This question was difficult for the candidates as they could not provide the required responses to parts (a) and (b).       The required responses to these parts are:

(ai)       Facing sand is used around the cavity while parting sand is used to separate the contents of cope and drag.

(aii)      Backfire occurs when the flame momentarily buns back into the torch and makes popping sound while a flashback occurs when the flame passes right through the torch into the hose due to the absence of the fuel gas in the system.

(aiii)     Lacquering produces a transparent tint while painting produces an opaque finish.

(b)       Allowance for contraction is provided on a pattern by making it slightly larger than the actual size of the workpiece.