# Cracks in sapwood



## JR Parks (Nov 13, 2016)

The photos are of portions of kd pecan slabs 2 7/8" thick 32-44 wide and 12'-20' tall. Some have developed cracks in the sapwood stopping at the heart wood and only on side of the slab. The first shows 3 cracks but none on the left side of the board; the 2nd shows a little closer view and the 3rd a closeup stopping right/ just passed heartwood as do all of the cracks in all of the slabs. So - these slabs are from different trees; not all have these cracks; cracks are always only on one side; all cracks stop at the sap/heart border. The boards are fine it is just curiosity that is killing the cat. Any ideas out there? @Mr. Peet


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## woodtickgreg (Nov 13, 2016)

Did it crack only on one side? If it did I would say the board shrunk more on the opposite side as it dried and that caused it to crack the softer sapwood as tension increased. Or the sapwood shrunk more than the heart wood causing the same efect.


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## JR Parks (Nov 13, 2016)

woodtickgreg said:


> Did it crack only on one side? If it did I would say the board shrunk more on the opposite side as it dried and that caused it to crack the softer sapwood as tension increased. Or the sapwood shrunk more than the heart wood causing the same efect.


Yes Greg only on one side-meaning the crack were on the left side of some boards but not on the right side or whatever the circumstance but only on one side. This is occurring on some boards same log but not on all. My experience on a sap/heart boundary is that most seem to be parallel with the boundary as heart dries diff than sap. But as you can see these are perpendicular to the heart/sap boundary.


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## justallan (Nov 14, 2016)

Although I know pretty near nothing about kiln drying, by chance is one edge drying faster than the other from possibly a fan hitting that side and causing it to shrink faster than the rest?
Just a crazy idea.


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## Mr. Peet (Nov 14, 2016)

Jim,

I think Greg has the answer. It looks like these slabs are from a salvage cut, standing dead or dead and down. The lignins in the sapwood have already started the decomposition process. This process most often happens in the sapwood before the heartwood since much of the waste materials of the tree are deposited in the heartwood, and these materials help fight off insect infestation and fungi attack. I would say your kiln schedule needed to be adjusted (lengthened) to reduce moisture at a slower rate to allow flex and flow.

Speaking of flow, did the perpendicular cracks all face one side of the kiln? If so, the circulatory system needs attention or the wood was to close to the intake (blower / fan versus vacuum?). The last thing to remember, sapwood as a slightly different density than heartwood. When decomposition has set into the sapwood and the heartwood is still sound, this differential is increased, and often easily expressed with results that you have shown, except the cracks are on both sides (edges) of the planks.

@JR Parks @woodtickgreg

Reactions: Like 1 | Thank You! 2 | Agree 1


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## vegas urban lumber (Nov 26, 2016)

every piece of pecan that my brother cut in texas is so crazy in the drying process, that sap wood cracking which we also had was the least of our worries. every time the weather changed that wood warped, twisted, split, bent, cracked, checked and swole/shrank like a sponge.


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