Question

The term “birdswings” and “spikes” used in glass refers to _______

(a) cold-treatment

(b) heating oven

(c) heat treatment

(d) defects.

The question was asked during an interview.

This intriguing question originated from Surface Treatment of Glass topic in section Glass Packaging Materials of Food Packaging Technology

Answer 1

The correct answer is (d) defects.

Easiest explanation: Some 60 defects can occur in finished glass containers, ranging from critical defects such as “birdswings” and “spikes” (long, thin strands inside the container that would probably break off when the container was filled) to minor defects such as “wavy appearance” (an irregular surface on the inside).