Unusual Checking in Hard Maple

      A case where every board sawn from a Maple log has checks through the middle. What's going on? February 17, 2012

Have you noticed hard maple to get an unusual level of heavy checks? Seems to happen when I've bought logs that were standing dead, and the checks go right through the plank, not just surface. I just unloaded my kiln and one whole log had checks in every board, down the middle of each plank. Every piece, jacket lumber, perfectly clear, as well as heartwood. Any piece in the whole log. The checks go clear through the piece like it's broken right down the middle, though it's not straight or continuous - they aren't connected like one big split. It's something similar that happens when we try to dry turn blanks of hard maple. Seems like the dead tree is more brittle? This damage occurs while air drying, before it ever goes in the kiln. Curious if this type of lumber might have been saved if we covered the air dry stacks with landscape fabric like our QSWO, though I'd be worried about sticker stain… I've seen this happen in other hard maple logs, and the only thing I can think of that is similar is that they were dead standing trees. I've never had it happen like this in any other species. Might have been really windy and dry when I stacked? Can't remember that.

Forum Responses
(Sawing and Drying Forum)
From Professor Gene Wengert, forum technical advisor:
This behavior is unusual and indicates that the wood was either weaker than normal (not likely) or that the checks developed in the tree and then were worsened in normal air drying. Not enough info to really tell what caused this unusual behavior.

From contributor A:
When you saw old dead standing logs, your MC in the log is all over the place. The log will have checked because the outside dried pretty fast when the bark came loose but the core remained wet. Just like cookies check to the core, so do the logs. I have sawed some with no real checking and others just fall apart.

One thing I have found is to saw and put into the kiln as soon as possible. Then keep it moist and raise the temp. The next trick is to keep it from drying too fast. Yes, mold and spalt is a risk, but chances are a dead standing tree has it anyway if it is going to have it. I like the spalt and it sells well anyway.

Most often the checking does not run from top to bottom of the log, so it is hard to saw around the stress cracks.

Form the original questioner:
Yes, this seems to be what happened. It only occurs in standing dead trees, and only hard maple, but happened to us a number of times. It does seem like the damage happens quite early on, maybe even in the log, but it's quite amazing that it's in every single piece of lumber, no matter its orientation in the log. Like stress cracks down the middle of each piece, not typical honeycomb, or checking like in oak. I have a whole load of standing dead sugar maple in the yard I need to saw, but now I'm worried about its survival. My kiln is quite leaky and hard to keep the RH up in when I run it. I'll work on sealing it up and see if I can keep this next stuff from breaking. I don't think many kilns saw standing dead hard maple so it's probably not a common thing to have trouble with. I've heard from other small mills like me who've had similar trouble, but we've never pinpointed when it happens or how to correct. I'll try your idea and see what happens.

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