Chapter 7

Question 1

develop due to anisotropic and hygroscopic nature of wood and are associated mainly with changes in moisture content of wood below fiber saturation point.

Answer 1

Seasoning or Drying defects

Question 2

two types, end checks and surface checks

Answer 2

checks

Question 3

more extensive than checks

Answer 3

splilts

Question 4

any distortion from the true plane of wood that occur due to differential shrinkage (anisotropy)

Answer 4

warping

Question 5

Types of warping

Answer 5

• bow - twist - diamond
• crook - cup - oval

Question 6

irregular depression and elevation on wood surface due to effect of excessive shrinkage

Answer 6

collapse

Question 7

presence of residual drying stresses brought about by tension in the wood core and/or compression in the shell

Answer 7

casehardening

Question 8

caused by too high kiln temperature and improper steaming, also called hollow horning, results to intensive internal checks and splits

Answer 8

honeycombing

Question 9

similar to shake on standing trees

Answer 9

ring failures

Question 10

occur on wood surrounding the pith during the initial stage of drying where there is too high initial temperature

Answer 10

box-heart splits

Question 11

What are the machining defects

Answer 11

Raised Grain
Loosened Grain
Fuzzy Grain
Chipped and Torn Grain

Question 12

the roughened condition of the surface of dressed lumber in which the hard summerwood is raised above the softer springwood, but not
torn from it.

Answer 12

Raised Grain

Question 13

This is attributed to lumber that are machined at MC greater than 12% and is increased by dull planer knives.

Answer 13

Raised Grain

Question 14

The wood surface is described as having a corrugated feel and appearance.

Answer 14

Raised Grain

Question 15

separation and curling of the tips of growth rings on the surface of flat-grained lumber.

Answer 15

Loosened Grain

Question 16

This causes curling of the loosened splinters when individual growth increments
are freed by sanding or planing.

Answer 16

Loosened Grain

Question 17

occurs when wood fibers become loosened on the surface of a board in large numbers. Wood cells that swell under the action of swelling agents, such as stains, or as a result of atmospheric humidity, maybe injured in the process of planing or sanding

Answer 17

Fuzzy Grain

Question 18

This may also be affected by the rate of feed of stock to machines with feeders and the slope or variation of the grain of the wood. Lumber with a surface MC of 5% or less is more prone

Answer 18

Chipped and torn grain

Question 19

Chipping may be minimized by

Answer 19

reversing the direction of the travel of the board through the planer.

Question 20

any abnormality that may lower its strength and durability and limit its utility.

Answer 20

Log defect

Question 21

two main categories of log defect

Answer 21

(a) those that reduce the volume of sound wood and/or lower its durability, and
(b) those that lower its strength and/or limit its utility.

Question 22

refers to such defects as knots, stains, holes, bark pockets and related defects usually included in the end-products of the logs, either in the form of rough lumber or lumber products.

Answer 22

A defect that lower its strength and/or limit its utility

Question 23

indicated by abnormal brittleness, torn grain, low density and reltively light color in the central portion of the heartwood.

Answer 23

Brash Center

Question 24

This is very common in most PMG species. It commonly occurs near or at the center of the logs, particularly the butt logs.

Answer 24

Brash Center

Question 25

This defect may cause lumber to break abruptly across the grain when roughly handled.

Answer 25

Brash Center

Question 26

This defect occurs in a log cut just at the base of a fork in which two separate pith centers appear and are often separated by a bark pocket.

Answer 26

Double Pith

Question 27

Sawn lumber from this defect is usually cross-grained and is likely to split near the bark pocket area.

Answer 27

Double Pith

Question 28

These are round or irregular channels of varying lengths, and the diameter varies from 3/8 to 1 inch caused by wood consuming grubs that hatch eggs, laid in the bark of standing trees or recently felled trees working their way inside the wood to the surface

Answer 28

Grub Channels

Question 29

A loose heart is the tangential separation of fibers completely around a growth ring within the heart or core of the log.

Answer 29

Loose Heart

Question 30

confined to the heart center, while a ring shake develops anywhere between the pith and bark.

Answer 30

Loose heart

Question 31

a tangential separation of the wood fibers along the parts of the growth ring. It may be found at the center and sometimes through the wood.

Answer 31

Ring Shake

Question 32

Lumber with _________ depending in size, may seriously weaken the resistance of wooden members to longitudinal shear.

Answer 32

Shakes

Question 33

This refers to a log in which the pith is outside the geometrical center of the log. Posing some problems in manufacturing, it indicates the presence of tension wood and shrinks excessively. not used for veenering

Answer 33

Off-center Pith

Question 34

These are tiny round holes, made by ambrosia beetles, roughly less than 1/16-inch in diameter.

Answer 34

Pinholes

Question 35

small wood-boring insects which attack newly cut timber, causing what is commonly called “pinhole” defect.

Answer 35

Ambrosia Beetle

Question 36

As its name implies, it is a defect found in butt logs. Usually, in Philippine dipterocarps, the rot starts right from the butt end up to the top or small end of the log.

Answer 36

Butt Rot

Question 37

– This is usually confined to the center of the log and affects its entire length. However, rot which results from wounds or rotten knots is usually found in the outer rim of the wood.

Answer 37

Center Rot

Question 38

This is sometimes called spider heart. It is a multiple radial separation of the wood fibers, starting from the pith center and extending out to at least three directions.

Answer 38

Heart Checks

Question 39

appear in lumber as short cracks or seams, sometimes filled with resin, and affecting the whole face of the board.

Answer 39

Heart Checks

Question 40

This is a single, radial split that extends to both sides of the pith. In some instances, it is restricted to the heart center of a log and, in others, it progressively enlarges with heartwood formation and then extends across the heartwood zone.

Answer 40

Wind Shake

Question 41

Log Surface Abnormalities

Answer 41

Bumps Burl Cat Face Knots Splits Stains Sweep and Crook Wormy and Unsound Sap Wounds

Question 42

a protuberance on the log which is overgrown with bark. may be abrupt or only a gradual undulation that tapers back in all directions to the the normal contour of the log.

Answer 42

Bumps

Question 43

a protruberance on the log which is sound, hrad and round or horizontally ridged without protruding limbs, twigs or stubs.

Answer 43

Burl

Question 44

causes the grain in the wood to be distorted, exhibiting a wavy, curly, or bird’s-eye effect.

Answer 44

Burl

Question 45

a scar found in on the surface of a log, and it may be fikked with wood and bark. This results from the wounding of a tree by falling trees, wind storms or lightning. (4) Knots – Knots are defined

Answer 45

Cat Face

Question 46

cuts or broken-off limbs or sprout branches, green or dead, protruding, flush, or depressed in which the exposed wood may be sound or rotten.

Answer 46

Knots

Question 47

a longitudinal separation of wood fibers, extending deeply into the log.

Answer 47

Split

Question 48

generally caused by accidents during operations. At times it is due to the release of internal stresses when the tree is cut.

Answer 48

Split

Question 49

a lengthwise separation of the wood, which extends from one surface to the opposite or adjoining side.

Answer 49

Split

Question 50

These are abnormal discolorations of wither black, blue, brown or olive-green, usually in variegated or streaky patches.

Answer 50

Mineral streaks and stains

Question 51

This is characterized by tangential bands or rings of dark reddish-brown in the sapwood zone. These bands appear as if normal of normal heartwood and are believed to be due to injury in the sapwood region. These are closely associated with mineral stains in the same log.

Answer 51

Pathological heartwood

Question 52

is defined as the amount of deviation of a log from a straight line drawn from one end to the other end of a log, over and above the amount of taper.

Answer 52

Sweep

Question 53

the abrupt bending or curving of a certain portion of the log.

Answer 53

Crook

Question 54

occurs when there are two of these curves or bends along the log.

Answer 54

Double crook

Question 55

When the sapwood of a log has been attacked by grub worms, this log is called

Answer 55

wormy.

Question 56

the sapwood are commonly caused by blue stains. Stains, caused by fungi, are almost invariably sapstains, although heartwood may be affected, in which case, incipient decay is indicated.

Answer 56

Unsound sap

Question 57

openings in the bark that expose the sapwood and sometimes the heartwood portion.

Answer 57

Wounds

Question 58

Shallow depressions on indentations in the surface of a board caused by shavings or chips getting imbedded in the surface during the process of dressing. They may be formed by a planer or jointer.

Answer 58

CHIP MARK.

Question 59

rather than running parallel to the long edge of a board, for example, the grain runs at an angle to it. Such wood is not permitted for structural applications in the American Forestry Association guidelines because it lacks the same structural strength as an equal-sized piece that has the grain running parallel to the edge.

Answer 59

DIAGONAL GRAIN.

Question 60

An irregularity in the surface of a board where wood fibers below the level of the dressed surface have been torn or broken out by a planer.

Answer 60

TORN GRAIN.

Question 61

more commonly associated with rough milled lumber. In the case of construction lumber (e.g., 2x4s), it can be bark or missing wood.

Answer 61

WANR

Question 62

A darkening of the wood due to overheating by machine knives or rolls when pieces are stopped in the machine.

Answer 62

MACHINE BURN

Question 63

A depressed cut of the machine knives at the end of the piece.

Answer 63

MACHINE BITE

Question 64

A groove cut by the machine below the desired line.

Answer 64

MACHINE GOUGE

Question 65

the process of converting raw timber to forms suitable for woodworking or construction projects.

Answer 65

CONVERSION

Question 66

WOOD DEFECTS FROM CONVERSION

Answer 66

1.1.CHIP MARK. 1.2.DIAGONAL GRAIN. 1.3.TORN GRAIN. 1.4.WANE. 1.5.MACHINE BURN. 1.6. MACHINE BITE. 1.7.MACHINE GOUGE.

Question 67

the process of drying lumber (either in a kiln or air drying) to an appropriate level of moisture for woodworking and other commercial uses.

Answer 67

Seasoning

Question 68

a nonspecific term that refers to a distorted or misshapen board.

Answer 68

WARP

Question 69

A curvature formed in the direction of the length of timber. A bowed board is flat, but bent, like a road going over a hill.

Answer 69

BOWING.

Question 70

Where the board curves in length and width like a propeller.

Answer 70

TWISTING.

Question 71

Where the face of a board warps up across its width such that if one looks at the end of the board, it will look like a shallow letter “U.” Is common with plain-sawn lumber.

Answer 71

CUPPING.

Question 72

Occurs when the board remains flat in width, but curves in length like a river going around a bend.

Answer 72

SPRING.

Question 73

is among the worst of drying defects because it’s irreversible and usually cannot be detected by looking at the face of the lumber.

Answer 73

HONEYCOMBING.

Question 74

internal stresses cause various radial and circular cracks to develop in the interior portion of the wood

Answer 74

HONEYCOMBING.

Question 75

NATURAL WOOD DEFECTS

Answer 75

BARK POCKETS. BIRD PECKS. BURLS. COARSE GRAIN. RAISED GRAIN. SHAKE. KNOTS. STAINS. SPALTING. TWISTED FIBERS.

Question 76

Formed when a small piece of the bark protrudes into the lumber. This area is generally considered unsound.

Answer 76

BARK POCKETS.

Question 77

Caused by birds, especially woodpeckers, which peck on trees when trying to feed on the insects living in or under the bark and in the wood of the tree.

Answer 77

BIRD PECKS.

Question 78

If the tree grows rapidly, the annual rings are widened. It is known as coarse-grain timber and possesses less strength and durability.

Answer 78

COARSE GRAIN.

Question 79

Anything that gives the wood a corrugated feel. Typically, this is caused by the harder summerwood rising above the softer springwood in the growth ring. The growth rings do not separate.

Answer 79

RAISED GRAIN.

Question 80

A group of splits radiating from the pith or center of the tree in the form of a star. It is wider on the outside ends and narrower on the inside ends.

Answer 80

Star Shake

Question 81

KNOTS. The base of the branches forms a mark on the stem as new branches grow, resulting in dark-coloured stains on the surface. These dark-coloured rings are due to the continuity of wood fibres and they are known as

Answer 81

Knots

Question 82

A knot usually lighter in color and generally never fall out

Answer 82

LIVE KNOT

Question 83

A knot darker in color and may fall off leaving a hole that can weaken the strength of the limber

Answer 83

DEAD KNOT

Question 84

A knot that is not inter-grown with the surrounding wood.

Answer 84

ENCASED KNOTS

Question 85

A hole left where the knot has been knocked out.

Answer 85

KNOTHOLE

Question 86

Limbs that have been cut across or cut lengthwise, showing the end grain or length section of the limb or knot. These knots generally have splits and severe grain deviations near them.

Answer 86

SPIKE KNOTS

Question 87

Any form of wood discoloration caused by fungi. It’s typically found in dead trees, so if the wood isn’t stabilized at the right time it will eventually become rotten wood.

Answer 87

SPALTING

Question 88

Types of spalting

Answer 88

Pigmentation White rot Zone lines

Question 89

These are known as wandering hearts and are caused by the twisting of young trees by fast-blowing wind.

Answer 89

TWISTED FIBERS.

Question 90

caused by a fungus that feeds on the sap. It does not live in live trees due to lack of oxygen. The color does not degrade the cellular structure and does not count against wood in the grading process.

Answer 90

BLUE STAIN

Question 91

A form of wood decay found only in softwoods that destroys the wood’s cellulose, eventually causing cracks across the grain.

Answer 91

BROWN ROT

Question 92

After the wood that was once infected with brown rot dries out, the cell walls of the remaining wood begins to break down and can be crushed to a dry powder.

Answer 92

DRY ROT

Question 93

This is formed when a branch has come out of the tree. The heart wood is exposed to an attack from insects and the elements. Ultimately, the tree becomes weak and it gives a hollow sound when struck with a hammer.

Answer 93

HEART ROT

Question 94

occurs when the fungus digests the lignin and cellulose therefore stripping out the darker colours with it. This gives the timber a soft spongy feel when touched.

Answer 94

WHITE ROT

Question 95

Insect defects

Answer 95

Wood boring beetles Pin-hole borers Marine borers

Question 96

In softwoods, the type of reaction wood formed is called ______ ___ while in hardwood, it is called _______ ____

Answer 96

compression wood, tension wood