How can today’s high-tech glass — found on smartphones, elevator walls, public kiosks, and more — be so tough that it withstands all the dropping, scratching, and splattering of everyday life?
Part of the answer lies in the ion-exchange process — a scientific treatment of the glass surface to dramatically increase its toughness.
Glass parts are immersed in a molten salt solution. Potassium ions (electronically charged particles) in the solution migrate into the glass surface, replacing the smaller sodium ions originally in the glass. As the glass cools, the larger potassium ions compress the glass together, creating a compressive stress layer that forms a tough surface.
It’s useful to imagine another scenario that illustrates this concept. A triangular billiards rack holds 15 pool balls closely together, but still with plenty of room to roll. Replace those balls with slightly larger tennis balls, and the rack will be packed too tightly to roll.