HST - Heat Soak Test

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The tempered glass produced by us meets all the requirements of the PN-EN 12150-1 European standard which strictly defines such quality parameters as mechanical strength, dimensions and tolerances, the nature of the crack pattern and the finish of glass edges.
However, float-type glass has a certain degree of imperfection which comes down to occasional infiltration of nickel sulphide (NiS) particles into the glass mass during the glass production process.  Heating the glass during tempering changes the volume of nickel sulphide particles, and when the glass is cooled quickly, which causes its hardening, this prevents the particles from returning to their previous volume and “keeps” them in such condition.  This creates additional stresses in the glass and may result in the breaking of the glass pane.

 

The Heat Soak Test is a method involving heating and maintaining the glass panes in a certain temperature and for a specified period of time, in a special, calibrated furnace in order to identify precipitations.  This significantly reduces the risk of spontaneous explosion of tampered glass.  The HST test does not cause deterioration of the strength parameters of tempered glass and is more and more often applied by investors in view of the growing safety requirements.