Heat treatment method for prestressed glass panes

The invention concerns a method for heat treatment of prestressed glass panes so as to eliminate specimens liable to spontaneous fracture following the growth of included crystals, in particular by the transformation of nickel sulphide of their alpha -phase into their beta -phase (heat soak test), the glass panes, after prestressing treatment, being maintained, during specific time intervals, at a temperature value accelerating the crystal growth; said method consists in bringing the temperature of the glass panes by controlling in the NiS alpha -inclusions from an initial temperature in the domain of a formation of germs of the beta -phase which is below 250 DEG C and above room temperature (domain of germ formation), the temperature modification when the germ formation domain is brought about by control being higher than 2 degrees K/minute and a temperature modification substantially slower is imposed or a specific temperature being maintained during a specific time interval within the germ formation domain. The method is particularly suitable to be executed immediately after prestressing thermal treatment of glass panes, by first of all lowering their temperature and by maintaining same within said germ formation domain.