Keywords: tempered glass breakage, spontaneous breakage, nickel sulfide inclusion, glass safety
Tempered glass is widely used for its strength and safety benefits—but under certain conditions, it can spontaneously break, even without any visible impact. For contractors and developers, this isn’t just a product issue—it’s a liability and a cost risk. Understanding the causes and solutions is essential to ensuring building safety and long-term performance.
The primary culprit is often Nickel Sulfide (NiS) Inclusion—a tiny contaminant introduced during the glass manufacturing process. Though harmless at first, NiS can transform over time, expanding inside the tempered glass and causing it to shatter without warning.
Other contributing factors may include:
Edge damage or microcracks during handling
Thermal stress from extreme temperature fluctuations
Poor installation leading to pressure points
But NiS inclusions remain the most unpredictable and concerning cause—especially in tempered glass, where internal tension is already high.
To reduce the risk of spontaneous breakage caused by NiS inclusions, a widely adopted solution is the Heat Soak Test (HST).
What is it? The HST involves reheating tempered glass to ~290°C and holding it for several hours. This accelerated process triggers NiS-related breakage in the factory rather than on-site.
Key benefits:
Removes high-risk glass before installation
Significantly lowers spontaneous breakage rate (down to 1 in 4,000 panes or better)
Enhances safety compliance and reduces after-sales service issues
For projects involving high-rise facades, glass canopies, or balustrades, glass breakage isn't just inconvenient—it's dangerous. Specifying HST-treated tempered glass in procurement documents can help mitigate risk from the start.
Here’s what to look for:
Supplier capability to perform and certify HST
Quality control of edge finishing and handling
Certification (e.g., EN 14179 or ASTM E2190)
Spontaneous glass breakage is rare—but when it happens, it can undermine a project’s safety, reputation, and profitability. As a contractor or specifier, you can’t control every atom in the glass—but you can choose a supplier who takes quality and testing seriously.
At YANYI Glass, we provide HST-certified tempered glass and work closely with global partners to deliver both performance and peace of mind.
Let’s talk glass that lasts.
