Natural and Manufactured Timbers
Timber in Design and Industry
Timber is one of the most versatile structural materials available to designers, and a common choice for the in-depth material area in the written exam. Understanding the difference between hardwoods, softwoods and manufactured boards—and knowing named examples of each—is essential. The distinction begins at the tree: hardwoods come from deciduous trees (broad-leaved, generally slow-growing), while softwoods come from coniferous trees (evergreen, needle-leaved, generally faster-growing).
Importantly, “hardwood” and “softwood” are botanical classifications, not descriptions of physical hardness. Balsa—which is famously soft to the touch—is technically a hardwood because it comes from a deciduous tree. Conversely, some conifers produce surprisingly dense timber.
Hardwoods come from deciduous (broad-leaved) trees; softwoods come from coniferous (needle-leaved) trees. The terms describe botanical classification, not physical hardness. Balsa is a hardwood despite being soft; some conifers produce dense timber.
Named Hardwoods
The following hardwoods are named in the specification and are likely to appear in exam questions:
- Oak—a dense, strong hardwood with an attractive grain and excellent durability. Used in furniture, flooring, wine barrels and construction. Oak can be finished naturally or stained; it reacts with iron fixings (producing dark stains), so stainless or brass fixings are preferred.
- Beech—a pale, fine-grained hardwood that is very hard and resistant to splitting. Commonly used in furniture (especially chair seats and legs), tool handles and children’s toys. Beech machines and sands very cleanly.
- Mahogany—a medium-density tropical hardwood with a rich reddish-brown colour and an interlocking grain that resists warping. Traditional choice for furniture, interior joinery and boat building. Sustainability concerns exist around tropical hardwood sourcing; look for FSC-certified stock.
- Balsa—extremely low density (as low as 100–200 kg/m3), making it the lightest commercial timber. Used for model making and structural cores in composite panels (e.g. wind turbine blades). Despite its softness, it has a high strength-to-weight ratio.
- Jelutong—a fine-grained, uniform hardwood widely used in D&T education for model making and pattern carving. It is easy to cut, sand and shape accurately, making it ideal for producing prototypes and moulding patterns.
Named Softwoods
- Scots pine—a widely available European softwood used for structural timber, joinery and furniture. It has a pale yellow colour with distinct resin pockets. Moderately strong and easy to work.
- Western red cedar—a naturally durable softwood with high rot resistance due to its phenolic oils. Used for exterior cladding, garden furniture and roof shingles without needing chemical treatment. Has a distinctive reddish-brown colour and pleasant aroma.
- Parana pine—a fine-grained softwood from South America, unusual in softwoods for being relatively knot-free. Used in high-quality interior joinery, staircases and shelving where a clean appearance is needed. Its limited availability has made it more expensive than other softwoods.
Western red cedar’s natural durability comes from its phenolic oils, not a chemical preservative treatment—making it an environmentally preferred choice for exterior use. Jelutong is the standard studio modelling timber in D&T because it machines and carves accurately.
Manufactured Boards
Manufactured boards are engineered sheet materials. They eliminate many of the defects of solid timber and are available in large, consistent sheets (typically 2440 × 1220 mm). Key types:
- Plywood—layers of veneer bonded with adjacent grains at 90° to each other. This cross-grain construction gives high strength in all directions and resistance to splitting. Structural grades (e.g. WBP—water and boil proof) are used in construction; decorative grades use hardwood face veneers.
- MDF (medium-density fibreboard)—fine wood fibres bonded with synthetic resin under heat and pressure. Produces a uniform, smooth surface with no grain, which takes paint and veneers extremely well. However, MDF is heavy, absorbs moisture at edges and cannot be used structurally where loads must be resisted.
- Chipboard (particleboard)—compressed wood chips bonded with adhesive. Cheaper than MDF or plywood; commonly used in flat-pack furniture (often surfaced with a melamine laminate). Weak at the edges and screws do not hold as well as in solid timber.
- Hardboard—a thin, dense sheet made from wood pulp fibres compressed under steam and heat. One face is smooth, the other textured. Used for drawer bases, backs of furniture and low-cost panels.
Natural timber contains inherent defects that affect quality and strength. Common defects include:
- Knots—where branches once grew. Knots disrupt the grain, weaken the timber at that point and can shrink and fall out over time. Structural timber grades limit knot size and position.
- Shrinkage and warping—timber continues to absorb and release moisture after felling. Uneven drying causes cupping (edges curl up), bowing (along the length) and twisting. Kiln-drying reduces but does not eliminate movement.
- Shakes—cracks that run along the grain. Ring shakes follow the annual growth rings; star shakes radiate outward from the centre. Both weaken the board and may open further as the timber dries.
- Fungal attack—wet rot and dry rot fungi degrade wood fibres if timber remains damp. Preservative treatment (e.g. pressure impregnation with copper-based compounds) is used for outdoor structural timber.
Manufactured boards overcome most of these defects because the manufacturing process eliminates directional grain dependence, large knots and growth-related stresses. This is a key advantage when selecting sheet material for flat furniture components.
Finishing timber protects it from moisture, UV light and physical wear, and enhances appearance. Common finishes include:
- Varnish—a clear resin coating that cures to a hard, durable surface. Polyurethane varnish is water-resistant and tough, suitable for floors and furniture. Satin and gloss sheens are available.
- Stain—penetrates the timber fibres to change colour without hiding grain. Oil-based stains are absorbed deeply; water-based stains raise the grain slightly but have lower VOC emissions.
- Paint—fully opaque finish that hides grain. Requires a primer coat on bare wood to seal the surface and improve adhesion. Suitable for MDF (which does not have a visible grain) and exterior joinery.
- Danish oil / linseed oil—penetrating oils that soak into the wood fibres, feeding the timber and giving a natural, low-sheen appearance. Often used on hardwoods where the grain is intended to be visible. Requires periodic reapplication.