A method of chemical tempering of a cylindrical glass preform or glass container and the glass container or cylindrical glass semi-finished product and use thereof

In methods for chemical tempering of a cylindrical glass preform, in particular a glass tube, or a glass container for the production of primary packaging for pharmaceutical purposes by ion exchange, a plurality of glass semi-finished or glass containers (30) in a carrier (15) brought in. The carrier with the plurality of semi-finished glass or glass receptacles (30) is immersed in a Kaliumsalzbad during a predetermined period to effect an ion exchange in the Kaliumsalzbad. According to the invention, a flow is formed in the Kaliumsalzbad to counteract an accumulation of ions, particularly sodium ions, to the near-surface portions of the glass semi-finished or glass container due to the flow during the predetermined period. Thus, an optimal concentration gradient can be realized at the interface between salt bath and glass surface constantly, so that the rate of ion exchange can be effectively increased and can be set desired penetration depths and profiles reliable. Instead of a permanent flow intermittently forming a suitable flow can be sufficient.