Spandrel glazing has developed to a stage where more efficient insulation can generate higher thermal stresses than can normally be resisted by heat strengthened (HS) glass on which ceramic enamel (frit) has been applied.
This article details: the evolution of spandrel glazing; a discussion of possible causes of the weakening of heat treated (HT) glass with applied ceramic enamel; and suggested design changes to eliminate this breakage.