Glossary of Terms


Air Dried Timber which has been seasoned by exposure to the atmosphere,in the open or under cover,without artificial heat.
Bark pocket A patch of bark partially or wholly enclosed in the wood. 
Tight Bark pocket A bark pocket in which the bark is firmly embedded in the surrounding wood.
Black heart An abnormal black or dark brown discolouration that may occur in the heartwood of certain timbers, not necessarily associated with decay.
Brittle heart See compression failure.
Check A separation of the fibres along the grain forming a fissure, but not extending through the piece.
Knot check A check occurring in a knot. 
Surface check A check confined to the surface of a piece.
Collapse A flattening or buckling of wood cells during drying which is seen as excessive and/or uneven shrinkage.
Compression failure A deformation or fracture of the fibres across the grain resulting from excessive compression parallel to the grain either by direct end compression or bending. It appears as a minute fracture running across the grain, the fibres being wrinkled by compression or broken transversely.
  It is often difficult to detect until the timber has been machined. “Brittle Heart” is wood characterized by brittleness caused by compression failure in the fibres during growth.Brittle heart is mostly located in the heartwood.
Decay Decomposition of wood by fungi
Defect Any irregularity in timber that affects its appearance,  strength, durability  or “use”. 
Dote The early stages of decay in which disintegration has not proceeded far enough to destroy the structure of, or soften, the wood perceptibly.
Grade An established quality or use classification of timber.
Appearance Grades Grades of timber for finishing and other uses determined basically from the appearance of the better face and edge.
Box Grades The lowest grade of timber.
Cutting Grades Grades capable of yielding  clear cuttings.
Structural Grades Grades of timber  determined basically  on the stiffness and strength of the piece.
Grain The general direction of the fibres or wood elements.
Heartwood The inner layers of the log which, in the growing tree, have ceased to contain living cells. Heartwood is generally darker in colour than sapwood.
Hole A hole extending partially or entirely through the piece and attributable to any cause.
Kaikaka A form of decay in the standing totara tree which does not affect the durability of the converted wood in service.
Kiln Dried Timber which has been dried under conditions of controlled temeratures and humidities in a dry kiln.
Knot A section of a branch which is embedded in the wood of the tree trunk or of a larger branch.
Decayed Knot A knot affected by or containing decay.
Intergrown knot A knot that is wholly intergrown with fibres of the surrounding wood. 
Knot combination (Appearance grades). Two or more knots (other than spike knots) occurring on one line drawn at right angles to the edge of the piece.
Knot group (Structural grades only). All knots inter- sected by one plane perpendicular to the length of the piece.
Loose knot A knot that is loose or likely to become loose in drying or machining; generally includes any knot exceed- ing 15 mm diameter that is fully enclosed in bark. 
Occluded knot A discontinuous knot normally formed as a result of pruning and subsequent clearwood  growth around the end of the branch stud.  
Partially intergrown knot A knot that has not more than half its perimeter separated from the surrounding wood by bark.
Pin knot In native timbers, a sound intergrown knot not exceeding 15 mm in diameter.
Sound knot A knot that is free from decay or insect attack.
Spike knot A branch cut longitudinally by the plane of the face and extending to the edge of the piece but also including  knots that would have been spike knots had they not been occluded.  
Double spike knot A pair of spike knots extending to opposite edges of the piece along the one line drawn at right angles to the edge of the piece.
Tight encased knot A sound knot in which more than half its perimeter is surrounded by bark, but which is so fixed by growth or size that it will firmly retain its place in the piece. In general, knots exceeding 15 mm diameter require some degree of intergrowth  to remain tight. 
Pinhole A hole not exceeding 2 mm diameter, usually darkly stained and not containing borer dust.  The insects which make these holes do not attack or continue to work in timber once the surface has dried.
Pith The central core of a stem consisting chiefly of parenchyma or soft tissue.  
Raised grain A roughened condition of the surface of dressed timber in which some elements are raised above but not torn loose from the general surface.
Resin Pocket A cavity that contains or has contained resin. 
Resin Streak Fibre that is saturated with resin. 
Rough Sawn Unsurfaced timber cut to full specified size.
Sapwood The living outer layers of the wood of a tree. Sapwood is generally lighter in colour than heartwood.
Shake A partial or complete longitudinal separation between wood fibres due to causes other than drying and usually originating in the standing tree.
Close shake A shake that is compactly filled with resin or gum, or in which the wood fibres are interlaced in contact.
Surface shake A shake that is visible only on one face of the piece.
Through shake A shake extending through a piece of timber from one surface to another.
Sloping grain An arrangement of fibres and other longitudinal elements at an angle to the longitudinal axis of the piece. 
Softwood Most softwoods have needle-like leaves.  The term softwood is a botanical term not necessarily related to the physical hardness of the wood.
Split A lengthwise separation of wood fibres extending through a piece of timber from one surface to another.
Stain In wood, discolouration  or variation from the natural colour due to chemical reaction, fungi, or other causes, but not associated with decay.
Wane The presence of the original underbark surface with or without bark, on any face or edge of a piece of timber. 
Warp Any variation from a flat surface. It may consist of bow, crook, cup, twist, or any combination  of these. 
bow A curvature from the plane of the face in the direction of the length.
crook A curvature from the plane of the edge in the direction  of length.  
cup A concave curvature across the grain, that is, across the width of the face. 
twist A spiral distortion along the length of a piece of timber. 
Woolly grain Sawn elements frayed out in sawing or planing.