1. A hard, woody outgrowth on a tree, more or less rounded in form, usually resulting from the entwined growth of a cluster of buds. Such burls are the source of the highly figured burl veneers used for purely ornamental purposes. 2. In lumber or veneer, a localised severe distortion of the grain generally rounded in outline.
A comprehensive guide to the most common timber terms from A to Z.
Burl
Butt joint
An end joint formed by abutting the squared ends of two pieces of timber.
Camber
Intentional vertical curve built into a beam or truss to offset load deflection or to improve its appearance.
Cambium
A thin layer of tissue between the bark and wood that repeatedly subdivides to form new wood and bark cells.
Cantilever
A projecting structural member which is rigidly fixed at one end but unsupported at the other
Carbon Sink
A carbon sink is something that removes or stores carbon dioxide from the atmosphere, for example growing vegetation.
Case Hardening
A drying defect characterised by the presence of compression stresses in the outer zone and tensile stresses in the core. It occurs when rapid drying has caused permanent set of the outer zones of a piece of wood.
Casein Glue
An adhesive, primarily for internal use, prepared from casein, sodium silicate, lime, soda and other compounds. It was used largely in plywood manufacturer, has some resistance to water but is not waterproof, ages well and can be made resistant to mould.
Cathedral Cut
A variation of the crown cut method of slicing veneers. The growth rings are exactly parallel to the slicer, producing on the face of the veneer an inverted 'V' figure resembling the spire of a cathedral.
CCA
Copper chrome arsenate, a wood preservative. More on timber preservation
Cell
In wood anatomy, a general term for the minute units of wood structure that have distinct walls and cavities, including wood fibres, vessel segments, and other elements of diverse structure and function. In dense hardwoods, the fibre cells are thick walled and make up the major part of whole zones of wood. These fibrous zones dry slowly.
Cellulose
The carbohydrate that is the principal constituent of wood and forms the framework of wood cells.
Certification
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Forest certification refers to the assessment of forest management by an independent third party auditor according to performance criteria for sustainable wood production. The Responsible Wood Forest Certification Scheme (formerly the Australian Forestry Standard, AFS), Programme for Endorsement of Forest Certification (PEFC) and Forest Stewardship Council (FSC) are the three certifications in Australia. Programme for Endorsement of Forest Certification
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Chain of Custody
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The process by which the source of a timber product is verified. This entails 'tracking' the timber from the forest through all the steps of the production process until it reaches the end user. The process is usually necessary before a timber product can be labeled as being produced from a sustainable source. |
Check
A separation of fibres along the grain forming a fissure, but not extending through the piece from face to face. Checks commonly resulting from stresses built up during seasoning. They run radially, across the growth rings.
Chisel
A wedge-like, sharp-edged tool used for cutting or shaping timber.
Chord
Either of the two outside members of a truss (a) connected and braced by the web (b) members. The term also applies to beam flanges or the perimeter members of a plywood diaphragm.
Cladding
The external covering or skin of walls of a building. Timber cladding includes natural or treated timber boards, and plywood.
Clear Span
The clear horizontal distance between the supports of a load bearing member.
Cleavage Test
A test that measures the resistance of a timber to splitting longitudinally along the radial and tangential planes
