1.2 Performance characteristics of materials - Key terms

air seasoning

a traditional, inexpensive method which involves stacking the wood under a shelter, protected from the rain

air circulates between the planks to slowly remove the excess moisture

kiln seasoning

a more expensive but controlled method which is very quick and can take just a few weeks

planks are stacked onto trolleys and placed in the kiln where both temperature and humidity are controlled

hardwood

a wood from a broad-leaved (deciduous) tree

softwood

a wood from a cone-bearing (coniferous) tree

rough sawn

wood that comes directly from seasoning and has rough edges produced from initial conversion

rough sawn wood will have nominal sizes rather than accurate finished sizes

PSE

plane square edge

wood has only one edge that is planed accurately, the rest are rough sawn

is about 3mm smaller in width from the original nominal size

PAR

planed all round

wood has sides and edges that are planed square, straight and level, leaving a smooth finish, and is ready to use

is about 3mm smaller all round than the original rough sawn nominal size

safe working temperature (polymers)

the temperature deemed safe for processing without possible degradation of the polymer properties

composite

a material comprised of two or more different materials, resulting in a material with enhanced properties

smart materials

materials whose physical properties change in response to an input or change in the environment, such as electricity, pressure, temperature or light

modern materials

materials that are developed through the invention of new or improved processes