Glass is one of the oldest synthetic materials, produced and used for diverse application since time immemorial. Its basic formula consists of melting simple ingredients such as sand, soda and lime. It is an indispensable part of everyday life, used for drinking vessels, light fixtures, windows, artworks, mobile phones, fibre-optic cables and much more.
Glass can be described as a solid with the molecular structure of a liquid. After melting the ingredients, slow cooling produces a viscous mass that can be elastically shaped with tools while still hot. Once cooled, this viscous mass forms a delicate finished product. The temperature of the mass is then above the glass transition temperature but below the melting temperature. Further cooling turns the viscous mass into a fragile finished product. Heating it above the glass transition temperature makes it malleable again. This magical transformation is documented in this film about the making of a vase
Yet we still do not know all the material-specific properties of glass. Indeed, scientists are still debating whether the three states of matter (gas, liquid and solid) should be expanded to include a fourth: the glassy state. However, the question remains unresolved and requires much further study. This shows just how special and complex glass is as a material.
