HEAT SOAKING
During the glass manufacturing process, a nickel sulphide inclusion may embed in the glass, often undetectable by the naked eye. This inclusion expands and contracts at a different rate than the surrounding glass, creating internal stress that can lead to spontaneous glass breakage.
Heat soak testing is an additional safety procedure that can be done to detect these nickel sulphide inclusions. The glass is heated to 700°C and then rapidly cooled under high pressure. If a nickel sulphide inclusion is present, the glass will break during testing.
Glass that passes this rigorous test ensures a significantly reduced risk of spontaneous breakage, offering added safety and reliability for tempered glass applications.
Heat Soak Testing for Tempered Glass
Heat soaking is a quality control process for tempered glass. Panels are held at an elevated temperature in a dedicated oven, which encourages glass containing nickel sulfide inclusions to break in the factory rather than after installation. It is widely specified for facades, curtain walls, glass railings, balconies and overhead glazing where spontaneous breakage would be costly or disruptive.
When to Specify Heat Soaked Glass
Heat soaking is recommended where tempered glass is hard to reach or replace, where public safety is a concern, or where the project specification calls for it. It is often combined with laminated glass for added post-breakage protection.
Frequently Asked Questions
Does heat soaking eliminate all risk of breakage?
Heat soaking greatly reduces the risk of spontaneous breakage caused by nickel sulfide inclusions, but no process removes every risk. It is one of the most effective quality measures available for tempered glass.
Can any tempered glass be heat soaked?
Most tempered panels can be heat soaked. Contact our team with your specification to confirm.