6
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Wood is basically made up of
cellulose and lignin.
❚❚
The heartwood is the most
suitable for woodwork.
❚❚
The stages in getting wood
are: logging and pruning,
transport, stripping the bark,
cutting, drying and planing.
Key concepts
1
trunk
:
the main part of a tree
2
log
:
a big piece of wood
3
sawmill
:
a factory that turns logs into
planks
4
plank
:
a long, thin, flat piece of wood
used for building or floors
Understand
4.
What do you think controlled logging is?
5.
What factors will affect the process of drying wood?
1.
WOOD
Wood is a
raw material
of plant origin. It is composed of
cellulose
fibres, which
is like the skeleton of all plants, and
lignin
which makes it hard and rigid.
Wood is under the bark of trees and bushes. Look at the different parts of a tree
trunk
1
:
Understand
2.
What are rings in a tree truck? Write a definition.
Apply
3.
Which part of the trunk would be most suitable for your puzzle?
Understand
1.
Find out how resin is
collected from pine
trees and what the
resin is used for.
Trees contain different substances
like resins, oils, sugars and
colouring.
Resin
is a dark or yellow sticky
substance that plants release. It
forms a layer on the surface that
protects it from wounds, cuts
and possible attacks from other
organisms.
Bark
: exterior layer;
protects plant from
attack from outside.
Cambium
: thin,
transparent layer of live
cells; where growth
takes place.
Sapwood
: recent growth; used for
more artistic woodwork.
Pith
: the middle part of the trunk; not very
resistant; generally not used.
Heartwood
:
hardest, driest
and darkest part;
best part for
woodwork.
When you cut down a tree you can see the rings in the form of concentric circles.
If a tree grows quickly, the rings are easier to see.
1.1.
Getting wood
❚❚
Logging and pruning
: They cut the tree at the base of the trunk. Once the tree
is down, they cut off the branches.
❚❚
Transport
: They use huge machines to lift the
logs
2
and pile them on the trucks
that take them to areas for easier access. Then they take them to a
sawmill
3
by
road, rail or by sea or rivers.
❚❚
Stripping the bark
: The bark stripping machine has rollers with teeth that
remove the bark from the logs as they turn.
❚❚
Cutting
: They cut the logs to the length they want and then these pieces are cut
into
planks
4
.
❚❚
Drying
: Before working with wood it must be dried so that it doesn’t change
shape with changes in temperature. Dry wood is lighter and lasts longer.
❚❚
Planing
: Planer machines eliminate any rough surfaces and make accurate-sized
sheets of wood.
ADVANCE EDITION
