my garage. If it was dripping wet oak, I might be more inclined to keep it outside. But most of the stuff I have cut is on the softer / quick drying side, and I believe it would dry too fast if left outside, especially in a summer like we've been having here. Also, anything I have left out in the sun begins to change color within a week. One more thing - I believe the way the lumber has been sawn has the greatest effect on whether or not it will dry straight. The straighter the grain is through the piece, the less it will move. That's why I always recommend sawing square to the heart center. Look at a pallet of 2x4's at home depot. Most of them will have a pith and it will not run square with the board. They will all be bowed or twisted, and you can predict which way by examining the heart (and therefore grain) runout.
Good idea there! I once stacked 1250 bd-ft of freshly milled red oak lumber in my steel pole barn. We left town for two weeks the very next day, so I left with the doors closed but a box fan on inside to keep the air circulating. When I got back all exposed metal surfaces were rusted/oxidized from the acids that vaporized from the wood. I'll never make that mistake again.
O.K. Your 2x2's will work perfectly ! I only mentioned that, because if your stickers are too wide, then the wood that is covered up and not exposed to the air dries slower than the rest which can cause problems with stresses, mildew, and/or sticker stain.
There's always many variables to consider. My garage is wooden and uninsulated. If it was airtight and metal, it would probably not be very good lumber storage. Drying wood is not exactly rocket science, but there are entire text books devoted to this specific topic. BTW black walnut makes lousy sticker wood.
One question to add into this. I have a barn with a loft that gets pretty smoking hot upstairs. If I put slabs up there with a fan will it work well or will they dry too fast and crack/twist. Also should I partially dry them somewhere else first?
Well I think you'd be setting up kiln type conditions in there. I've read a little bit about them and watched a few videos, but I haven't tried it myself. I think many of the big industrial type kilns use some amount of 'steam injection' to maintain a steady RH close to the current MC of the wood; which is then ramped down over time as it dries. Of course this probably isn't necessary for a DIY kiln, but I think it should probably be monitored closely. As far as cracking/twisting, I have found the best time to prevent that is when the lumber is sawn. I realize this is a bit outside of the orthodox thought, but hear me out. Twisting and cracking happens due to the internal tension forces in the wood. Clear, knot free lumber, with straight grain and little runout will have little issue with twisting and cracking, no matter how it's dried. If you've got a really crooked piece of lumber with a lot of branch wood, simply sealing the ends isn't going to do much to prevent it. Crooked in, crooked out.
If you're gonna do that, forego the fan and stack/sticker the wood as you'd normally do. I'd then get a couple cheap ratchet straps and maybe clamp the whole bundle down, periodically tightening the straps up as the wood dries. Humidity is a good thing when drying lumber, it keeps the wood from checking. The heat in the loft will help cook out the inner moisture.
