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The veneer sheet
on the underside of a plywood panel, corresponding in thickness, and often in
species, to the face veneer on the upper or exposed surface. Its grain runs
parallel to the grain of the core, and crosswise to the grain of the
cross-banding.
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BIRD'S EYE
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Due to local
sharp depressions in the annual rings, accompanied by considerable fiber
distortions. Once the depressions are formed succeding
growth rings follow the same contour for many years. Rotary veneer cuts the
depressions crosswise, and shows a series of circlets called bird's eyes. It
occurs only in a small percentage of Maple trees.
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BLISTER
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Produced by an
uneven contour of the annual rings. The veneer has the effect of being
blistered. Must be cut rotary or half-round.
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BOOK MATCHING
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Achieved when
successive veneer leaves in a flitch are turned over like the pages in a book
and are glued in this manner. Since the reverse side of one leaf is a mirror
image of the succeeding leaf the result is a series of pairs. Individual
panels can be matched this way, or you can achieve this look over many panels
by sequence matching the panels. Book matching is the most common match. A
common problem in book matching is when the “tight” and “loose” sides are
matched and reflect light and stains differently. This may yield color
variations in some species which may be minimized by proper finishing
techniques.
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BROKEN STRIPE
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A modification of
ribbon stripe, the markings tapering out and producing a broken ribbon. If
the log described in ribbon stripe also has a twist in the grain the stripes
are short or broken.
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BURL VENEER
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Produced from a
large, wartlike growth on the trunk of the tree.
The grain pattern typically resembles a series of eyes laid side by side.
Obviously the veneers leaf sizes are generally small and additionally are
defective. While producing beautiful patterns, Burl veneer is difficult to
work with.
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BUTT MATCHING
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Achieved when
veneers are matched as described for book matching but the ends of the sheets
are also matched. At times, the veneer being used is not long enough to cover
the desired panel heights. In this case the veneer leaves can also be flipped
end for end and the ends matched.
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A grain
appearance characterized by a series of stacked “V” and inverted “V”. Pattern
common in plain-sliced (flat-cut) veneer.
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CENTER MATCHING
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Each panel face
is made with an even number of flitch sheets with a center line appearing at
the midpoint of the panel and an equal number of veneer sheets on each side
of the center line. The number of leaves on the face is always even, but the
widths are not necessarily the same.
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CHECKS
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Small slits
running parallel to the grain of wood, caused chiefly by strains produced in
seasoning.
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CORE
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There are four
types of core construction used in plywood panels: a) Lumber Core: Consists
of a heavy core of sawn lumber between crossbands.
The thick center core permits doweling, splining
and dovetailing. b) Veneer Core: Method of plywood construction consisting of
3, 5, 7 or more plies of veneer laid with grain direction of adjacent plies
at right angles to each other. c) Particle Board: This type of core consists
of chips or flakes of resign-coated wood fused together under heat and
pressure to form a core for plywood. D) Medium Denisity Fiber Board a more
refined panel with a process similar to that of Particle core.
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CROSS BREAK
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Separation of the
wood cells across the grain. Such breaks may be due to internal strains
resulting from unequal longitudinal shrinkage or to external forces.
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CROSS FIRE
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Figures which
external across the grain as mottle, fiddle-back, raindrop and finger-roll
are often called cross figure or cross fire. A pronounced cross fire adds
greatly to the beauty of the veneer.
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CROSSBAND
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The veneer sheet
between the core and the face veneer. Its grain runs at right angles to the
grain of adjacent layers, thereby providing the remarkable stability of
hardwood plywood.
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CROSSBAR
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Type of figure or
irregularity of grain resembling a dip in the grain running at right angles,
or nearly so, to the width of the veneer.
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CROTCH VENEER
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Produced from the
portion of the tree just below the point where if forks into two limbs. The
grain is twisted, creating a variety of flame figures. Often resembling as
well formed feather. The outside of the block produces a swirl figure that
changes to full crotch flame figure as the cutting approaches the center of
the block.
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CURLY
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Found mostly in
Maple or Birch, and is due to the fibers being distorted and producing a wavy
or curly effect in the veneer.
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CUT MARKS
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A raised or
hollowed cross grain cut caused generally by a nick in the knife.
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Checks, splits,
open joints, knotholes, cracks, loose knots, wormholes, gaps, voids, or other
openings interrupting the smooth continuity of the wood surface.
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DIAMOND MATCH
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This is generally
done with a straight grain veneer. If a rectangle is divided into 4 quadrants
the veneers match at an angle to the quadrant line, and the grain forms a “V”
at these lines. The result is a diamond shape formed by the grain directions.
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DISCOLORATIONS
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Stains
in wood substances. Common veneer stains are sap stains, end stains, blue
stains, stain produced by chemical action caused by the iron in the cutting
knife coming in contact with the tannic acid of the wood, and those resulting
from the chemical action of the glue.
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The
better side of any plywood panel in which the outer plies are of different
veneer grades.
Also
veneer spliced to a certain pattern and cut to exact size.
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FIDDLE BACK
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A fine, strong,
even, ripple figure as frequently seen on the backs of violins. It is found
principally in Mahagony and Maple, but occurs
sometimes in other woods.
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FIGURE
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The pattern
produced in a wood surface by annual growth rings, rays, knots, deviations
from natural grain such as interlocked and wavy grain, and irregular
coloration. Appears across the grain. Mottle, fiddleback
and raindrop are often called cross figure or cross line.
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FLAKE (RAY)
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Flake figure is
developed only in those species which have very heavy medullary
ray growth, specifically Oak, Lacewood, and
Sycamore. When the saw or knife cut is directly on or near to the radial, it
is close to parallel with the medullary ray and
therefore develops the "Flake" effect.
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FLAT CUT
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Also called Plain
Slicing, is the most common method of veneer manufacturing, producing a grain
pattern known as cathedral. Because each leaf in the flitch is similar, a
consistent and even matching pattern is possible. Flat cut veneer is ideally
suited for wall panels and furniture.
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FLITCH
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a) A
section of a log made ready for cutting into veneers.
b) After
cutting, all bundles are laid together in sequence as they were sliced.
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Size and
arrangement of the cells and pores of the living tree. Grain is not
synonymous with figure. Woods fall into three groups: Fine grained (Birch,
Cherry, Maple, etc), medium grained (Walnut, Mahogany, etc.) and coarse
grained (Oak, etc.). Coarser grained woods can usually be cut to develop a
more conspicuous pattern.
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Similar to rotary
peeling, also producing a high veneer yield. Used primarily to add width to
narrow stocks by increasing the plane of cut. Also used to enhance a
particularly wild grain pattern. Matching is possible because the leaves can
be kept in sequence. Half round cutting may be used to achieve "flat
cut" veneer appearance.
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HARDWOOD
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General term used
to designate lumber or veneer produced from broad-leafed or deciduous trees
in contrast to softwood, which is produced from evergreens or coniferous
trees.
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HEARTWOOD
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The nonactive center of a tree generally distinguishable from
the outer portion (sapwood) by its darker color.
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HERRINGBONE
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Veneer strips are
used and matched to both sides of the center line, at an angle. The resulting
appearance is reminiscent of the bones of a fish as they are attached to the
back bone.
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HOLES, WORM
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Holes resulting
from infestation of worms.
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The line between
the edges or ends of two adjacent sheets of veneer or strips of lumber in the
same plane.
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Sound knots 1/4
inch or less that do not contain dark centers. Inconspicuous or blending pin
knots are barely detectable at a distance of 6' to 8', do not seriously
detract from the overall appearance of the panel, and are permitted in all
grades.
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KNOTS, OPEN
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Opening produced
when a portion of the wood substance of a knot has dropped out, or where
cross checks have occurred to produce an opening.
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KNOTS, SOUND,
TIGHT
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Knots that are solid across their face and fixed by growth to
retain their place.
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The process of
gluing pr bonding the component sections of the plywood into a single
permanent unit stronger than the original wood itself.
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LONGWOOD
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The trunk of the
tree is the part that begins just above the stump and continues to just below
the crotch, most veneers are cut from longwood by
quarter, rotary, or flat cutting.
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LOOSESIDE
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In knife-cut
veneer, that side of the sheet that was in contact with the knife as the
sheet was being cut. The bending of the wood at the knife edge causes cutting
checks.
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MATCHING
OF BURLS, CROTCHES, STUMPS
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Because of their
generally exotic grains, these wood figures need special treatment when being
matched into faces. Burls and crotches in particular have a tendency to be
buckled. In the process of making a panel face, the veneer needs to be
flattened and patched if needed. They also have a tendency to develop fine
hairline splits, so must be carefully handles in further manufacturing. This
extra labor and care adds to the expense of using these grains, but the
results are usually well worth the cost.
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MOTTLE
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A variegated
pattern which consists principally of irregular, wavy fibers extending for
short distances across the face. If there is also some irregular cross figure
in a log with twisted interwoven grain, the broken stripe figure becomes a
mottle.
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A panel composed
of small particles of wood and wood fiber that are bonded together with
synthetic resin adhesives in the presence of heat and pressure.
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PECKY
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Pockets of
disintegrated wood caused by localized decay, or wood areas with abrupt color
change related to localized injury such as bird peck. Peck is sometimes
considered as a decorative effect such as bird peck in pecan and hickory pr
pecks in cypress.
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PLY
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A single sheet of
veneer, or several pieces laid with adjoining edges,
which form one layer in a piece of plywood.
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PLYWOOD, HARDWOOD
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A panel composed
of an assembly of layers or plies or veneer ( or
veneers in combination with lumber-core, particleboard-core, MDF-core,
hardboard-core, or of special core material) joined with and adhesive. Except
for special constructions, the grain of alternate plies is always
approximately at right angles, and the face veneer is usually a hardwood
species.
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This cut requires
the largest diameter logs and produces straight grained veneers. The quarter
slicing of oak can result in the appearance flake.
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(Mismatched) A
panel having the face made up of specially selected dissimilar (in color and
grain) veneer strips of the same species and generally V-grooved at the
joints between stripes to simulate lumber planking.
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REVERSED DIAMOND
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This is commonly
done with a straight grain veneer, a rectangle is
again divided into 4 quadrants. The grain direction is from the center point
to the outside edge in each quadrant. The resulting appearance is that of a
series of "Vs" formed by the grain match at joint line pointed in
at the center point.
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RIBBON STRIPE
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Result of quarter
slicing a log and the appearance actually is between broken stripe and plain
stripe. It gives the general appearance of a ribbon sometimes slightly
twisted.
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RIFT CUT
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Produced by
cutting at a slight angle to the radial to produce a quartered appearance
without excessive ray flake. The Rift cut method, commonly used for Oak, can
only be used on sizable logs. Rift Cut veneer can easily be sequenced and
matched.
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ROPE
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If the twist in
the grain of broken stripe is all in one direction a rope figure results.
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ROTARY PEELING
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The log is turned
in a circular motion against a knife peeling off a continuous thin sheet of
wood veneer (like unrolling wrapping paper), the most economical method of
producing veneer, resulting in the highest yield. The grain is inconsistent
and leaves are most difficult to match. This type of veneer is best suited
for paint grade or utility surfaces.
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ROUGH CUT
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Irregular shaped
areas of generally uneven corrugation on the surface of veneer, differing
from the surrounding smooth veneer and occurring as the veneer is cut by the
lathe or slicer.
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RUNNING MATCH
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The panel face is
made from components running through the flitch consecutively. Any portion of
a component left over from a face is used as the beginning component or leaf
in starting the next panel.
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This is the outer
portion of the tree. As additional layers of growth accumulate on the outer
perimeter, the inner layers of the sapwood becomes
heartwood. Sap is lighter in color and the differentiation in color and
thickness of the sap layer varies considerably by species.
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SLICED
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Veneer produced
by thrusting a log or sawn flitch into a slicing machine which shears off the
veneer in sheets.
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SLIP MATCHING
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Means that veneer
leaves in a flitch are "slipped". Successive veneer leaves in a
flitch are "slipped" one alongside the other and edge-glued in this
manner. The result is a series of grain repeats, but no pairs. The danger
with this method derives from the fact that grain patterns are rarely
perfectly straight. Sometimes a grain pattern "runs off" the edge
of the leaf, a series of leaves with this condition could usually make a
panel - "look like it is leaning". In book matching the pairs
balance each other.
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SOFTWOOD
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General term used
to describe lumber or veneer produced from needle and/or cone bearing trees.
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SPECIES
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A distinct kind
of wood.
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SPLICED FACE
VENEERS
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Face veneers that
have been joined together in any one of several matching effects through the
careful factory process of tapeless slicing.
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SPLITS
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Separations of wood
fiber running parallel to the grain.
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STREAKS, MINERAL
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Natural
discolorations of the wood substance.
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STUMP VENEER
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Produced from the
base of the tree. Here the grain pattern is always swirly
twisted and often accompanied by cross fire and patches of burl. The sizes
are normally small.
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In knife-cut
veneer, that side of the sheet that was farthest from the knife as the sheet
was being cut and containing no cutting checks (lathe checks).
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A thin sheet of
wood, rotary cut, sliced, or sawn from a log or flitch. Veneering goes back
to the early days of the Egyptians, about 3,500 years ago. Down through the
years and cultures veneering ahs enriched furniture and architectural
interiors with sheets of rare and beautiful woods bonded to other plain,
sturdy wood based substraights to form a panel.
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