One of the perceived problems of smartphone OEMs switching to glass both back and front is their durability. Glass is, after all, perceived to be more fragile than metal or even plastic. The keyword here is “perceived”. Not all glass are made equal, especially not the glass used in smartphones. And, as JerryRigEverything’s triple stress test of the iPhone 8 shows, the addition of glass may have actually helped make Apple’s latest smartphone even sturdier than ever.
Glass has a few desirable properties over plastic or metal, depending on where on the phone it is. On the front, it offers scratch resistance, especially with Gorilla Glass 5. Like any other smartphone these days, the iPhone 8 only started scratching at a level 6.
Sapphire glass would be the ideal covering, but that’s expensive and yield rates are terribly low. Apple does claim to use sapphire glass for the rear camera. It turns out, however, that it might be a lower grade mix that scratches at a Mohs level 6 as well. It’ll still be safe from knives and cutters but, ironically, not from some sand and dust particles.
Glass on the back also protects the phone from scratches on that side as well. But there’s another benefit to having glass on both sides. It adds structural integrity and rigidity to the whole phone, making it nearly impossible to bend with bare hands or posteriors. There’s a bit of plastic at the edges of the glass that helps protect the glass from impact of drops.
That said, the disadvantage of glass is that it is also more susceptible to shattering from impact. So while the iPhone 8 does survive with flying colors from Zack Nelson’s scratch, burn, and bend test, it remains to be seen how well it will fare from a drop test.