Shower door glasses are made of tempered or also known as safety glass. The reason why it takes up this name, it is because they are heat resistant, more durable, and overall, five times stronger than annealed glass. Tempered glass is an excellent product from a safety perspective. However, this type of glass can suffer from spontaneous breakage due to something called ‘nickel sulphide inclusion’.
The nickel sulphide inclusion occurs during the process of manufacturing tempered glass, where nickel sulphide stones can form due to nickel contamination and end up creating tension zones on the tempered glass. These tiny stones which can measure from 0.003 to 0.0015 of one inch in diameter, may grow overtime around the surrounding glass, causing pressure and stress, eventually resulting in a spontaneous failure of the entire shower glass panel. It is important to mention, that spontaneous glass breakage from nickel sulphide inclusion is extremely rare.
In saying that, here are some of the key points to keep in mind about nickle sulphide:
- Spontaneous glass breakage caused by nickel sulphide only occurs in tempered glass, and not on heat-strengthened glass or annealed glass.
- The ASTM International, formerly known as American Society for Testing Materials, permits blemishes, including nickel sulphide stones between 0.020 and 0.100 of an inch depending on the glass size and quality level.
- Reputable glass manufacturers will typically have controls in place to reduce the possibility of nickel sulphide stones. If you are worried about Nickel Sulphide Inclusion, then you may be able to specify that you want your glass to undergo through Heat Soaking. This process includes thermally treating your glass in very high temperature soaking ovens, which will force Nickel Sulphide stones to shatter. Whichever glass survives this high temperature test, will then have a lower chance of containing impurities and will less likely break. Note that this process should naturally increase your cost and lead times, and this is just an extra step towards a safer glass, but it is does not guarantee 100% that your glass will not have nickel sulphide inclusions.
- Bear in mind, that currently there is no technology available that can completely erase the formation of nickel sulphide stones in float glass. Unfortunately, due to the small size of these stones, there is no practical way to identify their presence. Newline along with other reputable shower door suppliers recognizes that this is not caused by the customer and therefore, still fulfils this warranty.
Other causes for Spontaneous Glass Breakage
Poor Edge Quality
Shower doors panels may have their edges chipped during their pre-cutting, packaging, or shipping process. While they might not be apparent at first, overtime, the stress concentration around these chipped areas is worsened by the expansion and contraction of the shower door glass due to temperature changes and building movements. Eventually, the constant stress causes the shower door glass to explode. While this may have looked like it has exploded for no reason, in fact, these failures had been building up over a long period of time, until the explosion was inevitable.
Frame-related breakage & defective glass
As we know, glass will contract and expand due to temperature changes, therefore, if there is not enough space within the frame for the glass to expand, it can cause the glass to shatter. Alternatively, you may have purchased a defective glass, which has pre-existing cracks or chips that contributed to the spontaneous explosion.
Knocking the glass
We recommend you are careful when shutting your shower door. If you slam your door shut, then you might cause damages around the edge, which can eventually contribute to the failure of your shower door.
To sum up, the most common causes for the glass shattering include building movement, poor manufacturing process and frame-relate breakage. Overall, when tempered glass breaks, it shatters into hundreds of tiny pieces that are not sharp, therefore, making the risk of serious injuries very rare.
We recommend you carry out an annual check of your shower door glass edges by simply visually inspecting them. This will only take a couple of minutes, and if you do spot chips or cracks you may be able to carry out any repairs to avoid worsening the problem. You can check Newline Showers Warranty Information here.