Posts: 7,581
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Joined: Jan 2005
Location: New Zealand
I agree that it doesn't sound like end checks from drying. Those should only travel a small way into the board as the faster drying on the end grain only extends about 6" max into the wood. After that, the wood is drying at the same (slower rate) as the rest of the board. Plus if an end coating was used it should have reduced the chances of that happening.
Possibly a heart check, which is internal growth and drying stresses cracking the wood from the centre, like a star check in an embedded knot.
Or, I wonder if the the log was actually damaged as it was felled? Incorrect technique can result in the felling notch closing up as the tree is 1/2 way down. This tries to "stall" the trees fall, and put tremendous force on the end of the log, enough to split the tree in 1/2 occasionally. Or it three impacted on a heavy branch first, rather than hitting the ground flat. Again stress on the log, from the top end this time created the cracks.
I don't think it's drying problem. The issue was probably present in the log before it was even milled.