Wood Products Glossary, Definition, Definitions, Define, Technical Terms, Forestry, Logging, Sawmill, Planermill, Plywood, Pulp Paper, Panels


Absolute
	A measure having as its zero point or base the complete absence of the entity being measured.

Absolute pressure
	The pressure above zero absolute, i.e., the sum of atmospheric and gauge pressure. In vacuum related work it is usually expressed in millimeters, or inches, of mercury.

Acceptance sampling
	A statistical quality control method that seeks to determine the quality of a product by sampling a small portion of it. It does not assure that 100 percent of the product is acceptable, but reduces the likelihood of acceptance of a defective product.

Accumulator
	A container in which fluid (generally nitrogen) is stored under pressure as a source of fluid power.

Acre (a)
	A unit of area used in English-speaking countries, equal to 4,840 square yards (0.405 hectares). View: Metric / Imperial Conversion

Across the grain
	The direction at right angles to the length of the fibres and other longitudinal elements of the wood.

Active falling area
	The area within two tree-length radius of where a faller or a mechanized falling machine is operating.

Actuator
	A device for converting pneumatic or hydraulic energy into mechanical energy. A motor or cylinder.

Adhesive
	A substance capable of holding materials together by surface attachment. It is a general term and includes cements, mucilage, and paste, as well as glue.

Adult wood
	Wood which characteristically has relatively constant cell size, well-developed structural patterns, and stable physical behaviour; also called Mature wood.

Adverse (grade)
	Ascending grade in the direction of travel.

Aeration
	Air in the hydraulic fluid. Excessive aeration causes the fluid to appear milky and components to operate erratically because of the compressibility of the air trapped in the fluid.

Aerial logging
	A logging system which fully suspends the logs such as done by helicopters or balloons. Not to be confused with cable systems which use cables and supports.

Age class
	Any interval into which the age range of trees, forests, stands or forest types is divided for classification and use. Forest inventories commonly group trees into 20-year age class groups.

Air velocity
	The speed of airflow through the stickers, crossouts, and around the lumber expressed in feet per minute (fpm) or metres per second (mps).

Air-dried
	Lumber that was dried by exposure to air in a yard or shed, without artificial heat.

Airflow
	The pattern of air movement within a dry kiln. This pattern varies with kiln design, loading methods, and level of maintenance and operation.

Allowable annual cut (AAC)
	The volume of timber that may be harvested annually from a specific timber tenure.

Allowable cut
	The amount of wood that can be removed from a landowner's property during a certain time span, without exceeding the net growth during that same time on the property

Along the grain
	The direction parallel with the length of the fibres and other longitudinal elements of the wood.

Alternate top bevel
	A design for a circular saw blade where teeth are alternately beveled.

American Lumber Standards
	Provisions for softwood lumber dealing with recognized classification, nomenclature, basic grades, sizes, descriptions, measurements, tally shipping, provisions, grade marking, and inspection of lumber. The primary purpose of these standards is to serve as a guide in preparing or revising grading rules of the various lumber manufacturers' associations. A purchaser must, however, make use of association rules because the basic standards are not in themselves commercial rules.

Amplifier
	A device for amplifying the error signal sufficiently to cause actuation of the stroke control. Several types of servo amplifiers are used at the present time: electronic (DC, AC, phase sensitive, and magnetic) and mechanical.

Amplitude of sound
	The loudness of a sound.

Analog
	A continuous range of numbers or values.

Anisotropic
	Exhibiting different properties when measured along different axes. In general, fibrous materials such as wood are anisotropic.

Annual growth
	Layer of wood developed by a tree during a given year; same as annual or seasonal increment.

Annual growth rings
	The layer of growth that a tree puts on in one year. The annual growth rings can be seen in the end grain of lumber.

Annular area
	A ring shaped area - often refers to the net effective area of the rod side of a cylinder piston, i.e., the piston area minus the cross-sectional area of the rod.

Anti-sap stain
	A wood treatment used to prevent fungus from staining the wood.

Anvil (swage)
	The fixed jaw in a swaging device that supports the back of the tooth while the die or roller presses against the front of the tooth.

Appearance grades
	High-line regular board and dimension grades that include tighter restrictions on certain appearance characteristics, particularly wane.

Arbor
	The shaft on which a circular saw blade or chip head is mounted.

Atmospheric pressure
	Pressure exerted by the atmosphere at any specific location. (Sea level pressure is approximately 14.7 pounds per square inch absolute.)

Autoclave
	Cylindrical vessel in which wood is impregnated with a preservative under high pressure. Used to treat lumber, roundwood posts and poles or any other wood based product which must be protected from rot or insect attack. View: Post/Pole Treatment Autoclave

Axial force
	A push (compression) or pull (tension) acting along the length of a member, expressed in kilonewtons (pounds).

Axial stress
	The axial force acting at a point along the length of a member divided by the cross-sectional area of a member, expressed in kilopascals (pounds per square inch).

Back clearance
	The angle between the back of a tooth and a tangent of the circumference or cutting circle. Same as Clearance angle.

Back connected
	A condition where pipe connections are on normally unexposed surfaces of hydraulic equipment. (Gasket mounted units are back connected.)

Back pressure
	A pressure in series. Usually refers to pressure existing on the discharge side of a load. It adds to the pressure required to move the load.

Backcut
	The final cut in felling a tree by hand, made on the side opposite the intended direction of fall, after the undercut.

Backhaul
	A delivery by tractor-trailer originates from where the trailer is loaded, the load is delivered to a destination, then the trucker returns home. If the return is also a paying load to be delivered to the vicinity of the trucker's home, that load is called a backhaul. If the trucker returns home empty, that run is called a "deadhead".

Backing veneer
	The layer of veneer used on the reverse side of a piece of plywood from the face or decorative side.

Backrest
	A wood bench opposite the tensioner, used to support a circular saw when checking tension.

Baffle
	1. A barrier in a dry kiln used to deflect and control airflow through the lumber. 2. A device, usually a plate, installed in a reservoir to separate the pump inlet from return lines.

Baffle, end
	A hinged baffle in a dry kiln that closes the gap at the end of the lumber next to the doors.

Baffle, floor
	A hinged or stationary baffle in a dry kiln that closes the gap at the bottom of the lumber unit, preventing air from escaping under the load.

Baffle, overhead
	A hinged baffle in a dry kiln that closes the gap between the overhead fan deck and the top of the lumber load.

Baghouse dust collector
	An air pollution control device that captures particulate in filter bags. View: Baghouse Examples

Band saw
	A saw made from steel, butt welded into an endless belt or band with teeth on one or both edges arranged to cut sequentially.

Band sawmill
	An evolution in sawmill technology that uses a thinner band saw blade (less kerf therefore less sawdust waste) than a circular saw. A bandsaw can also have teeth on both sides that allows cuts to be made in two directions instead of just one, improving efficiency and productivity.

Bar or blade
	That part of the chainsaw upon which the cutting chain moves.

Barberchair
	A vertical split in a tree, generally caused by an insufficient undercut or by neglecting to cut the sapwood on both sides of a heavy leaning tree before felling. Results in a stump which looks like a high-backed chair. Very dangerous to the faller.

Bark
	The outermost, protective layer, of a tree.

Bark pocket
	A small area of bark around which normal wood has grown; an opening between annual growth rings that contains bark. Bark pockets appear as dark streaks on radial surfaces and as rounded areas on tangential surfaces. View: Bark Pocket

Barn poles
	Roundwood used for highway sign posts.

Barrier wrap
	Treated or untreated roundwood encased in a wrap for wood protection. Also keeps wood treatments from leaching into the surroundings. View: Barrier Wrap Examples

Basal area
	Cross sectional area of a tree, in square feet, measured at breast height. Used as a method of measuring the volume of timber in a given stand.

Base of tree
	That portion of a natural tree not more than three feet above ground level.

Basis weight
	1. The weight, in pounds, of a ream (500 sheets) of paper cut to a given standard size for that particular paper grade. 2. For linerboard and corrugating medium, the weight of the paper per 1,000 sq. ft.

Baud rate
	The speed at which data is transmitted and received over serial communication lines. The equipment on both sides of the communications line must be set up to send and receive data at the same rate.

BCTMP
	Bleached chemi-thermomechanical pulp.

Bearings
	A part on which the arbor, pivot, pin, or the like, turns or revolves.

Beehive burner
	A wood waste incinerator.

Belt
	Part of the conveyor on which pieces of wood are displaced.

Bending strength
	A measure of the resistance of wood to an applied bending stress which is a combination of three primary stresses, i.e., compressive, tensile, and shear stresses.

Bevel cut
	An angled cut through a board.

Big box stores
	Large, warehouse-type lumber and building material stores catering to do-it-yourself (DIY) shoppers. Home Depot and Lowes are examples.

Bight
	A work area made hazardous by a line or equipment under tension.

Biodegradable
	Something that breaks down to its component parts in the environment.

Biomass
	The quantity of biological matter of one or more species present on a unit area. With respect to trees, biomass can be expressed in terms of various components (wood, bark, foliage, roots, etc.) of all trees on a unit area or of a single tree; biomass quantities of trees are commonly expressed on an oven-dry weight basis.

Biomass boiler
	Biomass boilers burn bark, sander dust and other wood-related scrap not usable in product production. Also called "hogged fuel" boilers, biomass boilers make steam and heat for mill use.

Bit
	The smallest unit of memory in a computer. A bit is a single digit and can only have the values 0 or 1. Bits are combined into words of memory.

Bite (feed per tooth)
	The depth of cut per tooth, inch. In general, the formula is: bite = distance between teeth (in inches) times feed speed (in feet per minute) divided by saw velocity (in feet per minute). More simply it is the distance the log or cant advances into the saw between successive teeth. View: Bandmill Formula, Gang Edger Formula, Quad Sawbox Formula

Bleaching, pulp
	The process of removing residual lignin from pulp to improve the brightness and strength.

Bleed-off
	To divert a specific controllable portion of hydraulic pump delivery directly to reservoir.

Blow down
	Tree or trees felled by wind. Also known as Windfall.

Blue stain
	A bluish or dim-grayish discoloration of the sapwood caused by the growth of certain dark-colored fungi on the surface and in the interior of the wood, made possible by the same conditions that favor the growth of other fungi. Also known as Sap stain or Sapwood stain. View: Blue Stain

Board
	Lumber that is nominally less than two inches thick and two inches or more wide.

Board edger
	Machine centre for removing the wane from the sides of flitches. View: Board Edger Examples

Board foot
	A unit of measurement of lumber represented by a board 1 foot long, 12 inches wide, and 1 inch thick or its metric equivalent. In practice, the board foot calculation for lumber 1 inch or more in thickness is based on its nominal thickness and width and the actual length. Lumber with a nominal thickness of less than 1 inch is calculated as 1 inch. View: Board Foot

Boiler
	Steam generation equipment.

Bolt
	A short section of a tree trunk. In veneer production, a short log of a length suitable for peeling in a lathe.

Bolt circle
	A circle scribed around the arbor hole of a circle saw which has one or more holes laid out to receive bolts.

Bond strength
	The unit load applied in tension, compression, flexure, cleavage, or shear, required to break an adhesive assembly, with failure occurring in or near the plane of the bond.

Bone-dry ton (BDT)
	Material that weighs 2,000 pounds at zero percent moisture content. Also known as an Ovendry ton or Bone Dry Metric Ton.

Bone-dry unit (BDU)
	A quantity of wood residue that would weigh 2,400 pounds at zero percent moisture content.

Boom
	A raft of logs or a string of logs chained together, end to end, used to hold floating logs. A means of log storage or transportation.

Boomboat
	Any boat used to push or pull logs, boom, bundles, or bags, in booming ground operations.

Bound moisture
	Moisture which is closely bound to the cell wall constituents of wood.

Bound water
	Water that is bound within the cell wall of wood. Water held in wood below the fiber saturation point. Bound water moves by diffusion.

Bow
	A lumber defect referring to deviation from a straight line drawn end to end along the wide face of a piece of lumber. See also Warp. View: Bow

Braze
	As in welding, a method of adhering or soldering carbide or other hard metal teeth inserts, or joining pieces of metal.

Breather
	A device which permits air to move in and out of a container or component to maintain atmospheric pressure.

British thermal unit (Btu)
	The quantity of heat required to raise the temperature of one pound of water by one degree Fahrenheit. View: Metric / Imperial Conversion

Broad-leaved trees
	Trees which shed their leaves in the autumn. Most broadleaved or deciduous trees are hardwoods and have broad leaves.

Brow log
	A log or a suitable substitute placed parallel to any roadway at a landing or dump to protect the carrier and facilitate the safe loading or unloading of logs, timber products, or materials.

Brown rot
	Any decay in wood in which the attack is confined to the cellulose and associated carbohydrates rather than the lignin, producing a light to dark brown friable residue - hence the term "dry rot". An advanced stage of brown rot where the wood splits along rectangular planes, in shrinking, is referred to as "cubical rot".

Buck
	To saw felled trees into log lengths. Note: In some two person felling operations, one member may fall the tree and the other may limb and buck it. The second person is often called a "bucker". Usually the two members interchange the duties throughout the work day.

Bucking
	Cross-cutting felled trees into logs or bolts.

Buckskin
	A log or tree with the bark fallen off.

Building poles
	Roundwood that is commonly used vertically as supports for structures.

Bulbs
	General term referring to the drybulb and wetbulb sensors within a kiln.

Bulk density
	Factor used to convert between solid wood equivalent of processed wood such as chips, pulp, particleboard, and sawdust. The solid wood equivalent volume is considered to have a bulk density factor of one.

Bunk
	To place the empty trailer of a logging truck on the tractor unit's bunk for the trip back to the landing.

Bunk support
	The horizontal kiln truck supports on which the lumber is placed for drying.

Burl
	A swirl or twist in the grain of wood, usually occurring near a knot, but which itself does not contain a knot. Valued as the source of highly-figured burl veneers used for ornamental purposes.

Butt
	Bottom of a felled part of a tree; large end of a log.

Butt cut
	The first cut above the stump of a tree.

Butt log
	First log cut above the stump. Also known as Butt cut.

Butt rot
	Decay or rot characteristically confined to the base or lower bole of a tree.

Cable logging
	A yarding system employing winches and cables from a fixed position (usually a yarder and tower of some sort).

Cable yarding
	The movement of felled trees or logs from the area where they are felled to the landing on a system composed of a cable suspended from spars and/or towers. The trees or logs may be either dragged across the ground on the cable or carried while suspended from the cable.

Calender
	To make the surface of paper smooth by pressing it between steel rollers during manufacture.

Calibration
	1. Adjusting the control or recording equipment to reflect the actual control or recording temperatures. 2. Procedures that involve scanning an object of known size. Calibration is used to adjust scanner readings for greater accuracy.

Calorific value
	The potential heat-production value of a wood source. Depends on the cellulose-lignin ratio, the percentage of extractives, and the moisture content.

Cambium
	The layer of tissue dividing the bark from the wood, which forms new bark to the outside and new wood to the inside as the tree grows.

Can velocity
	The velocity of the gas in the passages between the filter units in the filter house of a gas filter.

Canopy
	The forest layer made up of the crowns of the tallest trees.

Cant
	Piece of wood produced by a canter that requires further breakdown.

Canter
	A machine that converts logs into a square, rectangular or two-sided cant for further processing. Canters may be configured with conical disk heads or drum heads. They may include double length or single length infeeds. Circular or band saw sections can be included to produce side boards. View: Canter Examples

Capillary action
	The combination of solid-liquid adhesion and surface tension by which liquid moves through a cellular structure.

Capping head
	Equipment used to form a cap (chamfer) on the end of roundwood posts. Consists of a rotating cutterhead. Also called doming/domer. View: Capping Head Examples

Carbide
	Tungsten carbide used for tooth inserts that are attached to the tooth face tip to provide a hard wear surface.

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
	A frame on which are mounted the headblocks, setworks, and other mechanisms for holding a log while it is being sawed, and also for advancing the log toward the saw line after a cut has been made. The carriage frame is mounted on trucks which travel on tracks, the carriage being actuated by a hydraulic piston, or motor and cable.

Cartridge
	1. The replaceable element of a fluid filter. 2. The pumping unit from a vane pump, composed of the rotor, ring, vanes and one or both side plates.

Casehardening
	A condition of stress-and-set in dry wood in which the outer fibers are under compressive stress and the inner fibers under tensile stress. The stresses persist after the lumber is dry and cause warp if the wood is remachined after drying. See Reverse casehardening.

Cat
	Often short for Caterpillar tractor, or any other brand of bulldozer-type tractor. May refer to a skidding tractor or a earthmoving bulldozer.

Cat face
	Deformed tree trunk surface usually caused by fire, disease or rot.

Cat skinner
	The person who operates a cat.

Cavitation
	A localized gaseous condition within a liquid stream which occurs where the pressure is reduced to the vapor pressure.

CCA
	Copper Chrome Arsenate, a wood preservative.

Cell
	General term for the minute units of wood structure including wood fibres, vessel segments and other elements.

Cellulose
	The carbohydrate that is the principal constituent of wood and forms the framework of the wood cells.

Celsius (C)
	The international temperature scale in which water freezes at 0 and boils at 100 under normal atmospheric conditions. °C = (°F - 32) ÷ 1.8. View: Metric / Imperial Conversion

Centimetre (cm)
	A metric unit of length equal to one hundredth of a metre. 2.54 cm is equal to one inch. View: Metric / Imperial Conversion

Centrifugal force
	The force which impels a thing, or parts of a thing, outward from a center of rotation.

Chainsaw firewood processor
	Equipment used to produce firewood as a business. Uses a chainsaw (often hydraulic powered) to buck the logs into blocks. View: Chainsaw Firewood Processor Examples

Channel
	A fluid passage, the length of which is large with respect to its cross-sectional dimension.

Charge (supercharge)
	1. To replenish a hydraulic system above atmospheric pressure. 2. To fill an accumulator with fluid under pressure. (See Precharge pressure)

Charge pressure
	The pressure at which replenishing fluid is forced into the hydraulic system (above atmospheric pressure).

Check
	A splitting of the wood fibers within or on a log or lumber. Checks result from uneven wood shrinkage. View: Checks

Check valve
	A valve which permits flow of fluid in one direction only.

Chemical pulp
	The product of the reduction of wood or other fiber into component parts during cooking with various chemical liquors in processes such as sulfate, sulfite, and soda pulping.

Chemically protected lumber
	Lumber treated with anti-stain chemicals to protect it in transit.

Chemimechanical pulp (CMP)
	A product made by pretreating chips with chemicals at a temperature usually below 100�C, followed by atmospheric refining.

Chip
	1. (n.) Small piece of wood used as fibre for the pulp process; the product of canter chipper heads and chippers. Chips are larger and coarser than sawdust. 2. (v.) To mechanically reduce logs or whole trees to small pieces for fuel, pulp, or chipboard manufacture.

Chip load
	The quantity of wood removed by an individual knife as it cuts on each pass.

Chipboard
	A paperboard, thicker than cardboard, used for backing sheets on padded writing paper, partitions within boxes, shoeboxes, etc.

Chipper
	Device used to transform pieces of wood to chips. View: Chipper Examples

Chipper canter
	A headrig machine that reduces debarked logs directly to chips and cants without producing sawdust.

Choke
	A restriction, the length of which is large with respect to its cross-sectional dimension.

Choker
	Short length of wire rope that forms a noose around the end of a log for hauling.

Chromated Copper Arsenate (CCA)
	The most commonly used chemical for pressure treating lumber.

Circuit
	An arrangement of components interconnected to perform a specific function within a system.

Circular headsaw
	A circular plate having cutting teeth on the circumference and used to ripsaw logs.

Circular saw
	A circular metal plate with teeth on the circumference that rotates on an arbor.

Circular saw firewood processor
	Equipment used to produce firewood as a business. Uses a circular saw to buck the logs into blocks. View: Circular Saw Firewood Processor Examples

Circular sawmill
	The traditional sawmill uses a circular 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 log for the next cut.

Clear
	Lumber or logs that are free or practically free of defects. First quality lumber or log.

Clear-cut
	An area in which all of the trees have been or will be felled, bucked and skidded in one operation. When all trees in a given area are felled.

Clearance angle
	The angle between a tangent to the cutting circle of a tooth and a line along the top of the tooth intersecting this tangent.

Climb cut
	The circular saw blade rotates in the same direction as the material is fed during the cutting process.

Climb sawing
	See Climb cut.

Clipper loss
	During the manufacture of veneer, the ribbon of veneer is cut to specific sizes by a device called a clipper. Losses during this step occur because of unacceptable defects (knots, rot, etc.) in the veneer, splits and breakage, or sizing.

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 center circuit
	One in which flow through the system is blocked in neutral and pressure is maintained at the maximum pressure control setting.

Closed center valve
	One in which all ports are blocked in the center or neutral position.

Closed loop
	A system in which the output of one or more elements is compared to some other signal to provide an actuating signal to control the output of the loop.

Co-gen operation
	Refers to the production of usable steam and electricity using a particular kind of fuel (for example, woodchips, oil, coal, hydro).

Cogeneration
	The process of burning fuel to produce electricity and usable steam.

Coils
	The radiant heating surface within steam or oil-heated kilns. The coils contain the steam or oil and transfer its heat through the coil wall to heat the kiln air, producing condensate in the process.

Coils, center
	The steam or oil coils that are positioned between the kiln tracks. Also called Booster coils.

Coils, overhead
	The steam or oil coils positioned overhead at or on the fan deck.

Cold deck
	A stack of logs left for later transportation (in the woods), or a deck of logs at the mill for winter use.

Collapse
	The flattening of single cells or rows of cells during the drying or pressure treatment of wood. Often characterized by a caved-in or corrugated ("washboarded") appearance of the wood surface.

Collar
	A flange mounted on the saw arbor to support the blade on one or both sides. If the collar is fixed to the arbor, it is called the fixed collar. If not, it is a loose collar.

Collarless saws
	The saw floats on the arbor being keyed directly to the arbor itself.

Column
	A free standing axially loaded compression member, usually vertical.

Combustion
	Consumption by oxidation, evolving heat, and, generally, also flame and incandescence.

Command signal (or input signal)
	An external signal to which the servo must respond.

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".

Compaction
	Close packing of chips in a given volume of space in order to minimize the voids between the individual chips.

Compensator control
	A displacement control for variable pumps and motors which alters displacement in response to pressure changes in the system as related to its adjusted pressure setting.

Composites
	Built-up, bonded products consisting wholly of natural wood, or in combination with metals, plastics, etc.

Compressibility
	The change in volume of a unit volume of a fluid when it is subjected to a unit change in pressure.

Compression failure
	Deformation of the wood fibres resulting from excessive compression along the grain either in direct end compression or in bending. In surfaced lumber, compression failures may appear as fine wrinkles across the face of the piece.

Compression wood
	Abnormal wood formed on the lower side of branches and inclined trunks of softwood trees. Compression wood is identified by its relatively wide annual rings (usually eccentric when viewed on cross section of branch or trunk), relatively large amount of summerwood, sometimes more than 50% of the width of the annual rings in which it occurs, and its lack of demarcation between earlywood and latewood in the same annual rings. Compression wood shrinks excessively lengthwise, as compared with normal wood. View: Compression Wood

Computer simulations
	Computer software that models actions or occurrences in the real world.

Condensate
	Water formed by removing heat from steam within the kiln heating coils.

Conditioning
	A process for relieving the stresses present in wood at the end of drying.

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.

Coniferous
	A type of tree which is cone-bearing and has needles or scale-like leaves, such as Pine and Spruce.

Containerboard
	The components (linerboard, corrugating medium and chipboard) used to manufacture corrugated and solid fiberboard.

Control
	A device used to regulate the function of a unit (See Hydraulic control, Manual control, Mechanical control, and Compensator control).

Control console
	Fabricated metal cabinet housing buttons and switches for the control of a machine center.

Control valve
	A device that controls the flow of liquids or gases.

Conventional cut
	The circular saw rotates in a direction counter or opposite to the direction of the feed. Also called Counter sawing.

Conveyor
	Wood transport system (logs, lumbers, chips, etc.).

Cord
	Stacks of wood 4' high by 4' wide by 8' long. 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). Commonly used for smaller timber utilized for firewood or pulping.

Cord
	A stack of wood consisting of 128 cubic feet (3.62 cubic meters). A cord has standard dimensions of 4 x 4 x 8 feet, including air space and bark.

Core
	The innermost portion of plywood usually composed of veneer. Also referred to as a "center." A core may also be made of fiberboard, particleboard or lumber.

Core stock
	A solid or discontinuous center ply used in panel-type glued structures such as furniture panels and solid hollowcore doors.

Corral rails
	Rails used for animal enclosures. Often consisting of roundwood use horizontally on a fence.

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.

Counter cutting
	The circular saw blade rotates in a direction counter or opposite to the direction of the feed.

Counterbalance valve
	A pressure control valve which maintains back pressure to prevent a load from falling.

Cracking pressure
	The pressure at which a pressure actuated valve begins to pass fluid.

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 deviation edgewise from a straight line drawn end to end of a piece of lumber. See also Warp. View: Crook

Cross laminated timber
	Cross laminated timber is an engineered building product manufactured by gluing layers of edge glued lumber panels in a cross pattern. This produces a peanel that is purther processed into specific sizes of cross laminated timber to be used for building framing.

Crosscut
	Cutting across the grain, e.g., a �crosscut� saw.

Crossouts
	Horizontal spacers between units of lumber. They align over the sticks and serve to separate the units for forklift handling.

Crown
	1. The live branches and foliage of a tree. 2. The upper part of a tree.

Cubic recovery ratio (CRR)
	In a material balance diagram, the ratio of wood product recovered divided by the wood raw material used, both measured in cubic volume. The fraction of wood raw material converted to the intended product.

Cunit
	A measurement equal to 100 cubic feet of solid wood.

Cup
	Deviation in the face of a piece of lumber from a straight line drawn from edge to edge of a piece of lumber. See also Warp. View: Cup

Cure
	To change the properties of an adhesive by chemical reaction (which may be condensation, polymerization, or vulcanization) and thereby develop maximum strength. Usually accomplished by the action of heat or a catalyst with or without pressure.

Curve Sawing
	Sawing a log or cant following the arc or curvature of the log or cant. Also referred to as sweep sawing or shape sawing. Some systems follow an arc and other systems can follow a coumpound curve. View: Curve Sawing Examples

Cushion
	A device sometimes built into the ends of a hydraulic or pneumatic cylinder which restricts the flow of fluid at the outlet port, thereby arresting the motion of the piston rod.

Cut sheets
	Fine paper cut to letter or legal size for use in printers, copiers and fax machines.

Cut-to-length harvester (CTL)
	A self-propelled tracked or wheeled harvesting machine, designed to fell, limb, and buck a tree into logs, usually 20 feet or less in length. Most commonly the harvesting head is mounted to an articulating arm. Not to be confused with a full-tree length harvester or feller-buncher. Most commonly CTL harvesters work with forwarders which transport the bunched log piles to the landing.

Cutting circle
	The circle described by the outer rim or extremity of the teeth of a circular saw.

Cylinder
	A device which converts fluid power or air into linear mechanical force and motion. It usually consists of a movable element such as a piston and piston rod, plunger rod, plunger or ram, operating within a cylindrical bore.

Dado
	A groove cut into one piece to accommodate another piece. A dado is three-sided and cut into a board, usually across the grain, as opposed to a rabbet, which has two sides and is at the edge of the board.

Dangling head
	A type of harvesting head, usually used on a CTL harvester, with a wrist-like action and attachment to the harvester boom. Also called a "single-grip harvesting head" and can rotate in all three axes.

DBH
	See Diameter at breast height.

De-superheater
	A device for removing the excess heat in steam as its pressure is reduced.

De-vent
	To close the vent connection of a pressure control valve permitting the valve to function at its adjusted pressure setting.

Deadband
	The region or band of no response where an error signal will not cause a corresponding actuation of the controlled variable.

Deadpile
	Stack lumber in units without stickers.

Debark
	To remove bark from trees or logs.

Debarker
	Machine which removes bark from a log. View: Debarker Examples

Decay
	The decomposition of wood substance caused by the action of wood- destroying fungi, resulting in softening, loss of strength, weight, and often in change of texture and color. View: Decay

Decay, brown rot
	Wood decay in which the attack concentrates on the cellulose and associated carbohydrates rather than on the lignin, producing a light to dark brown pliable residue. Sometimes referred to as "Dry rot".

Decay, heart rot
	Any rot characteristically confined to the heartwood originating in the living tree.

Decay, incipient
	The early stage of decay that has not proceeded far enough to soften or otherwise apparently impair the hardness of the wood. It is usually accompanied by a slight discoloration or bleaching of wood.

Decay, white-rot
	Decay attacking both the cellulose and the lignin, producing a generally whitish residue that may be spongy or stringy.

Deciduous
	A type of tree with broad leaves that usually are shed annually, such as aspen. Commonly referred to as Hardwood.

Deck
	A stack of trees or logs.

Decompression
	The slow release of confined fluid to gradually reduce pressure on the fluid.

Defect
	A characteristic of a tree, log, lumber, or other product that makes it either less desirable or completely unsuitable for the intended purpose. Examples are knots, decay, insect holes, and diagonal grain. View: Knot Defects, Manufacturing Defects, Natural Defects, Seasoning Defects

Degrade
	Drop in lumber grade due to manufacturing or drying practices.

Dehumidifier kiln
	A kiln working on the heat pump principle. Moisture evaporated from the timber by a flow of warm air is condensed on the evaporator coils of a refrigeration unit and drained away. The refrigerant is compressed and passed through condenser coils, re-heating the air stream.

Delamination
	The separation of the layers of laminated wood or plywood at the glueline, usually caused by moisture, mismanufacture, or defective glue.

Delimber
	Landing-based piece of equipment used to limb trees brought in unlimbed, usually cut with full tree length harvesters. May be of the stroke delimber type or pull-through delimber model.

Delivery
	The volume of fluid discharged by a pump in a given time, usually expressed in gallons per minute (gpm).

Delta
	The amount of change in a number, size or position.

Dense
	A reference to the specific gravity of wood. Lumber classified as "dense" has six or more annual rings per inch, plus one-third or more summerwood, measured at either end. Pieces averaging less than six rings per inch also qualify if the rings average one-half or more summerwood.

Density
	As usually applied to wood of normal cellular form, density is the mass of wood substance enclosed within the boundary surfaces of a wood-plus-voids complex having unit volume. It is variously expressed as pounds per cubic foot, kilograms per cubic metre, or grams per cubic centimetre at a specified moisture content. View: Metric / Imperial Conversion

Diameter at breast height (dbh)
	Breast height of a tree is considered to be four and one-half feet above ground level.

Diameter inside bark (dib)
	A measurement used in log scaling.

Die (swage)
	One of a pair of shaping tools, which, when moved toward each other, produce a certain desired form in an object. In a swage tool the die is the movable part of the shaper, the anvil the fixed part.

Differential current
	The algebraic summation of the current in the torque motor; measured in MA (milliamperes).

Differential cylinder
	Any cylinder in which the two opposed piston areas are not equal.

Diffusion
	Movement of moisture from areas of high to low concentration or temperature.

Dimension lumber
	Lumber that is sold in a nominal dimension. For example, a 2x4 is dimension lumber with an actual finished size of 1.5” thick by 3.5” wide.

Dimensional lumber
	Refers to the wood used in constructing the wall, floor and roof framing of a platform frame (2x4) house. Dimensional lumber is manufactured in a variety of sizes for use in wall framing, flooring systems, and roof trusses, as well as for exterior applications.

Directional valve
	A valve which selectively directs or prevents fluid flow to desired channels.

Dish
	Used to describe the shape of a "dished" or open saw � one that does not stand up straight, because it has been stretched too much in the inner area for the speed at which it is run. Hence, it assumes a dish shape.

Displacement
	The quantity of fluid which can pass through a pump, motor or cylinder in a single revolution or stroke.

Dissolving pulp
	A special grade of chemical pulp, usually made from wood or cotton linters, for use in the manufacture of regenerated cellulose (viscose rayon and cellophane) or cellulose derivatives such as acetate, nitrate, and others.

Dither
	A low amplitude, relatively high frequency periodic electrical signal, sometimes superimposed on the servo valve input to improve system resolution. Dither is expressed by the dither frequency (Hz) and the peak-to-peak dither current amplitude (ma).

Doming head
	Equipment used to form a dome (chamfer) on the end of roundwood posts. Consists of a rotating cutterhead. Also called capping. View: Doming Head / Domer Examples

Door carrier
	A device that lifts dry kiln doors and moves them away from the kiln opening along an overhead track.

Doors, access
	Small doors, usually located at ground level, which permit operator access to and escape from the dry kiln interior.

Doors, kiln
	Large openings through which lumber passes when loading a kiln.

Double acting cylinder
	A cylinder in which fluid force can be applied to the movable element in either direction.

Double sheave
	A pulley block with two grooved wheels.

Dowel mill
	Equipment used to process roundwood to an exact diameter the entire length. Also called a rounding machine. View: Dowel Mill Examples

Doweled products
	Roundwood with a tenon on the end to fit in a hole. Equipment used to create the tenon is called a tenoner. View: Tenoner Examples

Doweled rail fencing
	A fencing system using rails with tenons on the ends of the rails which fit into a corresponding hole in a fence post. View: Drill and Tenoner Examples

Doweled wood
	Roundwood turned to an exact diameter the entire length. Equipment used for this process are often called rounding machines or dowelers. View: Dowel Mill Examples

Doyle Log Rule
	The Doyle Log Rule, developed around 1825, is based on a mathematical formula and is widely used throughout the southern United States. This rule allows for a saw kerf of 5/16 inch and a slabbing allowance of 4 inches, which is about twice the normal amount. Because of this, the Doyle Rule is somewhat inconsistent; it underestimates small logs and overestimates large logs. As a seller of timber, you must be aware that for smaller logs the Doyle Rule will underestimate the actual volume of wood that you have in your trees. (Also see Scribner and International Rule.)

Drain
	A passage in, or a line from, a hydraulic component which returns leakage fluid independently to reservoir or to a vented manifold.

Dressed lumber
	Lumber that has been trimmed and planed at the sawmill.

Dressed size
	The dimensions of lumber after being surfaced with a planing machine. A 2- by 4-inch stud, for example, actually measures about 1-1/2 by 3-1/2 inches.

Drive pulley
	The first of a train of wheels, giving motion to the rest.

Dry
	Seasoned, usually to a moisture content of less than 19%.

Dry kiln
	A chamber in which lumber is dried by controlling the moisture, temperature and air circulation. View: Dry Kiln Examples

Dry lumber
	As applied to softwoods, lumber sold as "dry" or "kiln dried" is at 19% or lower moisture content, as specified by the American Softwood Lumber Standards. Hardwoods are generally considered dry when at 10% or lower moisture content, although there is no definitive standard as with softwood species.

Dry rot
	A term loosely applied to any dry, crumbly rot but especially to that which, when in advanced stage, permits the wood to be crushed easily to dry powder.

Dry weight
	The oven-dry weight, or simply dry weight, is the weight of wood after drying to a constant weight at a temperature slightly above the boiling point of water (215° to 220°F).

Drybulb
	A sensing device (thermometer) that measures the temperature of the air.

Drying defect
	A feature developing during drying which may decrease the value of a piece of timber.

Drying schedule
	A sequence of kiln conditions which result in a gradual decrease in moisture content of the wood.

Earlywood
	The portion of the annual growth ring that is formed during the early part of the growing season. It is usually less dense and weaker mechanically than latewood.

Edger
	A machine used to square-edge wany lumber and also to rip lumber. It consists of a frame supporting an arbor on which is mounted one to several saws and transmission gear. View: Board Edger Examples

Edging
	Trimming the width of a board of defects.

Efficiency
	The ratio of output to input. Volumetric efficiency of a pump is the actual output in gpm divided by the theoretical or design output. The overall efficiency of a hydraulic system is the output power divided by the input power. Efficiency is usually expressed as a percent.

Electro-hydraulic servo valve
	A directional type valve which receives a variable or controlled electrical signal and which controls or meters hydraulic flow.

Encoder
	Device attached to a moving chain that produces an electrical signal each time the chain moves a fixed distance. The encoder is attached to the chain and used to track the movement of the pieces through a scanner.

Energy
	The ability or capacity to do work. Measured in units of work.

Engineered wood products
	A composite wood product using glued fiber, lumber and/or veneer to meet specific design criteria. Such products include laminated veneer lumber (LVL), parallel strand lumber (PSL), and structural I-beams. Products under development include various molded, extruded, and other structural and non-structural composites. Although engineered wood products have a number of advantages over solid lumber (including the ability to make large-sized members from small diameter trees), engineered wood products are more costly to produce than lumber and require the use of more energy to manufacture.

Entering air control
	Sensing and controlling drybulb temperatures of heated kiln air as it enters the lumber load.

Environment
	The aggregate of physical, chemical and biological factors that act upon an organism or an ecological community and ultimately determine its form and survival.

Equalization
	The process of narrowing the moisture distribution between boards at the end of a drying charge.

Equilibrium moisture content (EMC)
	The moisture content at which wood neither gains nor loses moisture when surrounded by air at a given relative humidity and temperature.

Error (signal)
	The signal which is the albraic summation of an input signal and a feedback signal.

Evaporate
	Changing water from a liquid to a vapor form.

Excess air
	Refers to the quantity of air supplied that exceeds the minimum necessary to support the combustion chemistry.

Exiting air control
	Sensing and controlling drybulb temperatures of heated dry kiln air as it leaves the lumber load.

Expansion factor
	With respect to chips, bark, sawdust, and shavings, the ratio of volume occupied in one of these forms to the volume of solid wood before conversion.

Extractive
	Substances in wood, not an integral part of the cellular structure, that can be removed by solution in hot or cold water, ether, benzene, or other solvents that do not react chemically with wood components.

Eye
	The hole in the center of a circular saw blade so it can be fitted on the arbor.

Face bevel
	Saw tooth faces may be straight or angled (beveled) in one of several ways with respect to each other. The bevel is the angle to which the saw is filed with respect to the saw body. Teeth filed at 90� to the saw body are said to be straight. If they deviate from this, they are "beveled".

Face veneer
	1. High quality veneer that is used for the exposed surfaces on plywood. 2. The decorative veneer on the face of the panel; the exposed side, be it wall paneling, furniture, cabinet or other.

Factory lumber
	Lumber intended to be remanufactured after it leaves the sawmill.

Fahrenheit (F)
	The temperature scale in which water freezes at 32 degrees F and boils at 212 degrees F under normal atmospheric conditions. °F = (°C x 1.8) + 32. View: Metric / Imperial Conversion

Fan deck
	The overhead area in a dry kiln where the fans are mounted.

Fan pitch
	The angle of the fan blades measured one-third of the fan radius in from the tip.

Fan system
	The air moving equipment within a dry kiln.

Fans, cross-shaft
	Multiple fans mounted on a single shaft, which extends the length of a dry kiln.

Fans, variable-speed
	Fans whose motors turn at infinitely variable speeds by varying the line frequency of the power source.

Fascia
	A vertical board nailed to the lower ends of rafters.

Fast saw
	A circular saw that wobbles, weaves, or snakes because the rim is too long for the speed at which it runs.

FBM
	Feet, board, measure. View: FBM Formula, FBM / Volume Calculator

Feed speed
	The speed of a machine centre (canter, planer, etc.) usually expressed in feet per minute.

Feedback (or feedback signal)
	The output signal from a feedback element.

Feedback loop
	Any closed circuit consisting of one or more forward elements and one or more feedback elements.

Feller-buncher
	A machine with a fixed-grip harvesting head which can grasp, cut, lift, swing and bunch trees for yarding. Usually this machine does not limb or buck to log lengths as a "cut-to-length" harvester can do.

Fence (straightedge)
	A straightedge or linebar mounted parallel to the saw blade for guiding the lumber, cant, or flitch as it passes through the saw.

Fence posts (roundwood)
	Roundwood 10 feet or shorter in length designed to be placed in or on the ground for attachment of horizontal members or wire. These can be pointed and capped or blunt; butt treated, full-length treated or untreated. View: Fence Post Production Overview

Fence rails (roundwood)
	Roundwood rails used horizontally on a fence. These can be full round or half round, split rails, peeled, doweled or unpeeled.

Fiber saturation point (fsp)
	The moisture content at which moisture is saturated within the cell walls of wood and the cell cavities are free of water. This averages around 20 percent MC. Below FSP water is held in wood as bound water within the cell cavities or lumen.

Fiberboard
	A broad generic term inclusive of sheet materials of widely varying densities manufactured or refined or partly refined wood or other vegetable fibers. Bonding agents and other materials may be added to increase strength, resistance to moisture, fire, or decay, or to improve some other property. See also Medium density fiberboard.

Fibre
	A long narrow, tapering wood cell closed at both ends.

Filter
	A device whose primary function is the retention by a porous media of insoluble contaminants from a fluid.

Fine paper
	Paper used in making copy paper, computer forms, tablets, envelopes, printing paper, etc.

Fines
	A term referring to material passing through a chip screening process that is smaller than the acceptable minimum size.

Finger joint
	An end joint in which wedge shaped projections in one piece of timber fit matching recesses on the other piece and are bonded together by an adhesive.

Finpipe
	Pipe with circular steel coils on the outer surface to aid heat transfer in a steam or hot oil dry kiln.

Firewood processor
	High production equipment used to produce firewood as a business. Different types use similar principles but differ in configuration and how logs are bucked (chainsaw, circular saw or shear). View: Firewood Processor Examples

Firewood splitter
	Usually refers to a low production splitter for home owner use. Can consist of manual splitting mauls, axes, wedges or semi-automatic hydraulic/mechanical splitters. Also called a log splitter. View: Firewood Splitter Examples

Firmwood
	Solid wood free of decay and voids; a term used in log scaling.

Fixed collar
	A collar firmly attached to the saw arbor; distinguished from a loose collar, which is held to the arbor with a nut.

Flakeboard
	A particle panel product composed of flakes.

Flat top grind
	Used to describe a tooth filed square on top. The teeth may also be ground with various combinations of beveled tops. For example, alternate top bevels are often used for crosscutting saws. Tops may also be pointed or chamfered and alternated with flat tops on very hard, dense woods. This breaks the chip up to reduce tooth load.

Flitch
	A piece of lumber with wane on one or both edges.

Flooded
	A condition where the pump inlet is charged by placing the reservoir oil level above the pump inlet port.

Flow control valve
	A valve which controls the rate of oil flow.

Flow rate
	The volume, mass, or weight of a fluid passing through any conductor per unit of time.

Fluid
	1. A liquid or gas. 2. A liquid that is specially compounded for use as a power-transmitting medium in a hydraulic system.

Flute
	One of the wave shapes pressed into corrugated medium. These are categorized by the size of the wave.

Follow valve
	A control valve which ports oil to an actuator so the resulting output motion is proportional to the input motion to the valve.

Foot (ft)
	A linear unit of length equal to 12 inches or a third of a yard (0.3048 m). View: Metric / Imperial Conversion

FOPS
	Falling object protective structure.

Force
	Any push or pull measured in units of weight. In hydraulics, total force is expressed by the product P (force per unit area) and the area of the surface on which the pressure acts. F = P x A.

Forest license
	A license granted by the Ministry of Forests of British Columbia which entitles the holder to cut a specified volume of timber on specified lands.

Forest Management Agreement (FMA)
	An agreement granted by the Alberta government which entitles the holder to establish, grow and harvest timber on specified lands.

Forest management unit
	An area of forest land designated by the Minister of Environmental Protection of Alberta as a management unit.

Forklift units
	Lumber bundled or stacked into packages that can be lifted by a forklift.

Formaldehyde
	A component of resin used to manufacture plywood and panel products, and a naturally occurring component of wood.

Forwarder
	A special vehicle with a cradle or bunk or trailer used to forward logs. Usually it is equipped with its own log loader device and may be tracked or wheeled. Most commonly works with a CTL harvester.

Four-way valve
	A directional valve having four flow paths.

FPM
	Feet per minute.

Framing
	Lumber used for structural members in a house or other building. The skeleton to which roofs, floors, and sides are attached.

Free moisture
	Moisture which is present in the cell cavities of wood.

Free of heart center (FOHC)
	Lumber sawn to exclude the pith or heart center, as opposed to box heart.

Free on board (FOB)
	Refers to the point to which the seller will deliver goods without charge to the buyer; additional freight or other charges connected with transporting or handling the product become the responsibility of the buyer.

Free sheet paper
	Paper made from cooked wood fibers mixed with chemicals and washed free of impurities. As compared to groundwood paper.

Free water
	Water held within the cell cavities of wood. Its movement is primarily by capillary action.

Frequency
	1. The number of cycles per second of alternating current (example: 60 cycles per second or 60 hertz per second). 2. The number of times an action occurs in a unit of time. Frequency is the basis of all sound. A pump or motor's basic frequency is equal to its speed in revolutions per second multiplied by the number of pumping chambers.

Front connected
	A condition wherein piping connections are on normally exposed surfaces of hydraulic components.

Front end loader
	A mobile machine mounted on a wheeled or tracked chassis, equipped with a grapple, tuck, bucket, or fork-lift device, and employed in the loading, unloading, stacking, or sorting of logs or materials.

Full flow
	In a filter, the condition where all the fluid must pass through the filter element or medium.

Full sawn
	Lumber cut, in the rough, to its full nominal size.

Full taper
	Boards are sawn parallel to the sides of a log.

Full-tree length harvester
	A machine with a fixed-grip harvesting head which can grasp, cut, lift, swing and bunch trees for yarding. Usually this machine does not limb or buck to log lengths as a "cut-to-length" harvester can do.

Gallon (gal)
	A unit of volume. A US gallon is equal to 4 quarts or 231 cubic inches (approximately 3.79 liters). A British imperial gallon is equal to four quarts or 4.55 liters. View: Metric / Imperial Conversion

Gang drill (roundwood)
	Equipment with multiple drill heads for boring multiple holes simultaneously in roundwood fence posts. For use with doweled fence railing systems. View: Gang Drills / Drill Examples

Gang edger
	A machine having a battery of circular saws, all of which are fitted to the same arbor. The saws may be over arbor, under arbor, or double arbor. There are straight sawing gangs and curve sawing gangs. View: Gang Edger Examples

Gang sawing
	This term has several meanings, one being the use of multiple fixed saws on a common arbor. The term is also used in reference to "sash" gang sawing or "rotary" gang sawing, or sawing through and through with all saw lines parallel at the headrig. View: Gang Edger Examples

Gantry tower
	The short tower on a modern swing yarder, located just to the rear of the leaning yarder tower, used to accommodate the walking guy lines and lines to raise and lower the boom of a yarding crane.

Gauge
	The thickness of the saw blade, best expressed in decimals of an inch or millimetres.

Gauge pressure
	A pressure scale which ignores atmospheric pressure. Its zero point is 14.7 psi absolute.

Glue
	Originally, a hard gelatin obtained from hides, tendons, cartilage, bones, etc., of animals. Also, an adhesive prepared from this substance by heating with water. Through general use the term is now synonymous with the term "Adhesive".

Glue laminated beams
	Beams made of lumber glued together. Replacements for solid wood timbers and steel beams.

Glue laminating
	Production of structural or non-structural wood members by bonding two or more layers of wood together with adhesive.

Glueline
	The layer of adhesive that attaches two adherends. Also called a Bondline.

Glulam (glue laminated)
	Structural wood product made by bonding together laminations of dimension lumber.

Grade
	The designation of the quality of a manufactured piece of wood or of logs.

Grade stamp
	An inked marking put on lumber to show its important characteristics and mill information. View: Grade Stamp Examples

Grademark
	A stamp or symbol applied to a piece of lumber, by the grader at a planermill, to designate grade.

Grain
	The direction, size, arrangement, appearance, or quality of the fibers in wood or lumber. To have a specific meaning the term must be qualified.

Grain, close
	Narrow, inconspicuous annual 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.

Grain, coarse
	Wide, conspicuous annual rings in which there is considerable difference between springwood and summerwood. The term is sometimes used to designate wood with large pores, such as oak, ash, chestnut, and walnut, but in this sense the term "coarse-textured" is more often used.

Grain, cross
	Fibers that deviate from a line parallel to the sides of the piece; may be either diagonal or spiral grain or a combination of the two.

Grain, curly
	Fibers that are distorted so that they have a curled appearance, as in "birdseye" wood. The areas showing curly grain may vary up to several inches in diameter.

Grain, diagonal
	Has annual rings that are at an angle with the axis of a piece as a result of sawing at an angle with the bark of the tree or log. A form of cross grain.

Grain, edge
	Sawed so that the wide surfaces extend approximately at right angles to the annual growth rings. Lumber is considered edge-grained when the rings form an angle of 45 to 90 degrees with the wide surface of the piece.

Grain, end
	The grain as seen on a cut made at a right angle to the direction of the fibers (e.g., on a cross section of a tree).

Grain, flat
	Sawed parallel to the pith and approximately tangentially to the growth rings. Lumber is considered flat-grained when the annual growth rings make an angle of less than 45 degrees with the surface of the piece.

Grain, interlocked
	Fibers that for several years slope in a right-handed direction, and then for a number of years slope to a left-handed direction, and so on. Such wood is exceedingly difficult to split radially, though tangentially it may split fairly easily.

Grain, open
	The common classification for woods with large pores, such as oak, ash, chestnut, and walnut. Also known as "coarse-textured".

Grain, spiral
	Fibers that take a spiral course around the trunk of a tree instead of the normal vertical course. The spiral may extend in a right-handed or left-handed direction around the tree trunk. Causes slope of grain in lumber. Spiral grain is a form of cross grain.

Grain, straight
	Fibers that run parallel to the axis of a piece.

Grain, vertical
	Another term for edge-grained lumber.

Grain, wavy
	Fibers that collectively take the form of waves or undulations.

Gram (g)
	A metric unit of weight equal to one thousandth of a kilogram; one ounce is approximately 28 grams.

Grapple
	A hinged set of jaws capable of being opened and closed, used to grip logs during yarding or loading. Can also be attached to swing or non-swinging grapple skidder.

Grapple skidder
	A skidder equipped with a grapple to handle logs; used in place of chokers.

Grapple yarding
	Cable yarding with grapples instead of chokers.

Gravity packed unit (GPU)
	A unit (normally a 200 cubic foot space) filled with chips or other residue material and allowed to settle under the action of gravity.

Green lumber
	Freshly sawed or undried wood.

Green target sizes
	The size that lumber must be cut in the green form to allow for sawing deviation, shrinkage in drying and allowance for fibre removed in the finishing process. View: Target Size

Green weight
	The term green weight specifically refers to the weight of freshly harvested wood that has the same moisture content (MC) as the standing tree. MC is defined as the weight of water in the wood expressed as a percentage of the weight of the oven-dry wood (wood from which all moisture has been removed). Also see "Dry weight".

Green wood
	Freshly sawed or undried wood which still contains the moisture that was present in the standing tree.

Greenhouse gases
	Gases that provide an insulating effect in the earth's atmosphere, potentially leading to global climate change. These gases include carbon dioxide, methane, nitrous oxide, ozone, and water vapour.

Gross scale
	The volume of a log obtained from original geometric measurements without adjustments for potential processing losses associated with crookedness, decayed regions, and so forth.

Groundwood paper
	Newsprint and other inexpensive paper made from pulp created when wood chips are ground mechanically rather than refined chemically.

Groundwood pulp
	A mechanical wood pulp produced by pressing a debarked log against a revolving pulpstone and reducing the wood to a mass of fibers.

Growth ring
	One year’s growth increment of a tree composed of one band of springwood (earlywood) and one band of summerwood (latewood). Also called an Annual ring.

Guide blocks
	The arms of the saw-guide mechanism which hold the guide pins on a bandsaw.

Guide or saw guide
	A supporting device above and/or below the cut to restrain the saw from deviating off line. It generally uses metal holders with babbit faces precision machined for accurate tolerances.

Guide rail
	A rail that guides the movement of the sawmill carriage.

Gullet
	The area of the saw tooth in which the sawdust is carried.

Gullet area factor
	The factor (% usage) applied to the calculation using tooth pitch and gullet depth (essentially the area of a rectangle) to convert to the actual size of the gullet.

Gullet fill %
	The percentage of the gullet that is filled based on a specific feed speed, gullet size, etc. The feed speed calculations should not allow the gullet fill to exceed 100%. View: Bandmill Formula, Gang Edger Formula, Quad Sawbox Formula

Gum spots
	Accumulation of resinous material often found on panel surfaces. May be removed by sanding.

Gumming
	The process of cutting out the gullets of a saw.

Half taper
	Boards are sawn parallel to the centre of a log.

Hammer bench
	A wood bench as an extension of the anvil opposite the tensioner's position and supporting the rim of the saw when testing for tension; it contains a peg on a sliding panel for centering the saw while being hammered.

Hammering
	Straightening, tensioning, or flattening a saw blade manually with a hammer.

Hand (of mill)
	The hand side on which the log passes the sawyer as he faces the saw, right or left.

Hand-peeled (roundwood)
	Roundwood with the bark removed by hand. Usually done using a draw knife.

Hardboard
	A generic term for a panel manufactured primarily from interfelted lignocellulosic fibers (usually wood), consolidated under heat and pressure in a hot press to a density of 31 pounds per cubic foot or greater, and to which other materials may have been added during manufacture to improve certain properties.

Hardwoods
	Generally one of the botanical groups of trees that have broad leaves in contrast to the conifers or softwoods. The term has no reference to the actual hardness of wood. Also called Angiosperms or Deciduous.

Hayrack
	A type of log hauling trailer with multiple stakes to contain many small trees in the load.

Head
	The height of a column or body of fluid above a given point expressed in linear units. Head is often used to indicate gage pressure. Pressure is equal to the height times the density of the fluid.

Headblock
	That portion of a sawmill carriage on which the log rests. Each headblock consists of a base, a knee, a taper set, dogs, and a rack-and-pinion gear or some similar device for advancing the knees toward or withdrawing them from the saw line.

Headrig
	Sawing equipment used in the primary breakdown of logs.

Headsaw
	In a sawmill, the large band saw or circular saw used to saw the log into lumber.

Heartwood
	The wood extending from the pith to the sapwood, the cells of which no longer participate in the life processes of the tree. Heartwood may contain phenolic compounds, gums, resins, and other materials that usually make it darker and more decay resistant than sapwood. Heartwood is very pronounced in southern pine.

Heat
	The form of energy that has the capacity to create warmth or to increase the temperature of a substance. Any energy that is wasted or used to overcome friction is converted to heat. Heat is measured in calories or British thermal units (Btu's). One Btu is the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit.

Heat exchanger
	A device which transfers heat through a conducting wall from one fluid to another.

Hectare (ha)
	A metric unit of area, 100 metres by 100 metres (10,000 square metres); equivalent to 2.471 acres. View: Metric / Imperial Conversion

Heel boom
	A loader with a grapple or tongs at the end of a boom or arm which forces one end of the log being loaded against the underside of the boom to steady it and raise the front end of the log.

Helical
	Spiral-shaped: in the shape of a helix or spiral.

Hemicellulose
	A celluloselike material (in wood) that is easily decomposable as by dilute acid, yielding several different simple sugars.

Hertz (Hz)
	Unit of frequency; equal to one cycle per second (cps).

High-performance linerboard
	Papers with the same strength as regular paper grades but produced at a lower weight. This process gives more compression strength per pound of fiber than conventional liner, thus reducing total fiber use.

Hog fuel
	Waste wood that is used for generation of heat and process energy; made by reducing bark to a usable size.

Hollow grind
	Grinding the saw plate on both sides so that the blade is thinner toward the eye than at the rim but leaving a hub in the center the same thickness as the rim.

Holocellulose
	The total carbohydrate fraction of wood �that is, cellulose plus hemicellulose.

Honeycomb
	A cellular separation in the interior of a wood piece, usually along the wood grain, a result of internal stress. It normally occurs during kiln drying, particularly in White or Red Oak, when too much heat is applied too rapidly.

Honeycombing
	A drying defect which occurs when tensile stresses in the core (usually a result of collapse) result in the formation of internal cavities.

Hook
	The angle at which the face of the tooth contacts the material to be cut.

Horizontally laminated timbers
	Laminated timbers designed to resist bending loads applied perpendicular to the wide faces of the laminations.

Horsepower (hp)
	The power required to lift 550 pounds one foot in one second or 33,000 pounds one foot in one minute. A horsepower is equal to 746 watts or to 42.2 British thermal units per minute.

Hot deck
	A pile of logs from which logs are hauled as soon as they are yarded.

Husk
	A term used for the parts of the sawing system supporting the arbor, saw, saw guide, and splitter, usually on a circular saw headrig; more simply, the arbor support frame.

Hydraulic
	To move or convey by fluid.

Hydraulic balance
	A condition of equal opposed hydraulic forces acting on a part in a hydraulic component.

Hydraulic control
	A control which is actuated by hydraulically induced forces.

Hydraulics
	Engineering science pertaining to liquid pressure and flow.

Hydrodynamics
	Engineering science pertaining to the energy of liquid flow and pressure.

Hydrostatics
	Engineering science pertaining to the energy of liquids at rest.

Hygrometer
	An instrument for measuring the humidity of air.

Hygroscopic
	Changes its moisture content to be in equilibrium with the atmosphere.

I-joists
	Wooden members made of two pieces of LVL held together with a web of OSB. Substituted for wide dimensional lumber as a support for a ceiling or floor.

Implosion
	The sudden collapse of dry kiln wall panels due to unequal air pressure between the inside of the kiln. This usually occurs on startup as hot, expanded air suddenly cools and contracts as it passes through green lumber. The vents must open on startup to prevent this.

Inch (in)
	A unit of length equal to one-twelfth of a foot (2.54 cm). View: Metric / Imperial Conversion

Infeed
	The direction a workpiece is fed into a blade or cutter.

Infeed Rolls
	Rolls placed ahead of certain types of saws or chip heads to force the material through the machine.

Inserted point (inserted tooth)
	The tooth used in an inserted-tooth saw.

Insulating board
	A generic term for a homogeneous panel made from lignocellulosic fibers (usually wood or cane) characterized by an integral bond produced by interfelting of the fibers, to which other materials may have been added during manufacture to improve certain properties, but which has not been consolidated under heat and pressure as a separate stage in manufacture, said board having a density of less than 31 pcf (specific gravity 0.50) but having a density of more than 10 pcf (specific gravity 0.16).

International 1/4-Inch Log Rule
	This rule was developed in 1906 and is based on a reasonably accurate mathematical formula. The rule allows for a 1/4-inch saw kerf and a fixed taper allowance of 1/2 inch per 4 feet of log length. Deductions are also allowed for shrinkage of boards and a slab thickness that varies with the log diameter. Overall, the International 1/4-Inch Log Rule is the most consistent and is often used as a basis of comparison for log rules.

Isotropic
	Exhibiting the same properties in all directions.

Joinery
	Finished timber fixtures of buildings such as doors, windows, panelling, cupboards, etc.

Jointing
	The act of reducing the points of all knives on a planer head to coincide with the circumference of a circle when the head is rotated.

Joist
	One of a series of parallel beams used to support floor and ceiling loads, supported in turn by larger beams, girders, or bearing walls.

Joule (J)
	1. A unit of energy equal to the work done when a force of one newton acts through a distance of one metre. One joule is equivalent to one watt second or 0.737 foot pounds. 2. A unit of electrical energy equal to the work done when a current of one ampere is passed through a resistance of one ohm for one second.

Joystick
	Stick or handle type input device mounted on the operator's console. Some joysticks have buttons mounted on the handle. Moving the joystick handle can send either discrete or analog input signals to the PLC.

Juvenile spacing
	A silvicultural treatment to reduce the number of trees in young stands, often carried out before the stems removed are large enough to be used or sold as a forest product. Prevents stagnation and improves growing conditions for the remaining crop trees so that at final harvest the end-product quality and value is increased. See also Commercial thinning.

Juvenile wood
	The innermost rings of wood adjacent to the pith, formed during the initial development of that part of the stem by the live crown. As the crown moves higher with growth in subsequent years, "mature" wood rings are formed. Certain features of juvenile wood, such as cell structure and size, differ from those typical of mature wood.

Kappa number
	A test for the degree of lignification of pulps.

KD
	Kiln-dry wood. Dried in a kiln with the use of artificial heat to a specified moisture content.

Kerf
	1. Width of the cut made by a saw blade. 2. The width of the saw tooth at its outermost widest point.

Key
	A small, parallel-sided piece, flat or tapered on top, for securing pulleys and other parts to shafts.

Keyway
	A groove or channel for a key, as in a shaft or the hub of a pulley; a keyseat.

Kiln
	A chamber having controlled airflow, temperature, and relative humidity for drying lumber, veneer, and other wood products.

Kiln carts, trucks
	A framework equipped with wheels that supports a load of lumber for kiln drying. Used in track kilns. Trucks also refer to the wheel assemblies alone.

Kiln kink
	The distortion in lumber that results from the uneven forces applied by misplaced truck supports and crossouts. Once dried into the lumber their effect is permanent.

Kiln-dry wood
	Dried in a kiln with the use of artificial heat to a specified moisture content.

Kiln-drying schedule
	A stipulated set of dry- and wet-bulb temperatures and air velocities employed in drying a kiln charge of lumber or other wood products.

Kilns, direct-fired
	Dry kilns that are heated with combustion air (gas or wood fired).

Kilns, package
	A trackless compartment kiln for drying packages of stickered lumber. It has large doors through which a forklift loads lumber directly within the kiln.

Kilns, steam
	Kilns heated by steam.

Kilns, track
	Kilns loaded by placing lumber on kiln trucks that run on tracks within the kiln. These can be single- or double-tracked kilns.

Kilogram (kg)
	The basic unit of mass in the SI system, equal to 1,000 grams (approximately 2.2 lbs). View: Metric / Imperial Conversion

Kilometre (km)
	A measure of length equal to 1,000 metres or 0.62 miles. View: Metric / Imperial Conversion

Kinetic energy
	Energy that a substance or body has by virtue of its mass (weight) and velocity.

Knee
	The part of a sawmill carriage headblock that bears the carriage dogs, which hold the log being sawed. It also supports the levers used to operate both the carriage dogs and the taper set.

Knife marks
	The number of knife marks per inch created by a planer head. View: Knife Mark Calculator

Knot
	That portion of a branch or limb that has been surrounded by subsequent growth of the stem. The shape of the knot as it appears on a cut surface depends on the angle of the cut relative to the long axis of the knot. View: Knots

Knot, encased
	The rings of annual growth are not intergrown with those of the surrounding wood. View: Encased Knot

Knot, intergrown
	The rings of annual growth are completely intergrown with those of the surrounding wood. View: Intergrown Knot

Knot, loose
	Is not held firmly in place by growth or position and cannot be relied on to remain in place. View: Loose Knot

Knot, open
	Opening produced when a portion of a knot has dropped out or separated due to seasoning.

Knot, pin
	Is not more than � inch in diameter.

Knot, sound
	Is solid across its face, at least as hard as the surrounding wood, and shows no indication of decay. View: Sound Knot / Tight Knot

Knot, spike
	Is cut approximately parallel to its long axis so that the exposed section is definitely elongated. View: Spike Knot

Knothole
	Opening produced when knots drop from the wood in which they were once embedded. View: Knot Hole

Knuckleboom
	A hydraulically operated loading boom whose mechanical action imitates the human arm. Common on "forwarders".

Kraft (sulfate) process
	A chemical pulping process in which lignin is dissolved by a solution of sodium hydroxide and sodium sulfide.

Kraft paper
	Heavy brown paper sometimes treated to be water repellant.

Kraft pulp
	A chemical wood pulp obtained by cooking wood chips at a high temperature in a solution of sodium hydroxide and sodium sulfide.

Laminar (flow)
	A condition where the fluid particles move in continuous parallel paths.

Laminate
	A product made by bonding together two or more layers (laminations) of material or materials.

Laminated linerboard
	Two or more plies of linerboard adhered to one another for increased structural stability.

Laminated timbers
	An assembly made by bonding layers of veneer or lumber with an adhesive so that the grain of all laminations is essentially parallel.

Laminated veneer lumber (LVL)
	A structural lumber manufacture from veneers laminated into a panel with the grain of all veneer running parallel. The resulting panel is generally manufactured in 3/4 to 1-1/2 inch thicknesses and ripped to common lumber widths of 1-1/2 to 11-1/2 inches, or wider.

Landing
	A place where logs are collected prior to further transportation.

Latewood
	The portion of the annual growth ring that is formed after the earlywood formation had ceased. It is usually denser and stronger mechanically than earlywood. Also called Summerwood.

Layup
	The process of loosely assembling the adhesive-coated components of a unit, particularly a panel, to be pressed or clamped.

Lead
	Nonparallel alignment of the guide track and circle saw plate which offsets carriage travel with respect to the saw plane. The purpose is to provide clearance for the back of the saw and counteract the tendency of the saw to run out of logs. Also used to denote the tendency of a saw to pull or "lead" to one side in a cut, often caused by off-square.

Left-hand sawmill
	A sawmill in which the carriage and saw are on the left-hand side of a person standing on the log deck and facing the rear of the mill.

Level
	Perfectly horizontal.

Leveling
	The act of bringing a saw to a flat, even surface.

Lever-type swage
	A device for widening the tips of saw teeth by drawing out the tooth point between a lever-actuated die and a fixed anvil.

Leverage
	A gain in output force over input force by sacrificing the distance moved. Mechanical advantage or force multiplication.

Lift
	The height a body or column of fluid is raised; for instance, from the reservoir to the pump inlet. Lift is sometimes used to express a negative pressure or vacuum. The opposite of head.

Light framing
	The use of dimension lumber, trusses, and other small cross-section members to provide support and enclosure for a building.

Lignin
	The second most abundant constituent of wood, located principally in the secondary wall and the middle lamella, which is the thin cementing layer between wood cells. Chemically it is an irregular polymer of substituted propylphenol groups, and thus no simple chemical formula can be written for it.

Lily pad
	A thin slice of wood, sometimes taken off the stump and used to cover the saw if it's to be left out.

Limbing
	To cut branches off felled trees.

Limit switch
	Electrical device that transmits an electrical signal when in physical contact with an object.

Line
	A tube, pipe or hose which acts as a conductor of hydraulic fluid.

Linear actuator
	A device for converting hydraulic energy into linear motion - a cylinder or ram.

Linerboard
	The inner and outer layers of paper that form the wall of a corrugated container.

Liter (l)
	Basic unit of volume in the metric system equal to 1,000 cubic centimetres (1.056 US quarts). View: Metric / Imperial Conversion

Loader
	Any of a variety of machines, wheel or track mounted, designed primarily to lift and load a truck, train or other mode of transportation.

Log
	A segment sawed or split from a felled tree, such as, but not limited to, a section, bolt, or tree length.

Log Bin
	Transfer conveyor on which logs are kicked by the log sorter.

Log dump
	A place where logs are removed from transporting equipment. It may be either dry land or water, parbuckled over a brow log or removed by machine.

Log scales
	Determines the value of a log by estimating number of board feet of lumber it will yield (less allowances for bark, slab and kerf). Helps log sellers understand what they are getting for the product of their labor. Log buyers can usually predict the actual yield of board feet from a log depending on the log rule used. Three major log scales are used: Scribner Log Rule, Doyle Log Rule and International Log Rule, although there are others (Maine and Roy). It is vital that sellers understand the differences between the scaling methods so as not to be taken advantage of. Savvy buyers are flexible in the rules they use. A common rule of thumb is that International is always 25% better than Doyle, and Scribner is always 15% better. Doyle and International are dramatically different for small diameter logs, yet very similar for large diameter logs. If the average diameter range of logs is 14" to 20", you can convert Doyle to International by multiplying 1.2 And Scribner to International by multiplying 1.11. For example, if logs for a particular site scaled about 5,000 board feet in Doyle, this would convert to 6,000 board feet in International and 5,500 board feet in Scribner.

Log splitter
	Usually refers to a low production splitter for home owner use. Can consist of manual splitting mauls, axes, wedges or semi-automatic hydraulic/mechanical splitters. Also called a wood splitter. View: Log Splitter Examples

Long butt
	1. After a tree is felled a section of the butt-end may be sawn off because of rot. 2. A swelled or cull portion cut off of a butt log.

Long log
	To produce logs over 20 feet long , commonly 32 to 40 feet long. Also known as "Long wood".

Longitudinal
	Generally, parallel to the direction of the wood fibers.

Longitudinal direction
	Oriented in the direction of the length of the wood grain.

Loose collar
	The flanged collar that is fixed against the circular saw by attachment to the arbor by means of a nut.

LRF
	Lumber recovery factor. Measurement of lumber recovery or yield from a quantity of log volume. Most commonly expressed as thousand board feet per cubic meter or board feet per cubic feet. A true measure of LRF is the finished shippable lumber per unit of logs delivered (bush to box car). View: LRF Conversion, LRF By Diameter, Earnings Vs LRF

Lug
	A projection mounted on a chain to push material (logs or lumber).

Lumber
	The product of the saw and planing mill not further manufactured than by sawing, resawing, passing lengthwise through a standard planing machine, crosscutting to length, and matching.

Lumber dimensions
	1. Actual size: The dimensions obtained when an individual piece of lumber is measured with a caliper and tape. 2. Manufactured size: The dimensions for a given state of manufacture that are provided in product specifications. Examples are rough-green, surfaced-dry, and so forth. The manufactured size stated in the American Lumber Standards for a surfaced-dry 2x4 is 1.5 x 3.5 inches. 3. Nominal size: The size in name only; the commercial name by which lumber is known and sold on the market (e.g., 2x4) and the basis used to calculate lumber volume in board feet.

Lumber recovery factor (LRF)
	Measurement of lumber recovery or yield from a quantity of log volume. Most commonly expressed as thousand board feet per cubic metre or board feet per cubic feet. A true measure of LRF is the finished shippable lumber per unit of logs delivered (bush to box car). View: LRF Conversion, LRF By Diameter, Earnings Vs LRF

Lumber ruler
	A tool resembling a ruler with a handle at one end and a hood at the other which is used to calculate the board footage of a piece of lumber.

Lumber sorter
	Computerized system in which lumber is graded, measured, and sorted into bins. View: Lumber Sorter Examples

Lumber, factory and shop
	Lumber intended to be cut up for use in further manufacture. It is graded on the basis of the percentage of the area that will produce a limited number of cuttings of a specified minimum size and quality.

Lumber, matched
	Lumber that is edge dressed and shaped to make a close tongued-and-grooved joint at the edges or ends when laid edge to edge or end to end.

Lumber, patterned
	Lumber that is shaped to a pattern or to a molded form in addition to being dressed, matched, or shiplapped, or any combination of these workings.

Lumber, rough
	Lumber that has not been dressed (surfaced) but which has been sawed, edged, and trimmed.

Lumber, shiplapped
	Lumber that is edge dressed to make a lapped joint.

Lumber, side
	A board from the outer portion of the log � ordinarily one produced when squaring off a log while producing a cant.

Lumber, structural
	Lumber that is intended for use where allowable properties are required. The grading of structural lumber is based on the strength or stiffness of the piece as related to anticipated uses.

Lumber, surfaced
	Lumber that is dressed by running it through a planer.

Lumber, timbers
	Lumber that is nominally 5 inches or more in least dimension. Timbers may be used as beams, stringers, posts, caps, sills, girders, purlins, and so forth.

Lumber-core plywood
	Plywood where thin sheets of veneer are glued to a core of narrow boards. Lumber-core plywood differs from regular plywood in that regular plywood is made up of successive layers of alternating grain veneer.

Machine-peeled (roundwood)
	Roundwood with the bark removed by a machine. View: Roundwood Peeling / Debarking Examples, Debarkers Examples

Mainline
	The cable used to haul logs into the landing. Some cable yarder configurations, such as running skyline, may have more than one mainline.

Manifold
	A fluid conductor which provides multiple connection ports.

Manual control
	A control actuated by the operator, regardless of the means of actuation. Example: Lever or foot pedal control for directional valves.

Manual override
	A means of manually actuating an automatically-controlled device.

Manufactured housing
	Housing units partially or completely built in a factory.

Marine borers
	Mollusks and crustaceans which attack submerged wood in salt and brackish water.

Market pulp
	White pulp from hardwood trees that is dried into thick blotter-like sheets and baled for shipment to a paper mill for re-pulping to make paper products.

Material balance
	A relationship, often portrayed in a diagram, that shows how all components of a raw material are allocated and used.

Maul
	A maul or splitting maul is a heavy long handled hammer used for splitting a piece of wood along its grain. One side is shaped like a sledge hammer and the other is a broad head axe shape. View: Maul Examples

MBF
	Thousand board feet.

Mechanical control
	Any control actuated by linkages, gears, screws, cams or other mechanical elements.

Mechanical pulping
	The production of fibers and fiber bundles by grinding wood with pulpstones or by mechanical refiners as opposed to chemical methods.

Mechanically laminated timber
	Laminated timber where the laminations are joined with mechanical fasteners.

Medium density fiberboard (MDF)
	A panel product manufactured from lignocellulosic fibers combined with a synthetic resin or other suitable binder. The panels are manufactured to a density of 31 pcf (0.50 specific gravity) to 55 pcf (0.88 specific gravity) by the application of heat and pressure by a process in which the interfiber bond is substantially created by the added binder. Other materials may have been added during manufacturing to improve certain properties.

Mende-process board
	Made in a continuous ribbon from wood particles with thermosetting resins used to bond the particles. Thickness ranges from 1/32 to 1/4 inch.

Merchantable timber
	A tree or stand that has attained sufficient size, quality and/or volume to make it suitable for harvesting.

Meter
	To regulate the amount or rate of fluid flow.

Meter-in
	To regulate the amount of fluid flow into an actuator or system.

Meter-out
	To regulate the flow of the discharge fluid from an actuator or system.

Metre (m)
	The metric basic unit for linear measurement equal to 39.37 inches (1.094 yards). View: Metric / Imperial Conversion

Mfbm
	Thousand board feet.

Micron
	One-millionth of a metre or approximately .00004 inch.

Micron rating
	The size of the particles a filter will remove.

Mile (mi)
	A unit of linear measurement on land, equivalent to 5,280 feet (1,760 yd) or 1.6 kilometres. View: Metric / Imperial Conversion

Millimetre (mm)
	A unit of length equal to one thousandth of a metre (0.0394 inches). View: Metric / Imperial Conversion

Millwork
	Planed and patterned lumber for finish work in buildings, including items such as sash, doors, cornices, panelwork, and other items of interior or exterior trim, but not flooring or siding.

Mineral stain
	An olive to greenish-black or brown discoloration believed to show regions of abnormal concentrations of mineral matter in some hardwoods. It is common in hard maple, hickory, and basswood. See also Mineral streaks.

Mineral streak
	A discoloration of hardwood and hardwood veneer.

Mismanufacture
	Wood imperfections or blemishes that result from manufacture.

MMBF
	Million board feet.

MMSF
	A unit of measure for MDF equal to one million square feet on a 3/4 inch basis.

Modular housing
	A type of housing in which major components are assembled in a factory and then shipped to the building site to be joined with other components to form the finished structure.

Modulate
	To control within an infinite range between 0 percent and 100 percent as opposed to on/off control.

Moisture content
	The amount of water contained in the wood, either expressed as a percentage of the weight of the oven-dry wood or as a percentage of total weight of a piece.

Moisture distribution
	Variation in moisture content within a board and/or variation in moisture content between boards.

Moisture gradient
	The difference in moisture content between areas of a board. Usually refers to the moisture content difference between the surface and core of a board.

Monitor
	Screen on which an electronics systems display information.

Motor
	A device which converts electricity or hydraulic fluid power into mechanical force and motion. It usually provides rotary mechanical motion.

Motor control center (MCC)
	Central location for circuit breakers for mill equipment.

Moulding
	A wood strip having a curved or projecting surface used for decorative purposes.

Mountain pine beetle
	A beetle that kills pine trees by eating the living layer of circulatory tissue underneath the bark of the tree. If the infected trees are not harvested in a timely manner the infestation will kill trees at an increasing rate.

MSF
	Is a unit of measure for MDF and plywood equal to 1,000 square feet, on a 3/4 inch basis for MDF and on a 3/8 inch basis for plywood, and MMSF means one million square feet.

MSR
	Machine stress rated lumber is dimension lumber that has been evaluated by mechanical stress-rating equipment. The stress-rating equipment measures the stiffness of the material and sorts it into various modulus of elasticity (E) classes. View: MSR Examples

Multizone
	Technique of dividing a dry kiln into more than two zones of heat control. Used in steam and hot oil kilns.

NBSK
	Northern bleached softwood kraft pulp.

Net scale
	Log volume less defect scaling deductions.

Newton (N)
	Unit of force equivalent to the force that produces an acceleration of one metre per second per second on a mass of one kilogram.

Nominal size
	As applied to timber or lumber, the size by which it is known and sold in the market; often differs from the actual size. A 2x4 actually measures 1-1/2 by 3-1/2 inches.

Old growth (virgin timber)
	Old, naturally established trees often characterized by dense straight grain and a lack of knots and defects.

Open center circuit
	One in which pump delivery flows freely through the system and back to the reservoir in neutral.

Open center valve
	One in which all ports are interconnected and open to each other in the center or neutral position.

Open saw
	An open circular saw is one that is stretched too much in the inner area for the speed at which it is running. It will not stand up straight and will heat in the center while running. In inserted-tooth circular saws, worn shanks can also cause and open saw. Also called a "Dished saw".

Oriented strandboard (OSB)
	Composed of strand-type flakes aligned in directions which make a panel stronger, stiffer, and with improved dimensional properties in the aligned directions than a panel with random flake orientation.

Orifice
	A restriction, the length of which is small in respect to its cross-sectional dimensions.

Outfeed
	The side of a power tool where the board exits.

Oven-dry wood
	Wood dried to a relatively constant weight in a ventilated oven at 102� to 105�C.

Ovendry weight
	Weight obtained by drying wood in an oven at 102 degrees F (plus or minus 3 degrees F) until there is no more weight loss.

Overdry
	Lumber dried to the point of having low moisture content.

Overlay
	A thin layer of paper, plastic, film, metal foil, or other material bonded to one or both faces of panel products, or to lumber, to provide a protective or decorative face, or a base for painting.

Overrun
	The excess lumber, in board feet, actually sawn from logs compared to the amount of lumber predicted by a board foot log scale; usually expressed as a percent of log scale (Scribner).

Overs
	Chips larger than acceptable length or width.

Overstorey
	That portion of the trees, in a forest of more than one storey, forming the upper or uppermost canopy layer.

Panel products
	A descriptor that generally includes some or all of the following: plywood, waferboard and oriented strandboard, hardboard, insulation board, and composites using these materials.

Panel stock
	Stock panels which are 4′ wide and 8′ long. Therefore, the gross length of the veneer required for these panels is at least 98″ to 100″. It may include 9′ and 10′ lengths.

Paper
	Generally, a matted or felted sheet of vegetable fiber, formed on a screen from a water suspension, used for writing and printing as well as for wrapping and many other purposes. Paper is one of two broad subdivisions of the general term, papers; the other is paperboard.

Paper wrap
	Material used to wrap loads of finished lumber to protect it from weather and damage. Normally also display company name and logo.

Paperboard
	A general term describing sheets made of fibrous material 0.012 inch or more in thickness. Compared with paper, paperboard is heavier per unit area, thicker, and more rigid. Paperboard is the term used to describe any single variety, or group of varieties, of board materials used in the production of boxes, folding cartons, and solid fiber and corrugated shipping containers.

Parallam
	Parallel strand lumber (PSL). A composite wood product where veneers are clipped into 1" strips and pressed together (all grain parallel) into a large billet. Billets are cut into different sizes for high strength beam and column applications. The attractive material may be left exposed. CCA treated PSL is also available for exterior use.

Parallel strand lumber (PSL)
	A structural wood product made by gluing together long strands of wood that have been cut from softwood veneer.

Particleboard
	A generic term for a material manufactured from wood particles or other lignocellulosic material and a synthetic resin or suitable binder.

Particleboard, extruded
	Made by ramming binder-coated particles into a heated die, which subsequently cure the binder and forms a rigid mass as the material is moved through the die.

Particleboard, mat-formed
	Particles (being previously coated with the binding agent) are formed into a mat having substantially the same length and width as the finished panel. This mat is then pressed in a heated flat-platen press to cure the binding agent.

Particleboard, Mende-process
	Made in a continuous ribbon from wood particles with thermosetting resins used to bond the particles. Thickness ranges from 1/32 to 1/4 inch.

Particleboard, multilayer
	Wood particles are made or classified into different sizes and placed into the preprocessed panel configuration to produce a panel with specific properties. Panels destined for primarily nonstructural uses requiring smooth faces are configured with small particles on the outside and coarser particles on the interior (core). Panels designed for structural application may have flakes aligned in orthogonal directions in various layers which mimic the structure of plywood. Three- and five-layer constructions are most common.

Pascal (Pa)
	A unit of pressure or stress equal to one newton per square metre.

Peel
	To convert a log into veneer by rotary cutting.

Peeler
	Logs used for peeling into thin layers called veneer for the manufacture of plywood.

Pentachlorophenol (penta)
	A chemical used in wood preserving; it is usually applied under pressure so that it will penetrate the wood.

Photocell
	Device used to detect the presence of an object. A photocell is composed of a transmitter, which transmits an infrared signal to a receiver or reflector.

Photosynthesis
	A process that plants use to synthesize nutrients from water and minerals using sunlight.

Pile
	A long, heavy timber, round or square, driven deep into the ground to provide a secure foundation for structures built on soft, wet, or submerged sites (e.g., landing stages, bridge abutments).

Pilot pressure
	Auxiliary pressure used to actuate or control hydraulic components.

Pilot valve
	An auxiliary valve used to control the operation of another valve. The controlling stage of a 2-stage valve.

Piston
	A cylindrically shaped part which fits within a cylinder and transmits or receives motion by means of a connecting rod.

Pitch
	Accumulation of resin in the wood. This causes resistance moisture meters to read high.

Pitch pocket
	An opening between growth rings which usually contains or has contained resin or bark or both. View: Pitch/Bark Pocket

Pith
	The small cylinder of primary tissue of a tree stem around which the annual rings form; the center of a tree. View: Pith

Planer
	Machine centre used to process rough lumber into a finished product, leaving it smooth and uniform in size. View: Planer Examples

Planer mill
	Although sometimes a separate facility, the planer mill is usually that part of a sawmill where lumber is planed, graded, and sorted.

Planer shavings
	The residue obtained when a piece of wood is surfaced by a planer.

Planing allowance
	The quantity of wood, normally expressed in thousandths of an inch, that is set to be removed by a planer during surfacing.

Platform frame construction
	The type of construction most often used in home building in which the floor joists are completed first and completely covered with a sub-flooring to form a platform upon which exterior walls and interior partitions are erected.

PLC
	Programmable logic controllers. Industrial computer with I/O capability, which programs in ladder-relay logic.

Plenum baffle
	A fixed or adjustable baffle suspended in the plenum chamber of a dry kiln designed to split and direct airflow top to bottom through the lumber load.

Plenum chamber
	The space between the lumber and the outside walls of a dry kiln.

Plumb
	Straight up and down, perfectly vertical.

Plunger
	A cylindrically shaped part which has only one diameter and is used to transmit thrust. A ram.

Ply
	A single sheet of veneer forming one layer in a multi-layered piece of plywood.

Plywood
	A glued wood panel made up of relatively thin layers of veneer with the grain of adjacent layers at right angles, or of veneer in combination with a core of lumber or of reconstituted wood. The usual constructions have an odd number of layers.

Plywood, cold-pressed
	Refers to interior-type plywood manufactured in a press without external applications of heat.

Plywood, exterior
	A general term for plywood bonded with a type of adhesive that by systematic tests and service records has proved highly resistant to weather; microorganisms; cold, hot, and boiling water; steam; and dry heat.

Plywood, interior
	A general term for plywood manufactured for indoor use or in construction subjected to only temporary moisture. The adhesive used may be interior, intermediate, or exterior.

Plywood, marine
	Plywood panels manufactured with the same glueline durability requirements as other exterior-type panels but with more restrictive veneer quality requirements.

Plywood, molded
	Plywood that is glued to the desired shape either between curved forms or more commonly by fluid pressure applied with flexible bags or blankets (bag molding) or other means.

Plywood, postformed
	The product formed when flat plywood is reshaped into a curved configuration by steaming or plasticizing agents.

Pneumatic
	To move or convey an object by air pressure.

Pointing head
	Equipment used to form the point on the end of roundwood fence posts. Can consist of a rotating cutterhead (forms cone shaped point) or sets of cutting blades (two sided/four sided points). View: Pointing Head Examples

Poly under top tier (PUTT)
	A way of giving some protection to unitized lumber by the insertion of a piece of plastic between the next-to-top and top tiers.

Poppet
	That part of certain valves which prevents flow when it closes against a seat.

Port
	An internal or external terminus of a passage in a component.

Positive displacement
	A characteristic of a pump or motor which has the inlet positively sealed from the outlet so that fluid cannot recirculate in the component.

Potentiometer
	A control element in the servo system which measures and controls electrical potential.

Pound (lb)
	A unit of weight equal to 16 ounces (0.45 kilograms). View: Metric / Imperial Conversion

Powder-post damage
	Small holes (1/16" to 1/12" in diameter) filled with dry, crumbled wood, resulting from the work of beetles (mostly Lyctus) in seasoned and unseasoned wood.

Power
	Work per unit of time. Measured in horsepower (hp) or watts (W).

Power boiler
	A boiler that uses wood waste and natural gas as fuel to produce process steam.

Power cut
	The circular saw blade rotates in the same direction as the material is fed during the cutting process.

Power pack
	An integral power supply unit usually containing a pump, reservoir, relief valve and directional control.

Precharge pressure
	The pressure of compressed gas in an accumulator prior to the admission of liquid.

Precision end trimmed (PET)
	Lumber trimmed smooth on both ends and varying no more than 1/16" in nor more than 20% of the pieces. May be a condition of sale.

Prefabricated housing
	Housing units partially or completely built in a factory.

Preprinted linerboard
	Linerboard that is printed before being sent to a box plant for manufacture into a corrugated container.

Preservative
	Any substance that, for a reasonable length of time, is effective in preventing the development and action of wood-rotting fungi, borers of various kinds, and harmful insects that deteriorate wood.

Pressure
	Force per unit area. Usually measured in pounds per square inch (PSI) or kilopascals (kPa). A kilopascal is equal to 1000 newtons per square metre or 0.0102 kg/sq cm (0.145 lb/sq in).

Pressure drop
	The difference in pressure between any two points of a system or a component.

Pressure line
	The line carrying the fluid from the pump outlet to the pressurized port of the actuator.

Pressure override
	The difference between the cracking pressure of a valve and the pressure reached when the valve is passing full flow.

Pressure plate
	A side plate in a vane pump or motor cartridge on the pressure port side.

Pressure reducing valve
	A valve which limits the maximum pressure at its outlet regardless of the inlet pressure.

Pressure switch
	1. An electric switch operated by fluid pressure. 2. Switches that read the available pressure in air and hydraulic lines. These switches are often used as a safety feature, to prevent equipment from operating when there is not enough air pressure or hydraulic fluid pressure.

Pressure treating
	A process of impregnating lumber or other wood products with various chemicals, such as preservatives and fire retardants, by forcing the chemicals into the structure of the wood using high pressure.

Proportional flow
	In a filter, the condition where part of the flow passes through the filter element in proportion to pressure drop.

Proximity switch
	Photoelectric switches that are triggered as a piece passes near them. Proximity switches are used to detect the presence or absence of material.

PSI
	Pounds per square inch.

Pulp logs
	Logs of lesser value (smaller in diameter with acceptable defects) than sawlogs, of greater value than cordwood. Pulp logs are usually bought by the ton to be debarked, reduced to chips, and used to manufacture pulp and paper.

Pulpwood
	Small timber bucked to length (can be longwood or shortwood lengths) for use as a fiber source in a pulpmill.

Pulse generator
	Device attached to a moving chain that produces an electrical signal each time the chain moves a fixed distance. The pulse generator is attached to the chain and used to track the movement of the pieces through a scanner.

Pump
	A device which converts mechanical force and motion into hydraulic fluid power.

Quality control
	Any activity that helps to maximize the value of the raw material and lumber products through all phases of the manufacturing process. View: Quality Control Examples

Quartersawn
	Lumber sawn so that the annual rings form angles of 45 to 90 degrees with the surface of the piece.

Radial
	1. Coincident with a radius from the axis of the tree or log to the circumference. A radial section is a lengthwise section in a plane that passes through the center of the tree stem. 2. A longitudinal surface or plane extending wholly or in part from the pith to the bark.

Radial clearance
	Angular clearance on the sides of a saw tooth or saw blade.

Ram
	A single-acting cylinder with a single diameter plunger rather than a piston and rod. The plunger in a ram-type cylinder.

Random lengths (RL)
	Lumber of various lengths, usually in even two-foot increments. Lumber offered as random length will contain a variety of lengths which can vary greatly between manufacturers and species. A random length loading is presumed to contain a fair representation of the lengths being produced by a specific manufacturer.

Rate of growth
	The amount of tree growth each year expressed as the number of growth rings per inch.

Rays
	A ribbon-like aggregate of wood cells extending radially across the grain, radiating out from the pith to the bark.

Reaction wood
	Wood that forms in a tree in response to leaning. Called Compression wood in softwoods, since it forms on he underside of the stem or limb. In hardwoods it forms on the upper side and is called Tension wood. View: Compression Wood

Receiver
	Head of a scanner that monitors the infrared signals transmitted by the transmitter head.

Reciprocation
	Back-and-forth straight line motion or oscillation.

Recoverable heat
	Heat energy from combustion that is actually recovered to do useful work.

Recovery
	1. Product recovery: An expression of the amount of product (nominal or actual) that can be manufactured from a given input of raw material. 2. Logging recovery: The volume or weight of logs that can be harvested from a given volume of standing timber. View: Product / Lumber Recovery

Recovery boiler
	A boiler that recovers process chemicals for re-use and creates process steam with the heat it generates.

Recyclable paper
	Paper capable of being recycled. Almost all paper is recyclable if sorted by paper type and if contaminants (such as plastic and food products) are removed.

Regenerative circuit
	A piping arrangement for a differential type cylinder in which discharge fluid from the rod end combines with pump delivery to be directed into the head end.

Relative humidity
	Ratio of the amount of water vapour present in the air to that which the air would hold at saturation at the same temperature. It is usually considered on the basis of the weight of the vapour but, for accuracy, should be considered on the basis of vapour pressures.

Relief valve
	A pressure operated valve which by-passes pump delivery to the reservoir, limiting system pressure to a predetermined maximum value.

Reman
	Abbreviation for remanufactured, used to describe boards that require further manufacturing.

Replenish
	To add fluid to maintain a full hydraulic system.

Resaw
	A machine to cut boards, planks, slabs, or other material length-wise into two or more pieces, usually of equal length and width.

Resawing
	The process of sawing lumber in two lengthwise, parallel to the wide face. It is usually, though not always, done through the middle of the board, producing two equal sized boards, each approximately half the thickness of the original. Resawing changes the thickness of the lumber but not its width. Also see Ripping.

Residual fiber
	Leftover wood fiber from sawmills and plywood plants, and pulpwood derived from timber management activities.

Residue
	1. Logging residue: Unmerchantable tops, branches, and stumps of felled trees, and logs and standing trees that are too small or defective to be removed economically from the woods during a logging operation. 2. Mill residue: That portion of log input volume that remains after the primary product has been produced.

Resin
	An ingredient of coatings which acts as a binder and gives the coating physical properties such as hardness and durability.

Resolution
	The smallest unit used for taking measurements from a scanner or the encoder.

Resorcinol glue
	An adhesive made from resorcinol resin and formaldehyde.

Restriction
	A reduced cross-sectional area in a line or passage which produces a pressure drop.

Return line
	A line used to carry exhaust fluid from the actuator back to sump.

Reverse casehardening
	A final stress-and-set condition in dry lumber in which the outer fibers are under tensile stress and the inner fibers are under compressive stress. This condition is not reversible. See also Casehardening.

Reversing valve
	A four-way directional valve used to reverse a double-acting cylinder or reversible motor.

Right-hand mill
	A sawmill in which the saw and carriage are on the right-hand side of a person standing on the log deck and facing the rear of the mill.

Rim speed
	The speed of the saw blade at the extreme periphery when rotated. View: Gang Edger Formula, Quad Sawbox Formula

Rip
	To cut a board lengthwise, parallel to the fibers.

Rip tooth
	The type of saw tooth adapted for cutting parallel to the fibers of wood.

Ripping
	Sawing or cutting with the grain as with a rip saw. When ripping is done on a planer, it is usually called splitting.

Risers
	Small distribution ducts within a direct-fired dry kiln that distribute heated air between the tracks from an underground main distribution duct.

Roller
	A cylindrical body movable about its longitudinal axis.

Rotary actuator
	A device for converting hydraulic energy into rotary motion - a hydraulic motor.

Rotary cut
	Manner of cutting veneer whereby a log is centered in large lathe. As the log revolves, the cutting knife moves toward the center and a continuous sheet of veneer is peeled from the log.

Rotation age
	The period of years required to establish and grow a timbercrop to a specified condition of maturity. The intended age of harvest of mature trees. Long rotations mostly affect those features that are desirable in lumber and in structural and non-structural products made largely of wood in solid form. Harvest age has less impact on the usefulness of wood for use in paper and fiber products and in products in which wood is reduced to small pieces prior to manufacture.

Round-faced hammer
	A type of hammer used to flatten the surface and put tension in circular saws. It has a circular face with a convex plane, the curvature conforming to a radius of 4½ inches (114 mm).

Roundup
	The irregularly shaped pieces of veneer that are initially produced when a debarked, irregularly shaped and tapered log engages a rotary lathe during manufacture of veneer.

Roundwood
	Wood products that are round, such as pulpwood, posts, pilings, utility poles, and fencing materials.

RPM
	Revolutions per minute.

RTD
	A temperature measuring device that measures the change in electrical resistance to determine temperature (resistive thermal device).

Rung
	An element of the PLC ladder logic program. Each rung looks at input signals and turns output signals on or off. The program runs by scanning the ladder logic, testing the input points and the instructions on each rung, and turning the output points on or off.

Runout
	Deviation from flatness of circular saw near periphery when rotated.

S1S2E
	Surfaced one side and two edges.

S4S
	Surfaced four sides.

Sap
	The watery fluid that circulates through a tree carrying the chemical food that enables the tree to grow; rich in minerals and nutrients.

Sap stain
	A discoloration of sapwood, caused by certain molds and fungi, that is not accompanied by softening or other disintegration of the wood.

Sapling
	A young tree of small diameter, typically 2 to 5 inches at dbh.

Sapwood
	The outer layers of a tree stem that contain living cells. The sapwood is distinctly lighter in Southern Pine than the heartwood it encloses.

Sash gang
	A frame saw in which one or several straight blades are clamped in a reciprocating frame.

Saw eye
	The hole in the centre of a circular saw blade so it can be fitted on the arbor.

Saw kerf
	The width of the saw tooth at its outermost widest point.

Saw log
	A log suitable in size and grade for producing sawn lumber.

Sawdust expansion factor
	The amount to allow for sawdust to expand from its solid wood form after being sawn. This also allow for the air space between sawdust particles in the gullet.

Sawing deviation
	The deviation from target sawn sizes caused by the saws.

Sawn timber
	Timber finished to size with a saw.

Scaler
	The person who measures the diameter and length of the logs determines specie and grade, and makes deductions for footage calculations.

Scaling (lumber or logs)
	Logs are measured (or scaled) for the purpose of estimating the amount of lumber that can be obtained. Once logs have been processed into lumber it is again necessary to quantify volumes produced. The process of measuring lumber is called lumber scaling. The volume lumber yielded from a log may be greater than the estimated volume of lumber. Also see Yield.

Scallop depth
	The depth of the arc created by the planer head on the finished surface of lumber. View: Scallop Depth, Knife Mark Calculator

Scanner
	Generally an optical or laser/camera measuring device. Scanners are composed of a transmitter head and a receiver head, which permit electronics system to obtain the shape and the dimensions an object. View: Scanner Examples

Schedule
	The "recipe" for drying lumber, which dictates wetbulb and drybulb setpoints throughout the drying cycle.

Schoolmarm
	A tree stem that branches into two or more trunks or tops.

Scragg mill
	A special high-speed sawmill designed to saw small diameter logs. A scrag mill typically has two circle saws arranged in parallel which remove two slabs with one pass of the log producing a two-sided cant.

Scribner Log Rule
	The Scribner Log Rule, developed around 1846, is a good example of a diagram rule. It was created by drawing the cross-sections of 1-inch boards within circles representing the end view of logs. A space of 1/4 inch was left between the boards to account for saw kerf. The Scribner Rule does not have an allowance for log taper and typically underestimates logs, particularly if the log length is long. The Scribner Decimal C is a different form of the Scribner Rule; it rounds the volumes to the nearest 10 board feet. For example, 392 board feet on the Scribner is equivalent to 390 board feet on the Scribner Decimal C scale.

Scribner, East-side
	Reference to the method of applying the Scribner Log Rule and obtaining log measurements, other than in western Oregon and western Washington.

Scribner, West-side
	A term commonly used to refer to the method for applying Scribner Log Scale and taking measurements in western Oregon and western Washington.

Seasoned timber
	Timber that has been dried so that the maximum moisture content anywhere in the piece does not exceed 15%.

Seasoning
	Drying timber to a moisture content appropriate to the conditions and purposes for which it is to be used.

Select structural
	The highest grade of structural joists and planks. This grade is applied to lumber of high quality in terms of appearance, strength, and stiffness.

Select tight knot (STK)
	A grade term frequently used for cedar lumber. Lumber designated STK is selected from mill run for the tight knots in each piece, as differentiated from lumber which may contain loose knots or knotholes.

Semichemical pulp
	Pulp obtained by mild treatment of wood chips by any of the chemical pulping processes, which remove only part of the lignin from the wood chips, followed by mechanical treatment to complete the separation of individual cellulose fibers.

Sequence
	The order of a series of operations or movements.

Sequencing valve
	A pressure operated valve which, at its setting, diverts flow to a secondary line while holding a predetermined minimum pressure in the primary line.

Servo mechanism (servo)
	A mechanism subjected to the action of a controlling device which will operate as if it were directly actuated by the controlling device, but capable of supplying power output many times that of the controlling device, this power being derived from an external and independent source.

Servo valve
	Electro-mechanical device used to control a setworks hydraulic cylinder. An electrical signal is sent to the servo valve which opens, allowing hydraulic fluid to flow into the cylinder. The voltage level and direction of the electrical signal determine the speed and direction of the setworks movement.

Set complete
	The actual position of a setworks is within a certain distance of the command position to which it was sent.

Set complete range
	The maximum distance allowed between the actual position of a setworks and the position to which the setworks was sent. When the setworks position is in this range, the setworks is at set complete.

Sfpm
	Surface feet per minute of a saw.

SG
	Specific gravity. Also called relative density. As applied to wood, the ratio of the oven-dry weight of a sample to the weight of a volume of water equal to the volume of the sample at a specified moisture content (green, air-dry, or oven-dry).

Shake
	1. A separation along the grain, the greater part of which may occur at the common boundary of two rings or within a growth ring. It is usually considered to have occurred in the standing tree or during felling. 2. A western red cedar roofing and sidewall product made by splitting blocks of cedar, as opposed to shingles which are manufactured by sawing. View: Ring Shake

Shank
	A device for locking inserted teeth in a circular saw.

Shape Sawing
	Sawing a log or cant following the arc or curvature of the log or cant. Also referred to as curve sawing or sweep sawing. Some systems follow an arc and other systems can follow a coumpound curve. View: Shape Sawing Example

Shaper
	An implement, consisting of dies and levers, which is used to compress saw teeth to a prescribed pattern.

Shaving
	A small wood particle of indefinite dimensions developed in the planing process. This cutting action produces a thin chip of varying thickness, usually feathered along at least one edge and thick at another and generally curled.

Shear
	A mechanical cutting head, attached to a harvester, which severs the tree from the stump with a scissors-like action.

Shear firewood processor
	Equipment used to produce firewood as a business. Uses a shearing action to shear the logs into blocks. View: Shear Firewood Processor Examples

Sheathing
	The structural covering, usually of boards, building fiberboards, or plywood, placed over exterior studding or rafters of a structure.

Sheave
	The grooved wheel of a pulley.

Sheaves
	Pulleys mounted on the end of the drive and motor shaft over which belts pass to transfer rotational force from the motor to the shaft.

Shim
	A thin piece or strip of metal used to fill in, as in leveling.

Shingles
	Thin, rectangular pieces of wood, sawn along the grain and tapering in thickness, used like tiles for roofing and weatherboarding.

Shiplap
	Lumber that has been worked to make a rabbeted joint on each edge so that pieces may be fitted together snugly for increased strength and stability.

Shipping dry
	Having a moisture content (oven-dry basis) of 14 to 20%. Results in reduced shipping weight and less susceptibility to decay.

Short ton
	2,000 pounds or 0.9072 tonnes.

Shortwood
	Pulpwood less than 10 feet long.

Shrinkage
	The contraction of wood to water loss below fiber saturation point. Expressed as a percentage of the green dimension.

Side clearance
	The distance that the side of the saw tooth projects beyond the body of the saw.

Side dressing
	The act of adjusting all saw teeth on a saw to project laterally the same distance from the plate.

Side gauge
	A measuring device to indicate the amount of lateral (sidewise) projection of saw teeth beyond the surface of the saw.

Siding
	The finish covering of the outside wall of a frame building, whether made of horizontal weatherboards, vertical boards with battens, shingles, or other material.

Signal
	A control impulse from a control device or sensor.

Silviculture
	The process of growing and tending forests using both natural and enhanced methods.

Skidder
	A wheeled or tracked vehicle used for sliding/dragging logs from the stump to the landing.

Skyline
	A cableway stretched tautly between two points and used as a track for a block or carriage.

Slab
	The exterior portion of a log removed in sawing lumber.

Slash
	Tree tops, branches, bark, and other debris left after a forest operation.

Sliced
	This is the method by which most of the find face of veneers are cut. Flat cut and quartered veneers are cut on the slicer as are crotch blocks. The log is first sawn into flitches (sometimes called cants), and this is most commonly a quarter section or half section of a log. It may be trimmed to a many-sided section, but two parallel sides are necessary, one to be held against the surface of the flitch table on the slicer, which clamps the flitch and moves up and down by an electric drive in a slightly shearing motion. The slicer knife, on another section of the machine is fed toward the flitch table slowly, in increments depending on thickness of veneer being cut. In contrast t the feed on the veneer lathe, which moves the knife steadily into the log in rotary cutting, the slicer knife is moved toward the flitch the full amount of the thickness of veneer with each stroke.

Slope of grain
	The angle between the direction of the grain and the axis of a piece of lumber, expressed as a ratio.

Sludge
	Solid material separated from liquid pulp mill effluent during treatment.

Snag
	A dead or dying tree that is still standing.

Snaked saws
	Wavy saw line seen most often in band-sawed lumber. Graded as skipped dressing.

Snatch block
	A block that can be opened on one side to allow a cable or rope to be laid in the block, instead of threading it through from one end.

Sock, wetbulb
	A fabric wick placed over a drybulb that cools the drybulb by evaporation to determine the relative humidity of the drying conditions.

Soft rot
	A special type of decay that develops in the outer wood layers under very wet conditions, such as in cooling towers and boat timbers. It is caused by micro-fungi that attack the secondary cell walls (and not the intercellular layer) and destroy its cellulose content.

Softwoods
	Generally, one of the botanical groups of trees that in most cases have needlelike or scalelike leaves, the conifers, also the wood produced by such trees. The term has no reference to the actual hardness of the wood.

Solid tooth
	A saw tooth formed from and an integral part of the saw blade itself.

Solid wood
	Wood as it is observed in a tree, log, or piece of lumber and hence free of manufactured voids as would occur between chips or free of nonwood materials such as resins and other additives.

Solids fraction
	The portion of a space or container that is occupied by solid wood as opposed to voids between the pieces.

Southern Yellow Pine
	A species group, composed primarily of Loblolly, Longleaf, Shortleaf, and Slash Pines. Various subspecies also are included in the group.

Spar
	A tree, wood mast, or metal tower used to support rigging for one of the many cable yarding systems.

Species
	Type of wood: Spruce, Pine, Oak, Cedar, etc.

Specific gravity
	Also called relative density. As applied to wood, the ratio of the oven-dry weight of a sample to the weight of a volume of water equal to the volume of the sample at a specified moisture content (green, air-dry, or oven-dry).

Specific heat
	The heat in joules required to raise the temperature of one gram of wood 1°C.

SPF
	See Spruce-Pine-Fir.

Splitting maul
	A splitting maul or maul is a heavy long handled hammer used for splitting a piece of wood along its grain. One side is shaped like a sledge hammer and the other is a broad head axe shape. View: Splitting Maul Examples

Splitting wedge
	A triangular shaped tool used to separate two objects. Used in manual log splitting (2 way) or powered log splitters / firewood processors (2, 4, 6 or more ways). View: Splitting Wedge Examples

Spool
	A term loosely applied to almost any moving cylindrically shaped part of a hydraulic component which moves to direct flow through the component.

Spring set
	Alternately bending saw teeth to make the kerf wider than the blade.

Springwood
	The portion of the annual growth ring that is formed during the early part of the growing season. It is usually less dense and weaker mechanically than latewood.

Spruce-Pine-Fir (SPF)
	Canadian woods of similar characteristics that are grouped as one lumber type for production and marketing purposes. Kiln-dried SPF lumber is used as a structural framing material in all types of residential, commercial, industrial and agricultural building applications. SPF species range in color from white to pale yellow.

Sprung saw
	A twisted or bent saw which will manifest itself by chattering and heating.

Spur road
	A short, low standard branch road generally accessing one or two landings; often dead ending at the last landing.

Spur trim
	In the process of converting a log into veneer, devices called spur knives trim the raw veneer from a log to a desired veneer length; the difference between the log length and veneer length is the spur trim.

Square
	A measure of the amount of material (e.g., shingles) required to cover a surface area of 100 square feet when applied as recommended.

Square-faced hammer
	A type of hammer used to flatten the surface of and put tension in circular saws. The face has a rectangular outline with a convex plane, the curvature conforming to a radius of 9� inches.

Stack heat loss
	Loss of combustion heat via gas emissions in the smokestack of chimney.

Stacker
	A mechanical device for making up unit packages of lumber for drying. As each layer of lumber is deposited on the unit, sticks are inserted manually or by machine between the layers. View: Lumber Stacker Examples

Steam
	Vapor produced by heating water.

Steam sprays
	Mechanical equipment for introducing water vapor or steam to the kiln environment.

Stem
	The principal axis of a tree, capable of producing sawlogs, veneer logs, large poles, or pulpwood.

Stere
	A metric measure of cordwood or pulpwood representing a stack of such wood 1 x 1 x 1 metres. Approximately 0.27 cord.

Sticker
	A wooden strip laid between each layer of lumber as it is stacked for drying. Permits transfer of heat into and removal of water from the lumber stacks.

Strainer
	A coarse filter.

Strapping
	Metal or plastic bands tensioned around finished loads of lumber to hold the load together during transport. View: Strapping Examples

Streamline flow
	A condition where the fluid particles move in continuous parallel paths.

Stroke
	1. The length of travel of a piston or plunger. 2. To change the displacement of a variable displacement pump or motor.

Structural timbers
	Pieces of wood of relatively large size, the strength or stiffness of which is the controlling element in their selection and use. Examples of structural timbers are trestle timbers (stringers, caps, posts, sills, bracing, bridge ties, guardrails); car timbers (car framing, including upper framing, car sills); framing for building (posts, sills, girders); and crossarms for poles.

Stud
	One of a series of vertical load bearing members used as supporting elements in walls and partitions.

Stumpage
	1. The value of timber as it stands uncut in the woods. The residual value after all logging costs are taken from the delivered price of logs at the mill yard. 2. The price charged for the right to harvest timber from publicly or privately-owned forest land.

Sub-plate
	An auxiliary mounting for a hydraulic component providing a means of connecting piping to the component.

Suction line
	The hydraulic line connecting the pump inlet port to the reservoir or sump.

Sulfate process
	A chemical pulping process in which lignin is dissolved by a solution of sodium hydroxide and sodium sulfide.

Sulfite process
	A chemical pulping process in which wood is cooked in aqueous acid sulfite solution containing free sulfur dioxide.

Sulfite pulp
	A chemical wood pulp obtained by cooking wood chips in a bisulfite-sulfurous acid solution.

Summerwood
	The portion of the annual growth ring that is formed after the earlywood formation had ceased. It is usually denser and stronger mechanically than earlywood.

Sump
	A reservoir.

Supercharge
	1. To replenish a hydraulic system above atmospheric pressure. 2. To fill an accumulator with fluid under pressure (See Precharge pressure).

Surface checks
	Checks that occur on the wood surface during seasoning; they may extend to varying depths into the wood. View: Checks

Surfaced
	Lumber that has gone through a planer so that its sides are smooth and uniform in size.

Surfaced-dry (S-dry)
	The condition referring to lumber that has been air or kiln dried and subsequently planed to a smooth surface.

Surge
	A transient rise of pressure or flow.

Sustained yield
	The yield a forest can produce in perpetuity at a given intensity of management without impairment of the land's productivity, with the intent that there will be balance between timber growth and harvesting on a sustainable basis.

Swage or swedge
	A method of shaping a saw tooth to provide side clearance on both sides of each tooth.

Swamp
	To clear brush and obstructions for a cat clearing roads or skidtrails. The person doing this hand work is called a swamper.

Swash plate
	A stationary canted plate in an axial type piston pump which causes the pistons to reciprocate as the cylinder barrel rotates.

Sweep
	A gradual (but pronounced) bend in a log, pole, or piling; considered a defect. Sweep in a log is analogous to "bow" in a piece of lumber.

Sweep Sawing
	Sawing a log or cant following the arc or curvature of the log or cant. Also referred to as curve sawing or shape sawing. Some systems follow an arc and other systems can follow a coumpound curve. View: Sweep Sawing Example

Synchro
	A rotary electromagnetic device generally used as an AC feedback signal generator which indicates position. It can also be used as a reference signal generator.

SYP
	Southern Yellow Pine. A species group, composed primarily of Loblolly, Longleaf, Shortleaf, and Slash Pines. Various subspecies also are included in the group.

Tachometer (AC) (DC)
	A device which generates an AC or DC signal proportional to the speed at which it is rotated and the polarity of which is dependent on the direction of rotation of the rotor.

Tailspar
	A spar at the outer end of a skyline system, away from the landing, which elevates and supports one end of the skyline.

Tailtree
	A standing tree used as tailspar.

Tangential
	A tangential section is a longitudinal section through a tree perpendicular to a radius. Flat-grain lumber is sawn tangentially.

Tank
	The reservoir or sump.

Taper
	1. The difference in diameter between the top end and the butt end of a log. 2. Boards that are thicker or wider on one end than on the other. Graded as skip.

Target moisture content
	The amount of moisture targeted to be left in the lumber at the end of a dry kiln charge.

Target size
	The size that lumber must be cut in the green form to allow for sawing deviation, shrinkage in drying and allowance for fibre removed in the finishing process. View: Target Size

Temperature drop across the load (TDAL)
	Also called DAL and Delta T (change in temperature). The temperature of the air entering a package minus the temperature of the air exiting a package.

Temposonics
	Linear displacement transducer.

Tenoning head
	Equipment used to form a cylindrical tenon on the end of roundwood posts or poles. Consists of a rotating cutterhead. View: Tenoning Head Examples

Tension gauge
	Similar to a straightedge but having a convex edge, the curvature of which exactly coincides with the concave curvature of a properly tensioned saw; used when making the test for tension.

Tension or tensioning
	A method of stretching the saw body in the inner area of either a circular saw or band saw to compensate for heating that expands the circular saw periphery or the band saw edges. The amount of tension required is affected by gauge, saw speed, number and kind of teeth, diameter of a circle saw, width of a band saw, wood species, horsepower, feed speed, etc. As a general rule on circular saw, large, thin, fast, heavily loaded saws require more tension than small, thick, slow, lightly loaded saws. Wide, thick band saws require more tension than narrow, thin bands. A very thin, narrow band may need no tensioning.

Tension wood
	Abnormal wood found in leaning trees of some species and characterized by the presence of gelatinous fibers and excessive longitudinal shrinkage. Tension wood fibers hold together tenaciously, so that the sawed surfaces usually have projecting fibers, and planed surfaces often are torn or have raised grain. Tension wood may cause warping. View: Compression Wood

Thermal oil
	A heat transfer fluid used instead of steam. They are not interchangeable within the same kiln. Thermal oil is capable of higher temperatures at low operating pressure and is not susceptible to freezing.

Thermocouple (TC)
	A sensor that measures temperature based on the voltage difference between two dissimilar metals.

Thermomechanical pulp (TMP)
	A high yield pulp produced by a process in which wood chips are softened by preheating under pressure prior to mechanical separation into a mass of fibers.

Thermosetting glues and resins
	Glues and resins that are cured with heat but do not soften when subsequently subjected to high temperatures.

Thinning
	A practice in which certain trees are removed from a dense stand to allow the remaining trees adequate sunlight, nutrients and moisture to grow at an even rate.

Tier
	Horizontal course in a stack of lumber.

Timber supply area (TSA)
	An area of forest land designated by the Minister of Forests of British Columbia and allocated an AAC from which non-area based timber tenures are granted.

Timber, standing
	Timber still standing of the stump.

Timbers
	Lumber that is nominally 5 inches or more in least dimension. Timbers may be used as beams, stringers, posts, caps, sills, girders, purlins, and so forth.

Timbers, round
	Timbers used in the original round form, such as poles, piling, posts, and mine timbers.

Ton (T)
	1. US unit of weight equal to 2,000 lb; also called a Short ton. 2. British unit of weight equal to 2,240 lb (1,016 kg); also called a Long ton. View: Metric / Imperial Conversion

Tongue and groove
	Lumber machined to have a groove on one side and a protruding tongue on the other, so that pieces will fit snugly together, with the tongue of one fitting into the groove of the other.

Tonne
	A unit of weight in the metric system equal to 1,000 kilograms or approximately 2,204 pounds. Also called a Metric ton. View: Metric / Imperial Conversion

Tooth bite
	The length of cut for each tooth on a saw as wood is feed to the saw. Tooth bite will vary based on arbor rpm, tooth pitch, saw diameter and feed speed. View: Bandmill Formula, Gang Edger Formula, Quad Sawbox Formula

Tooth pitch
	The distance between teeth on a saw.

Tooth pressure
	The force each tooth exerts when cutting.

Top bevel
	An angle filed across the top of the tooth, usually staggered on alternate teeth. If all teeth are angled in one direction, the saw will pull to one side.

Top clearance
	The angle of clearance on the top of a saw tooth. Also "Clearance angle" or "Back clearance angle".

Torque
	A rotary thrust. The turning effort of a fluid motor usually expressed in inch pounds.

Torque converter
	A rotary fluid coupling that is capable of multiplying torque.

Torque motor
	A type of electromechanical transducer having rotary motion used in the input stages of servo valves.

Total reduced sulphur (TRS)
	Sulphur compounds produced in a kraft pulping process that can exhibit a "rotten egg" smell.

Total suspended solids (TSS)
	The total amount of suspended solids dispersed in a liquid.

Tower
	A steel mast or framework, generally portable, used instead of a spar tree for cable yarding.

TPD
	Tons per day.

Tracheids, longitudinal
	The elongated cells or fibers that comprise the majority of the anatomical structure of softwoods. Also present in some hardwoods.

Transducer (or feedback transducer)
	An element which measures the results at the load and sends a signal back to the amplifier.

Traps
	A device that separates condensate and air from the steam within the steam heating coils.

Traps, float and thermostatic
	Traps that discharge condensate at a rate dependent on the position of an internal float. Air is removed through a thermostatic air vent.

Traps, inverted bucket
	Mechanical traps that operate on the difference in the density between steam and water.

Traps, orifice
	Traps that discharge steam at a constant rate and have no internal moving parts to alter or stem its flow.

Traps, thermostatic
	Traps that use an internal bellows, which expands when steam flows to the trap, closing the orifice. As condensate accumulates the bellows contracts to release it.

Trim
	The amount of extra length allowed when bucking logs or sawing green lumber to compensate for end checking and damage in transit, and for "squaring up" at the mill. The allowance is specified in contracts and by log scaling agencies.

Trimmer
	Machine centre with multiple saws for trimming defect from boards and producing a defined length of lumber. View: Trimmer Examples

Trimming
	The manufacturing step that squares the length of boards.

Truss
	An assembly of members combined to form a rigid framework. All members are interconnected to form triangles. Light frame trusses are made from dimension lumber restrained by toothed plates. Heavy trusses are made for large members restrained by bolts and connectors or glulam rivets.

Turbine
	A rotary device that is actuated by the impact of a moving fluid against blades or vanes.

Turbulent flow (turbulence)
	A condition where the fluid particles move in random paths rather than in continuous parallel paths.

Turn
	Any log or group of logs attached by some means to power and moved from a point of rest to a landing.

Twin circular
	A mill that has both a right-hand and a left-hand saw; used to slab logs or to rip cants. Both saws may be so mounted as to permit altering the distance between them. Also used to describe an over-under circular saw headrig.

Twist
	A spiral distortion along the length of a piece of timber so that the four corners of any face are no longer in the same plane. View: Twist

Twists
	Ridged projections on the surface of a circular saw.

Two-way valve
	A directional control valve with two flow paths.

Undercut
	A notch cut in a tree to guide the direction of the tree fall and to prevent splitting or kickback.

Uninterruptible power supply (UPS)
	Provides conditioned power and battery backup for computers in the case of a power failure or brownout.

Unload
	To release flow (usually directly to the reservoir), to prevent pressure being imposed on the system or portion of the system.

Unloading valve
	A valve which by-passes flow to tank when a set pressure is maintained on its pilot port.

Unpeeled (roundwood)
	Roundwood without the bark removed. Commonly called "Barkies".

Unscrambler
	Machine that maximizes the loading by retrieving a single piece of wood from a pile and by transferring it to a conveyor or transfer. View: Unscrambler Examples

Vacuum
	Pressure less than atmospheric pressure. It is usually expresses in inches of mercury (in Hg) as referred to the existing atmospheric pressure.

Value-added product / value-added production
	Adding value to a product by further processing it. Examples of value-added wood products include joinery stock, windows, doors, kitchen cabinets, flooring and mouldings. Value-added pulp and paper products include such items as packaging, diapers, coated papers, tissue, business papers and stationery, and other consumer paper products.

Valve
	A device which controls fluid flow direction, pressure, or flow rate.

Velocity
	The speed of flow through a hydraulic line. Expressed in feet per second (fps) or inches per second (ips).

Veneer
	A thin layer or sheet of wood.

Veneer, rotary-cut
	Cut in a lathe which rotates a log or bolt, chucked in the center, against a knife.

Veneer, sawed
	Produced by sawing.

Veneer, sliced
	Sliced off a log, bolt or flitch with a knife.

Vent
	To permit opening of a pressure control valve by opening its pilot port (vent connection) to atmospheric pressure.

Venting
	The act of discharging hot, moisture-laden air from a dry kiln.

Vents
	The opening in a dry kiln roof or wall that can be opened and closed to control the wetbulb temperature in a kiln.

Vertical grain (VG)
	Lumber that is sawn at approximately right angles to the annual growth rings so that the rings form an angle of 45 degrees or more with the surface of the piece.

Vertically laminated timbers
	Laminated timbers designed to resist bending loads applied parallel to the wide faces of the laminations.

Viscosity
	A measure of the internal friction or the resistance of a fluid to flow.

Viscosity index
	A measure of the viscosity-temperature characteristics of a fluid as referred to that of two arbitrary reference fluids.

Waferboard
	A particle panel product made of wafer-type flakes. Usually manufactured to possess equal properties in all directions parallel to the plane of the panel.

Wane
	The absence of square wood on the edge of a board from any source. View: Wane

Wane allowance
	The maximum percentage of wane that can be left on the edge of a cut board.

Warp
	Any deviation from a true or plane surface in a board. View: Warp

Water box or trough
	A water container mounted under the wetbulb that supplies water to the wick or sock in a dry kiln.

Water hammer
	Potentially damaging condition in steam pipes where waves develop on the condensate surface within a pipe as steam rushes over it. If the peak of the wave becomes high enough to reach the roof of the pipe, the water in the wave is pushed violently to the far end of the pipe.

Waterlogged
	Condition of steam coils where condensate is not discharged at a sufficient rate to keep it from accumulating in the coil. Filled with condensate, the coils do not transfer significant heat to the kiln.

Weave or wobble
	A circular saw will weave, wobble, or flutter if the rim area is too long for the speed at which it operates. The speed at which it flutters is the critical speed for that particular saw diameter and tension.

Wedge
	A triangular shaped tool used to separate two objects. Used in manual log splitting (2 way) or powered log splitters / firewood processors (2, 4, 6 or more ways). View: Wedge Examples

Western Red Cedar
	Thuja Plicata. This species is found principally along the western edges of British Columbia, Washington and Oregon. The wood is soft, straight-grained, and extremely resistant to decay and insect damage. It is used extensively in roof coverings, exterior sidings, fences, decks, and other outdoor applications.

Wetbulb
	A drybulb with a wet sock pulled over it to measure the cooling effect of moisture evaporation from its surface. Used to monitor and maintain humidity conditions within a dry kiln.

Wetbulb depression
	The difference in wetbulb and drybulb temperatures.

White rot
	A type of wood-destroying fungus that attacks both cellulose and lignin, producing a spongy and stringy mass that is usually whitish but which may assume various shades of yellow, tan, and light brown.

White wood (roundwood)
	Roundwood with the bark removed by any method and left untreated.

Widow maker
	Any loose overhead debris such as limbs or tree tops that may fall at any time. Widow makers are extremely dangerous and present the faller with a continual source of danger. Limb or other loose material dropped or thrown from a tree toward the faller as the tree is felled.

Wobble plate
	A rotating canted plate in an axial type piston pump which pushes the pistons into their bores as it "wobbles".

Wood
	A solid lignocellulosic material naturally produced in trees and some shrubs, made of up to 40%-50% cellulose, 20%-30% hemicellulose, and 20% -30% lignin.

Wood biodeterioration
	The destruction and eventual reduction of wood to its component sugars and lignin elements through attack by organisms such as, fungi, and certain insects, for instance, termites.

Wood cells (vessels)
	The basic units comprising wood having open ends and set one above the other so as to form continuous tubes. The openings of the vessels on the surface of a piece of wood are usually referred to as pores.

Wood preservative
	Any suitable substance that is toxic to fungi, insects, borers, and other living wood-destroying organisms.

Wood residue
	Wood chips, shavings and sawdust produced by a sawmill.

Wood soap
	A naturally occurring bi-product of pulping wood chips.

Work
	The application of force over a definite distance. Work (W) = Force (F) x distance (s). Expressed in joules, ergs, and foot-pounds. The joule is exactly the amount of work done in exerting the basic metric unit of force, 1 newton, over the basic metric unit of distance, 1 metre.

Yard (yd)
	Unit of length equal to 3 feet (91.5 centimetres). View: Metric / Imperial Conversion

Yield
	1. Product recovery: An expression of the amount of product (nominal or actual) that can be manufactured from a given input of raw material. 2. Logging recovery: The volume or weight of logs that can be harvested from a given volume of standing timber.

Zoning
	The way a dry kiln is divided into temperature control areas.