What characterizes heat-strengthened glass?

Heat-strengthened glass is characterized by a specific manufacturing process that involves heating the glass to a high temperature and then cooling it down in a controlled manner, which contributes to its increased strength compared to standard glass. This process induces compressive stresses on the surface of the glass, making it more resistant to thermal and mechanical stresses, while still allowing for some flexibility in its applications.

In relation to the other options, heat-strengthened glass does not necessarily mean it is more brittle than standard glass; rather, it is designed to improve strength while maintaining some level of ductility. Heat-strengthened glass is not always tempered; while both processes increase strength, tempering involves a different cooling process that results in glass that is significantly stronger and more resistant to impact. Lastly, having a reflective coating is not an inherent characteristic of heat-strengthened glass; coatings can be applied to any type of glass depending on aesthetic or functional requirements, but they do not define the glass's strength characteristics.