Observation

Most of the candidates that attempted the question gave good definitions of the term corrosion. However, the aspect of the steps involved in surface preparation was poorly answered. The candidates were expected to provide some of the following as answers:

(a) It is the washing away of ferrous metals due to exposure to chemical and other atmospheric attack.

(b) Steps involved in the preparation of a corroded metal surface for gloss finishing.

i. Remove the rust effect with wire brush.

ii. Clean the dusty corrosive matter with a rag soaked in industrial spirit/kerosene.

iii. Allow the surface to dry properly.

iv. Apply the appropriate primer.

v. Allow primer to dry properly (overnight).

vi. Fill the dents (if any)

vii. Rub down slightly with a smooth sand paper/abrasive

viii. Apply the undercoat.

ix. Allow the under coat to dry overnight.

x. Rub down surface slightly.

xi. Apply the gloss finish.