Introduction Properties Types of natural wood Types of artificial wood How boards are made Joints Coatings Wood movement

1. WOOD

2. 1. Intro
2. Properties
3. Types of natural wood
4. Types of artificial wood
5. How boards are made
6. Joints
7. Coatings
8. Wood movement
Contents

3. Intro
• Wood is a porous and fibrous structural tissue
found in the stems and roots of trees.
• Organic material, a natural
composite of cellulose fibers (which are strong in
tension) embedded in a matrix of lignin which
resists compression.
• Heartwood is inner, dark, dead, resistant to decay
part of trunk
• Sapwood is outermost living wood containing
xylem, phloem for food and water transport.

5. Intro
• Over 100,000 different species of trees
• Many are endangered, many are inaccessible
• ~500 species harvested and dried for use
• Density can vary from unbelievably light—balsa is
less than 1/6th the density of water—to heavier than
concrete
• Some species, like certain pines, are so abundant
that they are used as disposable packaging material

6. • Lignum Vitae is so water-resistant and dense
that it is commonly used in bearings for large
naval craft and hydroelectric dams.

7. Properties
• Growth rings - Trees increase in diameter by
the formation, every growth season a new
layer is added, hence cut section shows rings.

8. Properties
• Janka is a measurement of the pounds of force
required to embed a steel ball of a certain
diameter into the surface of the wood
• Woods below 800lbf on the Janka scale can
be dented by pressing on them with your
fingernail

9. Grain type
• Straight grained wood is predictable and easy
to cut and sand.

10. Grain type
• Interlocked grain can cause unwanted
'tearout' during cutting, planing, and/or
sanding
• Wood that regularly changes its growth
direction slightly, causing the layers of growth
to interlock and overlap

11. •

12. Porosity
• Ring-porous woods have larger pores at the
edge of their growth rings

13. Porosity
• diffuse-porous woods have the same size of
pores throughout

14. Porosity
• Woods that are highly porous are harder to
sand to a smooth finish, and tend to absorb
more glue and finish than less porous woods

15. Shrinkage
• The amount of dimensional change in a wood
after it is dried.
• Seasonal movement

16. Colour
• Colours can range from pale yellows and greys
to vibrant hues of purple, red, and green, and
from rich browns to pure, solid black
• Some woods will change colour with exposure
to sun and oxygen over time

17. Colour
• Spalting occurs when a tree is infected with a
fungus, staining the wood with various streaks
and rings of altered colours.

19. • Natural defects such as knots and pits where
branches join the trunk
• In some cases this can be a desirable
appearance, while in others it can result in lots
of extra work and wasteful scrap.

20. Hardwood vs softwood
• Can be defined by their differences in the
woods microstructure which determines its
density and strength
• Hardwood comes from angiosperm — or
flowering plants, are slow growing and
expensive
• Comes from gymnosperm trees which usually
have needles and cones, lacks pores

21. Hardwood vs softwood
• The main difference between a hard and soft
wood is the vessels or pores in their
microstructures.
• The cells in hardwoods are closed so they cannot
function like a conduit and this is why they have
vessels where softwoods don't.
• Cells in softwood are open which enables them
to act as conduits and feed nutrients and water
throughout the tree.
• Hence they absorb adhesives/finishes properly

22. Types of natural wood
(Solid lumber)

23. • Pale yellow to light reddish brown
• Soft - 500lbf
• Structural stability
• Generally resistant to seasonal movement
• Inexpensive
• Large-scale structural work, such as framing for houses
• Straight-grained and ring-porous
• Low density, isn't highly porous
• Pallets

26. • Abundant, inexpensive
• Easy to work and remarkably durable.
• Lighter brown in color
• 1300lbf Janka
• Ring-porous, straight grained, high porosity
• Experiences moderate seasonal movement
• Glues easily, and takes stains and finishes beautifully
• Whiskey barrels

29. • Grows naturally in the tropical regions north of the Indian
Ocean
• High oil content, expensive
• Extremely high resistance to rot and decay
• So, water exposure is never an issue
• But has negative effect on gluing the wood
• Easy to work, relatively lightweight
• Minimal seasonal movement, 1000lbf Janka
• Diffuse-porous, straight-grained
• Wooden boat decks
• Low weight – Outdoor furniture and installations
• Sangwan

32. Sunfading – Graying on prolonged exposure to sunlight

33. Confidential content removed

34. Confidential content removed

35. Orienting wedge

36. • Sweet, rose-like scent when cut or sanded
• Certain species threatened with extinction
• Lighter brown to deep reds, browns and purples
• 2000lbf to 3000lbf Janka
• Real hard and real expensive
• Straight-grained and diffuse-porous
• High oil content
• Extremely resistant to rot and water damage
• Luxury furniture, panelling, veneer
• Sheesham

39. • Soft Maple – 700 to 900 lbf
• Hard Maple (comes from sugar maple tree) – 1450lbf
• Diffuse-porous, susceptible to decay
• Prone to tearout due to its occasionally interlocked grain
pattern
• Fair seasonal movement
• Hard Maple is also desired for its properties as a tonewood
- a type of wood that resonates sound particularly well
• Glues and finishes well, burns easily when exposed to high-
speed tools
• Baseball bats, guitars

42. • Dark tan to a deep chocolate brown
• Very little seasonal movement, 1000lbf Janka
• Straight-grained, semi-ring porous
• Glues well
• Furniture, flooring, countertops
• After pressure treating, splinters do not get
out

44. Live edge board

45. x
• Cherry is a pale, pinkish yellow hue when
initially cut.
• This color changes rather quickly to a darker
reddish brown with exposure to sunlight.
• Easy to cut, glue, sand, and turn on a lathe.
• Resistant to rot and decay, 950lbf Janka
• Stains poorly

49. • Durability, glues and stains well
• Darken to a rich, deep reddish-brown over time
• Straight-grained, diffuse-porous
• Minimal seasonal movement, 900lbf Janka
• Soft enough to be cut and sanded quickly but hard enough to resist
dents and scratches
• With a glossy finish, the wood will refract light so vibrantly that it
changes shades depending on your viewing angle
• Extremely resistant to decay and water + low density
• Can be found on all sorts of watercraft
• Is a tonewood
• Overharvested, is under CITES trade restrictions

52. • High density, black coloured, 2400lbf to 3200lbf
• Diffuse porous, interlocked grain
• Highly durable and rot resistant
• Significant seasonal movement
• Difficult to work hence used mostly in small projects
• Carvings, musical instruments, and lathe-turned items
• High natural oil content, expensive
• Luxury furniture, panelling

56. How Logs Are Turned Into Boards

57. Plainsawn
• Yields the most useable wood with the least
waste
• Simple, very fast, and the most cost-efficient
• Results in a face with ripples, large graphic ovals
and U-shaped patterns
• Have to be kiln-dried before use
• Distorts due to drying, aging and changes in
humidity
• Tension of the grain can cause the boards to
twist, cup and bow

62. Quartersawn

63. Quartersawn
• Used only where the grain, or look of the wood is
important
• Exhibits very little wood movement
• Least efficient to produce, yielding the most
waste.
• Most expensive type of board to produce
• Cuts are made perpendicular to the tree's growth
rings which creates a straight grain pattern that is
much more uniform
• Flooring, high-end furniture

67. Riftsawn

68. Riftsawn
• If a board isn't plainsawn nor quartersawn, it's
riftsawn
• Properties in middle

72. Artificial wood/Engineered wood
• Particle board, fiberboard, plywood, WPC
• Manufactured by binding or fixing the strands,
particles, fibers, or veneers or boards of wood

73. Particleboard
• Made from wood chips which are glued
together and then compressed under heat in a
large board shape
• It is then dried and cut into various sizes to be
sold.
• Mostly covered with thin sheets of veneer or a
plastic laminate

75. Particleboard
Advantages:
• Cost effective
• It is available in large sizes
• Veneer or plastic laminate can be applied to make it look
more like solid timber
• It doesn't have natural defects and it doesn't swell
• Renewable
Disadvantages:
• Still doesn't quite match the quality of solid timber
• Can be prone to chip or flake
• It isn't available in very thick sizes
• It isn't suitable for many joints

76. Plywood
• Made from layers of solid wood veneer that are usually
about 3 millimetres thick
• Because it is made in layers it is incredibly strong but also
light in weight.
• The interior layers of these boards are usually made from
an inexpensive wood while the outer veneer layers are
made from more expensive timber to give the board a nice
wood grain appearance.
• Manufactured from layers of veneer that are glued
together and compressed under heat
• With each new layer of veneer added the grain is rotated at
90 degrees each time, this is done to maximise the boards
strength and to prevent warping and twisting.
• Edges of board are unattractive and can't be covered

77. Plywood
English
• https://www.youtube.com/watch?v=xGnr8AT
HHX8
Hindi
• https://www.youtube.com/watch?v=aZL0U5r
pwDU

78. MDF
• Particle board is made from larger wood chips
and medium density fibreboard is made from
a very fine wood dust
• The resin used in this fibreboard is toxic
• Fibres are so fine they are easy to breathe in
so the timber should be cut in a well
ventilated area or somewhere with a dust
collection system.

79. MDF
Advantages:
• It is cost effective
• It's available in many sizes
• Has no natural defects
• Can be easily machined
Disadvantages:
• Contains toxic resins which means the saw dust created is
dangerous
• Not suitable for most joints
• Should be fully sealed to prevent toxins from escaping
• Can split
• Needs to be cut in ventilated areas or in a room with a dust
collection system
https://www.youtube.com/watch?v=qitenYvpSx4

80. Joints

81. • Most basic, simple
• Weak, not very aesthetically pleasing
• Held together with glue, nails, screws or dowel

82. • Easy to construct
• Marginally stronger and aesthetically better than
butt joint
• Has more surface area for glue
• Concealing the end grain giving it a nice flush look
• Picture frames

84. • Requires woodwork machinery for tight fit
• back of drawers

85. • Moderately difficult to construct
• Bonded together with adhesives and sometimes
a nail or screw is added for extra strength
• Allows the two pieces of wood to pass through
each other

86. • Better strength than butt joint

87. • Uncommon
• Helps to prevent movement and add strength
• Biscuit joiner - used to cut the biscuit shaped
holes in the wood

88. • Hard to construct, requires good precision
• Dovetails interlock into slots
• The pins are glued into the slots and a nail on each pin
can be inserted to help keep the dovetail joint strong
and square until the glue dries
• Front of drawers or wooden boxes
• Strength, aesthetics

89. • One of the strongest
• Difficult to construct
• Table legs

90. • Similar to the mortise and tenon
• Difference is in the size of the mortise and
tenon
• End grain visible hence little less attractive

91. • Tight fit that has plenty of surface area for
adhesives
• Flooring
• Requires right woodwork machinery
• More likely to buy timber with this joint
already in it

92. Coatings

93. Coatings
• There are three major types of finishes :
Evaporative, reactive and coalescing
• Wax is an evaporative finish because it is
dissolved in turpentine or petroleum distillates to
form a soft paste. After these distillates
evaporate, a wax residue is left over.
• Reactive finishes change chemically when they
cure
• Chemical change is typically a polymerisation
• Water based finishes generally fall into
the coalescing category.

94. • Hardwearing, transparent or coloured, decorative and preservative
finish that highlights and protects the wood surface below
• For interior or exterior use, is a reactive finish
Varnish

95. Stain
• Soaks into the wood to provide a decorative and sometimes preservative
finish. Darkens or colours wood
• For interior or exterior use

96. Dye
• Subtly enhances natural colour or evens out shades on different
pieces of wood. Dyes can be mixed to match an existing colour.
• Only for interior use

97. Wax
• Transparent or translucent decorative finish; some types can be
buffed to a high gloss. Feeds and protects the wood but will not
penetrate a sealed surface
• For interior use only

98. Oil
• Transparent finish that nourishes and protects wood.
External surfaces lose their finish but stay protected
• For interior or exterior use, penetrative finish

99. Wood preserver
• Prevents rot and insect damage. Available clear
or coloured with a matte or a semi gloss finish

101. Coatings
• Glazing and Toning are techniques used to highlight the details in
the woodwork or to unify and add depth to the colour. These two
techniques can also be used to give "age" to the finish. The process
is one of applying transparent pigmented liquid over or between
coats of finish.
• Pickling and Liming are traditional finishing processes used to
accentuate the wood grain. The highlighting is achieved by using
two contrasting colours : a base colour and another colour rubbed
into the grain.
• Bleaching is used to lighten the natural colour of wood or to
remove discoloration caused by moisture. Bleaching can also be
used to achieve the base colour in preparation for pickling or liming.
It is not used to remove stain or dyes.
• Distressing is a technique that can be used to give age and interest
to the finish.

102. Glazing and toning
Liming
Bleaching

103. Wood movement

104. Why Does Wood Move
• Wood in living trees is wet
• Its cells are swollen with sap, which is mostly
water, but also some minerals and sugars
• Water within cells is called "free water" and it can
be squeezed from the wood
• Water can still remain within the cell walls called
“bound water”
• It is only when the bound water is removed (by
drying) can the wood shrink and become strong

106. Why Does Wood Move
• Wood is hygroscopic, which means its moisture
content is directly related to the relative humidity of
the immediate environment
• You've dried your wood properly, worked it, and now
shipped your finished wood product to an area with a
different climate.
• That wood may still move, screwing up your joints
• As the humidity of wherever your piece is rises, the
moisture content of the wood rises and the wood
expands
• When the outside air becomes drier the moisture
content decreases and the wood contracts

107. Why Does Wood Move
• This process leads to the so-called equilibrium
moisture content or EMC
• A board can feel dry on the outside and still have
moisture on the inside
• Moisture meter is the device used to measure the
moisture content of wood
• Wood continues to move even in freezing
temperatures, because the moisture is protected
within the cells of the tree and doesn't freeze.

110. Controlling Wood Movement: The
Drying Process
• Drying begins in the outer layers of the log
and then moves inward
• If the outer layers dry too much (below what
is called the fibre saturation point) and the
centre layers remain wet then so-called
"drying stresses" cause rupturing in the wood
• This leads to checking
• Two ways to dry wood: Air dry or kiln dry

112. The Drying Process
• Wood is stacked in a kiln, where humidity and
temperature is controlled using steam and
drying is controlled with fans
• Takes about six to eight weeks
• Also takes care of resin if any of it is stuck
• Air drying takes about a year
• Low-density logs have thinner cell-walls so the
moisture movement is faster and this of
course leads to faster drying

115. Dealing with Wood Movement:
Design and Understanding

117. Panel door

118. Dealing with Wood Movement: Design
and Understanding
• Various panels are not just for aesthetics but
also functionality
• This is a time-tested, very clear-cut example of
how you use design to cope with wood
movement.

119. Basic terminology

120. Panels have tongues that ride inside grooves in the rails and stiles

121. Design and Understanding
• This tongue-and-groove arrangement allows the
panel to "float" within the frame, expanding and
contracting with humidity changes
• Depth of grooves calculated via EMC technique.
• Use of screws in slots
• The basic idea is this somewhat Buddhist-
sounding principle: You have a piece that is
attached, yet not attached, to another piece

123. Red arrows show all joints
You don't want the panel's expansion running out of room and cracking,
nor do you want it shrinking so much that you can see daylight between the pieces.

124. • Space Balls are little rubbery spheres that you can
shove into the grooves before you stick a panel in
• Spheres can expand and contract with the panel
• They prevent it from rattling in the door when it
shrinks, and they keep the panels visually centred
• Other hacks - Using silicone to draw a
circumferential bead that does the same thing

125. • I began trying to use wood "in the raw," but I discovered I
didn't know how. Then I became eager to learn ways to
"overcome" all the "problems" that wood has, and I
experimented with wood stabilizers and chemicals,
impatient to improve upon nature's product. In time,
however, I realized a certain distaste for trying to make
wood into something it isn't and for trying to make it do
things other materials do better. I'm back to using wood "as
is" now but with a different point of view. I concentrate on
learning what wood is, rather than worry about what it
isn't; I try to work with it, not against it. Whether this
makes me a better woodworker I am not sure, but I am
more satisfied, for certainly part of the reward of working
with wood is accepting the challenge of understanding it.
The dimensional behaviour of wood should be looked upon
as simply a property of wood to be taken in stride, not as a
problem to be corrected

126. • https://www.youtube.com/watch?v=BAe2kIVJ
0QI

127. THANK YOU