GCSE DT Revision Notes

WOODS
Is organic and will decay over time. In wetter conditions with decay will be quicker. It is also subject to conditions such as dry rot, or pests. The greater the density of wood, the greater its mechanical strength.

Knots also contained, formed where branches grew from main trunk, or where a bud was formed. Can generate weaknesses, or be aesthetic.

HARDWOODS o o

Deciduous (leaf-losing) trees.
Slower growing, making them denser. Some take up to 100 years to reach full maturity, making them unsustainable and expensive o Aesthetics
 Colour varies enormously, but oak is usually pale brown in colour and mahogany is reddishbrown. Beech often a light brown colour, ash usually creamy white. o Properties
 Contain lots of fibrous material
 Fibres are small and compact, which gives the wood a greater mechanical strength and hardness compared to softwoods.
SOFTWOODS
o Coniferous, or evergreen, and reach maturity in 30 years. o They are cheaper than hardwoods and more sustainable. o Aesthetics
 Resinous, and resin can leak from timber, leaving stain.
 Will change colour in sunlight, but usually pale yellow
 Prone to decaying, warping, bowing, cupping, and splitting o Properties
 Have a tube-like cell structure
 Less dense than hardwoods, and more prone to water damage
 Timber absorbs water like a sponge if end grain is left untreated
GROWTH OF WOOD o The growing season is normally spring to autumn
 Tree’s girth increases, and height o Cells produced during drier summer months have thicker cell walls o Age can be determined through annual rings o Once a tree has been felled, cut down, and taken to a sawmill, it is converted ready for seasoning o After timber dries, it is cut into smaller, more common shapes and sizes. Most timber sold in DIY stores is planed all round; PAR
MANUFACTURED BOARDS o Man made. Waste wood used to make MDF and chipboards. Other manufactured boards like plywood are layers of veneers glued