According to the (current) adverts of the major windscreen replacement and repair company “Autoglass” (TM), “all chipped windscreens will eventually crack”. Consequently, you’d best get them to fix yours asap! But is this claim true? Well, the first thing to point out is that eventually, the Sun will burn itself out and all life on Earth will perish, so we should not necessarily be too concerned about what might, or might not, happen eventually. What is true is that the strength of glass is greatly influenced by its surface condition and that the strength of glass in practice tends to be far lower than its theoretical strength because of surface defects. Quite simply, it is true to say that big cracks start out as little cracks, though if you want a somewhat more scientific analysis of that assertion, check out ‘Griffith crack theory’. But getting back to chipped windscreens, we have not managed to find any significant amount of scientific literature (published papers) which confirm that resin repairs reduce the incidence of cracking. Unless you can tell us differently, it seems that the jury is still out on this one.