A by-product of antiquated glass-making processes could find a new lease of life as an optical diffuser.

Manufacturers now avoid producing crystals, called devitrite, in their soda–lime–silica glass because they degrade the material's optical qualities. But Haider Butt at the University of Birmingham, UK, and his team show that this currently undesirable form of glass can act as a diffuser, owing to the fact that needle-like crystals of devitrite scatter light to wide angles of up to 120°. Because devitrite is both a highly efficient diffuser and cheap to produce, the authors say it could be used in applications such as medical lasers.

ACS Nano. http://doi.org/rpk (2014)