The chemical composition of glass is highly stable, and in its natural state, glass is not affected by sunlight, rain, or fog, leading to no performance degradation. Ordinary acids and bases generally do not harm glass. Under normal conditions, the factors that can affect the lifespan of glass are humidity and high temperatures.
Lifespan of Ordinary Glass:
Continuous exposure to humid air can lead to mold growth on glass, but the rate of mold growth is very slow at room temperature, typically taking several months. In normal usage environments, prolonged exposure to humid air for several months is rare. Mold growth is more likely to occur during the storage of glass sheets, especially in humid warehouses or when glass is exposed to rain during outdoor storage. Generally, untreated glass is more prone to mold growth than tempered glass.
Considering factors like thermal stress, temperatures below 300°C have no impact on the lifespan and chemical stability of glass. However, above 300°C, the physical and chemical properties of glass start to change with increasing temperature. Physically, ordinary glass begins to soften around 600 degrees. Chemically, higher temperatures can cause crystallization within the glass, gradually transitioning it from transparent to opaque. At 700°C, the process of crystallization and loss of transparency may take several days, while at 300°C, it might take months or even years. At room temperature, the process of crystallization and blurring could take thousands of years, practically negligible.
Lifespan of Tempered Glass:
Physical tempering involves heating glass and then rapidly cooling it, altering the molecular structure internally. Chemical tempering involves ion exchange on the surface of the glass at high temperatures. Both methods permanently change the microscopic structure of the glass material. Hence, under normal use, the properties of tempered glass do not deteriorate or change over time.
Lifespan of Insulated Glass:
Insulated glass consists of glass panes, spacer bars (aluminum), desiccants (molecular sieves), and sealing materials (butyl rubber, polysulfide or structural adhesive). The stability of glass and aluminum frames is usually high, and the lifespan of insulated glass depends on the desiccants and sealing materials.
In the composition of insulated glass, glass is highly stable. The concept of a 10-year warranty period was initially introduced in China by glass companies referencing American standards. The national standard for insulated glass suggests that the expected lifespan should exceed 15 years. For installed insulated glass, a simple method of evaluation is measuring the dew point or air humidity within the spacer layer.
