Tempering consists in thermal toughening by annealing glass in temperature between 670C and 730C, followed by rapid cooling, in order to cause specific contraction in its structure. This significantly reinforces glass and increases its bending strength and resistance to temperature variations. Tempered glass, according to PN-EN 12150, is referred to as safety glass. In practice, when broken, it shatters into small fragments of blunt edges, which are less likely to cause injury. Tempered glass is widely used both for furniture making and in construction engineering: