Concrete glass mysticism

In 1963, based on designs by artists Sigrid Theimann and Roswina Hermes, van Treeck produced 78 windows for the Coronation Church in Ergenzingen using the special dalle-de-verre technique, which uses up to 3 cm thick glass in various colours.

The art glaziers work the shaped glass panes with a hammer or a saw. To intensify the effects of refraction and reflection, they grind or bevel the edges of the resulting pieces, forming a pattern from the individual glass elements on a bed of sand. A wooden frame encloses the pattern so that a matrix material can be poured between the glass pieces and left to dry for around 24 hours.

Concrete glass windows are a wonderful architectural element: the thick glass creates deeper colour effects than conventional lead glazing. The technique was developed by the Parisian Jean Gaudin in the 1930s. It reached its peak in the 1950s and 1960s.