How are materials classified, and how do you justify the right one for a product?
Classification of papers and boards, timbers, metals, polymers and textiles into families, and the criteria used to select a material for a given product and context.
A focused answer to WJEC A-Level Design and Technology Unit 1 classification and selection of materials, covering the main material families (papers and boards, timbers, metals, polymers and textiles), how each splits into sub-groups, and the criteria used to justify a material choice for a product.
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What this dot point is asking
WJEC wants you to sort the materials you work with into their families, name the sub-groups within each family, and then justify which material suits a particular product. Classification is the vocabulary; selection is the skill examiners actually test, usually through a "discuss the factors" question worth several marks. The two go together: you cannot justify a choice without knowing what alternatives the material's family offers.
The answer
The five material families
WJEC organises materials into five families, each with sub-groups:
- Papers and boards. Made from cellulose fibre. Examples include cartridge paper, layout paper, bleed-proof paper, corrugated card, mounting board and foam board. Specified by weight in grams per square metre (gsm) for papers and thickness in microns for boards.
- Timbers. Split into hardwoods (from broadleaved, usually deciduous trees: oak, ash, beech, mahogany, balsa), softwoods (from coniferous trees: pine, spruce, cedar) and manufactured boards (MDF, plywood, chipboard, blockboard), which are engineered to be stable and wide.
- Metals. Split into ferrous (containing iron, so usually magnetic and prone to rust: mild steel, cast iron, high-carbon steel), non-ferrous (no iron: aluminium, copper, zinc, tin) and alloys (mixtures designed for improved properties: stainless steel, brass, bronze, duralumin).
- Polymers. Split into thermoplastics (reshapable on heating: acrylic, HIPS, PP, PVC, ABS, PET) and thermosetting polymers (permanently set on curing: urea formaldehyde, melamine, epoxy resin, polyester resin).
- Textiles. Split into natural fibres (cotton, wool, silk, linen), synthetic fibres (polyester, nylon, elastane, acrylic) and blends (polycotton), then constructed into woven, knitted or non-woven fabrics.
Why classification predicts behaviour
Selection: matching material to product
Selection is a decision against the product's requirements. WJEC expects you to weigh several factors together:
- Functional requirements - the properties the job demands (strength, toughness, heat resistance, flexibility, conductivity, water resistance).
- Aesthetic requirements - colour, texture, finish, grain or translucency.
- Ergonomic requirements - comfort, grip, warmth to touch, weight in use.
- Manufacturing factors - whether the material can be formed by the planned process at the planned scale, and its workability.
- Cost and availability - material cost, standard stock sizes and reliable supply.
- Sustainability - whether it can be recycled or sourced responsibly (for example FSC-certified timber), and its environmental footprint.
Examples in context
Example 1. A disposable coffee cup. The body is paperboard for low cost, printability and renewable sourcing, lined with a thin polymer film for water resistance. The choice trades recyclability (the laminate is hard to separate) against the functional need to hold hot liquid, a tension WJEC likes you to acknowledge.
Example 2. A garden tool handle. Ash is a traditional hardwood choice because it is tough, shock-absorbing and pleasant to grip, while a modern equivalent uses glass-filled nylon for weatherproofing and consistent moulded production. Comparing the two shows how the same function can be met from different families with different trade-offs.
Try this
Q1. Name the three sub-groups of metals and give one example of each. [3 marks]
- Cue. Ferrous (mild steel), non-ferrous (aluminium), alloy (stainless steel).
Q2. State three factors, other than cost, a designer should consider when selecting a material for a child's bath toy. [3 marks]
- Cue. Non-toxic and food-safe, waterproof and corrosion-resistant, soft or smooth with no sharp edges for safety, light enough to float, easy to mould at volume.
Exam-style practice questions
Practice questions written in the style of WJEC exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
WJEC 20196 marksA manufacturer is choosing a material for the body of a cordless kettle. Discuss the factors the designer should consider when selecting a suitable material.Show worked answer →
A strong answer treats selection as a balance of competing demands, not a single property.
Functional requirements come first: the body must withstand near-boiling water, so the material needs good heat resistance and must not distort or release harmful substances. A thermoplastic such as polypropylene or a food-grade copolymer suits this because it tolerates heat, is tough and is electrically insulating, which matters for safety around mains voltage.
Aesthetics and ergonomics matter for a consumer product: the material must take a good surface finish and colour, feel comfortable and stay cool enough to handle. Manufacturing factors follow: the chosen polymer must injection mould cleanly into a complex shell at the planned scale of production, which favours a material with good flow and a short cycle time.
Cost and availability constrain the choice, and sustainability is now examined explicitly: a recyclable single polymer that carries a recycling code helps end-of-life recovery. Markers reward a discussion that links each factor to the specific product rather than a generic list, and that names a plausible material with a justification.
WJEC 20214 marksExplain, using examples, the difference between a thermoplastic and a thermosetting polymer.Show worked answer →
A thermoplastic softens when heated and can be reshaped repeatedly because its long polymer chains are held only by weak intermolecular forces that relax on heating. Examples include acrylic (PMMA), high impact polystyrene (HIPS) and polypropylene (PP). This reversibility makes thermoplastics recyclable and suited to injection moulding and vacuum forming.
A thermosetting polymer sets permanently on first curing because heat or a hardener triggers cross-links (strong covalent bonds) between the chains. It cannot be re-melted and will char if overheated. Examples include urea formaldehyde (used for electrical fittings), melamine formaldehyde and epoxy resin.
Markers reward the structural reason (weak intermolecular forces versus permanent cross-links) plus at least one correct example of each type, and credit a consequence such as recyclability or heat resistance.
Related dot points
- Physical and mechanical working properties of materials - strength, hardness, toughness, ductility, malleability, elasticity, plasticity, density, durability, electrical and thermal conductivity - and how they govern selection and processing.
A focused answer to WJEC A-Level Design and Technology Unit 1 working properties of materials, covering the physical properties (density, conductivity, durability) and mechanical properties (strength, hardness, toughness, ductility, malleability, elasticity, plasticity) and how each affects material selection and processing.
- The sources, origins and primary processing of materials (timber seasoning and conversion, metal extraction, polymerisation of crude oil, fibre sources) and the standard stock forms in which they are bought.
A focused answer to WJEC A-Level Design and Technology Unit 1 sources and origins of materials, covering where timbers, metals, polymers and fibres come from, the primary processing each undergoes (seasoning, smelting, polymerisation), and the standard stock forms in which materials are supplied.
- The main categories of manufacturing process - wasting, shaping by casting and moulding, deforming and reforming, fabrication and joining - and how the chosen process depends on material, form and scale.
A focused answer to WJEC A-Level Design and Technology Unit 1 manufacturing processes, covering wasting, casting and moulding, deforming and reforming, fabrication and joining, with named processes such as injection moulding, vacuum forming, casting, turning and laminating, and how process choice depends on material and scale of production.
- The reasons for applying surface treatments and finishes (protection, durability, aesthetics, hygiene) and named finishes for timber, metal and polymer such as varnish, paint, galvanising, anodising, powder coating and self-finishing.
A focused answer to WJEC A-Level Design and Technology Unit 1 surface treatments and finishes, covering why finishes are applied (protection, durability, aesthetics, hygiene) and named finishes for timber (varnish, stain, oil), metal (galvanising, anodising, powder coating, electroplating) and polymers (self-finishing).
- Smart materials that respond to a change in their environment (shape memory alloys, thermochromic and photochromic pigments, quantum tunnelling composite, electroluminescent and piezoelectric materials) and modern materials developed through new processes.
A focused answer to WJEC A-Level Design and Technology Unit 3 smart and modern materials, covering materials that respond to their environment (shape memory alloys, thermochromic and photochromic pigments, quantum tunnelling composite, piezoelectric and electroluminescent materials) and modern materials such as precious metal clay and polymorph.
Sources & how we know this
- WJEC AS/A Level Design and Technology specification — WJEC (2017)