Criteria for Selecting Materials

This lesson covers the key criteria designers and manufacturers use when selecting materials for products, as required by the AQA GCSE Design and Technology specification (8552), Section 3.2.1. When designing any product, choosing the right material is one of the most important decisions. A poor material choice can lead to product failure, excessive cost, or environmental harm. Understanding these criteria will help you justify material choices in your NEA (Non-Exam Assessment) project and answer exam questions confidently.

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Functionality

The primary purpose of a material is to perform its required function. Functionality means the material must be fit for purpose — it must do the job it is intended to do.

Functional Requirement	What to Consider	Example
Strength	Can it withstand the forces applied during use?	A bicycle frame must resist bending forces — aluminium alloy or steel is chosen
Durability	Will it last for the expected product lifetime?	Outdoor garden furniture needs weather-resistant materials like teak or HDPE
Flexibility	Does it need to bend without breaking?	A phone case needs some flexibility — silicone or TPU is ideal
Hardness	Must it resist scratching or wear?	Kitchen worktops use granite or laminated MDF for scratch resistance
Thermal properties	Does it need to insulate or conduct heat?	Saucepan handles use thermosetting plastic (e.g. Bakelite) to insulate from heat
Electrical properties	Must it conduct or insulate electricity?	Electrical cable cores use copper (conductor) with PVC coating (insulator)

AQA Exam Tip: When asked to justify a material choice, always link the material's properties to the product's function. For example: "Stainless steel is suitable for a kitchen sink because it is corrosion-resistant, hard-wearing, and hygienic — all essential functional requirements for a product in constant contact with water."

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Aesthetics

Aesthetics refers to how a product looks and feels. The visual and tactile qualities of a material significantly influence consumer appeal and purchasing decisions.

Key aesthetic factors include:

• Colour — Can the material be dyed, painted, or does it have a natural colour that suits the design? Polymers can be coloured during manufacture by adding pigments to the raw material.
• Surface finish — Is the surface smooth, textured, matt, or glossy? Metals can be polished to a mirror finish; timbers can be varnished, stained, or oiled.
• Texture — How does the material feel? Fabrics for clothing must feel comfortable against skin; rubberised grips on tools improve handling.
• Transparency — Is the material opaque, translucent, or transparent? Acrylic (PMMA) is chosen for display cases because it is transparent and lighter than glass.
• Form — Can the material be shaped into the desired form? Thermoplastics can be vacuum formed into complex 3D shapes.

Real-world example: Apple designs its MacBook laptops using anodised aluminium because it provides a premium feel, a sleek brushed finish, and a range of subtle colours — all contributing to the product's aesthetic appeal.

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Environmental Factors

Designers must consider the environmental impact of material choices throughout the entire product life cycle.

Environmental Factor	Description	Example
Recyclability	Can the material be recycled at end of life?	Aluminium is infinitely recyclable and widely collected
Biodegradability	Will it break down naturally?	PLA (polylactic acid) is a biodegradable bioplastic used for packaging
Carbon footprint	How much CO2 is produced during extraction, processing, and transport?	Locally sourced softwood has a lower carbon footprint than imported hardwood
Toxicity	Does production or disposal release harmful substances?	Lead-free solder is now standard due to the toxicity of lead
Sustainability	Is the raw material from a renewable or finite source?	FSC-certified timber comes from sustainably managed forests

AQA Exam Tip: Environmental factors are increasingly tested in the exam. Be prepared to discuss the six Rs (reduce, reuse, recycle, refuse, repair, rethink) and how they influence material selection. A strong answer links specific environmental concerns to specific material properties.

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Cost

Cost is always a factor in commercial product design. The material must be affordable within the product's target price point.

Cost considerations include:

• Raw material cost — Precious metals and exotic hardwoods are expensive; mild steel and softwood are cheap.
• Processing cost — Some materials are cheap to buy but expensive to work with. Titanium is lightweight and strong but very costly to machine.
• Waste cost — Cutting complex shapes from sheet material produces offcuts. Minimising waste reduces overall cost.
• Volume discounts — Buying materials in bulk reduces unit cost. This is why mass-produced products can use more expensive materials than one-off prototypes.
• Finishing cost — Some materials need additional surface treatments (painting, plating, anodising) that add cost.

Real-world example: IKEA uses particleboard with melamine coating for many furniture ranges because it is extremely cost-effective compared to solid timber, while still providing an acceptable aesthetic finish for the target market.

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Availability

A material must be available in the required form, quantity, and timeframe.

• Stock forms — Is the material available in the sizes and shapes needed (sheet, bar, tube, rod, filament)?
• Supply chain — Can it be sourced reliably? Supply chain disruption (e.g. during the COVID-19 pandemic) can make certain materials temporarily unavailable.
• Geographic availability — Local materials reduce transport costs and lead times. Imported materials increase carbon footprint and may be subject to tariffs.
• Specialist vs standard — Standard materials are stocked by most suppliers; specialist materials may have long lead times and minimum order quantities.

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Bringing It All Together

In practice, material selection is always a compromise between multiple criteria. No single material is perfect in every respect. Designers use a selection matrix to weigh up the pros and cons.

Criterion	Weighting	Material A (ABS)	Material B (Aluminium)	Material C (Oak)
Functionality	30%	7	9	6
Aesthetics	20%	6	8	9
Environmental	20%	4	7	8
Cost	20%	8	5	4
Availability	10%	9	8	6
Weighted total		6.5	7.5	6.6

In this example, aluminium scores highest overall, making it the best choice for this particular product based on the designer's priorities.

AQA Exam Tip: In the exam, you may be asked to evaluate material choices for a given scenario. Always consider at least THREE criteria (e.g. functionality, cost, and environmental impact) and explain how they interact. Simply listing properties without linking them to the product's requirements will not gain full marks.

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Summary

• Material selection depends on functionality, aesthetics, environmental factors, cost, and availability.
• Functionality is usually the most important criterion — the material must be fit for purpose.
• Designers must balance competing criteria and make compromises.
• A selection matrix is a useful tool for comparing materials objectively.
• Always justify material choices by linking material properties to product requirements.