IAAI Certified Fire Investigator (CFI) Practice Test

Crazing is a web-like network of tiny cracks in glass that forms from internal tensile stresses rather than from a direct impact. This pattern often arises when glass experiences thermal stress, rapid temperature changes, or uneven cooling during tempering, which creates distributed microcracks that run in multiple directions like a spiderweb.

This differs from cracking caused by an impact, which typically produces larger, more obvious fractures or shattered pieces. Fogging refers to a haze or cloudiness, usually from moisture or residues, not a crack pattern. Etching involves chemical alteration of the surface that changes appearance without creating a crack network.

In investigations, recognizing a crazed surface helps indicate stress-induced damage rather than damage from a direct blow, pointing to conditions like thermal shock or improper tempering rather than physical impact.