Material Categories & Working Properties
Material Categories & Working Properties
Every product is made from something — and the material a designer chooses affects cost, strength, appearance and sustainability. This lesson covers the material categories named in the specification: papers and boards, timbers, metals, polymers and textiles — and the physical and working properties that let you compare them.
Papers & Boards
Paper is a thin, flexible sheet material made from wood pulp. The specification names three types: copier paper (general printing and photocopying, smooth and inexpensive), cartridge paper (thicker and slightly textured — used for sketching and painting because it takes pencil and light washes of colour without curling) and tracing paper (thin and translucent, used to copy or overlay a design).
Board is thicker and more rigid than paper, so it is used for packaging and display. Folding boxboard is a lightweight multi-layer board — a bulky mechanical-pulp core between two bleached chemical-pulp liners — which gives it stiffness at low weight and lets it crease cleanly without cracking; ideal for cereal boxes and cosmetics cartons. Corrugated board has a fluted layer glued between two flat liners, which traps air and resists crushing — used for transit boxes and protecting fragile goods. Solid white board is dense, smooth and takes high-quality print, so it is chosen for premium retail packaging.
Papers and boards are judged on three working properties: flexibility, printability and biodegradability.
Natural & Manufactured Timbers
Hardwoods come from broad-leaved, deciduous trees that lose their leaves each year and generally grow slowly, making them more expensive. Oak is strong and decorative, used for flooring and outdoor furniture. Mahogany has an attractive reddish-brown grain, used for quality furniture. Beech is hard and close-grained, used for furniture and tool handles. Balsa is technically a hardwood but is extremely low density, so it is used for models and prototypes rather than structural parts.
Softwoods come from coniferous, evergreen trees, which grow faster and are usually cheaper. Pine is pale, easy to cut and shape, used for construction timber and flat-pack furniture. Cedar contains natural oils that resist decay and insect attack, so it is used outdoors for cladding and garden sheds without needing a protective finish.
Manufactured timbers are made by processing wood waste or veneers, giving more consistent properties than natural timber. Plywood is built from thin layers of veneer glued with the grain of each layer running at right angles to the next, making it strong in every direction. Medium density fibreboard (MDF) is made from compressed wood fibres and resin — it has no visible grain, cuts cleanly and takes paint well, so it is widely used for flat-pack furniture.
Timbers are compared using hardness, toughness and durability. Oak scores highly on hardness and durability, which is why it survives outdoors for decades; balsa has almost none of either, which is why it is only used for lightweight models.
Ferrous & Non-Ferrous Metals
Ferrous metals contain iron, which makes most of them magnetic and prone to rusting if left unprotected. Mild steel is cheap, tough and easy to weld, used for car bodies and gates, but it corrodes without a protective finish. Stainless steel contains chromium, which forms a protective layer that resists corrosion — used for cutlery, sinks and surgical instruments. Cast iron is very hard and holds its shape under compression but is brittle, so it is used for manhole covers and cooking pans rather than parts that get struck or bent.
Non-ferrous metals contain no iron, so they resist corrosion better and are non-magnetic. Aluminium is light and naturally forms a protective oxide layer — used for drinks cans and aircraft parts. Copper is an excellent conductor of heat and electricity and is easily bent, used for electrical wiring and plumbing pipes. Brass resists corrosion and can be polished to a decorative finish, used for door furniture and musical instruments.
Metals are compared using three working properties. Ductility is why copper can be drawn into electrical cable. Malleability is why aluminium can be rolled into thin foil. Hardness is resistance to scratching or denting — high carbon steel is hardened to make cutting tools that keep a sharp edge.
Thermoforming & Thermosetting Polymers
Thermoforming polymers soften every time they are heated, so they can be reshaped repeatedly. Acrylic is rigid, can be polished to a high shine and is used for signage and display cases. High impact polystyrene (HIPS) is lightweight and vacuum forms easily, used for packaging trays and model bodywork. Biodegradable polymers such as Biopol break down naturally after use, reducing plastic sent to landfill, and are used for disposable cutlery and packaging film.
Thermosetting polymers undergo a permanent chemical change the first time they are heated or mixed with a hardener, so they cannot be reshaped again. Polyester resin is a liquid that cures hard once a catalyst is added; it binds glass fibre matting together in products such as boat hulls and car body panels. Urea formaldehyde is hard, brittle and an excellent electrical insulator, so it is used for plug sockets and electrical fittings.
Polymers are compared using three working properties: being a good insulator of heat, being a good insulator of electricity, and toughness. Urea formaldehyde is a good electrical insulator but has poor toughness, so it is used for static fittings rather than products that get dropped.
Textiles: Fibres & Fabric Construction
Natural fibres come from animals or plants. Wool, an animal fibre, is warm, absorbent and stretches back into shape, used for jumpers and blankets. Cotton, a vegetable fibre, is soft, absorbent and breathable but creases easily, used for t-shirts and bedding. Synthetic fibres are made from chemicals derived from crude oil. Polyester is strong, resists creasing and does not absorb much moisture, used for sportswear. Acrylic is a lightweight, warm substitute for wool that is cheaper but less durable, used in budget knitwear.
Fabrics are built from fibres in three main ways. Woven fabrics include plain weave calico, cheap and stable, used for testing patterns, and twill weave denim, with a diagonal weave that is hard-wearing, used for jeans and workwear. Non-woven fabrics include felted wool fabric, matted using heat, moisture and pressure, used for hats and insulation, and bonded fibres/webs, fused or glued, used for interfacing and disposable wipes. Knitted fabrics include weft-knitted fabric, which stretches in every direction and is used for t-shirts and jumpers, and warp-knitted fabric, which is more stable and runs less, used for swimwear and lace.
Textiles are compared using elasticity, resilience and durability. Elastane fibres give sportswear its stretch; denim's tight twill weave gives it high durability for workwear.
Choosing Materials for a Context
The specification expects you to justify material choices, not just name them. When selecting a material for a product, weigh up its properties, its advantages and disadvantages, and how it will be manufactured, then explain why it suits the specific context — the user, the budget, the required performance and the environmental impact. A material that is perfect for one product can be entirely wrong for another.
A designer is choosing a material for a reusable lunch box. A thermoforming polymer is tough, resists moisture and is food-safe, but a paper or board alternative would be more biodegradable. Aluminium would be light and durable but is a poorer thermal insulator, so hot food would burn hands. Justifying the final choice means comparing these properties against the brief — not simply listing what each material is made from.