heat strengthened glass breakage pattern

Thermal breakage typically originates from the glass edge. The fracture lines are fewer, cleaner, and walk across the pane in wavy, low-energy paths. Mechanical Impact

This process creates a surface compression layer between 3,500 and 7,500 psi.

Heat-strengthened glass is a semi-tempered glass produced by heating annealed glass to approximately 650–700°C (1200–1290°F) and then cooling it rapidly, but not as rapidly as fully tempered glass. The surface compression of heat-strengthened glass typically ranges from (compared to over 10,000 psi for fully tempered glass).

Impact failures feature a distinct point of origin with concentrated spider-web cracking. Radial lines propagate outward from this central impact zone. Inclusion Failures

The breakage pattern of heat-strengthened glass is a hybrid: it retains the large, sharp fragments of annealed glass but with a more branched, arrested crack network due to its moderate surface compression. Recognizing this pattern allows glaziers, architects, and forensic engineers to identify improper installations, evaluate thermal or impact failures, and ensure safety standards are met.