Topic 3 of 6 · Form 5
Manufactured boards and adhesives
Advantages: large sizes, stability, use of waste wood, uniform properties. Disadvantages: edges need lipping or banding, some are weak in moisture, formaldehyde emissions.
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Manufactured boards
- Plywood: odd number of veneers with grain at right angles – strong and stable in all directions; marine and exterior grades.
- Blockboard and laminboard: strips of wood sandwiched between veneers – good for shelves.
- Particle board (chipboard): wood particles and resin – cheap, flat, weak in moisture.
- Fibreboards: hardboard and MDF (medium-density fibreboard) – smooth, machinable, takes paint; dust is hazardous.
- Oriented strand board (OSB) for construction.
- Veneers and laminates (melamine-faced boards).
Advantages: large sizes, stability, use of waste wood, uniform properties. Disadvantages: edges need lipping or banding, some are weak in moisture, formaldehyde emissions.
Adhesives
- PVA: thermoplastic, easy, interior use.
- Urea-formaldehyde (UF): thermosetting, good water resistance, used in boards.
- Phenol-formaldehyde and resorcinol: waterproof, exterior and marine use.
- Epoxy: very strong, gap-filling.
- Contact adhesives: laminates.
- Animal glues (traditional).
Factors: moisture resistance, open and setting time, gap filling, strength, cost and safety.
Gluing technique
Clean surfaces, correct moisture content, even spread, adequate cramping pressure, and curing time.
Exam tip: Match adhesive to the service conditions – interior furniture versus exterior or marine use.
Check yourself
- Why does plywood have an odd number of veneers?
- Which adhesive is suitable for a boat?
- Give one disadvantage of MDF.
Show answers
- To balance the construction so it does not warp, with face grains running the same way.
- A waterproof resin such as resorcinol- or phenol-formaldehyde (or epoxy).
- Any one: swells in moisture, heavy, hazardous dust, poor screw holding at edges.
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