A University of Queensland research team has developed a way of detecting defects in the glass windows and balconies of hi-rise buildings - a technique which could be exported to building owners and glaziers throught the world. The technique detects minute stones of nickel sulphide (NiS) in the toughened glass panels of high-rise buildings. The stones, which range in size from 0.1 to 0.5mm in diameter, are present in all types of window glass and may be rendered unstable by the special heat process used by the manufacturrers for toughening glass. The stones can become unstable over time causing the windows to shatter without warning. Even though toughened glass is classified as a safety glass (when it breaks it shatters into small rounded pieces) the spontaneous fracture of glass panels is still a matter of concern.
