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How did slab glass and concrete provide an alternative to leaded stained-glass windows?

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The north rose window at Chartres Cathedral in France, featuring intricate stained glass with vibrant geometric and biblical designs in a large circular and five tall vertical panels. — stained glass The stained-glass rose window in the north transept of Chartres Cathedral, France.

Slab glass and concrete emerged as a significant technical innovation in 20th-century stained glass, providing a modern alternative to traditional leaded windows. Developed in France around 1930, this method functions as a variation of earlier masonry techniques, such as the cement tracery historically used in Islamic architecture.12

Instead of assembling glass pieces with grooved strips of leading, artists set thick slabs of glass directly into a concrete matrix. This technique allows for bold effects of texture and relief that are distinct from the graphic potential of traditional lead lines. By moving away from the constraints of lead cames, this approach enables stained glass to be utilized as a major, integral element of architectural design, as seen in works like the First Presbyterian Church in Stamford, Connecticut. The style was notably championed by artists such as Fernand Léger, whose work helped reveal the expressive potentialities of the medium.23