ZIMSEC O Level · Wood Technology and Design · Form 2, Form 3, Form 4
Adhesives
- PVA (white glue): easy, clean, strong for indoor work; not waterproof.
- Contact adhesive: bonds on contact; for laminates.
- Synthetic resin (e.g. urea-formaldehyde, epoxy): strong, water resistant, for outdoor work.
Use cramps while glue sets; wipe off excess glue before finishing.
Fittings
Nails (wire, oval, panel pins), screws (countersunk, round head; pilot and clearance holes needed), hinges (butt, piano, flush, concealed), handles, catches, locks and knock-down fittings.
Surface preparation
Plane, scrape and sand with glasspaper in the direction of the grain, working from coarse to fine grades. Fill holes with wood filler.
Finishes
Protect wood and improve its appearance.
- Oil (linseed, teak oil), wax and polish: bring out the grain.
- Varnish and polyurethane lacquer: hard-wearing.
- Paint: primer, undercoat and topcoat; protects outdoor work.
- Wood stains: change the colour.
- Preservatives (creosote and modern treatments): protect against rot and insects, especially for timber in contact with the ground.
Exam tip: Always sand along the grain – scratches across the grain show clearly after finishing.
Check yourself
- Which adhesive is best for indoor furniture joints?
- Why is a pilot hole drilled before inserting a screw?
- Name two finishes that bring out the grain of wood.
Show answers
- PVA glue.
- To guide the screw and prevent the wood from splitting.
- Any two: oil, wax, clear varnish, polish.
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