GDI 301: Knots and Wane

Two knots that touch are measured as one knot.

Knots may be classified as a Red Knot or a Black Knot depending on how much of the knot is integrown with the surrounding wood.  Use the following measuring guideline to classify an intergrown knot for grading purposes:

• Red Knot –  25% or more of the knot’s margin is intergrown with the surrounding wood.
• Black Knot – less than 25% of the knot’s margin is intergrown with the surrounding wood.

Knots that are “loose” are treated and measured as holes for grading classification purposes.

The maximum knot sizes listed for the Common grades may be exceeded in pieces of otherwise “exceptional quality”. “Exceptional quality” is interpreted as a board, excluding the oversize knot, that meets all other requirements for the next higher Common grade. For example, a red knot could be approximately 1/2″ larger:  a black knot could be approximately 1/4″ larger.

In Premium Grade, Black Knots of maximum size are limited to one in pieces 6 through 9 feet in length and two in pieces 10′ and longer, OR “Equivalent Smaller”.  Black Knots of Finish size are not limited as to number. Apply the following instructions based on length of the piece:

Boards 6 through 9 feet in length:

• If a maximum Premium size Black Knot is present, no other Black Knot can exceed the maximum size Finish knot.
• If no maximum Premium size Black Knot is present, two Black Knots of a size between a maximum Finish size and a maximum Premium size (Intermediate size knots) is permitted. These two “intermediate size” knots are considered to be the “equivalent” to one maximum size Black Knot.

Boards 10 feet in length and longer:

• If two maximum Premium size Black Knots are present, no other Black Knot can exceed the maximum size Finish knot.
• If one maximum Premium size Black Knot is present, two Black Knots of a size between a maximum Finish size and a maximum Premium size is permitted. These two “intermediate size” knots are considered to be the “equivalent” to one maximum size Black Knot.
• If no maximum Premium size Black Knots are present, three Black Knots of a size between a maximum Finish size and a maximum Premium size is permitted. These three “intermediate size” knots are considered to be the “equivalent” to two maximum size Black Knots.

Watch the video for a visual interpretation on applying this instruction.

Wane may be present on both edges(opposing sides) of a board.  When this occurs, the wane on both edges are measured and added together to determine the total amount of wane present.  This total wane is then used to determine the grade of the board, applying the wane limitation factors for each grade.

Wane may be increased in length on an equivalent basis IF the width and thickness of the wane is less than maximum allowed.