Reinforcement of glass articles - without loss of surface clarity

摘要

The articles are reinforced by surface exchange in an electric field at temps. close to or below the transformation point in which alkali metal ions in the surface region are exchanged for larger ones provided by a molten alkali metal salt. The cathode compartment of the ion source contains >=1 compound which is caustic and/or is capable of fixing the oxide of the alkali metal formed. The above salts are added in small amounts to a KNO3 bath.