| Term | Description |
| Cardboard | A thin, stiff paperboard made of pressed paper pulp or sheets of paper pasted together. Used for playing cards, greeting cards, etc. Corrugated containers are not made of cardboard. |
| Carriage | The sawmill device on which a debarked logged is placed which moves the log back and forth through the saw blade creating slabs, cants and lumber. The log is also turned on the carriage before making the next cut. |
| 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. |
| Case Hardening | A defect in the lumber caused by improper drying. Case Hardening is caused when a board is dried too fast. The outer layers in a case hardened board are compressed while the inner layers are in tension. |
| 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 |
| Cell | The smallest, microscopic, structure in wood. |
| Cellulose | The carbohydrate that is the principal chemical constituent of wood and which forms the framework of the wood cells. |
| Chamfer | A beveled cut along the edge of a piece of furniture. (Usually 45 degrees) |
| Check | A lumber defect caused by uneven shrinking of the wood during drying. A checked board has splits which develop lengthwise across the growth rings. |
| 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. |
| Checking | A lumber defect referring to the separation of wood fiber across the annual growth rings. Splitting of the wood in logs or lumber, often the result of drying. |
| Chemically protected lumber | Lumber treated with anti stain chemicals to protect it in transit. |
| Chipboard | A paperboard, thicker than cardboard, used for backing sheets on padded writing paper, partitions within boxes, shoeboxes, etc. |
| Chisel | A wedge-like, sharp-edged tool used for cutting or shaping timber. |
| Choker | Short length of flexible wire, rope, or chain used to attach logs to a winch line or directly to a tractor. 1) Noose of wire rope for hauling a log. 2) Short length of wire rope that forms a noose around the end of a log to be skidded and is attached to the skidding vehicle or to the butt rigging in a wire rope logging system. |
| 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. |
| Chromated Copper Arsenate (CCA) | The most commonly used chemical for pressure treating lumber. |
| Circular sawmill | The traditional sawmill uses a circular saw (large version of hand held power saw). Circular saws are thicker (larger kerf) than band saws and produce more sawdust. Logs can be cut moving on the carriage in only one direction, then the carriage returns and turns the the log for the next cut. |
| Classification of Lumber Sizes | Strip Under 3/4 inch thick and up to 3 inches wide Batten 3/4 inch and under 1.5 inches thick and from 1 to 3 inches wide Boards 3/8 inch to 1.5 inches thick and 3 inches and over wide Planks and Scantlings Over 1.5 inches and up to 4 inches thick and over 6 inches wide Heavy Scantling or Flitch or Baulk Over 4 inches thick and/or over 6 inches wide Deal Generally, European softwoods, between 2 and 4 inches thick and >9 inches wide. |
| Clean and bright | The freshly manufactured appearance of lumber as it comes from the planer. |
| Clear | 1. Lumber or logs that are free or practically free of defects. First quality lumber or log. 2. A select grade of lumber. |
| Clear | A board which is free of defects. |
| Clear span | The clear horizontal distance between the supports of a load bearing member |
| Clearcut | To harvest all trees from an area of forest land in a single cut. |
| Close- grained wood | Wood with narrow, inconspicuous growth rings. The term is sometimes used to designate wood having small and closely spaced pores, but in this sense the term “fine textured” is more often used. |
| Closed canopy | The description given to a stand when the crowns of the main level of trees forming the canopy are touching and intermingled, and form a barrier to light penetrating the forest floor from above. |
| Closed Coat | A piece of sandpaper with a surface completely covered with abrasive particles. This type of paper tends to clog easily with sawdust and is generally not used for woodworking. See also – open coat |
| Co-Gen Operation | Refers to the production of usable steam and electricity using a particular kind of fuel (for example, woodchips, oil, coal, hydro). |
| Coach screw | Similar to a wood screw except larger and with a hexagonal head so that it can be turned with a spanner. |
| Coarse-grained wood | Wood with wide conspicuous growth rings in which there is considerable difference between earlywood and latewood. The term is sometimes used to designate wood with large pores, but in this sense the term “coarse textured” is more often used. |
| Codominant trees | In stands with a closed canopy, those trees whose crowns form the general level of the canopy and receive full light form above, but comparatively little from the sides. In young stands, those trees with above average height growth. |
| Collapse | The flattening of single cells or rows of cells during the drying or pressuretreatment of wood. Often characterised by a caved-in or corrugated (“washboarded”) appearance of the wood surface. |
| Collar tie | A horizontal board that connects pairs of rafters on opposite roof slopes. |
| Collet | In a router, the sleeve that grips the shank of a bit. |
| Column | A free standing axially loaded compression member, usually vertical. |
| Commercial thinning | A silviculture treatment that “thins” out an overstocked stand by removing trees that are large enough to be sold as products such as poles or fence posts. It is carried out to improve the health and growth rate of the remaining crop trees. As compared to “juvenile spacing.” |
| Common Grade Lumber | Lumber with obvious defects. |
| Composite lumber | See “engineered wood products.” |
| Compound Cut | An angled cut to both the edge and face of a board. |
| Compression | A state or condition of being pushed or shortened by a force. |
| Compression failure | Deformation or fracture of wood fibres across the grain resulting from excessive compression along the grain. |
| Compression Failure | Localized buckling of fibers and other longitudinal wood elements resulting from excessive compression along the grain. It may also develop in standing trees due to bending by wind, snow, or internal longitudinal growth stresses, or it may result from stresses induced in the tree after it is cut. In surfaced lumber, compression failures may appear as fine wrinkles across the face of the piece. |
| Compression seat | A fabricated or cast metal bracket into which timber structural members abut, used to joint timber compression elements to other structural members. |
| Compression Wood | Reaction wood that forms on the lower side of a leaning softwood tree. |
| Compression Wood | Abnormal wood formed on the underside of branches and inclined boles of softwood trees. It is characterized by excessive longitudinal shrinkage and has physical properties that are different from those of normal wood. |
| Compressive Stress | The total compression force (force acting on a body which tends to shorten a dimension or reduce the volume of the body) divided by the cross-sectional area of the body upon which the force is being applied. |
| Comprssion wood | When an actively growing softwood stem is tipped from the vertical, it almost immediately begins producing wood on the underside of the leaning stem that is different from normal. Stems tipped as little as several degrees from the vertical may begin producing abnormal cells within several hours of the change in stem orientation. This wood, known as compression wood, is of interest because its properties are considerably different from, and much less desirable than, normal mature wood. In fact, compression wood has many of the same properties as juvenile wood. |
| Concave | An inward-curving shape. (I.E. A spoon) |
| Concentration yard | A large lumber storage and reload facility. |
| Conditioning | The exposure of a material, such as wood to the influence of a predetermined condition in the surrounding atmosphere for a specific time period or until a required relation between the atmosphere and the material is achieved. |
| Conditioning treatment | A treatment applied to equilibrate the moisture content of wood to a particular value. |
| Conifer | Tree that is a gymnosperm, usually evergreen, with cones and needle-shaped or scalelike leaves, producing wood known commercially as softwood. |
| Construction and demolition (C&D) | Though lumped together to refer to wood waste produced by construction or by demolition, the products can be quite different. Construction wood waste can be clean dimensionally cut lumber such as board ends or cutoffs. Demolition wood waste is often contaminated with nails, sheetrock, paint, etc. Markets for C&D are limited by how “clean” and free of contaminants the wood is. Some businesses specialize in processing and disposing of C&D. |
| Continuity strap | A piece of flat steel fixed over a butt joint between timber beams to provide a continuos tension connection. |
| Contract orders | Block orders covering multiple shipments. |
| Convergence | The coming together of futures market price and the cash market price at the expiration of a contract month. |
| Convex | An outward-curving shape. (I.E. My belly 🙂 |
| Cope-and-stick joint | A method of construction raised panel doors where the tongues of the rails (horizontal) connect to the grooves of the stiles (vertical). |
| Coppice | Forst regeneration by sprouting (vegetative reproduction) from stumps or roots. |
| Corbel | A length of timber laid horizontally on the top of a column to transfer loads and to provide a seat for beams. A compound corbel includes several lengths of timber instead of one. |
| Cord | A unit of measure often used for firewood stacked 4′ long x 4′ high x 8′ long. |
| Cord | Stacks of hardwood 4′ high by 4′ wide by 8′ long. It is the measure by which firewood is customarily sold , sawdust is sometimes sold, and small diameter logs sometimes bought. One cord is the equivalent of 128 cubic feet, 4.7 Cubic yards. The weight of a cord varies if it is green (freshly cut), seasoned (partially air dried), or dry (KD or kiln-dried). |
| Cord | Unit of measurement equalling 128 cubic feet true measure. |
| Corduroy | To build a road by cross-laying it with saplings or small poles |
| Core Stock | A solid or discontinuous center ply used in panel-type glued structures such as furniture panels and solid hollowcore doors. |
| Corrugated containers | Containers made with corrugating medium and linerboard. |
| Corrugating medium | The wavy center of the wall of a corrugated box which cushions the product from shock during shipment (see flute). This layer can contain up to 100% post-consumer recycled fiber content without reducing its ability to protect the product. |
| Count | The nominal thickness, width, and length used in determining board footage for invoicing purposes. |
| Countersink | A tool that allows you to drill a hole so that the head of a screw will sit flush with the face of a board. |
| Creep | Increase in deformation following prolonged loading. |
| Cripple | A cut in an unseasoned joist, bearer or stud designed to reduce movement in a floor or wall as the structural timber seasons. |
| Crook | A lumber defect where there is an edgewise warp effecting the straightness of the board. |
| Crook | 1. A lumber defect referring to a deviation from a straight line drawn end to end along the narrow face of a piece of lumber. 2. Abrupt bend in a tree or log. |
| Cross cut | to cut across the grain. |
| Cross grain | An arrangement in which the fibres and other longitudinal elements of a piece of wood deviate from a line parallel with the edges of the piece. |
| Cross-cut | To cut a piece of lumber perpendicular to its length. |
| Crosscut (crosscutting) | A cut made perpendicular to the grain of a board. See – Ripcut (Ripping) |
| Crotch | In lumber, a piece of wood taken from the fork of a tree. Crotch Veneer is highly valued for its figuring. |
| Crown | The live branches and foliage of a tree. |
| Crown cut | A method of slicing veneers whereby the average inclination of the growth rings to the wider face is tangential or less than 45 degrees. This method is also known as flat cut. |
| Cunit | A pulpwood measurement, equaling 100 cubic feet of solid wood. |
| Cunit | Unit of Measurement usually applied to roundwood for pulp manufacture. 1 cunit = 100 ft3 true measure |
| Cup | A defect in the lumber where the face of the board warps up like the letter U. |
| Cup | A concave curvature across the grain or width of the a piece |