What Is Tempered Glass? How Does It Break?

Tempered glass is stronger than regular glass and can withstand higher temperatures. It is also manufactured in a way that causes it to break into smaller pieces, which is safer than regular glass shattering into large shards. Unlike regular glass, which shatters into sharp shards that can potentially cause injuries, tempered glass breaks into smaller pieces that interlock with neighboring pieces and therefore dont fall readily. The characteristics of any glass type depend on the materials it is made with and the chemical and mechanical processes it undergoes during its manufacture. The way that tempered glass breaks into much smaller pieces is specifically attributed to the manufacturing processes. Glass (with nickel sulphide inclusions) is tempered by heating and then rapidly cooled to room temperature. Cooling takes place much faster at the center of the glass than at the surface, causing compressive stresses in the surface, whereas contraction and tensile stresses are caused in the center. The compressive stress gives toughened glass its increased strength; the higher the stress, the smaller pieces that the glass breaks into. The benefit of this differential heating comes in the form of increased endurance of the glass; it means that such glass can be stretched or pulled to a certain limit without breaking, which is a good thing to have in many forms of glass.