Knowledge O rganiser Year 9 Materials and their Working Properties

1. Paper and boards are usually made from wood pulp and convert to their final forms at a paper mill. Other cellulose sources can include textiles such as cotton, where resulting paper, known as rag paper, can be very high quality and can last many hundreds of years. Common Boards: Board thickness is usually quoted in microns or grams per square metre (gsm). 1000 microns is equal to 1mm of thickness. The lower the number, the thinner the paper or card. Knowledge Organiser Year 9 Materials and their Working Properties Common Papers: Paper is measured by weight in grams per square metre (gsm).

2. Common Hardwoods Natural Wood • HARDWOODcomes from Deciduous trees which loses there leaves in winter. • Tend to have a tighter grain • They can be very Expensive • These are usually quite hard but not always • They are slower growing trees it can take 100 years to grow fully • SOFTWOODcomes from Coniferous trees which keep there leaves in winter • They have a looser grain structure • These grow quite faster so are cheaper • These are usuallysofter, easy to work • They are often used as building material • The trees grow tall and straight, easier for the manufacturer to cut long straight planks of timber Common Softwoods Manufactured boards are usually sheets of processed natural timber waste products or veneers combined with adhesives. They are made from waste wood, low-grade timber and recycled timber. Manufactured boards 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 thin slices of a natural wood from the trunk of a tree. They are then bonded to the surface of cheaper sheet materials, such as medium density fibreboard (MDF) or plywood. Felling is a term used for cutting down a tree. Traditionally this was done by hand using an axe or a very long saw. Trees are now felled using chainsaws and modern chainsaw attachments are available for agricultural machines that can fell a tree, de-branch it and cut it into equal-length logs in one action. Manufactured Boards

3. Metals are found in the earth's crust. Some pure metals are mined as a whole metal but many are extracted as an ore Ore is a type of rock that contains a pure metal in small quantities. The ore is gathered through mining, then the metal is often extracted through using large furnaces The extreme heat of the furnace separates the metal from the ore and it is drawn off as molten liquid and processed into metals we commonly use Metals and Alloys • Ferrous Metals • All contain Iron (ferrite) • Most are magnetic • Will rust if exposed to moisture without a protective finish Alloys are a mixture of at least one pure metal and anther element. The alloying process combines the metals and other elements in such a way as to improve the working properties or aesthetics. • Non-Ferrous Metals • Not magnetic • Does not contain iron • Does not rust but can oxidise • Oxidation causes the metal to change colour and dull with time • For example Copper turns a deep turquoise called verdigris and is used for bespoke roofing material. • The thin oxide layer is know as a patina Polymers • Plastics are mainly synthetic materials made from polymers. • Traditionally derived from finite petrochemical resources such as oil, gas and coal. • Sustainable sources such as vegetable starches are becoming more popular. • There are some naturally occurring plastics such as amber and rubber. • There are two types; thermoforming and thermosetting plastics.

4. Polymers Thermoforming Plastics known as thermoplastics are more flexible when heated. Polymers chains are quite loosely entangled with very few cross links. This allows them to easily slide past each other when heated. They can be formed into complex shapes and reformed multiple times. Thermo plastics are commonly used in processes such as vacuum forming, injection moulding and blow moulding. They are also easier to recycle. Thermosetting plastics or thermosets are more rigid and once they are set they cannot be reformed. The long polymer chains have many more cross links between them which stops the molecular chains in the plastic moving. As a result they are generally harder and more brittle than thermoplastics. They make excellent electrical insulators and have good resistance to heat and chemicals. When thermosets are heated, they tend to burn rather than melt making most thermosetting plastics difficult to recycle. New types of recyclable thermosetting plastics are being developed. This technology has the potential to reduce waste.

5. Textiles Natural fibres come from plants and animals, cotton comes from plants and wool comes from Sheep. These are Renewable resources. They are also biodegradable and recyclable, which makes natural fibres fairly sustainable. Synthetic fibres come from polymers. These molecules come mainly from oil and coal. These are non-renewable resources, therefore synthetic fibres are not very sustainable.

6. Woven Textiles Knitted Textiles Weft Knitting • The commonly used types are plain weave and twill weave • A loom weaves two threads – the warp and the weft - at right angles to each other • The self-finished edge is known as the selvedge, which stops the fabric from fraying Weft knit fabrics are made by hand or by machine using a single yarn that form interlocking loops across the width of the fabric. They tend to by quite stretchy due to the method of interlocking and can therefore loose their shape quite easily. Weft knit fabrics are very warm owing to the amount of air trapped. Warp Knitting The loops in warp knit fabrics interlock vertically and are less prone to unravelling and laddering which makes them easier to cut into sections and sew together for the construction of complex garments. They are less stretchy than weft knits and tend to hold their shape more effectively. Warp knit fabrics are complex structures, often using multiple yarns ad are therefore made by machine rather than by hand. Non-Woven Textiles Non-woven fabrics are made directly from fibres without being spun into yarns. The most commonly available non-woven fabrics are bonded fabrics made from a web of fibres held together with heat or adhesive. Common uses of non-woven fabrics include disposable products such as garments worn by surgeons and crime scene investigators, dishcloths and interfacing. Can be given special treatments such a flame resistance to make head rest covers on trains and aircraft.