SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/wood-check-definition

What is a "check" in a board?

A lengthwise crack across the growth rings from drying stress.

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  1. A lengthwise separation across the growth rings ✔
  2. A knot with a dark ring
  3. A stain from a mineral streak

Why: Checks form when wood dries and the outside shrinks faster than the inside. They run along the grain, usually across the rings. End checks are common on freshly cut ends.

Huh, didn't know that: Reaction wood with excessive lengthwise shrinkage can develop cross breaks in zones of high shrinkage.

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References

Answer: A lengthwise separation across the growth rings. Checks form when wood dries and the outside shrinks faster than the inside. They run along the grain, usually across the rings. End checks are common on freshly cut ends.

  1. Wood Handbook: Wood as an Engineering Material, FPL-GTR-282 (USDA Forest Products Laboratory, 2021) research.fs.usda.gov/treesearch/62200
    A lengthwise separation of the wood that usually extends across the rings of annual growth
    Checked 2026-10-10.

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Trades & ShopAt about what moisture content does a drying board begin to shrink?Trades & ShopWhich direction does wood shrink the most as it dries?Trades & ShopAs wood loses moisture, how much does a board shrink along its length?

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