Most candidates were able to:
- state the cause of the given timber defects;
- state the advantages of kiln seasoning over air seasoning;
- differentiate between Iroko and Obeche trees.
However, few of them could not state the cause of some of given timber defects.
The expected response to question 2 is as given below:
(a) (i) Interlocked grain: Occurs when the fibres of adjacent layers in
the growing rings are inclined at different angles to the axis of the timber.
(ii) Cupping: Caused by shrinkage, poor or bad stacking while drying.
(iii) Waney edge: Caused by inadequate edging of boards during conversion.
(iv) Thunder shake: Caused by strong wind, storm and thunder strike
resulting in a distress or separation of wood layers in a living tree.
(b) Advantages of Kiln Seasoning Over Air Seasoning
- Permits exact/accurate moisture content to be obtained.
- Minimises degrade (seasoning defects).
- Kills/destroys insect lavea.
- Leads to greater turnover.
- Faster in drying timber.
- Requires less timber yard storage space.
- Temperature, humidity and air circulation can be more easily controlled.
- Allows for larger quantities of timber to be seasoned at a time.
(c) (i) Iroko: Yellowish-brown to dark chocolate. Used for good
quality interior and exterior joinery, doors, windows, laboratory furniture, roofing, boat/canoe building, chairs, frames, tables, chairs, tennis rackets.
(ii) Obeche: Near-white to pale yellow. Used for fittings, interior
decoration, carving, veneers, plywood, corestock, boxes, handicraft work, temporary structure.
(d) The escutcheon is used mainly to protect/prevent the wearing of keyholes;
it may also serve as a decoration. |
