I believe many of you have encountered or heard of it: a piece of good glass suddenly "bang" and shatters, with small glass particles all over the floor. It’s not only startling, but also takes time to clean up and money to replace. It’s even more troublesome if someone gets hurt.First, let’s talk about tempered glass — it’s really everywhere now: office building curtain walls, home windows, shower screens, balcony partitions, almost everywhere. People choose it because they think it’s strong and safe, and it won’t hurt people when broken. But why does this "safety glass" suddenly explode on its own?
Let me briefly introduce our Guoxin Glass first: we were founded in 2006 and have been in the glass industry for nearly 20 years — we can be regarded as old players in the industry. We mainly produce building glass such as aluminum windows, fireproof glass, laminated glass, and insulating glass. We have accumulated a lot of experience in R&D, production and sales. Over the years, we have received many customers, and the questions they ask most are "why does tempered glass explode on its own" and "how to avoid it". Today, I’ll explain this clearly in plain language that ordinary people can understand, and share some practical prevention methods to help you avoid pitfalls.
First, we need to understand: what exactly is tempered glass? What’s the difference between it and ordinary glass? It’s actually very simple. Tempered glass is not inherently strong — it’s made by "special treatment" of ordinary float glass: heat ordinary glass to a nearly melted state (about 650℃), then blow it cold quickly with cold air. After this process, the surface of the glass forms pressure, and the core forms tension, making its strength 5-10 times that of ordinary glass. Moreover, when it breaks, it doesn’t form sharp fragments, but dense small blunt particles that won’t hurt people — that’s why it’s called "safety glass".
Precisely because it’s strong and safe, it’s widely used in building glass — whether it’s home windows, doors, skylights, shower screens, or office building curtain walls, it’s indispensable. And it can also be used together with other glass types, such as Insulating Glass (two layers of glass with a cavity in the middle, which is thermal insulation and soundproof), Low-E Insulated Glass (a special coating applied on Insulating Glass to reflect heat and be more energy-saving), and PVB Laminated Glass (two layers of glass with a film in the middle, which won’t fall off when broken).
But no matter how good something is, it has flaws — tempered glass has a hidden "bug": it may explode on its own without any external force. Although this situation is not common (about 3 out of 1,000 pieces), once it happens, it’s very troublesome: cleaning broken glass is tedious; if it’s at a high altitude (such as an office building curtain wall), there may also be safety hazards, and replacement is costly and time-consuming.So why exactly does this happen? Combining our years of production and after-sales experience at Guoxin, I’ll break down the most common reasons for you. The first and most important one is the "small impurities" in the glass — nickel sulfide (NiS).
This nickel sulfide is not artificially added. It’s tiny particles formed by the reaction between nickel inherently contained in raw materials (such as quartz sand and limestone) and sulfur added (to remove bubbles in the glass) during glass production. They are invisible to the naked eye. Usually, they are quiet, but after tempering treatment, they become "time bombs". Because during tempering, the glass is heated to a high temperature, and these small particles also heat up. When the glass is quickly cooled, they haven’t had time to cool down and are "frozen" in a high-temperature state. In the following days, months or even years, they will slowly cool down and expand in volume by 2%-4%, just like slowly "pushing" from the inside of the glass. When it pushes to the point where the glass can’t stand it, it will suddenly burst — this process has no warning, so some people also call it "glass cancer".
In addition to this number one culprit, another common reason is "extreme temperature changes" — thermal stress. As we all know, thermal expansion and contraction also apply to glass. For example, in summer, the outdoor temperature is 38℃, while the indoor air conditioning is only 22℃. The outer layer of the glass expands due to heat, and the inner layer contracts due to cold. The tension and pull create internal stress, which can easily cause explosion over time. This is especially problematic for standalone tempered glass windows without a thermal insulation layer — the larger the temperature difference, the higher the risk. Insulating Glass and Low-E Insulated Glass, on the other hand, can greatly alleviate this stress and are less likely to explode because of the cavity in the middle that reduces heat transfer. There are also extreme situations, such as sudden heavy rain after the glass is scorched by the sun at noon in summer — the sudden cooling of the glass can also cause explosion.
The third reason is small flaws during production. No matter how advanced the production technology is, negligence is inevitable — for example, small stones, bubbles in the raw glass, or slight scratches on the surface. These small flaws are not visible at ordinary times, but after tempering treatment, they become stress concentration points. The internal stress of the glass is unbalanced, and over time, it is easy to burst from these points. In addition, if the tempering process is not in place — for example, some parts are hot and some are cold during heating, and the cooling is also uneven — the internal stress of the glass is disordered, which will also increase the risk of self-explosion. That’s why we at Guoxin have always emphasized quality control — every piece of glass undergoes strict inspection to minimize such flaws and avoid problems later.
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Company Name: Jiangsu Guoxin Glass Co., Ltd.
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Country: China
Website: https://www.gxglasswindow.com/
