Production of heat-strengthened glass is very similar to that of tempered glass. Float or decorative glass that is suitable for tempering is heated to the plasticity limit and then cooled by air.

The difference is in the cooling time, which is longer than for tempered glass. In such a way, we obtain glass that is categorized by its mechanical and thermal characteristics between float and tempered glass. In case of breakage, semi-tempered glass breaks into a multitude of larger fragments with rounded edges. After being thermally toughened, heat-strengthened glass cannot be processed any further. Therefore, cutting, grinding and drilling must be done before the heat treatment process. Heat-strengthened glass combined with a laminated safety glass obtains safety properties.