This paper presents a groundbreaking technological breakthrough in the optical quality of tempered glass. For decades, scientists and glass experts have sought to minimise anisotropies—visible iridescence and optical distortions commonly referred to as leopard spots—in tempered and heat-strengthened glass. Despite significant efforts, achieving a true solution remained elusive.
Anisotropy inline scanners have advanced the industry’s ability to quantify optical retardation across the glass surface, enabling precise detection of these strain-related distortions. However, while such scanners help measure and categorise anisotropies, they do not offer a means to eliminate them, leaving end clients, designers, and façade experts to grapple with the visual impact of strained glass.
The most advanced specification in this field, DIN SPEC 18198, classifies optical quality into three levels (A, B, and C), with Level A representing the highest standard. Yet even Level A glass often exhibits visible strain patterns under polarized light, which can detract from its aesthetic and functional value.
After years of intensive research and investment, we are proud to introduce a technological breakthrough that eliminates visible anisotropies in tempered glass, including both flat and curved formats by means of lamination bending down to approximately 7-9 metres radii. This breakthrough represents a significant advancement for many architectural applications.
Initially, our research focused on uncoated glass, where the results were extraordinary. Furthermore, coatings applied after the heat-treatment process enhance the optical properties even further, broadening the scope of applications.
Curved geometries, often favoured by architects for innovative building designs, benefit immensely from this development. Relaxed curves, combined with the mechanical advantages of tempered glass, are now achievable without the visual drawbacks of anisotropies. This advancement paves the way for a new era in glass façades, where optical perfection meets structural performance.