WoodWood

Javier Gómez Calzada1ºESO

What wooden objects are around us?What wooden objects are around us?

At home:• Furniture• Floor• Doors• Beams

In Technology lab

• Handles of tools• Boards of tables• Shelves

Why are they made of wood?Why are they made of wood?Because it has some good properties• Pleasant to look at and to touch• Good insulator of heat• Strength• Quite rigid• Easy to work with it• It is available in most of the places• Very different types of wood depending on the aplication

(and the money you want to spend!)

But it has some disadvantages too• Natural wood contains some natural defects (knots, rot,

cracks, resin)• Natural wood has bad ressistance to heat and humidity

(so it rots and bends)

Types of wood: Natural woodTypes of wood: Natural wood

Hardwood• Trees with leaves that drop

every autumn (deciduous trees)• Trees take a long time to grow• Not environmentally friendly (we

use them faster than they grow!!)

• Expensive• Harder than softwoods

Spain: Oak, elm, beech, ashNon-native: mahogany, teak, ebony

Softwood• Conifers (evergreen trees) with

needles• Trees grow faster

• More environmentally friendly

• Cheap• Softer, lighter and easier to cut

than hardwoods

Pine, white deal, cedar, spruce,

Depending on the structure of the tree:

HARDWOODSHARDWOODS

Oak Elm

Teak Ebony

SOFTWOODSSOFTWOODS

Scots pine

Spruce

Types of wood: Manufactured woodTypes of wood: Manufactured wood

More common in recent times because:• Lower cost• Lack of availability of natural wood

Made using different materials from natural woods:• Fibres or strips of wood• Veneers: thin layers of natural wood used to cover a

manufactured wood

MDF (medium density fibre)• Made from fine wood fibres glued together• Very strong• MDF dust is very fine and can damage lungs if inhaled

► Cover your mouth, nose and eyes when working with MDF!!!!

Plywood• Made by sticking together several veneers• Flat and strong• It is often very thin• Uses: packages and boxes, drawer bottoms, …

Chipboard (practicle board)• Made by gluing and compressing together tiny pieces

of wood• Not very strong and difficult to join• Can crumble and break• Cheap• Often used with a veneer facing for modern furniture

Manufactured woodManufactured wood

Manufactured woodManufactured wood

ADVANTAGES• They are flat, cheap and can be strong• They can be cut easily• They do not have any knots• They do not rot when damp• Their width is not limited to the width of the tree• They are more environmentally friendly

DISADVANTAGES• They do not look as nice• They can contain a lot of chemicals• They may irritate the eyes and lungs

Which are the effects of using Which are the effects of using wood on the environment?wood on the environment?

We are using the wood faster than it grows in nature► Loss of forests, specially in the tropics (rainforests)

Mato Grosso, Brazil, 1992 Same area in 2006

► Loss of forests damages the planet and contributes to the global warming