Chemical strengthened glass is different with Air-cooled glass, is chemically strengthened by a surface finishing process. Glass is submersed in a bath containing a potassium salt. This causes sodium ions in the glass surface to be replaced by potassium ions from the bath solution.
These potassium ions are larger than the sodium ions and therefore wedge into the gaps left by the smaller sodium ions when they migrate to the potassium nitrate solution. This replacement of ions causes the surface of the glass to be in a state of compression and the core in compensating tension.
Compare with Air-cooled glass, thin, small and complicated shape of glass can be strengthened by chemically, and no distortion or warp.