Sources and Origins
The raw materials which make up products all have to be processed before the can be sent to a factory. It is important for a designer to be aware of the lifecycle of materials to help make choices about the environmental background and choosing properties best suited to your design.
Paper and boards
Trees are chipped into small pieces and mixed with chemicals to make pulp. Pulping breaks the wood down into thin fibres which is then bleached white and fed through rollers into sheets. Other materials can also be pulped such as bamboo and grasses, or recycled paper which is re-pulped and rolled again. Unbleached pulp keeps the wood colour and is often used as card.
Timber based material
Trees are felled and bark removed, it is then cut into planks and seasoned. Seasoning dries wood out with air or a carefully controlled kiln. Seasoning improves the strength of timber and its ability to withstand rot. Good quality soft and hard wood such as pine, ash and oak will then be worked into standard planks and moulding for building and furniture production. Other timber is processed into board.
Chipboard is wood chips and sawdust compacted together with glue and formed into sheets.
MDF is processed into pulp in the same way as cardboard, it’s flattened and dried.
Plywood is thin layers of timber cut and glued together at 90 degrees, this makes if strong and rigid.
Metal based materials
Metal ore is mined from the ground in rock form. The rocks have to be heated either in a furnace or by passing an electrical current through it. This melts the metal out of the ore. This first separation still has some impurities in the metal so it is then refined either in a furnace or by electrolysis. The pure metal is then cast into the required shapes and cooled.
Plastics (polymers) come from crude oil. The oil is mined from underground and then refined in a process called fractional distillation separating the oil into chemicals called fractions. These fractions can be split into monomers, when monomers or joined together by chemicals they become polymers – polymerisation. Some fractions are too big to be joined so are heated in a process called cracking, this makes them small enough to be polymerised. Once polymers are chemically formed they can be moulded.
Textiles based materials
Natural fibres come from animals or plants, their fibres are short and hairy (called staple fibres) making them easy to spin into a thread. Examples of natural fibres are wool, cotton and silk. Natural fibres are harvested, cleaned and spun.
Synthetic fibres are polymer based so originate from crude oil. The polymer is melted and forced through a tiny hole. This gives a smooth, continuous length called a filament. It is then woven or knitted in the same way as natural fibres. Examples include nylon, polyester and elastane.
Regenerated fibres are natural fibres which are treated with chemicals and forced through a tiny hole to make a filament. Viscose is made from wood pulp mixed with sodium hydroxide.