Dalle de verre ( literally “slab of glass” ) is a French term for a block of cast glass, usually 3-5 cm thick and measuring 20x20cm or 30x20cm. The use of dalle de verre is a derivation from traditional stained glass techniques, in which windows are constructed from pieces of slab attached to each other with concrete or resins. The execution of a window in dalle de verre requires the same initial steps as would a traditional stained glass window set with lead came. Beforehand, there must be generated a model on a scale of 1:10, a cartoon to establish reference points, a precise layout transferred to tracing paper, and thick paper cutouts of each piece. Cutting the very thick sheets is begun by scoring with a saw or diamond, then completed with a tungsten carbide plated hammer. The cut can be left rough and jagged intentionally to create an interesting play of light. The pieces are then placed inside a wooden frame of the window’s exact dimensions. Before proceeding to pouring, a metal support must be prepared for the concrete. The practitioner pours a first layer of concrete, then puts in place the metal support, before pouring a second layer. After a few hours the whole surface of the window is covered in saw dust to help clean the glass of any excess concrete or resin.

Introduced by the master French glassmaker Jean Gaudin, this modern technique first appeared in 1927. Its development coincided with the emergence of contemporary reinforced concrete architecture and the construction of certain postwar religious edifices. Dalle de verre eventually triumphed over the prejudices of its detractors and became instrumental in the reconstruction of older edifices as well. It gave birth to some masterpieces like the vast window by Fernand Léger for the Sacré Coeur church of Audincourt in 1951. Certain practitioners are just as comfortable using traditional stained glass as they are using dalle de verre -- like Gabriel Loire who introduced this technique to the United States in 1955 at the First Presbyterian Church of Stamford, Connecticut. His Children’s Tower at the Japanese Museum in Hakone draws us into its spiral, evoking the poetic universe of childhood. Similarly, the artist Alfred Manessier uses with equal assurance both dalle de verre and the ancestral technique of stained glass, using the one in the church of Alby-sur-Cheran (1978) and the other in the Fribourg cathedral (1976).

Nowadays, the technique of the "Dalle de Verre" is in constant evolution thanks to the discovery of new resins which make it possible to improve its aesthetic possibilities.

BRISAC Geneviève,”Le Vitrail”, Editions de La Martinière, Paris, 1994 BLONDEL Nicole, “Le Vitrail - Vocabulaire typologique et technique”, Imprimerie Nationale, Paris, 1993