| Term |
Definition |
| Cambium | Thin, slimy layer of tissue between the bark and sapwood that subdivides to form new wood cells (on the inside) and new bark cells (on the outside). |
| Cant | Sawn timber in a large cross-section size, suitable for re-sawing into smaller sizes. Sometimes also called ‘flitch’ or ‘baulk’. |
| Case hardened | Drying fault that occurs in timber when the outer fibres (case) shrink too quickly for the inner fibres (core) to compensate, resulting in compressive stresses in the case and tensile stresses in the core. |
| Charge | Bundle or parcel of timber that has been prepared for loading into a kiln (for drying) or into a pressure cylinder (for preservative treatment). |
| Check | Separation of fibres along the grain – generally caused by drying stresses –not extending from one surface to another. (Note that when it extends from one surface to another it is called a ‘split.) |
| Collapse | Drying fault caused by the flattening of cells as they buckle under the changing internal pressure during the drying process. Sometimes called ‘washboarding’. |
| Compression | Force that tends to crush the wood fibres – such as in a post supporting a load. |
| Compression failure | Fracture across the grain resulting from excessive compression – generally either in the growing tree or during felling (if that part of the stem lands heavily on an obstacle). Fibres may appear crinkled or broken across the grain, especially after the timber has been milled. |
| Compression wood | Type of ‘reaction wood’ (abnormal growth that forms to withstand forces such as a leaning trunk or continual strong winds) that occurs in softwood trees. Fibres tend to be harder, denser and more brittle than normal growth. |
| Corewood | Wood that includes the pith or is near the pith, with a density less than 80% of a mature tree. For plantation softwoods, ‘corewood’ is material within a 50 mm radius of the pith. |
| Creep | Gradual sagging, or increase in the deflection of a beam, as it withstands the force of a long-term load. |
| Cross shake | Broken or separated fibres across the grain, generally resulting from stresses in the growing tree or a heavy blow during felling operations. |
| Cross fracture | Broken or separated fibres across the grain – often used interchangeably with ‘cross shake’ or ‘compression failure’. |
| Cross section | End section of a piece of timber, cut at right angles to its length. Expressed in terms of width x thickness, such as 100 x 50. |
| Cross laminated timber (CLT) | Engineered structural product made from layered strips of timber, where each layer has the grain running at 90 degrees to the layer above and below. Not to be confused with ‘glue laminated timber’. |
| Chatter marks | Series of ridges across a dressed surface caused by the faulty operation of the cutting head in a planing machine. Also called ‘cutter marks’ or beat marks’. |
| Cup | Deviation across the surface of a piece that causes it to curve away from a flat plane. |
| Decay | Breakdown of wood fibres caused by wood-eating fungi. |
| Degrade | Timber that no longer makes the grade it was originally given, due to damage or deterioration over time. |
| Density | Mass (weight) of a timber species expressed in kilograms per cubic metre. See also ‘green density’ and ‘air dry density’. |
| Dressed all round (DAR) | Planed to a smooth finish on all four surfaces in a square or rectangular cross section. |
| Durability | Natural resistance of timber to fungi and insects. Can also be used to describe the timber’s resistance after it has been treated with a preservative chemical. |