Got Wood? Domestic Wood Turning Blanks Glossary of Wood Terminology, Part 3

Wood Terminology, Part 3 - Defects
Check Checks are typically very slight separations in the wood, protruding only slightly into the surface of a piece. Crack Cracks are typically much deeper separations in a piece of wood, protruding deeply into the interior portions of the piece. Split The term split is usually used for the deepest of separations in a piece of wood, potentially going so far as to completely separate a piece into two sections.
Loose Knot/Open Knot A knot which has broken away either partially or entirely from the surrounding wood. Tight Knot/Intergrown Knot/Closed Knot A knot which contains no gaps or voids and does not reduce the strength of the surrounding wood. Spike Knot Produced when a knot has been cut across its length, displaying its grain pattern across the face of a board. Pin Knot Very small knot, typically less than 1/4" in diameter.
Blue Stain (Fungal) A blue discoloration in wood caused by a fungal infection in the wood. It does not weaken the cellular structure of the wood. Seen more commonly in softwood species. Blue Stain (Iron) When iron comes in contact with certain acidic woods, such as red oak and sycamore, the wood will become stained a dark blue color over time.
Brown Rot Rotting of the wood caused by brown rot fungi which feed on the lignin in wood, weakening the cell structure and producing eventual breakup. Brown rot in wood occurs much more quickly than white rot, shown below.
White Rot Rotting of the wood caused by white rot fungi which feed on the lignin in wood, weakening the cell structure and producing eventual breakup. The breakdown of the lignin produces a bleached out color to form, as shown at right.
Honeycomb Drying defect caused by the breakdown of the inner portions of a piece of wood, producing a honeycomb-like effect in the appearance of the wood. Typically produced by improper kiln drying of thick stock.
Ring Shake Separation of the rings of a tree due to varying types of stress the tree incurred while growing. Fire damage and fungal infections are frequently the culprits in these situations, having affected the trees ability to tightly bind the wood fibers between the affected wood and newly grown wood. Wind Shake Separation of the rings of a tree due to stresses produced by wind. Similar to ring shake, only caused by a different means.
Wane/Bark Inclusion/Bark Incursion/Natural Edge/Live Edge Any area of a piece of lumber that includes the naturally occurring edge of the tree it was cut from.