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.