Acclimatisation
The process of allowing seasoned timber to adjust to the humidity and temperature of its final environment before construction, preventing post-build movement.
Read the definitionThe glossary
The trade terms you'll come across.
Plain-English definitions for the words that turn up when you're buying, specifying or working with timber.
Aggregate rays
Two or more wood rays that are closely grouped or fused together, appearing as a single larger ray in cross-section. Characteristic of some species.
Read the definitionAir drying
The natural process of seasoning timber by stacking it exposed to ambient air flow. Boards are separated with spacers (stickers) to allow air circulation. Much slower than kiln drying but requires minimal energy investment.
Read the definitionAngiosperm
A flowering plant (hardwood tree group) whose seeds are enclosed within an ovary, which becomes a fruit or nut.
Read the definitionAnisotropic
Having properties that vary with direction. Wood is anisotropic because it behaves differently along the grain versus across the grain.
Read the definitionAnnual growth ring
One year’s worth of wood growth in a tree, typically visible as a single ring on end grain (earlywood + latewood).
Read the definitionApical meristems
Growth regions at the tips of shoots and roots where cells divide rapidly, producing new tissues that extend the plant’s length (primary growth).
Read the definitionAxial parenchyma
Wood cells oriented parallel to the tree axis, arranged in longitudinal bands or diffuse patterns. Important for distinguishing tropical hardwood species.
Read the definitionBanded parenchyma
Axial parenchyma arranged in continuous tangential bands, creating visible banding in cross-section. An important identification character in species identification.
Read the definitionBark pocket
A pocket or inclusion of bark embedded within the wood, typically caused by damage to the tree during growth that allows bark to become enclosed as new wood grows over it.
Read the definitionBench hook
A simple cross-grain jig used on the workbench to hold boards for crosscutting or planing, preventing the workpiece from slipping.
Read the definitionBending strength
The maximum stress wood can withstand in bending before failure, measured as Modulus of Rupture (MOR) in MPa or psi. Critical value for structural members like joists and beams.
Read the definitionBevel
An edge cut at an angle other than 90° to the face of the board. Used for mitred joints, decorative edges, and angled fits.
Read the definitionBird’s eye
A distinctive figure characterised by small, elliptical patterns resembling eyes. Most associated with Appalachian sugar maple (Fagus grandifolia). Created by the intersection of vertical and inclined grain when quartered.
Read the definitionBlistered figure
A figure pattern on quartered timber showing raised, rounded zones resembling blisters, caused by the interaction of grain direction and figure. Common in quilted maple.
Read the definitionBlockboard
An engineered panel with a core of narrow softwood strips edge-glued together and faced on both sides with veneer. Used for shelving and furniture panels.
Read the definitionBlue stain
A bluish-grey discolouration of wood caused by the sapstain fungus Ceratocystis, carried by bark beetles. Affects appearance but not structural integrity. Common in pine.
Read the definitionBoard foot
A unit of volume for measuring hardwood lumber, equal to a board 1 inch thick by 12 inches wide by 12 inches long (144 cubic inches). Formula: (T x W x L)/144.
Read the definitionBound water
Moisture absorbed into the cell wall structure itself, chemically bonded to cellulose and hemicellulose. Removal of bound water causes wood shrinkage and dimensional change.
Read the definitionBow
A curvature along the length of a board's face, where the board deviates from a flat plane. The board curves in an arc from end to end.
Read the definitionBowing
Bowing is a lengthwise curve along a board’s face (the board arcs like a shallow bow). It is a type of warp commonly caused by uneven moisture content through the thickness or along the length, drying stresses, or grain/runout effects.
Read the definitionBoxed heart (boxed pith)
Boxed heart (boxed pith) describes a board or timber section that contains the pith/centre of the log. It is higher risk for splitting, distortion, and stress-related movement during drying and machining.
Read the definitionBrittle heart
A zone of weakened, brittle wood in the central core of some trees, particularly eucalyptus. Caused by extractive accumulation and cell wall alteration as heartwood forms.
Read the definitionBurls
Rounded, abnormal growths on tree trunks or roots with intense, irregular grain patterns. When sliced into veneers, they produce dramatic decorative figures valued in luxury furniture.
Read the definitionBurr
A mass of distorted grain and figure in a tree trunk, often containing many small knots and irregular tissue patterns. Highly prized in decorative veneers and turned objects.
Read the definitionCabinet scraper
A small, flat steel tool with a burnished cutting edge, drawn across wood to remove fine shavings and produce a tear-out-free surface.
Read the definitionCambium
A thin layer of living tissue just beneath the bark that produces new wood (xylem) inward and new bark (phloem) outward.
Read the definitionCant
A cant is a log that has been squared (typically by removing slabs) to create flat faces before further sawing. Many mills break logs down into cants first, then saw boards or structural timber from the cant for efficiency and predictable dimensions.
Read the definitionCase hardening
A drying defect where the outer shell of timber dries and hardens too quickly, trapping moisture inside. The stressed shell can split under machining pressure. Often caused by excessively high initial kiln temperatures.
Read the definitionCellulose
The main structural carbohydrate in wood cell walls. It forms strong microfibrils that provide most of wood’s tensile strength.
Read the definitionCellulose microfibrils
Cellulose microfibrils are tiny, strong bundles of cellulose chains in the wood cell wall. Their orientation (microfibril angle) largely controls stiffness and helps explain why swelling/shrinkage happens mostly across the grain rather than along it.
Read the definitionChamfer
A beveled edge cut at an angle (typically 45°) to remove the sharp corner of a board. Reduces splintering and adds decorative detail.
Read the definitionChatoyance
An optical effect where wood appears to shimmer or change colour when viewed from different angles. Produced by ribbon-stripe figure in interlocked grain, most famously in figured maple.
Read the definitionChecking
Surface cracks in timber that extend partially through the wood, caused by the surface drying and shrinking faster than the interior during seasoning.
Read the definitionChecks
Cracks that form as wood dries, often starting at the ends (end checks) or on the surface (surface checks) due to drying stress.
Read the definitionClear fell
A harvesting method where all trees in an area are cut down in a single operation. Most economical method but has significant ecological impacts.
Read the definitionClear heart
A grading term for premium-grade hardwood lumber free of knots, with the entire heartwood section usable. The highest quality grade.
Read the definitionClosed grain
A wood texture where pores/vessels are small and not prominent, so the surface feels smoother and needs little or no grain filling.
Read the definitionCollapse
A severe drying defect where the cell structure of wood shrinks unevenly, causing distortion and crushing of cell walls. Particularly problematic in high-density species.
Read the definitionCompression failure
A structural failure caused by compressive overload along the grain, creating buckling or crushing of wood fibres. Visible as a wrinkled or creased appearance.
Read the definitionCompression strength
The maximum compressive load wood can withstand parallel to the grain before crushing. Essential for columns, studs, and load-bearing structures.
Read the definitionCompression wood
Compression wood is reaction wood formed in softwoods on the underside of a leaning stem or branch. It develops under compressive growth stress, often has abnormal structure and higher longitudinal shrinkage, and can cause boards to bow, twist, and move unpredictably during drying and machining.
Read the definitionCoppice
A method of woodland management where trees are cut to near ground level, and multiple new stems regrow from the stump (stool). Used for sustainable production of poles and small timber.
Read the definitionCoppicing
The traditional sustainable practice of repeatedly cutting trees (such as hazel, chestnut, or willow) at ground level to harvest new shoots, yielding a renewable supply of small-diameter timber.
Read the definitionCrook
A curvature along the edge of a board rather than its face. The board deviates from straight when viewed from above, caused by proximity to the pith or tangential shrinkage in flatsawn boards.
Read the definitionCross-laminated timber (CLT)
Cross-laminated timber (CLT) is an engineered panel made from thick layers of timber boards laminated in alternating grain directions. Cross-lamination reduces directional movement and enables large, stable structural panels.
Read the definitionCrosscutting
Cutting wood across the grain (perpendicular to the fibres), typically producing a clean end face and severing fibres rather than splitting between them.
Read the definitionCup shake
A separation along an annual growth ring, creating a partial detachment of the growth ring from the rest of the wood structure.
Read the definitionCupping
A warp where a board curves across its width, forming a shallow ‘U’ shape, typically driven by uneven shrinkage across growth-ring orientation.
Read the definitionCurly grain
A figure pattern where the grain appears wavy or rippled on quartered surfaces, caused by changes in grain direction. Highly prized in musical instrument making.
Read the definitionDado
A rectangular groove cut across the grain of a board, wider on the bottom than at the top. Used for shelf joints and partition fitting.
Read the definitionDebarking
Debarking is the removal of bark from a log before sawing. Mills do this to reduce grit/contamination that dulls blades, improve cut quality, and reduce bark content in downstream products.
Read the definitionDecay
The breakdown of wood fibres caused by fungal action, typically when moisture content exceeds 20%. Results in loss of strength, discolouration, and eventual structural failure.
Read the definitionDecay resistance
The natural ability of certain wood species to resist fungal degradation, largely determined by extractive content, particularly in heartwood. Teak and white oak are naturally decay resistant.
Read the definitionDensity
Mass per unit volume. For timber it is usually reported in kg/m³ at a stated moisture content (often ~12% MC).
Read the definitionDiffuse-porous
A hardwood with pores of relatively uniform size throughout the growth ring (no strong earlywood pore band).
Read the definitionDilated rays
Horizontally oriented wood rays that have been widened or expanded. Often seen in quarter-sawn timber as distinctive figure elements.
Read the definitionDimensional stability
Dimensional stability is how little (or how much) a piece of wood changes size as moisture content changes. It depends on species shrinkage values, T/R ratio, cut angle, board width, moisture range in service, finish, and construction method.
Read the definitionDovetail
A interlocking woodworking joint consisting of trapezoidal pins and tails, creating a strong mechanical bond without adhesives. Cornerstone of fine cabinetmaking.
Read the definitionDrying rate
The speed at which timber loses moisture during seasoning. Varies by species, thickness, and initial moisture content. Ring-porous hardwoods typically dry faster than diffuse-porous species.
Read the definitionDrying stress
Drying stress is internal stress created when wood dries unevenly, producing moisture gradients between shell and core. It can lead to checking, honeycombing, and case hardening if not managed during drying and conditioning.
Read the definitionDurability
In timber, durability is the natural resistance of wood (especially the heartwood) to biological deterioration such as fungal decay and insect attack when exposed to moisture. It is distinct from strength: a wood can be strong but not durable, and vice versa.
Read the definitionEarlywood
Wood formed at the start of the growing season, typically lighter and less dense (with larger cells).
Read the definitionEdge-glued panels
Solid wood panels created by joining narrow strips of boards edge-to-edge with adhesive. Also called butcher block or glued-laminated panels.
Read the definitionEnd checking
End checking is cracking that starts at a board’s ends because moisture leaves end grain much faster than face grain. It’s reduced by end-sealing logs/boards soon after sawing and by controlling early drying conditions.
Read the definitionEnd grain
The surface produced when wood is cut across the fibres, exposing the ends of cells.
Read the definitionEnd splitting
Cracks that originate from the ends of timber boards and run parallel to the grain, caused by rapid moisture loss from the exposed end grain.
Read the definitionEnd-sealing
End-sealing is applying wax, paint, or a commercial sealer to the ends of logs or boards to slow end-grain moisture loss and reduce end checking during drying.
Read the definitionEngineered wood
Engineered wood is wood-based material made by bonding layers, veneers, strands, fibres, or particles (e.g., plywood, MDF, CLT). Engineered construction reduces or redistributes anisotropic movement, making panels far more dimensionally stable than solid wood.
Read the definitionEquilibrium
The stable moisture content that wood achieves when it matches the surrounding air conditions. Reaching equilibrium is the goal of proper seasoning.
Read the definitionEquilibrium moisture content
The moisture content at which wood neither gains nor loses moisture from the surrounding air. This balance depends on the relative humidity and temperature of the environment. EMC varies by region and season.
Read the definitionExtractives
Non-structural chemicals deposited in wood (especially heartwood), such as oils, resins, tannins, and phenolics.
Read the definitionFAS
First and Seconds — the highest grade in the NHLA hardwood lumber grading system. Minimum clear-face yield of 83-1/3% (FAS) or 83-1/3% plus small defects (1F).
Read the definitionFAS/1F
A combined NHLA grade for hardwood lumber meeting either FAS or FAS 1F standards. FAS requires 83-1/3% clear face; 1F allows small defects on the best face.
Read the definitionFibre saturation point
The moisture content (approximately 25-30%) at which all free water has been removed but cell walls remain fully saturated. Below this point, wood begins to shrink.
Read the definitionFibre saturation point (FSP)
Fibre saturation point (FSP) is the moisture content at which the cell walls are fully saturated with bound water but the cell cavities (lumens) contain no free water. Below FSP, changes in bound water cause shrinkage and swelling; above FSP, dimensional change is minimal.
Read the definitionFibres
Long, thick-walled cells (especially prominent in hardwoods) that provide much of wood’s mechanical strength.
Read the definitionFiddleback
A pronounced ribbon-stripe figure caused by interlocked grain, typically seen in quartered timber. Named for its use on violin backs. Common in sycamore, maple, and eucalyptus.
Read the definitionFigure
The pattern of light and dark areas on the surface of wood, created by growth rings, rays, knots, grain deviations, and colour variations. Determines the decorative value of timber.
Read the definitionFilm-forming finish
A film-forming finish is a coating that creates a continuous surface layer (e.g., varnish, lacquer, paint). It slows moisture exchange between wood and air, reducing the rate of movement (but not stopping it).
Read the definitionFlat-sawn
Flat-sawn (also called plain-sawn) describes boards cut so the growth rings are roughly parallel to the wide face. Flat-sawn boards often show cathedral grain and usually have greater tangential movement across their width, making them more prone to cupping than quarter-sawn boards.
Read the definitionFlat-sawn (plain-sawn)
Boards sawn so the growth rings are roughly parallel to the wide face (typically 0–30° ring angle).
Read the definitionForest management
The planning and implementation of practices to maintain and enhance the health, productivity, and value of forest lands for various purposes.
Read the definitionFree water
Moisture held in the cell cavities (lumens) of wood, not chemically bound to cell walls. Free water is removed first during drying and does not cause shrinkage.
Read the definitionFrost crack
A longitudinal crack in a tree trunk caused by rapid temperature drop, creating tension in the outer wood layers. Common in hardwoods in cold climates.
Read the definitionFSC certification
Forest Stewardship Council certification — an independent third-party label verifying that forest products come from sustainably managed forests meeting environmental and social standards.
Read the definitionFungal attack
Any invasion of wood by fungi, ranging from surface discolouration (stain fungi) to structural degradation (decay fungi). Fungi require moisture, oxygen, and temperatures between 20-35°C to grow.
Read the definitionG-layer (gelatinous layer)
The G-layer (gelatinous layer) is a special cellulose-rich layer found in tension wood fibres in many hardwoods. It changes the way the cell wall behaves and is associated with elevated longitudinal shrinkage and distortion in boards containing tension wood.
Read the definitionGlueability
The ability of wood to form strong adhesive bonds. Affected by moisture content, extractive content, surface porosity, and machining quality.
Read the definitionGrade scale
The systematic classification of lumber quality based on the percentage of clear-face cuttings obtainable from each board. Governed by NHLA rules for hardwoods.
Read the definitionGrain
The orientation and visible pattern of wood cells and fibres in a piece of timber. It describes both direction (how fibres run) and appearance (the grain pattern you see).
Read the definitionGrowth rings
Concentric bands in a tree trunk visible on end grain, typically representing seasonal growth cycles (often annual).
Read the definitionGrowth stress
Growth stress is internal stress that develops in a living tree as wood forms and the stem supports itself. When logs are sawn, growth stresses can be released, causing boards to spring, bow, or move even if moisture content is uniform.
Read the definitionGrowth stresses
Growth stresses are internal stresses that develop in a living tree as it grows and supports itself. When a log is sawn, these stresses can be released unevenly, contributing to warp, spring, and distortion even before drying stresses are involved.
Read the definitionGum duct
A tubular channel within wood that produces and transports gum or resin. Present in some hardwoods like those of the Proteaceae and Myrtaceae families.
Read the definitionGum pocket
A localised accumulation of gum or resin within the wood, often appearing as dark, soft patches. Common in cherry, walnut, and some eucalyptus species.
Read the definitionGum vein
A narrow channel through wood filled with accumulated gum or resin, often appearing as a dark line. Common in cherry, eucalyptus, and some tropical hardwoods.
Read the definitionGymnosperm
A seed-producing plant group (conifers) whose seeds are not enclosed in fruit, often borne in cones.
Read the definitionHand scraping
A final finishing technique using a cabinet scraper hand tool to remove tearout and achieve a glass-smooth surface before applying finish.
Read the definitionHardboard
A dense engineered panel made from exploded wood fibres, created by steaming and pressing under extreme pressure. Smooth on one side, textured on the other.
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