Stained Glass Glossary
Stained Glass Glossary
The process of etching the surface of glass, usually flashed antique glass, with hydrofluoric acid. Acid-etched decoration is produced by covering the glass with an acid-resistant substance through which the design is etched. A mixture of dilute hydrofluoric acid and potassium fluoride is then applied to etch the exposed areas of glass.
One of the types of glass used in leaded stained glass. Antique glass is any glass that is made by the same methods as those employed by medieval glassmakers. The glass is full of imperfections that give it character. Bubbles, striations, and varying thicknesses break up the light and cause highlights in each piece. It is also often called "pot metal glass" because the molten glass is colored, when in a pot, by addition of metal compounds. Antique glass is hand-made by blowing or spinning the molten glass.
Stained glass designed, made, and installed to harmonize with the structure and function of a building.
A decorative glass, usually clear, in which the edges of the glass have been angle cut (beveled). As light passes through the beveled part of the glass, it acts as a prism and will create brilliant highlights and small rainbow color effects.
BRACES, REBAR, OR SADDLEBARS
A flat or rounded steel bar that is anchored in the framing on the side of a window panel and attached by solder or wire ties to the lead joint across the panel. Its purpose is to strengthen the window and hold it in a flat plane. In a window that has begun to bulge, the bulging is usually reduced before a new brace is applied.
BROKEN OR SHATTERED GLASS
A glass that has been so broken or shattered that it cannot be retained and must be replaced.
One of the more common symptoms of problems with a leaded stained glass panel. It is a general sign of weakening of some part of the structural support system. In a worst-case scenario, bulging can cause glass to be pulled from the lead, the lead to tear, or the glass to break.
A grooved strip of metal, generally with an H or U shaped cross section, used to join the individual glasses in stained glass windows. Usually lead, but zinc, brass, and copper are also sometimes used.
The name for the full size working drawing for a stained glass design that contains all the cutlines. It can also contain paint lines, color, grain directions, piece numbering, and other information. It is essentially the blueprint for the work.
A rolled glass that can be clear or patterned. It is usually one color per sheet and transparent like antique glass. It can have regular or irregular surface patterns impressed into it by the surface textures of the rollers. It lacks the character and beauty of antique glass.
The material used to waterproof the edges of a window section, seal it into its frame, and often to seal the frame into the building. It is also often called a sealant.
CEMENTING AND RECEMENTING
The act of forcing a putty-like substance (cement) between the glass and the lead flanges to add strength and support to the window. In recementing, the cement is brushed over the exterior surface of the window to join with any of the old cement and fill up any holes that may have developed.
The technique of joining pieces of glass where foil is centered on the edge of each glass piece, then bent over the edge to cover a very small portion of the back and front faces of the glass. Pieces are abutted and solder is melted over the exposed foil surfaces, causing the foil-covered glass edges to become joined. It also refers to the mil-thickness copper material, often adhesive backed, used to join separate pieces of glass.
A cracked glass that can be sealed so as to retain the original glass.
Antique glass in which the molten glass is spun at a high speed to create a large flat disk in which concentric circular lines are formed. The center of the spun glass is quite thick and was originally thought to be inferior in quality to the rest of the disk. However it is now often used to give windows a vintage look.
DALLE DE VERRE
A French term ("paving stone of glass") for an inch (or more) thick slab of stained glass. It is shaped with epoxy or cement in a window. Their faceted surfaces break the light into textures and patterns. Also called Faceted Glass.
Metal T-shaped bars with stops that are used to divide and support stained glass panels and protective covering panels.
This term usually means two individual layers of glass separated by a dead air space. Any window with a protective storm covering would be double-glazed. It also used to mean plating.
The painting on glass that defines the drapery robes of figures, usually Biblical or Historical.
Glass that is formed into a pattern by manipulation when in a molten state to simulate draped material. Drapery glass was quite often used by Tiffany and others to give form and texture to the garments of figures in their windows.
To cover a crack during repair, a flange of lead is applied over the crack, tucked under adjoining leads and soldered in place. This procedure has generally been replaced with either edge gluing or a thin copper foiled line.
A clear drying glue composed of a resin and hardener, generally mixed in equal parts. Its uses include gluing glass to glass or in construction of Faceted stained glass (Dalle-de-Verre). It is the cement-like matrix that binds the individual pieces of thick glass in a faceted glass window. By varying the negative space of the epoxy between the glasses, the best designers can create extremely interesting designs.
Usually clear glass in which the design is incised into the glass by acid, sandblasting, or an engraving wheel.
A more contemporary approach to decorative glass, it consists of roughly cut pieces of glass (about one inch thick) that are bound into panels with concrete, or more often, an epoxy resin. Rarely is any painting used on faceted glass windows. Instead, the design of the window panel is formed in the manner of a mosaic by the combination of the different sizes and colors of the glass and the negative space of the epoxy matrix. Faceted glass can be especially effective in large monumental openings.
FIRE CRACKED GLASS
Stained glass that has been exposed to the heat of a building fire where the sudden cooling of the glass causes fine cracks through the glass. In some cases fire cracked glass can be saved and restored, although the crack usually remains visible. In some cases fire cracked glasses will just completely fall apart when removed from their lead support.
A type of antique glass in which two or more colors are combined in a sheet of glass so that they have one color on one side of the sheet and a different color on the other. In that antique glass is quite transparent, this creates a third color as light passes through the glass. Thus a yellow flashed on blue glass would appear to be green. By etching away the yellow layer the stained glass craftsperson can create a piece of glass where a controlled area of the two colors green and blue can appear in the same pieces of glass.
The technique of adhering glass to other glass surfaces using heat, generally in a kiln. The degree of attachment ranges from a point where they are tacked together, but still two separate pieces; to where the pieces are fully embedded into the bottom glass layer. It also means the heating of painted glasses until the paint bonds with the surface of the object.
GLASS DALLES OR DALLE DE VERRE
One-inch thick slabs of glass usually eight inches by twelve inches. They are made by pouring the molten glass into molds on a flat surface. The individual "dalles" or "slabs" are then cut by hand or with special saws to form faceted glass window designs.
The act of joining the glass and the lead in a leaded window to form the designs. Each lead joint is soldered on both sides after assembly.
A window style consisting of mostly panels of clear or light colored glass painted with geometric or foliate designs in black paint (stencil glass.
A comprehensive plan for the subjects of works of art, not necessarily Christian.
INSET INTO EXISTING FRAMES
The act of cutting individual patterns of a protective covering material and setting them into an existing frame pattern or tracery. This is done most often when a window has an impressive appearance, and covering it in any other manner would disturb the architectural integrity of the exterior appearance.
A decorative glass technique in which two or more layers of glass are glued together to form the design.
A long, narrow window, often with a pointed or rounded arch.
The H shaped lead strips that surround each piece of glass in the windows. It is the traditional method of framing and supporting the glass shapes that make up the design of the window.
The traditional decorative glass technique that is used primarily in window openings, and as decorative inserts in doors, furniture, and lamps. It consists of glasses (colored or clear) about 3/16" thick that are bound by lead came to form a decorative design.
LOW FIRE ENAMEL TECHNIQUE OF PAINTING ON GLASS
This type of glass painting differs in two major ways from the traditional trace and matte technique: it is fired at a lower temperature and the paint is made of colored enamels that are very lightly tinted or clear. In Trace and Matte, the color is in the glass. Being a low fire technique it does not fuse as well as a traditional trace and matte painting, and often will fade or peel after 50 years.
The delineated picture of the symbol area of a window.
A medieval style window made up of repeated geometric shapes showing different biblical scenes or symbols.
Glass that has been completely removed from the lead.
The vertical strips dividing the panes or lancets of a window.
A muntin is a strip (either real or illusory) separating panes of glass. Because it was impossible or prohibitive to manufacture large sheets of glass prior to the 20th century, big expanses of windows were achieved by holding many, smaller panes of glass together by muntins. A true muntin is a strip of wood or similar material completely separating panes of glass. In the modern world, the illusion of muntins is created by sandwiching thin strips of aluminum or plastic between double-paned glass, or by affixing these grilles onto the outside of the glass.
NORMAN SLAB GLASS
A type of antique glass in which the molten glass is blown into box-shaped molds, and when it solidifies is cut into rectangles. These slabs are thicker in the center and thinner along the edge, giving each piece a great depth of color and beauty. Unfortunately, Norman slab glass is not made anymore.
A type of glass made famous by Tiffany and LaFarge in the United States. It is translucent rather than transparent and has a mildly opaque appearance, with colors streaked through it.
Any glass in which paint has been applied for design purposes and the glass baked to make it more permanent. There are two basic types of painted glass used in stained glass: the traditional Trace and Matte technique, and the Low Fire Enamel technique.
The metal perimeter of a frame of a window or a protective covering.
The act of joining two or more layers of glass in a leaded window to create a special effect of color change.
A covering on the exterior of the leaded stained glass windows that protect the windows from the weather, and from accident or vandalism. It also can help insulate the building. Protective coverings are usually made of float glass or plastic.
Diamonds or rectangles of glass leaded together in a lattice design.
RELEADING OR REGLAZING
The act of completely disassembling a leaded window, cleaning the glasses, and reassembling the window with new lead. Releading is needed only when the lead can no longer perform its function of joining and supporting the glasses in a window. Depending upon condition there are some windows that need releading in 100 years; while there are windows in Europe that have lead that is 500 years old.
The thick center of crown glass. It is sometimes also called "bottle glass" as some people thought that these small thick circles were the bottoms of bottles.
A generic term for colored and colorless glasses that are used in a decorative manner in window openings. Leaded glass, faceted glass, and laminated decorative glass can all be called stained glass.
Straightening a bulge means that the probable cause of the bulge will be determined and eliminated and the leaded panel will be restored to as flat a plane as possible, eliminating the pressures on the glass and the lead. This does not always mean the bulged area will be a totally flat plane as measured by a carpenters level. For example, to create special visual effects many leaded windows are constructed with glasses of varying thickness. Examples would include Norman Slab Glass, pressed jewels, and panels that are plated with extra layers of glass. In such cases the panels or the glass will always have a slightly bulged appearance.
TRACE AND MATTE TECHNIQUE OF PAINTING ON GLASS
In this technique the color is inherent in the stained glass before any painting is applied. For example, if the particular piece of glass is to be a face, a flesh colored piece of glass will be utilized. A special high fire glass paint (usually in shades of black or brown) is applied to the colored glass to control the flow of light. The darkness or lightness of this paint is what forms the designs on the glass. The glasses are then fired at high temperatures to fuse the glass and the ground glass-based paint. This is the same traditional type of glass appointing that has been used for over 1,000 years.
The elaborate framework of a Gothic Rose window. Sometimes called kites.
The part of a stained glass window that opens to allow for ventilation. In older windows it is usually made of steel or wood. In most new windows it is aluminum.
An H shaped zinc strip that is used similar to lead came. Stiffer than the lead came, it can give greater structural support but is very difficult to work with—especially on small, intricately curved pieces of glass. Today it is most often found in door panels when heavier beveled glass is used.
Willet Hauser is a stained glass window firm with over a century of stained glass design, repair, and restoration experience. Each year, we work with hundreds of churches and other institutions to design beautiful new glass windows or to repair, restore, and protect their existing treasures.