Discover Benefits of Heat Soaked Thermally Tempered Glass
What is Heat Soaked Thermally Tempered Glass?
Heat-soaked thermally tempered glass is a two-stage safety glass product. It begins as standard thermally Tempered Safety Glass and then undergoes a controlled, post-tempering heat treatment process called heat soaking.
The purpose of this secondary process is to artificially "age" the glass, identifying and causing the spontaneous breakage of panes containing a specific critical flaw before they are installed, thereby eliminating a rare but significant safety risk.
Process: Standard annealed glass is heated to over 600°C and then rapidly cooled (quenched) with high-pressure air jets.
Result: This creates a state of high compression on the glass surfaces and compensating tension in the core. This "pre-stress" gives tempered glass its characteristic safety (it breaks into small, dull granules) and strength (4-5 times stronger than annealed glass).
A microscopic, and unavoidable, impurity in the raw materials (sand, nickel from stainless steel handling equipment) can lead to the formation of nickel sulfide particles within the glass matrix.
The Problem: This NiS molecule can exist in two crystalline forms (alpha at high temp / beta at low temp). The transformation from the high-temperature alpha phase to the low-temperature beta phase causes the particle to expand volumetrically. This expansion, combined with the high tension stored in the glass core, creates immense localized stress, exceeding the glass's strength and causing spontaneous, violent breakage with no external trigger.
The heat soak process is specifically designed to force any NiS inclusions through their phase transition in a controlled factory environment.
Process:The already-Tempered Glass Panels are stacked in a specialized oven and heated to approximately 290°C (±10°C) and held at that temperature for a sustained period (typically 2-8 hours, following the European standard EN 14179-1).
How it works: This sustained high temperature converts any alpha-phase NiS inclusions to the beta phase, simulating years of natural aging in hours. If an inclusion is sufficiently large and located in the high-tension core, the induced stress will cause the pane to break in the oven.
Result: Any glass that survives the heat soak cycle is statistically free from critical NiS inclusions and has an exponentially lower probability of spontaneous breakage for the remainder of its service life.