What does heat soak testing prevent?
Heat soak testing is a controlled post-tempering process that identifies tempered panels at risk of spontaneous breakage caused by nickel sulfide inclusions, a microscopic contaminant that can be present in raw float glass and that expands slowly inside a panel over time. Tempered glass containing an inclusion can fracture without warning months or years after installation; heat soak testing forces that failure to happen in the factory instead, by holding panels at an elevated temperature for a sustained period so an unstable inclusion expands and breaks the glass before it ships. KH Glass Group runs heat soak testing on site as a standard step for tempered glass destined for facade, balustrade, and overhead applications, where in-service breakage carries the highest consequence. Running the test in-house, immediately after tempering, means a failed panel is identified and replaced from the same batch rather than flagged after the glass has left the facility. It is one of the ten processes treated as integral to tempered glass supply, not an optional add-on.