Spontaneous breakage of tempered glass is a problem that can occur in a finished facade with a probability of 1 case per 8 tons of glass. The cause of self-destruction is a nickel particle that enters the glass along with sand and later becomes a sulfide. In non-tempered glass, this particle does not manifest itself, so the glass manufacturer cannot detect it. During the tempering process, the nickel sulfide particle does not have enough time to cool down along with the entire mass of the glass. The glass traps it in a stressed state. Later, after a month, a year, or two, this particle, if present in the glass, will inevitably destroy it. After the glass is tempered, we can artificially create conditions for its destruction if there is nickel sulfide in the glass. This is the HST test, in which tempered glass is held for 2 hours at a temperature of 260°C. We conduct this test upon request and provide guarantees that spontaneous breakage will not occur. By ordering the HST test, you eliminate the potential issues of dismantling a shattered glass unit and avoid the risk of falling small glass fragments from a height. The test is the final step towards obtaining completely safe glass.