Characteristics 102: Fiber Failures

A Check is a separation of the wood normally occurring across or through the rings of annual growth and usually a result of seasoning.

Surface Check – a check that occurs on the face of a piece of lumber.  [Standard Grading Rules for Northeastern Lumber para. 704.0 (a)

Star Check – found in knots and sometimes referred to as a Star-Checked Knot, these include radial checks within a knot itself.  [Standard Grading Rules for Northeastern Lumber para. 718.00 (v)]

Through Check – a check that extends from one surface of a piece of lumber to the opposite or adjoining surface.  [Standard Grading Rules for Northeastern Lumber para. 704.0 (b)]

Checks can be identified by the kind of Check as well as the size of the check.   [Standard Grading Rules for Northeastern Lumber para. 704.00 (c),(d),(e)]

Sizes are classified as Small, Medium or Large according to this chart.

An Edge Break is a break extending through the edge of a piece to the face of the board.

Splits are defined as a separation of the wood through the piece to the opposite surface or to an adjoining surface due to the tearing apart of the wood cells.  Splits are identified by their sizes.  [Standard Grading Rules for Northeastern Lumber para. 742.0]

Very Short – is equal in length to 1/2 the width of the piece

Short – is equal in length to the width of the piece and in no case exceeds 1/6 the length.

Medium – is equal in length to twice the width of the piece and in no case exceeds 1/6 the length.

Long  – is longer than a medium split.

Shake is a lengthwise separation of the wood which occurs between or through the rings of an annual growth (Standard Grading Rules for Northeastern Lumber 740.0).

Light Shake – not over 1/32″ wide

Medium Shake – not over 1/8″ wide

Surface Shake  – occurs on only one surface of a piece

Through Shake  – extends from one surface of a piece to the opposite or to an adjoining surface (shown)