At the HTC booth at CTIA, the world was shown a beautiful display of the 6 stages of production of the HTC One S chassis. In the display were sheets of aluminum detailing each step, the final step being a finished chassis.
One of the steps is the notorious micro-arc oxidation technique. Essentially, HTC takes the piece of aluminum and sends massive amounts of electricity through it, giving it a ceramic feel and look. According to HTC, it also hardens the metal 5 times, leading to the claim that the HTC One S does not need a case.
But for many people, the MAO coating has been chipping without any trauma. Apparently, the brittle coating often peels off of the more flexible aluminum underneath. This isn’t happening to everyone, but a fair amount of users have experienced this. HTC said they’d be doing something about this, so let’s hope that the problem is over.
Source: Android Central