Question

During cooling, the outside surface is hotter than the inside.

(a) True

(b) False

The question was posed to me in an international level competition.

This interesting question is from Manufacture of Glass topic in portion Glass Packaging Materials of Food Packaging Technology

Answer 1

Correct choice is (b) False

To elaborate: The given statement is false. During cooling, the inside surface is hotter than the outside; this results in compression on the outer surface but tension at the inner surface. Sudden cooling results tensile stresses into the outer surfaces and compressional stresses in the interior surfaces. Poor annealing may result in breaking or cracking if interior is bruised or tension is high.