Question 2
(a) List four manufactured boards.
(b) Name one timber defect caused by each of the following:
(i) drying timber too rapidly;
(ii) improper stacking.
(c) State two advantages of casein glue over animal glue.
Observation
Candidates were expected to:
(i) List four manufactured boards;
(ii) Name one timber defect each caused by drying timber too rapidly and improper stacking;
(iii) State two advantages of casein glue over animal glue.
The solution is shown below:
Manufactured boards
- plywood;
- laminboard;
- fibreboard;
- softboard;
- hardboard;
- blockboard;
- battenboard;
- particleboard;
- chipboard.
Timber defects caused by drying timber too rapidly:
- honeycombing;
- casehardening;
- collapse;
- checks;
- splits.
Timber defects caused by improper stacking:
- twisting;
- warping;
- bowing (camber);
- cupping;
- springing;
- splitting.
Advantages of casein glue over animal glue:
- casein glue takes shorter time to prepare than animal glue;
- assembly time for casein glue is longer than that of animal glue;
- heat can be used to accelerate the setting of casein glue while heat will
re-melt animal glue;
- casein glue is more resistant to water than animal glue;
- casein glue is easier to apply/use than animal glue;
- casein is more resistant than animal glue.