Using & Working with Materials

Properties in Action

Every commercial product relies on the physical and mechanical properties of its materials to function reliably. Physical properties — density, thermal conductivity, electrical conductivity — determine how a material behaves in its environment. Mechanical properties — strength, hardness, toughness, elasticity — determine whether it can withstand the forces placed on it during use. In the exam, questions ask you to link specific properties to specific products and explain why those properties matter.

Papers & Boards

Workability is the defining property of papers and boards. Corrugated cardboard is lightweight yet has excellent compressive strength, protecting goods during transit. Folding boxboard used for card food packaging has a smooth, printable surface combined with enough stiffness to hold its shape on a supermarket shelf. A cereal box, for example, must be rigid enough to stack, printable for branding, and low-cost for mass production — folding boxboard meets all three requirements. However, papers and boards absorb moisture and lose strength when wet, which limits their use in damp or food-contact environments without modification.

Timber

Timber's high strength-to-weight ratio and ease of machining make it ideal for flat-pack furniture. Components such as shelving panels are cut to precise dimensions, sanded smooth, and joined using cam-lock fittings — a system that is only possible because timber-based boards like MDF and chipboard are dimensionally stable and accept screws reliably. Solid hardwoods such as oak are used for tabletops where surface hardness is needed to resist scratching. The natural moisture content of timber varies, which can cause warping and splitting unless the material is properly conditioned before use.

Metals

Metals combine high strength, thermal conductivity and formability, making them the material of choice for cooking utensils such as pots, pans and baking trays. Stainless steel's resistance to corrosion and its non-reactive surface make it food-safe; aluminium's high thermal conductivity and low density allow a pan to heat quickly while remaining lightweight. Malleability allows metals to be pressed or rolled into complex shapes — deep-drawn stainless steel sinks and aluminium cooking pots are formed this way in commercial manufacturing.

Polymers

Polymers are mouldable, lightweight, electrically insulating, and available in a huge range of colours — which is why injection-moulded polypropylene seating is standard in schools and offices. Polypropylene has sufficient impact resistance to survive everyday use, enough flexibility to hinge (the 'living hinge' is a classic polypropylene design feature), and a surface that can be moulded in any colour without painting. High-density polyethylene (HDPE) is used for outdoor polymer seating and playground equipment because it combines UV resistance with toughness and will not rust, rot or splinter.

Textiles

Sportswear demands textiles that combine strength, elasticity, moisture management and light weight. Lycra (elastane) blended with polyester gives compression sportswear its stretch and recovery. Nylon's high tensile strength and abrasion resistance make it ideal for sports shoe uppers and kit bags. Performance fabrics such as Gore-Tex exploit expanded PTFE membranes to be simultaneously waterproof and breathable — a critical property combination for outdoor sports clothing. In contrast, cotton and linen are used in casual sportswear where comfort and breathability matter more than elasticity or water resistance.

Electronic & Mechanical Systems

Domestic appliances combine materials from multiple categories, but their electronic and mechanical systems have their own material requirements. Copper's electrical conductivity makes it the standard conductor in wiring and PCB tracks. Steel and engineering polymers such as nylon and acetal are used in gears, bearings and structural brackets within appliances because they combine strength with low friction. Housings for electronics must be electrically insulating, lightweight and capable of being moulded to complex ergonomic shapes — ABS polymer is the default for appliance casings, remote controls and tool housings.

Modifying Properties — Papers & Boards

Raw paper absorbs moisture readily — a serious problem for food packaging. Additives to prevent moisture transfer, such as wax coatings, polyethylene laminate layers or clay-coated barrier treatments, are incorporated into food-grade board. A milk carton or juice box is made from folding boxboard laminated with a thin layer of polyethylene on the inside surface — the board provides structural rigidity while the polyethylene prevents liquid from soaking through. This modification allows a paper-based material to perform in a wet food environment where unmodified board would collapse within minutes.

Modifying Properties — Timber

Freshly felled ('green') timber contains a high moisture content — up to 100% in some species — which causes it to shrink, warp and crack as it dries. Seasoning removes this excess moisture in a controlled way. Air seasoning stacks timber in open sheds for months or years; kiln seasoning uses heated chambers to reduce moisture content in days. Properly seasoned timber is dimensionally stable and far less likely to split or distort in service — an essential property for flat-pack furniture joints and high-quality joinery.

Modifying Properties — Metals

Some metalworking processes cause metals to become hardened and brittle through work-hardening — repeated cold forming introduces internal stresses that make the metal crack if further forming is attempted. Annealing reverses this by heating the metal to a set temperature and allowing it to cool slowly. This restores the metal's softness and malleability, making further forming possible. Copper pipe is annealed to allow it to be bent without splitting; steel sheet is annealed between rolling passes to allow it to be reduced to thin gauges.