Considerations concerning velocity distribution of the glass melt in conditioning devices, dependent on temperature distribution, are made for circular cross-sections. An analogous application of the results to rectangular cross-sections is possible. There are limits for the cooling performance for a given channel design which cannot be exceeded simply by further lowering of the margin temperature or by using a stronger cooling outside. Strong cooling can cause devitrification and thermal reboil. These problems can be avoided by mathematical simulation and appropriate measures derived from them. It is advantageous to increase the platinum wall thickness in some areas. As a result of optimisation, better operation and high thermal homogeneity for hollow glass forming is possible together with reduced gob mass fluctuations down to 0.5-0.1%.
