Counter-intuitively, the glass is strengthened by introducing a network of microscopic cracks, according to a study published in the journal Nature Communications on Tuesday.
A team at McGill University in Montreal began their research with a close-up study of natural materials like mollusc shells, bone and nails which are astonishingly resilient despite being made of brittle minerals.
The secret lies in the fact that the minerals are bound together into a larger, tougher unit.
The binding means the shell contains abundant tiny fault lines called interfaces. Outwardly, this might seem a weakness, but in practice it is a masterful deflector of external pressure.
To take one example, the shiny, inner shell layer of some molluscs, known as nacre or mother of pearl, is some 3,000 times tougher than the minerals it is made of.
Read more at: Phys.org