Grade Application 203: Discoloration and Defects

Pitch is an accumulation of resinous material.  The chart below shows the limitations of Pitch in each grade. Watch the video below for a visual example of the various accumulations of pitch that are found in the NELMA Eastern White Pine grades.

Pith is the small soft core in the structural center of a log.  See below for the limitations of Pith in each grade.  View the image to the right as a refresher on identifying pith in a board (Click on the image to enlarge, then click on the “x” to return to the course page)

A seam is an area of ingrown bark.  A seam is often ingrown at a knot and is sometimes independent of a knot. Seams are often surrounded by an accumulation of heavy pitch; the heavy pitch must be included within the measurement of the seam.  Click on the image to the right as a refresher on identifying Seams in a board (Remember: Click on the image to enlarge, then click the “x” to return to the course page). The chart below shows the limitations of seams for each grade.  For a complete tutorial on identifying and measuring seams watch the video below.

Stain is a discoloration of the wood.  Blue and  Brown (Coffee) stains are treated the same, based on the limitations of the grade. The following chart quantifies these limitations for each grade.  View the image to the right as a refresher on identifying Stain in a board (Click on the image to enlarge, then click anywhere outside the image to return to the course page). Watch the video below for a visual representation of Blue Stain.

Important Note: In practice, Blue or Brown Stain is not typically accepted by the consumer.