The art of stained glass calls for a complex technique that integrates glass, often painted, into a structure of came. The glass used is blown and sometimes plated (or doubled) to allow for engraving. The production of a strained glass window begins with the realization of a model on a scale of 1:10, and the choice of a color scheme from a glass color chart -- a fundamental step for the stained glass painter, who then proceeds to execute a cartoon in the window’s exact dimensions. From this cartoon, the stained glass painter makes a precise tracing to record the contours of the came. The tracing is carbon copied onto thick paper upon which are indicated the numbers of each piece and panel, and which will serve as a reference throughout the process. Then, with the aid of double bladed scissors, the outline of all the pieces is cut out creating future templates, as well as thin strips of the thick paper which correspond to the width of the came. The cutting of the glass pieces according to their template is carried out by using a diamond cutter to score the glass which is then broken by gentle tapping with a small hammer. Any irregularities in the cut can be removed with grozing pliers followed by grinding and filing of the edges. If the artist’s project requires painting, a temporary glazing of the panel with wax must be done; placed before a light source, vertically before a window, or horizontally on a transparent table. The paint used --”grisaille”-- is made from powders of copper or iron oxides mixed together with flux, thinned with water or vinegar, and supplemented with gum arabic or essential oils. Different paint brushes are used to draw fine lines ( soft hair brushes ), cover broad surfaces ( usually badger brushes ), or apply small strokes ( brushes made from hog’s hair ). The engraving of plated glass, which was originally affected with emery or files, is now possible using grinding wheels or hydrofluoric acid. The firing of this grisaille -- as well as silver stain, Jean Cousin, and enamels (see below) -- is done at approximately 600°C, following a progressive and regular curve of temperature over time. These steps are completed by glazing the window which involves setting the glass elements in the came; these grooved strips are fashioned with a solid core and flanges designed to be pressed down over the glass with a boxwood knife. The network of came is assembled by soldering with a tinned soldering iron. Water proofing of the window is ensured by brushing a “mastic” -- or cement putty -- under the flanges of the came. Finally, the window is fitted with a metal skeleton of iron bars that fasten the window to its opening and hold each panel secure.

It would be impossible to retrace the long history of stained glass and its techniques in a few short lines, so we must settle for a brief overview. The origins of stained glass probably coincide with the invention in the first century BCE of flat glass, used by the ancient Romans in the fabrication of windows. It is also known that in the Muslim world there existed “claustra” which made use of glass in decorative installations, but when exactly glazing with lead began to replace mountings in plaster, stucco or wood remains unclear. In Medieval times stained glass established itself as a dominant force in religious architecture, transcribing in glass imagery the lives of Christ, his mother, and the Saints, to create veritable walls of light of monumental proportions. The very earliest vestiges uncovered at San Vital in Ravenna seem to date from around 540. After that, one must wait until the VIIIth or IXth century before finding any other significant fragments, but it is at the beginning of the XIIth century that stained glass will really start to develop on the construction sites of the great cathedrals. Romanesque stained glass, while still closely linked to the refined arts of miniature painting and enameling, has now taken on the important function of providing light for these edifices, making use of brilliant colors like the famous blue in the Chartres windows (circa 1150). The technical principles of stained glass making, from the composition of the glass to its painting and the fabrication of windows, are recorded in the Rhenish monk Theophile’s treatise “Schedula Diversarum Artium” which dates from the first third of the XIIth century. The glass was blown using either the cylinder method in which a hollow cylinder is opened and flattened in a kiln, or the crown method whereby a disc of flat glass is created by rapidly spinning a punty iron. The paint used for decorating the glass -- “grisaille” -- was composed of oxides of copper or iron, finely ground glass, and a binder of urine or wine. It was painted on in three consecutive layers of flat tints of varying thickness , to indicate the major lines and contours; the details were achieved by removing the still wet paint with a needle or a paintbrush handle. The XIIIth century is the period when stained glass evolves into the primordial element of the religious edifice, whose style varies depending on the region, the atelier, or even the innovative artisan. Take for example the rebuilt Chartres, Bourges, Notre Dame de Paris, the Sainte Chapelle.... The revolutionary technique of the XIVth century is silver staining -- a mixture of silver salts and ochre yellow -- which makes it possible to color white glass yellow, to avoid unnecessary cuts, and to generate colors by complementarity. More and more in the XVth century, stained glass begins to rival contemporaneous painting, and continues to thrive in the XVIth century owing to technical advances like the diamond cutter, an increasingly rich palette of colors, and the more frequent use of engraved plated glass. Other developments include the popularization of a sanguine called Jean Cousin (prepared from a base of red iron hematite for the rendering of flesh tones), as well as enamels, or vitrifiable colors, which will be widely used beginning in the XVIIth century up to and including the XIXth century. Stained glass experiences a period of decline during the XVIIth and XVIIIth centuries when “one no longer wants anything that might diminish the light”, “neither in the home nor in the church”, and some secrets of fabrication start to disappear. At the beginning of the XIXth century, a resurgence of interest in the Middle Ages as well as several large restoration projects help stimulate a renewal of interest in the age old art of stained glass. In the second half of that century, France’s Maréchal of Metz develops the “vitrail tableau” (stained glass painting), and in England William Morris and his colleagues further the evolution of both religious and secular stained glass, laying the groundwork for Art Nouveau. Four European architects -- the Catalonian Antonio Gaudi, the Scot Charles Rennie Macintosh, the Frenchman Hector Guimard and the Belgian Victor Horta -- will restore stained glass to monumental pre-eminence by renewing the decorative repertoire and incorporating new glass, like American and opalescent glass, into their buildings. In France, Jacques Gruber, one of the remarkable figures from the Nancy School, developed a sophisticated technique that combined superimposed acid etched glass, textured American glass, dichroic glass, and a complex method of glazing. In the United States, John LaFarge and Louis Comfort Tiffany invented original stained glass that was opalescent, iridised and textured. Tiffany also developed an innovative method of glazing. Early in the XXth century, influenced by Frank Lloyd Wright and the Bauhaus School, stained glass styles will be refined, giving way before 1930 to the first abstract experiments of Theo van Doesburg, Jean Arp, and Sophie Taeuber Arp -- experiments that will not be renewed until the 1950’s. After 1945, in the wake of devastation of another World War, vast rebuilding projects provide many opportunities to create new stained glass windows in Europe, but it is often difficult to reconcile the modern aesthetic sensibilities of the artists interested in this medium with the conservatism of the clergy. In France the Dominican priest Marie-Alain Couturier takes a courageous stand that will release stained glass from its academic yoke. The stained glass windows at the chapel of Assy (circa 1950), after cartoons by Georges Rouault, Jean Bazaine, Marc Chagall...will serve as examples for further innovations like the incorporation of non-figurative windows in a religious edifices. Following the initial experiment of “les Bréseux” the painter Alfred Mannessier devises several abstract windows, Henri Matisse applies his creative process to the windows of the Chapelle du Rosaire in Vence, and Le Corbusier revives the spirit of Romanesque windows in Ronchamp. Among the many edifices that have benefited from this creative movement, let us not fail to mention the Metz cathedral with windows by Jacques Villon, Roger Bissiere and Marc Chagall, as well as the Saint Dominic chapel in Varangeville with windows by Georges Braque. During the 1960’s, European painters were often commissioned to execute religious cartoons, but the tradition of secular stained glass comes to an end, except in the United States -- specifically in California. Stained Glass Today

The practitioners of stained glass still collaborate with painters, among whom we should name Pierre Soulages of Conques, Jean Pierre Raynaud of Noirlac, and Claude Viallat of Aigues-Mortes.

GRODECKI Louis, “Le Vitrail Roman”, Office du Livre, Fribourg, 1977 GRODECKI Louis , BRISAC Catherine, “ Le Vitrail Gothique”, Office du Livre, Fribourg, 1984 “Le Vitrail en Lorraine”, Inventaire général des monuments et richesses artistiques de la France, Catalogue d’exposition, Nancy, 1983 BRISAC Catherine, “Le Vitrail”, Editions de la Martinière, Paris, 1994 BLONDEL Nicole, “Le Vitrail , Vocabulaire typologique et technique”, Imprimerie Nationale, Paris, 1993