chapter 15 - natural and manufactured timbers

natural wood is categorised as hardwood or softwood

These names reflect the cell structure of the tree and not the strength of the wood

hardwood:

From a deciduous tree
Usually broad leafed variety that drops its leaves in winter
Generally have a less porous and denser cell structure than softwoods
Makes many varieties harder wearing and less prone to rotting
Balsa wood, although light and fragile, is also known as a hardwood
- It is very slow growing, and so soft you cannot make furniture out of it, so it is used for modelling instead
Come in a variety of colours and has many sought after aesthetic and physical properties
Since the value of hardwood is so high, there is much illegal felling of trees, especially in rainforest areas
Really strong but take a long time to grow
Because they take time to grow, the grains inside the logs of the tree are closer together than in softwoods

NAME	APPEARANCE	IMAGE	CHARACTERISTICS	EXAMPLE USES
Ash	Pale brown / cream		Flexible, tough and shock resistant, laminates well	Sport equipment and tool handles
Balsa	Pale cream/white. An open grained large and unusually fast growing hardwood tree		Very soft and spongy, very lightweight but can snap in thin sections	Prototyping and modelling - especially model aircraft
Beech	Dense/close grain with an attractive pink hue		Fine finish tough and durable	Children's toys and models, furniture and veneers
Mahogany	Rich reddish brown		Easily worked, durable and finishes well	High end furniture and joinery, veneers
Oak	Light brown with an interesting and variable grain		Tough, hard and durable, high quality finish possible	Flooring, furniture, railway sleepers and veneers

softwood:

From a coniferous tree
Usually bears needles and cones
Frequently called evergreen trees as most of them keep their needles all year round
Generally has a more porous cell structure than hardwood
If left unprotected from elements, it can absorb moisture and begin to rot
- Some softwoods, such as cedar, contain natural oils which protect them and make them therefore suitable for outdoor use, for example roofing
It is not available in as many colours as hardwood
Easy to add stains, so it is frequently coloured to look like more expensive hardwoods
Softwood is commonly used in the construction industry: it is relatively cheap and readily available
The most sustainable wood due to its faster growth rate and the fact that it is widely planted, especially in Europe and Scandinavia

NAME	APPEARANCE	IMAGE	CHARACTERISTICS	EXAMPLE USES
Larch	Pale to reddish brown with a contrasting grain		Durable, tough, good water resistance, good surface finish and machines well. Issues with loose knots	Exterior cladding, flooring, machined mouldings, furniture and joinery
Pine	Pale yellow to pale brown, attractive grain that darkens with age		Lightweight, easy to work, can split and be resinous near knots	Interior construction (and exterior if treated), cheaper furniture, decking
Spruce	White/cream with a fine even grain		Easy to work, high stiffness to weight ratio. Variable results when staining	Construction, furniture and musical instruments

manufactured boards:

Also known as engineered wood or composite boards, and comprise of a range of sheet materials
Usually sheets of processed natural timber waste products or veneers combined with adhesives
Made from waste wood, low grade timber, and recycled timber
Have a pale brown natural finish, but can be covered with thin slices of high quality wood to give the appearance of solid wood
- This covering is called a veneer
Veneers are produced by taking sleeves of a natural wood from the trunk of a tree, and then bonded to the surface of cheaper sheet materials, such as MDF

NAME	APPEARANCE	IMAGE	CHARACTERISTICS	EXAMPLE USES
MDF (medium density fibreboard)	Smooth, dull, light brown finish available in many veneered options. Edges can be hard to finish well		Rigid and stable, good value with a smooth easy to finish surface. Very absorbent so not good in high humidity or damp areas	Flat pack furniture, toys, kitchen units and internal constructions
Plywood	Alternating layers of neutral grain veneers with the outer material usually of a higher quality for aesthetics		Very stable in all directions due to alternate layering at 90 degrees, with outside layers running in the same direction. Thin flexible versions available (flexi ply)	Furniture, shelving, toys and constructions. Interior exterior and marine grades are available for greater water resistance
Chipboard	Pale grey/brown with no natural grains. Frequently covered with a laminate such as melamine formaldehyde (Formica)		Good compressive strength, not water resistant unless treated, good value but prone to chipping on edges and corners	Flooring, low-end furniture, kitchen units and worktops

Felling is the term used to describe the cutting down of a tree

Traditionally this as done by hand using a long saw or an axe

They are now felled using a chainsaw and modern chainsaw attachments which can fell a tree, de branch it and cut it into equal length logs in one action

Timber is made into planks when it falls from a tree

It is then seasoned which increases the durability of the wood and helps to remove moisture

Then it is produced into boards, square sections, mouldings and/or dowels

Finally, sold to customers by length, width, thickness and diameter