The strength of float glass depends largely on the duration of the load and the environmental conditions. This is due to subcritical crack growth: under tensile stress, water molecules from the air humidity react with the silicon-oxygen bonds at the crack tip. This causes existing microcracks to grow over time until they reach a critical length and the component fails.

The central hypothesis of this work is that laminating with a PVB film seals the glass surface so effectively that moisture is prevented from reaching the crack tip, or at least greatly delayed. As a result, the side facing the polymer could have a significantly higher effective strength than a free glass surface.