Question

____________ castings are pickled in hydrofluoric acids.

(a) Iron

(b) Brass

(c) Steel

(d) Aluminum

The question was asked by my school teacher while I was bunking the class.

I want to ask this question from Fettling and Cleaning of Castings topic in section Concept of Gating and Risering of Foundry and Forging

Answer 1

Right answer is (a) Iron

Best explanation: Iron that is the ferrous castings are pickled in hydrofluoric acid (48% of hydrofluoric acid and 25 parts of water). Hydrofluoric acids attack sand on the castings and hence the cleansing becomes easy.