Materials scientist Anna Ploszajski said that glass does not actually melt at high temperatures but behaves as a supercooled liquid [1].
This distinction challenges common perceptions of how solid materials respond to heat. Understanding the molecular transition of glass is critical for fields ranging from industrial manufacturing to architectural engineering.
Speaking for the Royal Institution, Ploszajski said the unusual thermal behavior of the material [1]. While many assume glass reaches a distinct melting point like ice, it instead undergoes a gradual softening process. This characteristic allows glass to be shaped and molded without the abrupt phase change seen in crystalline solids.
The process involves the material becoming a supercooled liquid [1]. In this state, the substance retains a disordered atomic structure similar to a liquid, but its viscosity increases so significantly that it appears solid to the observer. This lack of a defined melting point is what defines the amorphous nature of glass.
Ploszajski said the goal of the explanation was to educate the public on these properties [1]. By clarifying the science, she said that the perceived "melting" is actually a transition in viscosity, a slow shift that allows the material to flow under extreme heat without a sudden change in state.
This behavior differs from most metals or salts, which have a precise temperature at which they transition from solid to liquid. Glass remains an anomaly in the material world due to this specific thermal trajectory [1].
“Glass does not actually melt at high temperatures but behaves as a supercooled liquid.”
The classification of glass as a supercooled liquid rather than a traditional solid clarifies why it lacks a specific melting point. This amorphous structure is what enables the versatility of glassblowing and industrial molding, distinguishing it from crystalline materials that transition abruptly between phases.
