WOOD WORKYeh Yeh Yeh

WoodWood is one of our most abundant natural resources. It is also a renewable resource. By planting new trees and caring for our forests, we can maintain an ample supply of wood to meet our needs. Remember it takes at least 25 to 50 years for a tree to grow to a size suitable for harvesting.

Lets discuss the two main categories of wood.Deciduous (hardwood) and Coniferous (softwood)

Hardwood: category

Usually comes from deciduous trees, whose leaves are broad, flat and fall off in autumn.

Example: birch, maple, oak, poplar, ash, basswood, walnut.

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Softwood: category

Usually comes from evergreen or coniferous trees. These are trees that keep their needlelike leaves all year round.

Example: cedar, spruce, fir, redwood, hemlock, larch, juniper, pine.

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Structure of Wood

The natural structure of wood provides strength, durability and flexibility. A cross section of a tree trunk shows the main parts of the tree.

Six Major Parts of the Tree

Bark

Pith

Cambium

Heartwood

Latewood

Earlywood

Structure of Wood

Structure of Wood

Summer or late growth,

Early or spring growth.

Spring: the spring growth is rapid and is shown as a broad band.

Summer: the growth rings are darker, narrow layer of wood due to less moisture and slower growth in hot weather.

Tropical Climates: the growth rings are more even and difficult to distinguish.

Structure of Wood

One spring and one summer ring equal one years growth.

You can find the age of a tree by counting the number of annual rings.

Structure of Wood

Grain Annual Rings

Grain: Indicates the degree of contrast between the earlywood (spring growth and latewood (summer growth). The grain is the pattern you see on the face side of a board.

Structure of WoodBark: outer protective layer of the tree. Without bark, the tree cannot survive

Cambium: layer where the growth of the tree actually takes place.

Heartwood: inner part of the tree. This is the desirable part of the tree for a woodworker.

Sapwood: outer part of the tree. It is lighter in colour and softer than the heartwood.

Annual Rings: shows the growth of a tree in a single year. There are two parts to the annual

ring, spring and summer.

• Spring - lighter, wide layer of wood due to lots of moisture and rapid growth.

• Summer - darker, narrow layer of wood due to less moisture and slower growth.

Grain: indicates the degree of contrast between the earlywood (spring) and latewood

(summer). The greain is the pattern you see on the face side of a board.