Acid-Etch: A method of removing layers of flashed glass with hydrofluoric acid.
Acrylic: Also called Plexiglas, is of limited use for protection glass as it discolors quickly when exposed to sunlight.
Antique Glass: Refers to a traditional method of manufacture, not age—antique glass is mouth-blown to eventually form a sheet when cut open and allowed to flatten in a kiln.
Architectural Glass: A clear glass with geometric or linear texture patterns.
Art Glass: Specialty glass manufactured for use in stained glass projects and restoration.
Beveled Glass: A technique whereby thick pieces of clear glass are miter-cut and polished to create a prismatic effect.
Blown Glass: Glass that is gathered in its molten form and blown and into shapes or vessels.
Board-Up: A temporary plywood window cover installed while a leaded panel is being repaired/restored.
Border: A frequently used linear design element in leaded glass. Borders serve a structural function as they can absorb shocks and stresses, protecting the interior pictorial section of the panel. Lowermost borders can be susceptible to folding.
Bulge: See DEFLECTION.
Came: A channel extruded in a ‘U’ or ‘H’ profile and wrapped around individual glass pieces to build leaded glass panels.
Cartoon: A full-scale working drawing used to make patterns for glass painting, cutting, and glazing.
Casement Window: A window frame that swings open on hinges like a door; frequently made of wood or steel.
Cast Glass: Dimensional shapes formed by filling a mold with glass pieces and heating to 1450-1550F in a kiln.
Cathedral Glass: A transparent colored glass that is machine-rolled.
Cement: A particular kind of putty used in leaded glass, cement is applied to fill the gaps between the glass and the channel of the lead came. This serves to both weatherproof the panel and patina the lead.
Chip-Out: The process of removing old putty or mortar from the exterior perimeter of a glass panel to release the panel from the frame.
Cold Paint: Paint applied to the surface of glass that is not permanent, as it is not kiln-fired.
Condensation: Moisture that forms from air trapped between two planes of glass.
Copper Foil: Copper coated tape that is used to wrap around glass pieces providing a surface that can be soldered. Used as a method of building intricate windows and lampshades.
Copper Ties: Short lengths of copper wire soldered to the interior surface of a leaded glass panel. These wires are twisted around a steel ‘saddle’ or round steel support bar to keep the window in plane.
Daylight: Any place in a leaded window where cement is missing or the lead is compromised allowing daylight to be seen where it should not be.
Deflection: A noticeable bulge or warp in a leaded panel. Lead will sometimes stretch due to heat expansion and the pressure of its own weight, causing the panel to distort. Commonly occurring with age, deflection can cause cracks in the glass and/or broken solder joints and copper ties.
Diamond-Light: A traditional design in leaded glass windows, diamond shapes can fill a large space with pattern. These windows are also highly vulnerable to bulging or folding.
Dutchman: A glass repair using an applied lead strip to cover a single crack.
Edge-Glue: The process of gluing a crack or cracks in a piece of glass using a clear or tinted epoxy.
Enamels: Specially formulated colored glass pigments that are applied to the surface of painted glass and fired.
Epoxy: A two-part adhesive resin used to bond cracks in glass.
Faceted Glass: Glass panels that incorporate 1″ thick cast blocks called ‘dalles‘. Pieces are cut from these blocks and bound together with a matrix of poured epoxy to create a solid flat panel. The edges of the glass pieces are later chipped or faceted to create scalloped surfaces that capture light.
Fish Tape: A thin band of steel used for adding horizontal strength to a leaded panel. Fish tape is inserted under the lead next to the glass as the panel is being glazed.
Flare: The beginning of a crack in glass originating at the edge or running off of an existing crack.
Flashed Glass: Antique sheet glass that is made using 2 layers of different colors. When one layer is removed by etching, the second color is revealed.
Float Glass: A term describing the manufacture of most modern clear window glass. Float glass is rolled out onto a bath of molten tin, making it perfectly flat.
Fold: A common occurrence in a leaded glass panel when a border or horizontal design element runs edge-to-edge creating a fold line.
Full Restoration: A documented process whereby a leaded glass window is removed from an opening, carefully taken apart, and rebuilt with new lead came, solder, and cement.
Fused Glass: Two or more separate pieces of glass that, when kiln-fired at high temperature, become permanently bonded.
Glass: A hard transparent material created by heating silica, lime, and potash to a molten state allowing formation of desired shapes or sheets before cooled. Colors are created with the addition of various metallic oxides.
Glass Paint: A vitreous paint that is applied to the surface of the glass. Kiln fired at 1100-1250F, a permanent bond is created between the paint and glass surface.
Glazing: The process of building a stained glass window using lead came and solder to join pieces of glass together into a panel.
Glazing Compound: A linseed oil-based putty that is applied soft and hardens as it dries. Used to set and seal windows into frame openings.
H-Bar: A rigid aluminum channel used in installation to stack multiple panels on top of each other. A structural reinforcement, it is attached to the window frame and the panels it holds.
Jewel: A dimensional piece of cast glass used as an accent in stained glass windows.
Joint: The intersection of two or more lead cames in a stained glass panel that are joined with solder.
Kiln: A high temperature oven used by glass artists to fire glass paint to glass surfaces; to cast or slump glass; or to fuse layers of glass together.
Laminated Glass: Two pieces of plate glass bonded together with an adhesive plastic sheet. Used as ‘safety glass’ it holds together upon moderate impact. Auto windshields are made from laminated glass.
Lead: A heavy metal that is malleable and fairly easy to shape or solder.
Lead Overlay: Came or sheet lead used as a design element or repair by soldering it to the face of the leaded glass panel.
Lead Profile: Refers to the size and shape of lead came. Commonly either flat or rounded, lead comes in a variety of widths.
Lexan: Brand name of the most current polycarbonate material commonly used as an exterior protection cover over stained glass windows. Lexan is resistant to impacts even including low caliber bullets. Can be saw-cut to size for use as protection glass when vandalism is a concern.
Matte: Glass paint used to create depth and form to an image. After being evenly washed over the surface of a piece, the paint is then selectively removed to create a shaded image. Kiln firing makes the paint permanent.
Medallion: A central design element in stained glass often depicting an image of a historical or religious symbol.
Mullion: A main vertical division of a large divided window frame.
Muntins: A set of structural divisions within a window that divide a larger opening into smaller ‘lights’ or ‘panes.’
Nameplate: A piece of glass within a leaded panel that displays the name or names of the donors of the window. Most commonly applied with glass paint or by acid etching on flashed glass, nameplates are located in the lower portion of the panel.
Off-Color Repair: A term used to designate a piece of glass from a prior repair that is a poor match in color or texture.
Opalescent Glass: An art glass with a milky quality that causes varying degrees of density. The amount of opacity in glass effects light transference.
Oxidation: A naturally occurring condition in metals. Oxidation in lead is accelerated by moisture trapped in close proximity to the metal. The resultant lead oxide is particularly hazardous to inhale or ingest. Oxidation eventually compromises the structural integrity of lead in a stained glass panel after about 80 – 100 years.
Patina: The chemical alteration of a metal surface resulting in color change. Naturally occurring in lead when exposed to the elements, it can also be achieved more quickly by applying chemicals to the surface of the metal. Lead with a patina typically has the color and luster of graphite.
Pattern: A piece of a window design traced on and cut from paper. Pattern pieces are used to cut glass from a large sheet into smaller glass pieces of specific shape, size and color
Plate Glass: A term used for common annealed window glass.
Polycarbonate: See LEXAN.
Protection Glass: A protective barrier installed to the exterior of a stained glass window. Commonly plate glass, laminated glass, tempered glass, or polycarbonate, the protection glass should be installed at least 3/4”away from the leaded panel.
Rabbet: The ‘L’-shaped recess in a frame into which a stained glass window is set.
Rebar: Round or flat steel bar soldered or wired to a leaded glass panel. Rebar lends structural stability as it is then secured under the framing material holding it tightly in place.
Re-Glaze: To apply new caulk or putty to the exterior perimeter of a window. Or to completely rebuild a leaded panel during a full restoration.
Re-Lead: The process of disassembling a leaded glass panel and rebuilding it using new lead cames and sealants.
Rondel: A mouth blown disc of glass used as an accent piece in stained glass windows.
Rose Window: A large round window divided into sections that radiate from the center.
Rubbing: A pattern made from a leaded glass window by placing paper over the panel and rubbing with a lead or wax crayon.
Sandblasted Glass: A frosted dimensional effect created by masking off the surface of glass and spraying exposed areas of design with abrasive material.
Sash: A frame typically made of wood containing glass panels, either operable as in ‘double hung’, or stationary as in ‘fixed’.
Sealant: a material used to seal the exterior perimeter of a glass pane or panel from the outside.
Seeds: Small bubbles in clear and colored antique glass, often intentionally created to add nuance to light transmission.
Silver Stain: A type of glass painting colorant; fumes from heated silver stain fuse into the back surface of the glass when fired. Silver stain runs from light yellow-gold to deep orange-amber in color.
Slip-Lead: A wide H shaped lead that can be used in installation for stacking leaded panels on top of each other.
Soak Tank: A large flat steel pan that is filled with water and used to soak leaded glass panels. Commonly used for flattening bulges, cleaning glass, and in taking apart old leaded windows during a full restoration.
Solder: An alloy of tin and lead, solder is heated with a soldering iron and used to join lead came or copper foil.
Stone-Set: Refers to windows that have been set into stone openings and secured in place with mortar.
Stops: Wood or metal strips used to secure window panels; they are installed into the frame around the perimeter of the panel.
T-Bar: A T-shaped steel bar used as a horizontal structural element in installation when stacking leaded windows on top of each other in an opening.
Tempered Glass: A float glass that is heat or chemical treated to create tension in the surface causing it to break into tiny bits upon impact. Created to be a ‘safety’ or ‘strengthened’ glass. Tempered glass can be several times stronger than standard plate glass.
Template: A pattern of an opening taken in situ to obtain an accurate size and shape of the frame.
Texture: A raised surface on art glass that creates a visual interest.
Trace: Vitreous glass paint applied to the surface of glass and kiln fired for permanence. Traditionally used to create dark solid line.
Transom: A rectangular or arched window above a door.
Ventilator: A small section of a stained glass window that is set within a pivoting or hinged frame to allow for air circulation.
Window Glass: Clear float glass, usually 1/8″ thick, or ‘double strength’; it has no discernable color or texture.
Zinc: a hard metal that is formed into rigid channels and used to build or frame leaded glass panels. Zinc is frequently used to build beveled glass panels.