I copied this from another forum
From personal experience: The wood will not dry in log form. I have cut into small (12”) diameter logs that have been setting for 5 years and the center is still wet. I have salvaged walnut heart from trees downed 15 years ago in a hurricane, and it was still wet.
Seal the ends so that moisture escaping from the capillary grains slows down to the rate that it is escaping from the sides, or it will split. Some people use latex paint, which I have not had much luck with, or a wax-based end-grain sealer like anchorseal which I use. This is best applied as soon as possible after the tree is felled.
Depending on the species of wood, it will need about 6 months to a year per inch thickness of air drying (protected from sun and rain and with spacers between slabs) before it is ready to move into the shop. After initial milling to smooth the sides, etc, it may need a couple weeks or more to dry and quit moving (warping).
The trick initially is to let the moist fresh cut wood dry slowly enough so that the moisture readily escaping from the exposed surfaces does not evaporate faster than the moisture can move from the inside wood to the outer surface. If it dries too quickly, the outside layers of wood are dryer and want to shrink without the moisture in the cells. However, it is prevented from shrinking in size because the inner wood it is attached to is still loaded with water. So, the outside wood splits to relieve the stress.
In log form, the outer wood is initially protected by bark. As the bark drys, it cracks off, letting the outside layers dry too quickly, and it starts splitting in from the sides. The cut ends dry quickly because they are used to letting the moisture (sap) run through them, so also will split. This is if you have them off the ground. If not, the bugs have already invaded under the bark and will keep it moist so they can devour it. Seemingly contra-intuitive , though, the best way to preserve logs is to submerge them in fresh water and mud, where they can last for years undamaged.
Now, saying you do it all perfectly, then you may still have the results of what the tree went though while it was alive and growing. If on a hill side or subjected to a lot of wind, it built up a lot of strength in some spots to counteract the environment. This will result in some layers of wood being a lot denser than others.. After perfect drying, the internal stress of the different densities can still cause the wood to split where the higher/lower density wood meets. This is usually called wind shakes. Nature of the beast and nothing you can do to prevent it and impossible to determine ahead of time unless you were there to drop the tree and were able to deduce the hazard. (That is why some sawyers like to go deep into the woods on flat ground to get the prize tree).
And then there is case hardening and other defects caused in a kiln drying process where the temperature is not regulated enough to allow the internal stresses to be relieved before further drying. To complicate things, different species dry at different rates and have different vulnerabilities.
Personally, I follow Johnnyfurniture’s method, but sticker at about 16” (put a row of spacers, all the same thickness of 1” between boards all directly over the ones in the layer below. The spacers are called “stickers”). Putting a strap around the stack for longer boards helps reduce twisting and warping of the top boards, or weight (a lot of weight) can be put on top. I strap close grained woods like cherry, sweet gum and maple, all prone to twisting and warping.
If the bark is tight on your logs, wait for cool weather (which is now fast approaching or may be already here in your area) to slab them out. The moisture loss rate from the initial cut (anywhere from 35 to 50% moisture content) until you get it down to 20% is when most the damage happens, and cooler weather slows the rate of moisture loss. After you get it down below 15%, then the rate can be faster (stick them in your attic, for instance, or consider kiln drying). Cutting them and immediately bringing them into a heated/low humidity shop in the winter is probably not your best choice.
Although 7% is considered the optimum for furniture making, I have used 12% wood, letting it set a couple days after the initial rough dimensioning for my project, so that it can finish moving and dry a bit more, with good results. My shop is not climate controlled, and my endeavors are mostly used by family that does not have central air-type climate controlled homes, so 7% is a moot point in my high humidity environment.
My stated moisture content percentages are based on a cheap and less than reliable moisture meter, tho, so take them with that caveat.
Good Luck. I am an amateur at this and the above is based on about 5 years limited experience and trying to find out what I did wrong. 5 years is not long considering it takes a couple years to find out you messed up. My initial woods were green cut from sawyers, I now am milling some of my own with a chain saw mill, so still have a lot to learn. Most of the info I received from sawyers who do this professionally.
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