Question

____________ involves a danger of retaining acid in small interstices of castings.

(a) Shot blasting method

(b) Pickling

(c) Hydrolysis

(d) Hydro blasting

This question was posed to me in a national level competition.

The above asked question is from Fettling and Cleaning of Castings in section Concept of Gating and Risering of Foundry and Forging

Answer 1

Right answer is (b) Pickling

The explanation is: Pickling is one of the methods used in chemical cleaning of the castings manufactured. Pickling makes use of dilute acids for removing sand from the surface and inaccessible pockets of the castings. Hence, there is a danger of retaining a little amount of acid.