Dalle de verre, is a glass art technique that uses pieces of coloured glass set in a matrix of concrete and epoxy resin or other supporting material.

Glass applique, is an applique technique that is frequently used in glass art, whether or not in combination with glass fusing. The method is often used to decorate large glass surfaces or to give a certain figuration, while the representation and the wall remain transparent.

Technique
The technique was developed by Jean Gaudin in Paris in the 1930s. Slabs of coloured glass, 20 centimetres (7.9 in) to 30 centimetres (12 in) square or rectangular and typically up to 3 centimetres (1.2 in) thick, are shaped by breaking with a hammer or cutting with a saw. The edges of the resulting pieces may be chipped or faceted to increase the refraction and reflection effects.

The forms of glass that have been accurately cut out in advance and are usually colored differently are glued to a flexible, transparent core of plexiglass with an equally flexible and transparent glass glue. This flexibility is necessary for the glass decoration thus created to be resistant to internal stress differences within the materials used, or to stress caused by temperature differences. In addition, the glue has the option of filling in small differences in thickness of the glass layers used without losing any transparency.

The pieces are laid out to a design, similar to traditional stained-glass work. The pieces are laid on a bed of sand, bounded by a wooden casting frame. A matrix material, sand and cement or epoxy resin, is poured between the glass pieces and allowed to dry, typically requiring 24 hours to harden. The visible glass faces are then cleaned and the resulting solid panel can be relocated, embedded or hung as required.

The use of thicker glass produces deeper colour effects than traditional lead came stained-glass, especially when illuminated by bright natural or artificial light.

The technique achieved prominence in the stained glass literature of the 1950s and 1960s.

From the 1980s onwards, artists also began to use the glass applique method for the creation of independent glass images. Here too, a Plexiglas core is used, on which the colored, cut-out, flat glass shapes are glued to one or two sides thereof. When both sides of the core are used, it is possible to mix colors by using a different color on each side. The light falls through the entire glass image and will thus mix both color layers together. To give the glued layers a three-dimensional suggestion, clear pieces of glass are glued here and there on the colored glass. These have been fused in a glass oven to soften sharp edges and corners.

From the 1990s onwards, glass appliqué is increasingly displaced by glass fusing and sandblasting, Or is used in combination with these techniques.

Problems and conservation
The resulting works may be subject to structural problems over time and, just like more traditional stained glass works, pose challenges to conservators and restorers.

Artists
Artists who have independently performed many glass appliqué works are Louis la Rooy, Jan Dijker and Willem van Oyen. Also Karel Appel has made some work in this technique.

Application
Since 1945 many glass walls, glass facades and wall decorations have been realized with this technology in the Netherlands. Artists such as Lex Horn developed this technique in collaboration with, among others, glaziers from Van Tetterode. Glass applique has the advantage that colored and cut-out glass shapes can be incorporated into the flat surface in all sorts of ways, without the glass having to be heated. Nor is lead used as a carrier. This glass-on-glass technique was widely used in the reconstruction period to make glass artworks as part of modern architecture.

Dalle de verre in the UK
Dalle de verre was brought to the UK by Pierre Fourmaintraux who joined James Powell and Sons (later Whitefriars Glass Studio) in 1956 and trained Dom Charles Norris in the technique. Norris was a Dominican Friar who went on to become arguably the most prolific British proponent of dalle de verre. His work is incorporated in several Modernist listed Catholic churches.

Examples of dalle de verre by Gabriel Loire of Chartres can be found in The Holy Name RC Church, Oakley, Fife, (1958), Saint Paul’s RC Church, Whiteinch, Glasgow (1960), Our Lady of Mount Carmel RC Church, Kilmarnock, Ayrshire (1963) and St John’s RC Church, Stevenston, Ayrshire, (1963).