Heat Soaked Test (HST)

As we know tempered glass have many advantages compare to annealed glass, but there is  one weakness of spontaneous glass breakage which is inevitable . During the production process of float glass, there is a risk of  nickle sulphide inclusions in the glass. This phenomenon causes an increase in internal stress in tempered glass, which can ultimately led to spontaneous rupture. Although this phenomenons is extremely rare, we  need to be very careful and must take some measures to prevent it.  This method is called Heat Soak Test (HST). It consists of heating the tempered glass to a certain temperature  and maintaining it there for a predetermined time. During this process,  tempered glass with defects will shatter in the furnace.