WOOD!What is wood?
• An organic, natural composite of cellulose fibres • A living structure combining strength & flexibility
• Contains WATER, even when dried, making it pliable.• Weight for weight has the best engineering properties
of any material• Excellent insulator compared to metal, plastic and
concrete
Types of Timber• SoftwoodComes from EVERGREEN trees with needles. Typically grows quickly and in colder climates making it relativelycheap to buy.
• HardwoodComes from DECIDUOUS trees which grow slowly in warmer climates making it more expensive. Is denserthan softwood with a tighter grain.
The terms soft and hardwood are misleading as hardwoods are not necessarily hard or softwoods soft. Balsa (a hardwood) is actually softer than most softwoods. Though evergreens do tend to be less dense.
Types of SOFTWOOD Pine
Pale yellow with brown streaksand knots.• CHEAP• LIGHT
• QUITE STRONG• DURABLE
Cedar
Pale red and fragrant with a uniform,straight grain.• DURABLE
• NATURAL RESISTANCE TO ROT• EASY TO WORK
• LIGHT•GOOD INSULATOR
Types of HARDWOODTeak
Yellow/dark brown with a tight grain and high natural oil content.
• STRONG•DURABLE
• CURVES WELL / PLIABLE• NATURAL RESISTANCE TO RAIN
Mahogany
Pink/reddish brown with an attractive, interlocking grain.
• FAIRLY STRONG•ATTRACTIVE•DURABLE•EXPENSIVE
Oak
Light to medium brown with an open grain.
• STRONG•HARD• TOUGH•HEAVY• POROUS
Ash
Pale, light golden brown with an open grain.• FLEXIBLE• TOUGH•DURABLE
• EASY TO WORK
Beech
White – pinky brown with a close grain.• HARD• STRONG
• WARPS EASILY• TOUGH
• SUSCEPTABLE TO SHRINKAGE
Elm
Light to medium brown with an interlocking grain.
• PLIANT / BENDS WELL•TOUGH
• RESISTS SPLITTING• DURABLE IN WATER
• RESISTS DECAY WHEN WET
Types of Manufactured BoardPLYWOOD
Layers of thin wood sheets glued together at 90 degree angles to
each other. Often veneered.• STRONG IN RATIO TO WEIGHT•PLIABLE / CAN BE BENT• RESISTANT TO SPLITTING,
WARPING
BLOCKBOARD
Strips of softwood between 7-25mm thick are glued together side by sideand sandwiched between 2 layers of
veneer.• CHEAP• STRONG
• NOT SUITABLE FOR OUTDOOR USE
CHIPBOARD
Small wood particles mixed together with glue, heated and pressed in to
sheets. Usually plastic veneered.• VERY CHEAP
• CAN BE MADE FIRE RESISTANT• NOT VERY STRONG
• ABSORBS WATER AND SWELLS•RESISTANT TO WARPING (IF DRY)
MDF – Medim Density Fibreboard
Softwood waste is broken down into tiny fibres, mixed with urea
formaldehyde, heated and compressed into panels. Often veneered.
• CHEAP•DOESN’T WARP WHEN DAMP
• EASILY MACHINED• CAN BE MADE FIRE OR WATER
RESISTANT
HARDBOARD
Similar to MDF but denser. Made from compressed, glued fibres. Has one smooth side and one textured.
• CHEAP•EASY TO WORK
•POOR RESISTANCE TO MOISTURE• DOES NOT SPLIT OR CRACK
Which wood for
which purpose ?
TEAK Resists moisturePliable/curves well Durable
ELM Resists decay
Durable in waterTough
ASHEasy to work
FlexibleTough
Quiz time!
What wood mightthis be made of?
PLYWOOD!
And these?
Mahogany Oak
Or these?
MDF Pine
Finishes
• Sanding • Planing
Finishes
• Varnishing • Staining
Finishes
• Bleaching • Waxing
Finishes
• Oiling • Distressing
Finishes
• Lacquering
Health and Safety
• Wood manufacturing has one of the highest accident rates in the industry (www.hse.gov.uk)
• Wood dust can create health problems if a person inhales it or is exposed to it over a long period of time
• Dust/chippings can get in eyes• Wood dust can be slippery
Health and Safety
• Can get splinters if wood is untreated• Wood can be quite heavy• Machinery is dangerous eg. Saws, drills• Electrical equipment can break or be faulty• Noise of some machinery can cause heath
problems after long exposure• Fire risk – both wood/wood dust and the
products that treat it e.g varnish, paint
Sustainability
• Wood regarded as sustainable material• Grows naturally• Renewable• Uses CO₂ that humans create burning fossil
fuels, breathing etc.
Sustainability
• LCA (Life Cycle Assessment) method rates wood highly in sustainability.
• Evaluates materials of course of their life.
Sustainability
• Wood is good for environment in terms of:Global warming potentialResource useEmbodied energyAir pollutionWater pollution
Sustainability
• Global warming potentialStores CO₂Uses it as energyLower energy usage than in making of plastic and metal
Sustainability
• Resource useResource is renewableUsually easily recyclable/reusableDurable/long term
Sustainability
• Embodied energySum of all energy used to produce woodLower than other materials such as plastic and metalFrom raw material extraction, transport, manufacture, assembly, installation through to dis-assembly, deconstruction and decomposition
Sustainability
• Air pollutionWhen wood is living tree good for air pollutionExtraction and construction is lower than most resourcesOnly bad for air pollution when burned
Sustainability
• Water pollutionLow level pollution concerning wood and waterRated against other resources
Recycling
Pros Environmentally
friendly Raises awareness of
deforestation Saves landfill space If can be used in place
of plastic/metal, saves non renewable sources
Cons Recycled wood costs
less, but recycling costs high and time consuming
Demolition becomes more time consuming and complicated
Not well established trade
Recycling
• Wood can be recycled in different waysBecome fuelFlooring/deckingBeamsMulch
• Can either be broken down (fuel/mulch) or kept in original condition and refinished (beams/flooring)
By Ellie, Laura and Sophie