Wood Defect Diagnostic
Describe what you see or choose a symptom. The diagnostic searches 35 technical references covering growth, sawing, drying and storage defects.
35 possible matches
Bird's Eye Figure
Bird's eye is a distinctive figure pattern in wood consisting of small, circular indentations that resemble bird's eyes scattered across the surface. It is most commonly found in hard maple but can occur in other species. The exact cause is debated but is believed to involve localized fiber distortions during growth.
Cause, examples & related terms →Blue Stain
Blue stain is a blue-gray to black discoloration in wood caused by fungi that colonize the sapwood, feeding on stored sugars and starches. It does not significantly affect the wood's structural strength but changes its appearance. Blue stain is most common in pine and other softwood species.
Cause, examples & related terms →Bow (Lumber Defect)
A warp along the length of a board's face, causing it to curve from end to end like a shallow arc.
Cause, examples & related terms →Bow (Lumber Defect)
Bow is a warp in lumber where the board curves along its face from end to end, like a shallow arch. It is measured by placing the board flat and checking the gap between the board's midpoint and a straight edge. Bow is caused by uneven drying, internal stress, or grain irregularities.
Cause, examples & related terms →Cathedral Grain
Cathedral grain is the arched, pointed pattern of growth rings visible on the face of flat-sawn lumber, resembling the pointed arches of a gothic cathedral. It occurs because flat-sawing cuts tangent to the growth rings, revealing their curved shape as peaked, nested arches. It is the most common grain pattern in construction lumber.
Cause, examples & related terms →Check (Lumber Defect)
A crack or split along the grain of wood, usually caused by uneven drying or stress, that does not extend through the full thickness of the board.
Cause, examples & related terms →Check (Wood Defect)
A check is a crack or split in wood that occurs along the grain, typically caused by stresses during drying. Checks usually appear on the end grain or surface of lumber and do not extend through the full thickness of the board. They are distinguished from shakes, which occur between growth rings.
Cause, examples & related terms →Crook (Lumber Defect)
Crook is a warp defect where the board curves along its edge from end to end, sometimes called crown. Unlike bow which curves along the face, crook curves along the narrow dimension. It is measured by the deviation from a straight line along the edge.
Cause, examples & related terms →Cup (Lumber Defect)
A warp across the width of a board that causes the face to curve inward, forming a concave shape from edge to edge.
Cause, examples & related terms →Cup (Lumber Defect)
Cup is a warp across the width of a board, causing the face to curve from edge to edge like a shallow trough. It is most common in flat-sawn lumber where the growth rings are tangent to the wide face. Cup is measured as the height of the arc from a straight edge laid across the board's width.
Cause, examples & related terms →Curly Grain (Tiger Stripe)
Curly grain, also called tiger stripe or fiddleback figure, is a wavy distortion of wood fibers that creates alternating light and dark stripes across the face of a board. The stripes seem to move and shimmer as the viewing angle changes. It is most valued in maple, cherry, and birch.
Cause, examples & related terms →Delamination
The separation of bonded layers in engineered wood products such as plywood, laminated beams, or veneered panels when the adhesive bond fails.
Cause, examples & related terms →Dry Rot
A type of wood decay caused by fungi that breaks down the cellulose and lignin in wood, leaving it brittle, crumbly, and structurally compromised.
Cause, examples & related terms →Flat Sawn (Plain Sawn)
Flat sawn, also called plain sawn, is the most common method of sawing lumber where the log is cut with parallel passes straight through, producing boards with growth rings at less than 30 degrees to the face. This method maximizes yield and produces the familiar cathedral grain pattern. It is the most economical sawing method.
Cause, examples & related terms →Heartwood vs Sapwood
Heartwood is the dense, dark inner core of a tree trunk that no longer transports water or nutrients, while sapwood is the lighter-colored outer layer that actively conducts sap. Heartwood gets its color from extractive chemicals that also provide natural decay resistance. Sapwood is lighter in color and generally more susceptible to rot and insect attack.
Cause, examples & related terms →Hit-or-Miss
Hit-or-miss is a surfacing specification where lumber is run through a planer set to skim the surface without guaranteeing full coverage. Some areas will be smooth (hit) while others retain the rough-sawn texture (miss). It is used to bring lumber close to dimension or to reveal the wood's character without committing to a full surfacing pass.
Cause, examples & related terms →Knot
A circular or oval imperfection in lumber caused by the base of a branch that was embedded in the trunk as the tree grew.
Cause, examples & related terms →Medullary Rays
Medullary rays are ribbons of cells that radiate horizontally from the pith to the bark, transporting and storing nutrients across the tree trunk. When exposed by quarter-sawing, they create the distinctive fleck or ray fleck pattern prized in species like white oak, sycamore, and beech. Their visibility depends on species and sawing angle.
Cause, examples & related terms →Pitch Pocket
A pitch pocket is a well-defined lens-shaped opening between growth rings in softwood lumber that contains liquid or dried resin (pitch). They are most common in species like Douglas fir, pine, and spruce. Pitch pockets are graded as defects and can cause finishing problems if the resin bleeds through coatings.
Cause, examples & related terms →Pith
Pith is the soft, spongy core at the very center of a tree trunk, representing the original sapling's growth. In sawn lumber, boards containing pith are prone to splitting, checking, and warping because the wood immediately surrounding the pith has unstable juvenile characteristics. Pith is generally considered a defect.
Cause, examples & related terms →Quilted Figure
Quilted figure is a dramatic three-dimensional pattern in wood that creates an appearance of billowing, pillow-like shapes across the surface. It is most commonly found in bigleaf maple and sapele. Quilted figure is extremely rare and commands some of the highest prices of any figured wood.
Cause, examples & related terms →Rift Sawn vs Quarter Sawn
Rift sawn and quarter sawn are two lumber cutting methods that orient the growth rings differently relative to the board face. Quarter-sawn boards have rings at 60-90 degrees to the face, producing ray fleck and excellent stability. Rift-sawn boards have rings at 30-60 degrees, producing straight, consistent grain without ray fleck. Both waste more wood than flat-sawing.
Cause, examples & related terms →Rough Sawn Lumber
Rough sawn lumber has been cut from the log but not planed or surfaced, retaining the texture marks left by the sawmill blade. It is sold at full sawn dimensions (thicker and wider than surfaced lumber) and offers the most flexibility for custom milling. Rough sawn is the standard form for wholesale hardwood lumber.
Cause, examples & related terms →S2S (Surfaced Two Sides)
S2S stands for Surfaced Two Sides, meaning the lumber has been planed smooth on both faces but the edges remain rough or unfinished. This is a common surfacing specification for hardwood lumber, allowing buyers to see the wood's character while retaining the flexibility to rip to custom widths.
Cause, examples & related terms →S4S (Surfaced Four Sides)
S4S stands for Surfaced Four Sides, meaning the lumber has been planed smooth on both faces and both edges to a specific finished dimension. S4S lumber is ready to use without additional milling. It is the standard finish for dimensional lumber at retail lumberyards and home centers.
Cause, examples & related terms →Shake (Wood Defect)
A shake is a separation between growth rings in wood, creating a gap or crack that follows the ring boundary. Unlike checks, which radiate outward from the pith, shakes run parallel to the growth rings. Shakes can occur in the standing tree from wind stress or frost, or they can develop during drying.
Cause, examples & related terms →Skip Dressed
Skip dressed lumber has been run through a planer but not aggressively enough to produce a uniformly smooth surface — some areas show planer marks while other areas retain rough-sawn texture. This is common in lower-grade or economy surfacing where the goal is to bring the board close to dimension without achieving a finished surface.
Cause, examples & related terms →Spalting
Spalting is the discoloration and patterning in wood caused by fungal colonization, producing dramatic zone lines, bleaching, and color changes. It occurs in the early stages of decay and is prized by woodworkers for its striking visual effects. The wood must be dried or stabilized before the fungi compromise its structural integrity.
Cause, examples & related terms →Sticker Stain
A discoloration appearing on lumber at points where drying stickers contact the wood surface during seasoning, typically showing as dark or grayish bands across the board.
Cause, examples & related terms →Surfaced Lumber (Dressed Lumber)
Surfaced lumber, also called dressed lumber, has been planed to a smooth finish and specific dimension after sawing. The surfacing removes saw marks and reduces the board to its final dressed size. Surfacing can be done on two sides (S2S), one side and one edge (S1S1E), or all four sides (S4S).
Cause, examples & related terms →Twist (Lumber Defect)
Twist is a warp defect where the four corners of a board do not lie in the same plane, creating a propeller-like distortion. It is measured by holding three corners flat and measuring how far the fourth corner rises. Twist is often caused by spiral grain in the tree or improper drying.
Cause, examples & related terms →Twist (lumber defect)
A lumber defect where the board warps so the four corners no longer lie in the same plane, creating a propeller-like distortion caused by irregular grain and uneven drying.
Cause, examples & related terms →Wane
Wane is the presence of bark or missing wood along the edge or corner of a piece of lumber. It occurs because the board was cut from near the outer edge of the log, where the round shape prevents a full rectangular cross-section. Wane is considered a defect in most grading systems and reduces the usable width or thickness of the board.
Cause, examples & related terms →Wane
The presence of bark or absence of wood along the edge or corner of a sawn board from the log's natural round shape, considered a defect in graded lumber but embraced in live-edge work.
Cause, examples & related terms →Warp
Any deviation from a flat, true plane in a piece of lumber, including bow, crook, cup, and twist, caused by uneven drying, internal stresses, or irregular grain.
Cause, examples & related terms →