Studied by 2 people
Contains info: Timber, metals and alloys, glass, textiles, composite.
Hardwoods
Hardwoods come from deciduous trees (broad-leafed trees) and generally have the following characteristics:
Slow growth (100+ years) & expensive (due to slow growth)
Stronger & more durable than softwoods
Wider planks available
More dense
Dark colour
Softwoods
Softwoods come from coniferous trees (cone bearing) and generally have the following characteristics:
Fast growth (20 years) & Low cost (due to the fast growth)
Long straight shape
Narrow planks
Less dense
Knotty
Grain
The lines/pattern running the length of the wood
These are growth rings of the tree
Wood is stronger parallel to the grain than perpendicular
Knots
Knots are branches that have grown from the trunk
Knots are very hard to cut and can fall out
Colour
Different types of timber have different colours
Some timbers (hardwoods) are selected because of their deep rich colour
Natural Characteristic - Smell
Some natural timbers have a unique/distinct smell
This can enhance the user experience/create an emotional response/evoke memories
Cedar is often used in saunas and it has a distinctive smell
Hickory and other aromatic woods are used for smoking foods and infusing flavour
Reason for seasoning
Timber is typically about 85% moisture
Once cut, the timber begins to lose moisture
Timber needs to have a moisture content below 20% for exterior applications and below 15% for interior applications
Seasoning
Once timber is felled and sawn it must be seasoned to prevent it from distorting →
Seasoning removes the moisture from the tree evenly
Correctly seasoned timber improves the strength, stability, resistance to decay of the wood and makes it easier to apply finishes or use adhesives/fasteners
Air-Dried Seasoning
Air-dried seasoning is the least expensive method
Air-dried timber planks are stored under cover and left to dry naturally
Air dried timber can only be used for outdoor applications as the moisture content of the wood is the same as the air outside
Kiln-dried seasoning
Kiln-dried seasoning is the most expensive method
Kiln-drying uses steam to artificially dry the timber and speed up the drying process
Produces the straightest timber that can be used indoors as it has a lower moisture content
Sustainable Timber production
Timber is considered to be a sustainable product as new trees can be grown to replace felled trees
In many parts of the world, timber is harvested faster than the rate it is being replanted
This causes many environmental problems such as desertification, deforestation and global warming
Sustainable Timber Production - sustainability
This means the supplier should be able to prove the timber has been sustainably harvested
FSC (Forest Stewardship Council)
Man-made Timber
Man-made timber is made in a factory by combining timber with adhesive
They can be made from waste wood, low-grade or recycled timber
Developed as an alternative to natural timbers
Are so popular now that companies are making all their products from manufactured boards
Man-made Timber - Plywood
Layers of veneer are glued together. The grain of each layer is perpendicular to each other
Very strong and stable and does not warp
Layers are visible on edges
Man-made Timber - MDF (medium density fibreboard)
Small wood fibres are pressed together with adhesive
Smooth surface, no wood grain
Not water resistant. The fine wood dust can cause health problems when sanding
Man-made Timber - Particle Board
Large wood chips are pressed together with adhesive
No wood grain
Not water resistant. Poor quality surface and edges. Usually covered with veneer
Advantages of man-made timber
Available in much larger sheets than solid timber
Can make large pieces of furniture without joining wood together
Consistent thickness & properties throughout the board
No knots or uneven parts in the wood
Advantages of man-made timber
They do not warp or twist as much as natural timbers
No need for seasoning
Smooth surface finish which requires little preparation
Available in many different finishes, veneers, and laminates
Lower cost compared to similar sized natural timber
Disadvantages of man-made timber
Toxic glues like Urea Formaldehyde used in the production which makes recycling difficult and cutting/sanding hazardous
Fall apart when wet (MDF and Particle Board)
Only available in thin sheets (up to 20mm)
Cannot support heavy loads over large spans (MDF and Particle Board)
Unattractive edges/surfaces that need to be covered with a finish
Do not take fasteners well (screws, nails)
Finishes
Timber needs to be finished for two reasons:
Enhance the aesthetics of the timber
Protect the timber against damage from the elements/wear or insects
Note
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