Tempered glass shatters into small pieces due to its manufacturing process, which creates a precisely engineered stress pattern throughout the material. During tempering, glass is heated to approximately 1200°F, then rapidly cooled with air jets. This process creates high compression on the surfaces and tension in the center—storing potential energy throughout the glass like a coiled spring. When damage penetrates the compressed outer layer and reaches the tensile zone, this stored energy releases instantaneously, propagating cracks at nearly 3,000 mph throughout the entire piece. The controlled stress pattern causes the glass to fracture along precise lines into small, relatively harmless cubic fragments rather than dangerous shards. This predictable failure mode is an intentional safety feature, dramatically reducing injury risk compared to standard glass.
