Materials & Their Working Properties
Materials & Their Working Properties
Choosing the right material is one of the most important decisions a designer makes. This lesson covers the five main material categories — papers and boards, timbers, metals, polymers and textiles — along with the physical and working properties you need to know for your exam.
Papers & Boards
Papers are thin, flexible sheet materials made from wood pulp. Boards are thicker and more rigid. Key types include:
Papers: bleed-proof paper (for marker pens), cartridge paper (general drawing), grid paper (technical drawing), layout paper (lightweight tracing for design development) and tracing paper (transparent, for copying designs).
Boards: corrugated card (packaging — strong, lightweight, cushioning), duplex board (food packaging), foil-lined board (insulating food containers), foam core board (mounting and model-making), ink jet card (printing) and solid white board (premium packaging).
Natural & Manufactured Timbers
Hardwoods come from broad-leaved, deciduous trees and are generally harder, denser and more expensive. Examples: ash (tough, flexible — tool handles), beech (hard-wearing — furniture), mahogany (attractive grain — furniture), oak (very durable — flooring, outdoor furniture) and balsa (extremely lightweight — model-making).
Softwoods come from coniferous, evergreen trees and grow faster, making them cheaper. Examples: larch (durable outdoors — fencing), pine (versatile — construction, furniture) and spruce (lightweight — construction, musical instruments).
Manufactured boards are made from processed wood. MDF (medium density fibreboard — smooth, easy to shape, good for painting), plywood (layers of veneer glued at right angles — strong in all directions) and chipboard (compressed wood chips — cheap, used in flat-pack furniture).
Hardwoods (oak, mahogany, beech, ash, balsa) are from deciduous trees — harder, denser, more expensive. Softwoods (pine, larch, spruce) are from coniferous trees — faster growing, cheaper. Manufactured boards (MDF, plywood, chipboard) offer consistency in large sheets.
Metals & Alloys
Ferrous metals contain iron. Low carbon steel (mild steel) is cheap and easy to work — used for car bodies, nuts and bolts. Cast iron is very hard but brittle — used for manhole covers and engine blocks. High carbon (tool) steel is extremely hard — used for cutting tools and drill bits.
Non-ferrous metals do not contain iron. Aluminium is lightweight and corrosion-resistant — used for drinks cans and aircraft. Copper is an excellent electrical conductor — used for wiring and plumbing. Tin resists corrosion — used for coating steel cans. Zinc is used for galvanising steel to prevent rust.
Alloys are mixtures of metals. Brass (copper + zinc) is corrosion-resistant and attractive — used for taps and musical instruments. Stainless steel (iron + chromium + nickel) resists corrosion — used for cutlery and surgical instruments. High speed steel (HSS) stays hard at high temperatures — used for drill bits.
Thermoforming polymers (thermoplastics) soften when heated and can be reshaped repeatedly. Key examples: acrylic/PMMA (transparent — display cases, signs), HIPS (easy to vacuum form — packaging, yoghurt pots), HDPE (tough — bottles, pipes), polypropylene/PP (flexible hinge — food containers, folders), PVC (durable — window frames, pipes) and PET (clear, strong — drinks bottles).
Thermosetting polymers set permanently when heated and cannot be reshaped. Key examples: epoxy resin/ER (strong adhesive — bonding composites), melamine formaldehyde/MF (heat-resistant — kitchen worktops), phenol formaldehyde/PF (electrical insulator — plugs, handles), polyester resin/PR (used as matrix in GRP/fibreglass) and urea formaldehyde/UF (hard — electrical fittings, adhesive).
Textiles
Natural fibres: cotton (soft, absorbent, breathable — t-shirts, towels), wool (warm, elastic — jumpers, blankets) and silk (smooth, lustrous — scarves, formal wear). Synthetic fibres: polyester (strong, crease-resistant — sportswear), polyamide/nylon (strong, elastic — tights, ropes) and elastane/lycra (very stretchy — sportswear, underwear).
Blended/mixed fibres (e.g. cotton/polyester) combine the best properties of both. Woven fabrics (plain weave — interlocking warp and weft threads) are strong and stable. Non-woven fabrics include bonded fabrics (fibres stuck together — disposable cloths) and felted fabrics (fibres matted by heat/moisture — hats, craft). Knitted fabrics are stretchy and comfortable — used for jumpers, socks and t-shirts.
Textiles include natural (cotton, wool, silk), synthetic (polyester, nylon, elastane) and blended/mixed fibres (cotton/polyester). Fabrics are made by weaving, knitting, bonding or felting.
Physical & Working Properties
You need to know two types of material properties:
Physical properties describe a material's characteristics in its natural state. Absorbency — resistance to moisture (cotton absorbs, polyester resists). Density — mass per unit volume (lead is dense, balsa is not). Fusibility — ability to melt and be reshaped (crucial for casting metals and moulding polymers). Electrical and thermal conductivity — how well a material conducts electricity or heat (copper conducts well, wood does not).
Working properties describe how a material behaves when force is applied. Strength — resistance to breaking under force. Hardness — resistance to scratching or denting. Toughness — ability to absorb impact without fracturing. Malleability — ability to be hammered or pressed into shape. Ductility — ability to be drawn into wire. Elasticity — ability to stretch and return to shape.