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Pat Barry
07-13-2015, 1:22 PM
I've got a good sized stack of maple planks, ~ 2inch thick, 18+ inches wide, 8ft long stacked and stickered in my garage. I live in Minnesota, and my garage is unheated - not quite freezing in the dead of winter and kinda humid in the summer. Its been there, undisturbed, since last fall when I had a local guy with a portable bandsaw mill cut it up for me in my driveway. Before that, it had been felled from my backyard about two months previous. I did not seal the ends of the planks and I am getting some splitting at the ends. I don't know how far back that goes into the length of the planks - I hope not too far. Anyway, my question is how long does it need to sit there stacked up before it is dry enough to use? I assume the answer is to get a moisture meter, pull apart the stack, and sample test the planks toward the middle or bottom and then wait for the moisture content to be acceptable but that is a lot of work (very heavy planks). I'm wondering if there is any rule of thumb, for instance, just leave it 2 years minimum, or is there another way to determine the moisture content for the interior planks?

Tom Hogard
07-13-2015, 1:54 PM
Pat,

Soft maple will dry a bit more quickly than hard maple. There are charts available that give estimates for drying time for various hardwoods, based upon "drying days". In the upper Midwest there are normally about 240 drying days in a calendar year. 8/4 maple would probably be somewhat over a year (for yours, perhaps next spring to reach 'air dry'), there aren't many drying days over the winter months.

Moisture meters are available over a wide range of prices but when air drying I don't know that absolute accuracy is as important as relative moisture content; whether it is 10% or 12% is less of a concern as whether it is 24% or 12%. For that level of need, an inexpensive meter ($30-50) should be fine, keeping in mind that meters are not reliable at moisture contents above 30%. With 8/4 planks you'll want a meter with the longest pins you can find. I understand the anticipated work involved, the good news is that each time you restack, it should be lighter :)

An alternative that might lend some guidance would be to choose a board that is not on the outside of the stack (not on the top or at the edge), maybe go down a layer or two and get one from the center. Weigh that board as accurately as you can, and write down the date and the weight. Put it back in the stack. In a month or so, weigh that same board again and record the weight. As it dries the weight decreases. As it gets closer to equilibrium with your environment the rate of change will taper off, or stop. At that point you are probably as dry as it is going to get. That is the point I would take it into my 'environmentally controlled' shop or storage area to continue drying. For more accuracy there are procedures you can take to take a sample, oven dry, and then calculate the exact moisture content. For a home shop project, that would be a lot of work - probably unnecessary.

Cody Colston
07-13-2015, 4:38 PM
Drying rate depends upon three factors...heat, air flow and relative humidity. Drying in an unheated garage, the only factor that you can influence much is air flow. I'd recommend putting a couple of box fans in there blowing through the stickered stack. I can't tell you how long it will take to dry to EMC but fans will accelerate the process.

The General brand moisture meters from the box stores are accurate enough to tell you when the lumber is dry. Since they are short-pin meters, however, you will need to cut a short section out of one of the boards (at least one ft from the end) and then rip it in two and check against the fresh long grain.

End checks generally do not extend past the first sticker.

Danny Hamsley
07-13-2015, 9:11 PM
Yes, fans will really help with maple. It dries fast and dries well. One of the faster woods to dry. Fans will keep the air moving and reduce the risk of gray stain, an ugly gray blotching that is caused by a chemical oxidation reaction in the sugars in the wood when it is subject to high temp and high humidity. Fans will remove the evaporating moisture from between the boards and help to keep the wood nice and white.

I expect that 8/4 with fans to move out the moisture will take around a year or a little less to get to 15% moisture. It will take a kiln to get it much below that unless you bring it inside in a climate controlled (humidity) environment.

Pat Barry
07-15-2015, 1:46 PM
Thanks guys. I will get a fan or two set up. I hope its not too late (gray staining).

Prashun Patel
07-15-2015, 2:24 PM
The rule of thumb is sometimes 1 inch = 1 year.

I would still seal the ends. The damage may have been done, but you can prevent some of the unchecked boards from degradation.

Did you sticker with stainless material? Using bad stickering material can lead to staining or worse localized spalting.

If you have a decent amount of it, I would take a sample board or two and start milling it up. Over the next couple weeks, you'll get an idea of its stability.

Last, I've found a $20 moisture meter to be a good investment. Mine's not the most accurate, but by testing a bunch of stuff, I can get a rough idea where I stand relatively.

Danny Hamsley
07-15-2015, 9:36 PM
Your stickers must be dry, especially with maple, which is prone to sticker stain .