Toughened or tempered glass is commonly used when manufacturing products like stove tops and hobs, cookware, tableware and shower screens. It’s made by heating glass to a molten state at about 600 degrees Celsius followed by sudden chilling with compressed air. This cooling process causes the surface to contract rapidly, forming a rigid outer layer around the glass making it much stronger than conventional glass and far more resistant to impact stress and temperature change.
Toughened glass can break
A break in toughened glass such as a shower screen can occur when a small chip or weakening in the hard outer layer of the glass disturbs its surface tension. This could cause it to burst inwards or implode without warning.
Fortunately, when toughened glass implodes, it’s small blunt cube-like granules that are far less dangerous than the jagged shards.
Standards for shower screens
The Building Code of Australia requires shower screens and shower doors comply with two Australian Standards:
- AS 1288:1994, Glass buildings-Selection and installation
- AS/NZS 2208:1996, Safety glazing materials in buildings.
AS 1288 includes information on the selection and installation requirements for glass in buildings, including toughened glass, as well as human impact safety requirements. The Standard specifies that glass used in shower screens is glazed in either Grade A (toughened and laminated) safety glass or Grade B (wired) safety glass.
The minimum thickness of framed toughened glass is 4mm; the minimum thickness of partly framed and frameless toughened glass is 6mm. AS/NZS 2208 details the test requirements for glass including toughened glass.
Care and maintenance
Manufacturers often include a leaflet which lets you know how to care for your glass and hardware. It’s important to follow the manufacturer’s instructions. The potential risk of glass implosion can be minimised if the glass and hardware (hinges etc.) are properly maintained and cared for.
Hinges and other hardware
The best way to maintain hinges and other hardware is to wipe them down after every use. When the hardware is kept clean, it will not collect mineral deposits that require the use of soap solution to remove. After your shower, use a dry towel to thoroughly dry the hinges. If you’re unable to dry your hinges after every use, we suggest a weekly clean using a mild soap and warm water mixture and a soft non-abrasive cloth. After you have cleaned the hardware, rinse it thoroughly with clean warm water and dry.
It’s also important to keep your glass clean. Glass that is neglected will accumulate water spots, which will eventually turn into mineral deposits. The best way to keep your glass free of damaging water spots is to squeegee the glass after every use. Do not use any abrasive or cream cleanser.
The likelihood of an implosion is greater if a moving part, such as an unframed edge of a pivotal glass door, is in close contact with another hard surface. If an unframed edge is rubbing on another surface, get the glass and door hinges adjusted immediately. Poor installation and maintenance increase the risk of toughened glass imploding.
Purchase copies of AS 1288-1994 and AS/NZS 2208 from the SAI Global website or by calling 13 12 42.
If you become aware of an unsafe situation or item, whether or not anyone has been injured, you should alert the supplier about the issue. You can also report it by lodging a complaint on our website or via the Product Safety Australia website.