Woods

Asked WHY beech suits a turned or steam-bent part, most candidates cannot give the property: beech is CLOSE-GRAINED — a tight, even, dense grain with no large open pores — so it turns cleanly on a lathe and bends without splintering. Weaker answers say only that it is strong or cheap. Learn the property word and link it: close-grained → clean turning and a smooth finish.

Two grain terms are weakly known. END GRAIN is the surface exposed when you cut ACROSS the fibres, at the end of a board — more absorbent and harder to finish. SHORT GRAIN is where the grain runs the wrong way across a narrow section, leaving it weak and liable to SNAP. So end grain is a cut face; short grain is a weakness in a thin part.

Plywood's properties are often under-stated. It is generally CHEAPER than solid wood for large panels and more DIMENSIONALLY STABLE — its veneers are glued with grain crossed at right angles, so it resists the warping and splitting solid timber suffers. Its drawbacks are edges needing lipping and harder working. State the genuine advantage, not a guess.

Because MDF is cheap and cuts easily, candidates assume it is LIGHT — but it is a densely compressed fibre board, usually as heavy as or heavier than solid softwood the same size. Its selling points are smooth grain-free faces, low price and taking paint well; weaknesses are weight, water absorption, and fine dust. Never offer "lightness" as an MDF advantage.

Solid wood keeps MOVING after manufacture — expanding in damp, shrinking in dry, mostly across the grain. When a solid-wood top is fixed to a frame, the screws sit in SLOTTED holes so it can slide as it moves. Most candidates give the wrong reason — that slots ease fitting. Really: fixed tight through round holes, the movement builds stress and the wood CRACKS.

For a laminate or large sheet, the right glue is a CONTACT adhesive: spread on BOTH faces, left until touch-dry (tacky), then bonded over the whole area with NO clamping. Candidates lose the mark by adding a clamping stage — a clamp cannot reach the middle of a large sheet. Contrast PVA and resin joints, which DO need clamping while they cure.

The words hardwood and softwood do NOT describe how hard the wood is — the classification is BOTANICAL. A hardwood comes from a broad-leaved (deciduous) tree, a softwood from a coniferous tree, whatever the real hardness. Balsa is a HARDWOOD yet one of the softest, lightest woods, while yew is a softwood yet quite hard. Classify by tree type, not by hardness.