|A bluish gray discoloration on the woods surface. This feature is
most common in woods like Holly, Pine, and Sycamore.
||Mold that grows in warm and moist area, usually poorly ventilated.
||Discoloration of wood.
||Can be cut off, placed out of sight, or concealed with a dark stain.
||A curve along the face of a board that usually runs from end to end.
||Improper storage. Usually moisture evaporation from one side and not the other.
||Stock is difficult to work with and cut.
||Cut in to smaller pieced, even out on a jointer, or nail (screws are better) in place
with bow bulging out.
|Checks or Splits
|Breaks at the end of a board that run along the grain. Checks and
splits are usually restricted to the end of a board.
||Can effect the strength and appearance of the board.
||Should be cut off or worked around.
||Warping along the edge from one end to the
other. This is most common in wood that was cut from the center of the tree near the pith.
||Can be caused by improper drying and storage or the presence of reaction wood.
||Can be difficult to work with.
||The higher spots can be cut away on a table saw or jointer using a special jig.
|Warping along the face of a board from edge to edge.
This defect is most common of plain-sawn
||This defect can be caused when one board face dries at a faster rate
than the other.
||Stock can be difficult to work with. Trying to "force it
flat" can cause cracking along the grain.
||You can try allowing the board to dry at the same moisture content
under pressure, rip it into smaller pieces on a table saw, or use a jointer to remove the
|Dead or Loose Knot
|A dark, usually loose knot.
||This is caused by a dead branch that was not fully integrated into the tree before it
was cut down.
||Can mar the appearance of the wood, fall out, become loose, or weaken stock.
||Should be cut out, around, or glued in place and filled with a wood putty.
|Gum, Sap, or
|Accumulations of a resinous liquid on the surface or in pockets
below the surface of wood.
||Injury to the tree.
||May cause difficulty when finishing.
||Should either be cut off or scraped out and filled.
||Dark streaks along the face of a board.
||Usually caused by planer blades that are dull or spun on a part of the board for too
||Discoloration to the surface. Sometimes the burn can penetrate into the board.
||Can be sanded off or cut down with a jointer. The depth of the board often determines
the amount of work needed.
||Breaks in the wood along the annual growth rings.
||Improper drying or damage during transport.
||Can effect strength or appearance.
||Should be cut around, place out of sight, or glued down.
|A know which is tightly integrated into the surrounding wood.
||This was once a branch that was incorporated into the tree as its girth increased.
||Does not effect the lumber's strength.
||May be removed for appearance purposes. Some lumber such as Knotty
Pine, is highly prized for this feature.
||Warping in lumber where the ends twist in opposite directions. (Like
twisting a towel)
||Growing conditions, uneven drying or the presence of reaction wood.
||Can be difficult to work with.
||Can be cut into shorter boards or the high spots can be removed on a
|Small holes in the wood.
||This is caused by insects boring through the wood.
||Can be used to simulate old or wormy wood.
||Cut around worm holes or uses as is for decorative purposes. Be sure
the insects are dead.