Alkaline earth silicate glass (AES) is a recent development by Saint-Gobain demanding environmental conditions such as fire protection. Comparison of AES physical properties to that of standard soda-lime-silica glass at room temperature shows there are no significant differences. The process for producing thermally toughened products out of both kinds of glass is similar. Consequently, both are sensitive to potential spontaneous breakage caused by NiS. The application of AES glass in fire protection glazing involves a particular risk because a fire acts on it like a heat soak test so that every critical NiS inclusion should cause spontaneous failure at the most awkward moment. Therefore, it is necessary to apply a heat soak test if AES glass is to be used in fire protection applications to guarantee long term security. The HST conditions must be the same as for standard glass because HST does not act directly on the glass, but provokes the premature transformation of the NiS inclusions. NiS transformation is exactly the same in both types of glass.
