Glossary of Lumber Terms Malawi
|We hope that you will find below list of terms to be helpful in
your understanding (or clarification) of terms used in lumber business. If you find that we have omitted a definition or that we have something
incorrect, feel free to contact us.|
Air-dried lumber - Lumber
that was dried, usually outside, to an equilibrium moisture content with air it was exposed to. Any lumber below 30% MC is classified as air dried. Construction grade is
around 19% MC and in southern Ontario relative humidity is usually between 50 to 60 %
which lumber will equalize to moisture content to between 8 to 14% MC.
Annual growth rings - layer of growth that a
tree puts on in one year. annual growth rings can be seen in and grain of lumber.
Birds-eye figure - A figure on wood,
usually maple and a few other species. figure is composed of many small rounded areas
resembling a birds eye. figuring is most common on plain and rotary sawn lumber.
Board Foot - A form of wood measurement,
where one board foot equals volume of a board I inch thick, 12 inches wide, and 12
Bookmatch - A term in veneering or
sawing, where successive pieces of veneer, or boards, from a flitch, or log, are arranged
side by side. A properly done bookmatch will resemble a mirror image of opposite side.
Other names are sisters, butterflied and mirrors.
Bound water- water found within cell
wall of wood.
Bow - A defective piece of lumber that
has warped along its length.
Brad - A small finishing nail up to
Burl - Bulges and irregular growths that
form on trunks and roots of trees. Burls are highly sought after for incredible
veneer they yield and are used in turning as well.
Butt Joint - A woodworking joint where
edges of two hoards are placed against each other.
Cambium - live, actively growing,
layer of a tree. cambium is one cell thick and resides between sapwood and the
phloem. It repeatedly divides itself to form new wood end causes tree to grow and
expand. It is layer that becomes either bark or wood and lies dormate in winter.
Case Hardening - A defect in lumber
caused by improper drying. Case Hardening is caused when a board is dried too fast. The
outer layers in a case hardened board are compressed while inner layers are in
Cell - smallest, microscopic,
structure in wood.
Check - A lumber defect caused by uneven
shrinking of wood during drying. A checked board has splits which develop lengthwise
across growth rings.
Clear - A board which is free of defects.
Common Grade Lumber - Lumber with obvious
Compound Cut - An angled cut to both the
edge and face of a hoard.
Crook - A lumber defect where there is an
edgewise warp effecting straightness of board
Crotch - In lumber, a piece of wood taken
from fork of a tree. Crotch Veneer is highly valued for its figuring.
Cup (cupping)- A defect in lumber
where face of board warps up like letter U.
D2S - Lumber that has been dressed on two
Deciduous - Generally trees that have
broad leaves that are shed in fall. Usually it is a hard wood.
Defect - An irregularity found in a board
that lowers its strength and value. Common defects are knots, staining, checks, etc..
Edge Joining - Smoothing and squaring the
edge of a board so that it can be glued up |
squarely to another piece.
Equilibrium moisture content(EMC) - When
level of moisture in a board is equal to moisture in surrounding air.
Face Veneer - High quality veneer that is
used for exposed surfaces on plywood.
Flat-sawn Lumber - A method of sawing
lumber where log is cut tangential to growth rings.
Free Water - Moisture found in cell
cavities of wood.
Girth - distance around a tree; the
Grain - size, alignment, and color of
wood fibers in a piece of lumber
Green Lumber(Live) - Freshly cut lumber
that has not had time to dry. Lumber that is above 30% moisture content.
Heartwood - dead inner core of a
tree. Usually much harder and darker than new wood.
Infeed - direction a work piece is
fed into a blade or cutter.
Kiln - In lumber drying, a kiln is a room
or building where temperature, moisture, and air circulating are controlled to dry
Latewood - part of a trees annual
growth ring that is formed later in season
Linear Foot - A measurement of length
of a board.
Lumber - Logs which have been sawn,
planed, and cut to length.
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
Lumber ruler - A tool resembling a ruler
with a handle at one end and a hood at other which is used to calculate board
footage of a piece of lumber.
Medium density fiberboard (MDF) - A
special type of tempered hardboard characterized by a very fine, smooth finish. MDF is
used in cabinet making.
Mill-run- Lumber that is in varying
widths and grades.
- A measure of amount of water in a piece of lumber.
Nominal Size - rough-sawn size of a
piece of lumber. When purchasing planed lumber it is sold by its nominal, rough sawn,
size. For example a 2"x4" is nominal size for a board whose actual dimension
is 1.4" x 3.25".
Ogee - A decorative molding profile with
a S shape.
Outfeed - side of a power tool where
board exits, (see infeed)
Oven-dried weight -The weight of a piece
of lumber that has been dried, under high temperatures, in an oven until it is devoid of
all water. Used to calculate moisture content of wood.
Particleboard core plywood - Plywood that
is made by gluing a thin layer of veneer to a piece of particleboard.
Phloem - inner part of a tree's bark
that delivers water and other nutrients.
Photosynthesis - A process that plants
use to synthesize nutrients from water end minerals, using light.
Pitch Pocket - A pocket of resinous sap
confined within grain of many conifers.
Pith - soft core in center of a
Plain-Sawn lumber - A method of sawing
lumber where log is cut tangential to growth rings, also called n when referring
Porous wood - Wood with larger than
normal pores and vessels
Quarter-sawn - A method of cutting lumber
where annual rings are relatively perpendicular to face of board. Quarter-sawn
lumber tends to be more dimensionally stable than other forms of lumber, such as
Radial Shrinkage - Shrinkage in a piece
of lumber that occurs across growth rings as it begins to dry.
Ray - A ribbon like figure caused by the
strands of cells which extend across grain in quarter-sawn lumber.
Reaction Wood - Abnormal wood tissue that
was formed in a leaning tree. Reaction wood is very unstable and prone to warping and
cupping when sawn into lumber.
Relative Humidity - amount of
moisture in air is measured as a percentage of total amount of moisture air
can hold at a particular temperature. This is known as relative humidity. ideal
relative humidity for a home is between 35% and 45%, too much above or below these levels
problems can begin to occur.
Ripcut (ripping) - A cut made parallel to
grain of a board.
Rotary-cut Veneer- Veneer which was cut
from a log in one long sheet. Rotary cut veneer is cut from a log like a roll of paper
Rough-sawn - Lumber that is either green
or dried that has not been dressed. (planed).
Sap - water in a tree which is rich
in minerals and nutrients.
Sapwood - new wood in a tree that
lies between bark and heartwood. Sapwood is usually lighter in color, and becomes
heartwood as tree ages.
Seasoning - process of removing the
moisture from green wood to improve its workability and stability.
Selects - In softwood, lumber which has
been graded strictly for its appearance. In hardwood, lumber which is one grade below
first and second.
Softwoods - Generally lumber from a
conifer such as pine or cedar. name softwood does not refer to density of the
wood. There are some hardwoods which are softer than some softwoods.
Sound - A term referring to a board which
has no or very few defects which will effect its strength
Specific Gravity - ratio of the
weight of wood to an equal volume off, rater. higher specific gravity, heavier
Stain - A discoloration in wood caused by
a fungus, minerals or chemicals. A or pigment used to discolor wood.
Sticker - A " to 1" wood
strip that is inserted between stacks of green wood and spaced between 16" to
24" to allow air to flow through stack to ensure proper drying..
Surfaced Lumber - A piece of wood that
has been planed smooth on one or more surfaces.
Surfacing - Way a piece of lumber has
been prepared at lumber mill.
Taper - A piece of wood that has been cut
so that it is wider on one edge than other.
Tongue and Groove - A joinery method
where one board is cut with a protruding "groove" and matching piece is cut with
matching grove along its edge.
Twist - Warping in lumber where ends
twist in opposite directions.
Veneer - A thin sheet of wood cut from a
Veneer-core Plywood - Plywood made from
three or more pieces of veneer glued up in alternating-grain patterns.
Wane - Found usually in mill run lumber,
it is bark running along edge length of board.
Warp - A defect in lumber characterized
by a bending in one or more directions.
Wormholes - Holes and channels cut in
wood by insects.