Alkali-containing inorganic glass products can be readily strengthened by immersion in a bath of molten alkali salts at temperatures lower than the strain point of glass. The larger batch alkali ions gradually exchange with the smaller host alkali ions of the glass resulting in a stuffed surface which leads to practical strengthening. Chemical strengthening technology of glass is greatly affected by glass composition chemistry such as soda-lime-silicate, borosilicate and aluminosilicate. Likewise, the chemistry differences of "tin" and "air" surfaces influence the strengthening behaviour of float glass. With progressive exchange, the bath chemistry alters due to increasing impurities and needs to be brought under control for a successful product technology. The physics of surface compression development has been described in detail earlier. This review discusses the effects of variations in the chemistry of glass and the immersion bath.
