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AAMA 3 American Architectural Manufacturers Association. A national trade association that establishes voluntary standards for the window, door, storefront, curtain wall, and skylight industries.
ANSI 3 American National Standards Institute. Clearing house for all types of standards and specifications.
ASTM 3 American Society for Testing and Materials. Organization that sets standards for testing of materials.
Abrasion 4 The technique of grinding shallow decoration with a wheel. The decorated areas are left unpolished. 
Absorptance 2 The amount that is taken into a medium.
Absorptance 3 The ratio of radiant energy absorbed to total incident radiant energy in a glazing system.
Acanthus 4 (1) A group of Mediterranean, Asian, and African plants with large, spiny leaves; hence, (2) ornament that resembles the leaves of the species Acanthus spinosus. 
Acid etching 4 The process of etching the surface of glass with hydrofluoric acid. Acid-etched decoration is produced by covering the glass with an acid-resistant substance such as wax, through which the design is scratched. A mixture of dilute hydrofluoric acid and potassium fluoride is then applied to etch the exposed areas of glass. Acid etching was first developed on a commercial scale by Richardson's of Stourbridge, England, who registered a patent in 1857. An effect superficially similar to weathering may be obtained by exposing glass to fumes of hydrofluoric acid to make an allover matte surface. 
Acid polishing 4 The process of making a glossy, polished surface by dipping the object, usually of cut glass, into a mixture of hydrofluoric and sulfuric acids. The technique was developed in the late 19th century. 
Acid stamping 4 The process of acid etching a trademark or signature into glass after it has been annealed, using a device that resembles a rubber stamp. 
Acrylic 3 A thermoplastic with good weather resistance, shatter resistance, and optical clarity, used for glazing.
ACTUAL DIMENSION 1 The outside horizontal and vertical measurements of a window or door excluding the nailing fins. Also referred to as overall dimension.
Aeolipile (Greek) 4 The name sometimes given to globular or pear-shaped objects with a narrow neck and mouth. The function of these objects is uncertain. The word was originally applied to a device, invented in the second century B.C., in which a closed, water-filled vessel, when heated, was made to rotate by jets of steam issuing from one or more projecting, bent tubes. Most surviving aeolipiles, however, are Islamic; they are believed to be containers. See also Grenade. 
Aerogel 3 A microporous, transparent silicate foam used as a glazing cavity fill material, offering possible U-values below 0.10 BTU/(h-sq ft-°F) or 0.56 W/(sq m-°C).
Agate glass 4 See Calcedonio. 
(Air Infiltration)
3 The amount of air leaking in and out of a building through cracks in walls, windows, and doors.
AIR LEAKAGE (AL) 1 Heat loss and gain occur by infiltration through cracks in the window assembly. Air leakage is expressed in cubic feet of air passing through a square foot of window area. The lower the AL, the less air will pass through cracks in the assembly. While many think that air leakage is extremely important, it is not as important as U-factor and the Solar Heat Gain Coefficient.
Air-leakage rating 3 A measure of the rate of air-leakage around a window, door, or skylight in the presence of a specific pressure difference. It is expressed in units of cubic feet per minute per square foot of frame area (cfm/sq ft). Formerly expressed as cubic feet per minute per foot of window perimeter length (cfm/ft) but not now in use. The lower a window's air-leakage rating, the better its airtightness.
AIRSPACE 1 The measured distance between the inner surfaces of the two pieces of glass in an insulated unit. Also used in reference to the thickness of the spacer bar.
Air trap, air lock  4 An air-filled void, which may be of almost any shape. Air traps in stems are frequently tear-shaped or spirally twisted. See Diamond air trap and Twist. 
Air twist  4 See Twist 
Alabaster glass  4 A type of translucent white glass, similar to opal glass, first produced in Bohemia in the 19th century. In the 1920s, Frederick Carder (1863-1963) introduced alabaster glass at Steuben Glass Works in Corning, New York. Carder's alabaster glass has an iridescent finish made by spraying the object with stannous chloride and then reheating it. 
Alabastron (Greek), alabastrum (Latin) 4 A small bottle or flask for perfume or toilet oil, usually with a flattened rim, a narrow neck, a cylindrical body, and two small handles. 
Ale glass 4 A type of English drinking glass for ale or beer. Ale glasses, first made in the 17th century, have a tall and conical cup, a stem, and a foot. They may be enameled, engraved, or gilded with representations of hops or barley. 
Alembic (Arabic al-anbiq, "the still") 4 An apparatus used for distilling. 
Alkali 4 In glassmaking, a soluble salt consisting mainly of potassium carbonate or sodium carbonate. It is one of the essential ingredients of glass, generally accounting for about 15-20 percent of the batch. The alkali is a flux, which reduces the melting point of the major constituent of glass, silica. 
Almorrata (Spanish) 4 A rose water sprinkler with many spouts, made in northern Spain between the 16th and 18th centuries. 
Amberina 4 A type of Art Glass that varies in color from amber to ruby red or purple on the same object. This shaded effect is due to the presence of gold in the batch. The object is amber when it emerges from the lehr, but partial reheating causes the affected portion to become red or purple. Amberina, developed by Joseph Locke (1846-1936) at the New England Glass Company in East Cambridge, Massachusetts, was patented in 1883. 
Amen glass 4 A rare type of English wineglass with a drawn stem. The bowl is decorated by diamond-point engraving with verses from the Jacobite Hymn followed by the word "Amen," and with emblems associated with the Jacobite uprising of 1715. See Jacobite glass. 
Amulet 4 A charm believed to protect the wearer against evil or to bring good fortune. 
Annagrün (German) 4 A type of yellowish green glass colored by adding uranium oxide to the batch. Developed by Josef Riedel (1816-1894), who named it for his wife, Anna, this glass was made from the 1830s and 1840s. See also Uranium glass. 
Ancient glass 4 A term frequently used to mean all pre-Roman and ancient Roman glass.
ANGLE TOP 1 Any window with a horizontal sill, vertical jambs, and a straight sloping head (See TRAPEZOID)
ANNEALED GLASS 1 Non-tempered glass. The most common glass used in window products.
Annealed glass 3 Standard sheet of float glass which has not been heat-treated.
Annealing 3 Heating above the critical or recrystallization temperature, then controlled cooling of metal, glass, or other materials to eliminate the effects of cold-working, relieve internal stresses, or improve strength, ductility, or other properties.
Annealing 4 The process of slowly cooling a completed object in an auxiliary part of the glass furnace, or in a separate furnace. This is an integral part of glassmaking because if a hot glass object is allowed to cool too quickly, it will be highly strained by the time it reaches room temperature; indeed, it may break as it cools. Highly strained glasses break easily if subjected to mechanical or thermal shock. See Lehr
ANODIZE 1 An electrochemical process that increases the natural oxide coating of aluminum. Clear anodizing gives aluminum a smooth consistent surface that reduces corrosion, especially in salt air. Color anodizing can be effected by the use of dyes or special alloys. Anodizing is not normally used in residential applications, except in some coastal areas.
Applied decoration 4 Heated glass elements (such as canes, murrini, and trails) applied during manufacture to a glass object that is still hot, and either left in relief or marvered until they are flush with the surface. See also Marquetry and Pick-up decoration. 
APPLIED MUNTIN 1 A muntin in a glazed window that does not actually separate individual lights of glass. This muntin may be of a material different than the main frame- work of the window. The applied muntin may be attached to the glass with an adhesive or placed over the glass and held in place by the glazing bead. 
Arabesque 4  (1) In Islamic art, an intricate pattern of interlaced ornament consisting of curvilinear stems and tendrils that terminate in leaves; (2) in Renaissance and later European art, a pattern of interlaced curvilinear stems, scrolls, and leaves, sometimes containing animal motifs. 
ARCH TOP 1 Any window with a horizontal sill, vertical jambs, and a head that is curved upward. (See CIRCLE TOP and EYEBROW)
1 An early method of sizing Awning windows for frame construction.
Argon 3 An inert, nontoxic gas used in insulating glass units to reduce heat transfer.
Art Glass 4  (1) Several types of glass with newly developed surface textures, shaded colors, or casing, made in the United States from about 1870 and in Europe between about 1880 and 1900; (2) more generally, any ornamental glassware made since the mid-19th century. 
ASHRAE 3 American Society of Heating, Refrigerating and Air Conditioning Engineers.
ASSEMBLED 1 A condition of a sliding glass door when all of the parts are in place, as opposed to Knocked Down (KD).
ASTRAGAL 1 A channel on a sliding glass door panel, which allows another panel to slide into it. May also be used on screen doors.
At-the-fire 4 The process of reheating a blown glass object at the glory hole during manufacture, to permit further inflation and/or manipulation with tools. 
Awning 3 Window similar to a casement except the sash is hinged at the top and always swings out.
AWNING WINDOW 1 A window with the sash hinged at the top that can be opened outward. Awning windows can have more than one sash and allows for a maximum venting area. Though once common in Florida and more tropical areas, it is less popular today.
Aurene glass 4 A type of ornamental glass with an iridescent surface made by spraying the glass with stannous chloride or lead chloride and reheating it under controlled atmospheric conditions. Aurene glass was developed by Frederick Carder (1863-1963) at Steuben Glass Works in Corning, New York, in 1904. 
Aventurine (from French ave) 4 Translucent glass with sparkling inclusions of gold, copper, or chromic oxide, first made in Venice in the 15th century. Aventurine glass imitates the mineral of the same name, a variety of quartz spangled with mica. 

BOCA 3 Building Officials and Code Administrators.
Btu (B.T.U.). 3 An abbreviation for British Thermal Unit, the heat required to increase the temperature of one pound of water one degree Fahrenheit.
BACK BEDDING 1 The same as Glazing Compound.
BACKER 1 A strip of aluminum glued to the interior side of a raised grid unit. When applied with a raised grid, the look simulates a true divided light.
Balance 3 A mechanical device (normally spring-loaded) used in single- and double-hung windows as a means of counterbalancing the weight of the sash during opening and closing.
BALANCE 1 A device in a hung window that allows the sash to be adjusted to any position between fully open and fully closed. Originally, balances were weights attached to the top corners of the sash and draped over a pulley on either jamb. The weights and the friction of the pulleys "balanced" the weight of the sash. Balances normally are placed in pairs for each sash, one at each jamb. A heavier window may use two balances on each jamb. (See BLOCK AND FRICTION BALANCE, SPIRAL BALANCE, or TACKLE BALANCE)
BALANCE ROD 1 Same as Spiral Balance.
BALANCE TOOL 1 A hook-like tool used for adjusting spiral balances.
Balustroid 4 A variety of baluster glass with an elongated stem, current in England between about 1725 and 1760. 
Bandwurmglas (German, "tapeworm glass") 4 A variety of Stangenglas decorated with a notched trail wound spirally, like a worm, around the wall. Glasses of this type were made in Germany between the 15th and 17th centuries
Bar 4 A single piece of glass formed by fusing several canes or rods. A bar can be cut into numerous slices, all with the same design, to be used as inlays or appliqués, or in making mosaic glass. 
Barilla 4 (1) A plant, Salsola soda, which grows extensively on seashores in Spain, Sicily, and the Canary Islands; hence (2) an impure alkali made by burning plants of this and related species, formerly used in the manufacture of soda, soap, and glass. 
Batch 4 The mixture of raw materials (often silica, soda or potash, and lime) that is melted in a pot or tank to make glass. Cullet is added to help the melting process. 
Battledore 4 A glassworker's tool in the form of a square wooden paddle with a handle. Battledores are used to smooth the bottoms of vessels and other objects. 
BAY 1 A combination of three window units mulled together with the end units offset at a 45 degree angle. The center unit, which is parallel to the wall, can be a mulled window of two or more units.
Bay window 3 An arrangement of three or more individual window units, attached so as to project from the building at various angles. In a three-unit bay, the center section is normally fixed, with the end panels operable as single-hung or casement windows.
Bead 3 A wood strip against which a swinging sash closes, as in a casement window. Also, a finishing trim at the sides and top of the frame to hold the sash, as in a fixed sash or a double-hung window. Also referred to as bead stop.
Bear jar 4 A 19th-century American pressed glass jar in the form of a bear, probably for bear grease. 
Berkemeyer (German) 4 A type of drinking glass, similar to a Römer, but with a funnel-shaped mouth. It was made in Germany and the Low Countries in the 16th and 17th centuries. 
Biedermeier style 4 A style of decorative art favored by the German middle class between about 1820 and 1840. The name is derived from two fictional bourgeois characters, Biedermann and Bummelmeier, in the satirical verses of Ludwig Eichrodt. During the period in which the Biedermeier style was popular, glassmaking revived in Bohemia, where new kinds of glass such as Lithyalin and elaborate flashed, wheel-engraved, and enameled glass were produced for middle-class consumers. 
Bird fountain 4 A flameworked centerpiece or mantel ornament consisting of a tall fountain with two birds perched on the rim, and two or more shorter pedestals, each with a bird on the top. The birds have tails made of glass fibers. Bird fountains were made in England in the mid-19th century. 
Bitters bottle 4 A bottle for bitters, alcoholic beverages flavored with bitter herbs. Bitters, sold as medicine rather than as liquor (and for this reason, taxed more leniently), were immensely popular in America in the second half of the 19th century. 
Blackbody 3 The ideal, perfect emitter and absorber of thermal radiation. It emits radiant energy at each wavelength at the maximum rate possible as a consequence of its temperature, and absorbs all incident radiance.
Blank  4 Any cooled glass object that requires further forming or decoration to be finished. 
Blankschnitt (German, "polished cut") 4 A style of engraved decoration in which the relief effect is enhanced by polishing the ground part of the intaglio. Blankschnitt decoration is frequently found on glasses engraved in the German city of Nuremberg in the 17th and 18th centuries. 
Bleeding glass 4 See Cupping glass. 
Blobbing 4 The technique of decorating hot glass by dropping onto the surface blobs of molten glass, usually of a different color or colors. 
Block 4 A block of wood hollowed out to form a hemispherical recess. After it has been dipped in water to reduce charring and to create a "cushion" of steam, the block is used to form the gather into a sphere, prior to inflation. 
BLOCK AND TACKLE BALANC 1 A type of balance that employs a block and tackle apparatus and coiled spring. This type balance allows the sash to be easily removed from the window frame. A block and tackle balance can normally carry a heavier load than a spiral or friction balance. (See BALANCE)
BLOCK MODULAR 1 A method of sizing Awning windows for concrete block construction. Dimensions are based on full or half block sizes.
Blowing 4 The technique of forming an object by inflating a gob of molten glass gathered on the end of a blowpipe. The gaffer blows through the tube, slightly inflating the gob, which is then manipulated into the required form by swinging it, rolling it on a marver, or shaping it with tools or in a mold; it is then inflated to the desired size. 
Blown three-mold glass 4 Glassware made in America between about 1815 and 1835 that was blown in a full-size mold that (despite the popular name) consisted of between two and five pieces. 
Blowpipe 4 An iron or steel tube, usually about five feet long, for blowing glass. Blowpipes have a mouthpiece at one end and are usually fitted at the other end with a metal ring that helps to retain a gather. 
Borsella (Italian) 4 A tonglike tool used for shaping glass. The borsella puntata has a pattern on the jaws, which was impressed on the glass. 
Bottle glass 4 A common, naturally colored, dark greenish or brownish glass. The color is characteristic of glass that includes traces of iron found in the natural silica used as the major ingredient. Sometimes, additional iron, in the form of iron oxide (or other materials), is added to darken the color. 
Bottom rail 3 The bottom horizontal member of a window sash.
BOW 1 A combination of two or more windows mulled together with each window offset at a small angle (usually between 10 and 20 degrees). A horizontal cross section would resemble an archer's bow. Bow window units normally consist of four to six individual hung windows or picture windows or a combination of both types.
Bow window 3 A rounded bay window that projects from the wall in an arc shape, commonly consisting of five sashes.
Brick molding 3 A standard milled wood trim piece that covers the gap between the window frame and masonry.
Brilliant-cut glass 4 Objects with elaborate, deeply cut patterns that usually cover the entire surface and are highly polished. In the United States, the vogue for brilliant-cut glass lasted from about 1880 to 1915. 
Broad glass 4 See Cylinder glass 
Broken-swirl ribbing 4 Mold-blown decoration that has two sets of ribs. This is made by blowing the gather in a vertically ribbed dip mold, extracting and twisting it to produce a swirled effect, and then redipping it in the same or another dip mold to create a second set of ribs. 
Bubble 4 A pocket of gas trapped in glass during manufacture. The term is used for both bubbles introduced intentionally (also known as air traps or beads) and bubbles trapped accidentally during the melting process. Very small bubbles are known as seeds. 
BUCK DIMENSION 1 The height or width a window will finish to on the inside of the structure.
Burmese glass 4 A type of translucent pink-shading-to-yellow Art Glass made by the Mount Washington Glass Company in New Bedford, Massachusetts, between 1885 and about 1895. 
BUMPER 1 A soft vinyl or rubber cushion that prevents the moving panel of a sliding glass door from striking the jamb on the fixed panel side of the door.
BYPASS DOOR 1 A sliding glass door style whereby the door panels pass around each other on separate tracks.

Cable 4 A pattern resembling the twisted strands of a rope. 
Cage cup 4 An ancient Roman vessel decorated by undercutting so that the surface decoration stands free of the body of the glass, supported by struts. The vessel appears, therefore, to be enclosed in an openwork cage. Cage cups are sometimes known as diatreta or vasa diatreta. 
Calcedonio (Italian, "chalcedony") 4 Glass marbled with brown, blue, green, and yellow swirls in imitation of chalcedony and other banded semiprecious stones. Calcedonio was first made in Venice in the late 15th century. 
CALL OUT SIZE (C.O.S.) 1 The nominal size of a window or door. In other words the "name" of the size. For instance, a window that is 3 feet wide and 4 feet high would have a call out size of 3040.
CAM LOCK 1 A pivoting type latch usually attached by a screw or rivet to the top rail of a single hung sash or the centermost side rail of a sliding window sash. The latch locks to the meeting rail, some type of keeper, or strike plate attached to the meeting rail.
Came 4 A grooved strip of lead or (rarely) another metal, generally with an H-shaped cross section, used to join separate parts of glass windows. 
Cameo glass 4 Glass of one layer covered, usually by casing, with one or more layers of contrasting color(s). The outer layers are acid-etched, carved, cut, or engraved to produce a design that stands out from the background. The first cameo glasses were made by the ancient Romans. The genre was revived in England a nd, to a lesser extent, in America in the late 19th century. 
Candelabrum 4 A candle holder or lamp with several arms or branches
Candlestick 4 A stand with a socket or spike for one candle.
Cane 4 A thin, monochrome rod, or a composite rod consisting of groups of rods of different colors, which are bundled together and fused to form a polychrome design that is visible when seen in cross section. See Bar, Millefiori, and Rod. 
Cántaro (Spanish) 4 A drinking vessel shaped like a closed pitcher, with a ring handle at the center and two spouts, a short one for filling and pouring, and a longer one through which the beverage can be poured into the drinker's mouth. 
Carnival glass 4 Inexpensive pressed glass with vivid gold, orange, and purple iridescence, made in the United States between about 1895 and 1924. It is so called because it was frequently offered as fairground prizes. 
Carving 4 The removal of glass from the surface of an object by means of hand-held tools. 
Casement 3 A window sash that swings open on side hinges: in-swinging are French in origin; out-swinging are from England.
Casing 3 Exposed molding or framing around a window or door, on either the inside or outside, to cover the space between the window frame or jamb and the wall.
Casing 4 The application of a layer of glass over a layer of contrasting color. The gaffer either gathers one layer over another gather, or inflates a gob of hot glass inside a preformed blank of another color. The two components adhere and are inflated together (perhaps with frequent reheating) until they have the desired form. Sometimes, the upper layer is carved, cut, or acid-etched to produce cameo glass. 
Casting 4 The generic name for a wide variety of techniques used to form glass in a mold. 
Castor 4 A small vessel with a perforated top from which one casts or sprinkles sugar or condiments such as pepper. A castor set is a matching group of castors, which, together with cruets, form a condiment set. 
Caulking 3 A mastic compound for filling joints and sealing cracks to prevent leakage of water and air, commonly made of silicone, bituminous, acrylic, or rubber-based material.
CAULKING 1 A soft semi liquid material used to seal cracks around a window and doorframe adjacent to the wall opening. Normally, this is applied from a tube in a caulking gun.
Celery handle 4 A handle with vertical ribbing like a celery stalk. 
Celery vase 4 A tall, narrow vase used at the table for holding celery. 
CENTER JAMB 1 The same as Lockstile.
CERTIFICATION 1 A document that certifies a window or door has been tested and has met certain requirements of strength, safety, air and water infiltration, and resistance to forced entry. Qualified testing labs issue certifications after testing or witnessing the test of a manufacturers product.
CFM 3 Cubic Feet per Minute.
Chalk glass 4 A colorless glass containing chalk, developed in Bohemia in the late 17th century. Vessels of thick chalk glass were often elaborately engraved. 
CHANNEL GLAZING 1 A method of glazing that entails a soft vinyl or rubber gasket-like material folded over the edges of the glass and then fitted inside a channel opening in the sash frame members. It is most commonly used in sliding glass doors. Also known as marine or wrap around glazing.
Chandelier (French, "candlestick") 4 A lighting fixture suspended from the ceiling, with two or more arms bearing lights (originally, candles) or two or more pendent lights. Many chandeliers have faceted lead glass arms, candle cups, shafts, and prisms, which reflect the light and sparkle like tiny mirrors. 
Chair 4 (1) The bench used by the gaffer while forming a glass object. Traditionally, this is a wide bench with arms, on which the gaffer rests the blowpipe with its parison of molten glass and rolls it backward and forward so that the parison retains its symmetrical shape during the forming process. (2) The team of glassworkers who assist the gaffer. 
Check rail 3 The bottom horizontal member of the upper sash and the top horizontal member of the lower sash which meet at the middle of a double-hung window.
Chimney 4 A glass tube, open at both ends, used to shield the flame of an oil lamp, to trap soot, and to increase the draft. 
Cinerary urn 4 A vessel for cremated human remains. In the Roman period, cremation was a widely used method of disposing of the dead, whose ashes were sometimes placed in glass cinerary urns. 
CIRCLE 1 A fixed lite window in the shape of a whole circle
CIRCLE TOP 1 A fixed lite window whereby the head of the window is formed into a full radius half circle. This curved head is either attached to the jambs of a window or to a sill section that can then be attached to a horizontal head of a standard window. Circle top units are occasionally used alone.
Clamp 4 A tool sometimes used instead of a pontil to hold the closed end (usually the bottom) of a partly formed glass vessel while the open end (usually the mouth) is being shaped. See also Gadget. 
Clapper 4 A tool consisting of two rectangular pieces of wood joined at one end by a leather hinge. There is an aperture in one of the pieces of wood, and this holds the stem of a goblet or wineglass while it is being made. The clapper is used to squeeze a blob of glass in order to form the foot. 
Claw beaker 4 A beaker decorated with claw- or trunklike protrusions made by applying blobs of hot glass that melted the parts of the wall to which they were attached. The blobs were then blown outward and manipulated to resemble hollow claws. Claw beakers were made in Europe between the fifth and seventh centuries A.D. Similar decoration was made in Germany in the 16th century. 
CLERESTORY 1 A window in the upper part of a lofty room, usually out of reach from the floor. These windows can be fixed or operating and an extension device is used for operating clerestory windows.
Clerestory 3 A window in the upper part of a lofty room that admits light to the center of the room.
Clichy rose 4 A slice of a cane depicting an open rose. Canes of this type were frequently used in paperweights made at the Clichy factory in France in the 19th century. 
CLOSED POCKET DOOR 1 A sliding glass door style whereby the door panels stack up inside a wall.
Clutha glass 4 A type of glass with air traps and specks of aventurine, patented in the 1890s by James Couper, Christopher Dresser, and George Walton. 
Cluthra glass 4 A type of glass developed in the 1920s by Frederick Carder (1863-1963) at Steuben Glass Works in Corning, New York. 
COLONIAL LITE 1 Windows with small rectangular panes or divided lites and designated as a 12-lite, 16-lite, and so on.
Cold colors 4 Pigments applied as decoration to glass by cold painting. 
Cold painting 4 The technique of decorating an object by applying paint such as artists use on other materials. This is in contrast to enameling, in which powdered glasses of various colors are fused to the surface by heating. See also Enamel. 
Cold working 4 The collective term for the many techniques (such as copper-wheel engraving) used to alter or decorate glass when it is cold. 
Collar 4  (1) A band of applied glass around the rim of a vessel. On bottles, the collar is used to secure the cork. (2) A threaded metal ring around the font of a lamp, used to attach a screw-in burner. 
Colored glass 4 Glass that is colored by (1) impurities in the basic ingredients in the batch or (2) techniques of coloring glass by one of three main processes: (a) using a dissolved metal oxide to impart a color throughout, (b) forming a dispersion of some substance in a colloidal state, and (c) suspending particles of pigments to form opaque colors. 
Coil base 4 A trail or thread of glass drawn out to form a ring or conical foot on which the vessel stands. 
Coin weight 4 The term popularly applied to Islamic coin-shaped weights or tokens, most of which were made in Egypt between the eighth and 12th centuries. 
Combed decoration 4 A wavy, festooned, feathery, or zigzag pattern of decoration in two or more colors, produced by applying threads of opaque glass of a color different from that of the molten glass body. The threads are rolled into the glass body by marvering, after which they are combed or dragged to achieve the desired effect. 
Commedia dell'arte figures (Italian) 4 Figures representing 16 characters in Italian commedia dell'arte, a theatrical genre that was especially popular in the 17th and 18th centuries. Flameworkers made models of these figures, often copying illustrations in Lelio Riccoboni's Histoire du théâtre italien (1728–1731) 
COMMERCIAL WINDOW 1 A window used in commercial buildings, which are normally heavier than residential windows and often anodized.
COMMODITY 1 A Florida window industry method of determining standard window opening sizes.
Composite frame 3 A frame consisting of two or more materials for example, an interior wood element with an exterior fiberglass element.
Compote 4 A dish, usually with a stem and a base, and sometimes with a cover, for serving compote (fruits cooked in syrup) or a smaller dish of similar form used for individual servings. 
Concentric paperweight  4 A type of paperweight in which the slices of cane are arranged in concentric circles. 
CONDENSATION 1 A condition caused by warm moist air coming into contact with a colder object with moisture appearing on the colder surface. A large difference in the temperature of either side of a window and humid air present on the warmer side will cause condensation to appear.
Condensation 3 The deposit of water vapor from the air on any cold surface whose temperature is below the dew point, such as a cold window glass or frame that is exposed to humid indoor air.
Conduction 3 Heat transfer through a solid material by contact of one molecule to the next. Heat flows from a higher-temperature area to a lower-temperature one.
Convection 3 A heat transfer process involving motion in a fluid (such as air) caused by the difference in density of the fluid and the action of gravity. Convection affects heat transfer from the glass surface to room air, and between two panes of glass.
Copper-wheel engraving  4 A technique of decorating the surface of an object. Copper disks (wheels) of various sizes and rim profiles are rotated on a spindle. An abrasive such as Carborundum® (in the past, emery was frequently used), mixed with oil, is applied to the edge of the wheel. The wheel presses the abrasive against the glass so that it removes the surface by grinding. 
Cord 4 Accidental colorless streaks in glass caused by local differences in refractive indexes. Cord is often produced by poor mixing of batch. 
Core 4 The form to which molten glass is applied in order to make a core-formed vessel. In pre-Roman times, the core is thought to have been made of animal dung mixed with clay. 
Core forming 4 The technique of forming a vessel by trailing or gathering molten glass around a core supported by a rod. After forming, the object is removed from the rod and annealed. After annealing, the core is removed by scraping. 
CORNER KEY 1 A metal or plastic device used to secure the corners of a sash, frame, spacer bar, or screen section. The device is generally an "L" shaped part that fits inside mitered ends of the perimeter parts. The corner key can be crimped (staked) in place or screws can be inserted. The corner key makes a rigid joint possible. (See CORNER LOCK)
CORNER LOCK 1 The same as Corner Key.
C.O.S. 1 Same as Call Out Size and Nominal Size.
Cowhorn 4 The large end of a mosaic glass cane that is shaped like the tapering horn of a cow. 
CRF (Condensation Resistance Factor) 1 A number assigned to a tested window that determines how much moisture might condense on its inner surfaces. The testing is done in a chamber with controllable different temperatures on each side of the window. 
CRF 3 Condensation Resistance Factor. An indication of a window's ability to resist condensation. The higher the CRF, the less likely condensation is to occur. Based on AAMA standard.
Cracking off 4 The process of detaching a glass object from a blowpipe or pontil. 
Crackle glass 4 See Ice glass. 
Crimper 4 A tool used for decorating objects by giving them a crimped or wavy edge. 
Cristallo (Italian, "crystal") 4 A term first used in Venice in the 14th century to describe glass that resembles colorless rock crystal. Most Venetian cristallo, however, has a gray or brownish tint. 
Crizzling, crisseling 4 A chemical instability in glass caused by an imbalance in the ingredients of the batch, particularly an excess of alkali or a deficiency of stabilizer (usually lime). The instability of the glass results in an attack by atmospheric moisture, which produces a network of cracks in the surface. Crizzling can be slowed or perhaps even halted, but it cannot at present be reversed. 
Crown glass 4 Sheet glass made by blowing a parison, cutting it open, and rotating it rapidly, with repeated reheating, until the centrifugal force has caused it to become a flat disk. After annealing, the disk is cut into panes of the required shape and size. "Bull's eye" panes come from the centers of the disks and preserve the thickened area where the parison attached to the pontil. 
Crown weight 4 A hollow paperweight that incorporates thin white or colored filigree canes arranged vertically on the sides and drawn together at the top. 
Cruet 4 A small, ewerlike vessel, usually with a lip or spout, a handle, and a stopper, for serving condiments at the table. 
Crystal 4 A popular term for colorless lead glass which has a high refractive index and consequently is particularly brilliant. Today, the word is often used to describe any fine glass tableware. 
Cullet 4 (1) Raw glass or pieces of broken glass from a cooled melt; (2) scrap glass intended for recycling. 
Cup plate 4 A small plate on which users set their tea or coffee cup while drinking from the saucer. Between about 1825 and about 1865, it was fashionable to drink from saucers, and cups were placed on cup plates to avoid staining the tablecloth. 
Cupping glass 4 A small cup in which a partial vacuum is created for cupping. Cupping is the technique of drawing blood to the surface of the body, usually for bloodletting. 
Custard glass 4 A vessel for an individual serving of custard, a sweetened mixture of milk and eggs, which may be baked, boiled or frozen. 
Cutting 4 The technique whereby glass is removed from the surface of an object by grinding it with a rotating wheel made of stone, wood, or metal, and an abrasive suspended in liquid. See also copper-wheel engraving, carving, and wheel engraving. 
Cylinder glass 4 Window glass made by inflating a large gather and swinging it until it forms a cylinder. The cylinder is then detached from the blowpipe, and both ends are removed with shears. Next, the cylinder is cut lengthwise, reheated, and either tooled or allowed to slump until it assumes the form of a flat sheet. After annealing, the sheet is cut into panes. 
CYLINDER LOCK 1 A type of adjustable pin lock, cylindrical in shape, used in sliding glass doors and storm doors for security.

Daumenglas (German, "thumb glass") 4 A large cylindrical or barrel-shaped forest glass beaker with circular indentations for the user's fingers and thumbs. Daumengläser were made in Germany and the Netherlands in the 16th and 17th centuries. 
Decanter 4 A decorative bottle with a stopper, used for serving wines and spirits. 
Decolorizer 4 A substance (such as manganese dioxide or cerium oxide) used to remove or offset the greenish or brownish color in glass that results from (1) iron impurities in the batch or (2) iron or other impurities in the pot or elsewhere in the production process. 
Degree day 3 A unit that represents a one-degree Fahrenheit deviation from some fixed reference point (usually 65° F) in the mean, daily outdoor temperature. See also heating degree day.
Deposition Process 2 A form of physical vapor deposition (PVD) often used for deposition of metal films. Film is drawn through a tank containing metal ingots where a vacuum is created by reducing the pressure in the tank, which is then flooded with argon gas and the ingots are heated. The heat causes the metal to give up particles that migrate to the film's surface.
Depression glass 4 Inexpensive, machine-pressed American glassware made between about 1920 and 1950. 
Desiccant 3 An extremely porous crystalline substance used to absorb moisture from within the sealed air space of an insulating glass unit.
Dewpoint 3 The temperature at which water vapor in air will condense at a given state of humidity and pressure.
Devitrification 4  (1) The process whereby glass becomes partly crystallized as it cools (usually too slowly) from the molten state; (2) the crystals formed by this process. Devitrification may also occur on the surface as a result of unsuccessful annealing or accidental heating to a high temperature. It is not caused by chemical reaction between glass and its environment, which is known as weathering. 
Diamond air trap 4 Decoration consisting of bubbles of air trapped in the glass in a diamond-shaped pattern. This is achieved by blowing a gather of glass into a mold with projections of the desired design, withdrawing it, and covering it with a second gather, which traps pockets of air in the indentations. This technique was patented by W. H., B. & J. Richardson of England in 1857. 
Diamond-point engraving 4 The technique of decorating glass by scratching the surface with a diamond, introduced by the Venetians in the 16th century and carried to some of its greatest artistic heights in the Netherlands during the 17th century. See Stippling. 
Diatreta 4 A term used by Frederick Carder (1863-1963) to describe openwork objects, which he made by lost wax casting. 
DIVIDED LIGHT 1 A pattern of muntin bars using horizontal and vertical members to form a "tic tac toe" design on a light of glass. Originally, these crossed muntins divided a single glazed light into smaller pieces (called true colonial). Insulated glass can have the muntin bars placed between the panes of glass (called internal muntins) or attached as a grid on the inner side of the structure, but not outside the insulated glass light itself (called external muntins). Divided light windows are sometimes referred to Colonial Lite, "Cut Up" windows or True Colonial.
Divided light 3 A window with a number of smaller panes of glass separated and held in place by muntins.
Diatretum, vas diatretum (Latin) 4 A term frequently used to refer to a cage cup. The plural form is vasa diatreta. 
Dichroic glass 4 Glass that is one color when seen by reflected light and another color when light shines through it. This is sometimes due to the presence of minute quantities of colloidal gold. 
Dip mold 4 A cylindrical, one-piece mold that is open at the top so that the gather can be dipped into it and then inflated. See also Optic mold. 
DOE-2.1E 3 A building-simulation computer program used to calculate total annual energy use.
DOGHOUSE WINDOW 1 A fixed-lite window with a horizontal sill, vertical jambs and a peaked head that resembles the front view of a common doghouse. Also known as a pentagon or a double rake head.
DOOR 1 A movable device used to close off the entrance to a structure, room, or covered enclosure, typically consisting of a panel of glass, wood or metal. It slides horizontally or swings on hinges.
DOUBLE 1 Two windows mulled side by side to form one unit. Also known as a twin window.
DOUBLE HUNG 1 A type of window with two vertically moving sashes, with each sash employing balances. (See BALANCE and HUNG)
Double-hung window 3 A window consisting of two sashes operating in a rectangular frame, in which both the upper and lower halves can be slid up and down. A counterbalance mechanism usually holds the sash in place.
Double glazing 3 In general, two thicknesses of glass separated by an air space within an opening to improve insulation against heat transfer and/or sound transmission. In factory-made double glazing units, the air between the glass sheets is thoroughly dried and the space is sealed airtight, eliminating possible condensation and providing superior insulating properties.
DOUBLE STRENGTH GLASS 1 Glass that is approximately 1/8” (3mm) thick. (See DSB, SINGLE STRENGTH GLASS, SSB)
Double-strength glass 3 Sheet glass between 0.115" and 0.133" (3­3.38 mm) thick.
Drip 3 A projecting fin or a groove at the outer edge of a sill, soffit, or other projecting member in a wall designed to interrupt the flow of water downward over the wall or inward across the soffit.
DROP IN GLAZING 1 A type of glazing that attaches directly to the glazing leg in the sash and frame members using glazing compounds or tape and glazing bead.
DSB 1 This symbol represents Double Strength sheet glass, which is 1/8" (3mm) in thickness. The B specifies “B quality” glass that at one time was a lesser grade than “A quality”. Improvements in glass manufacturing are now such that B quality is of very good strength and clarity. The term “A quality” is not used today.
Dyed Film 2 Window film that uses either a submersion process or a dyed adhesive process to deposit dye onto its surface to achieve the qualities and look of tinted film.

Edge effects 3 Two-dimensional heat transfer at the edge of a glazing unit due to the thermal properties of spacers and sealants.
EGRESS 1 The act of leaving an enclosed space. In the window industry, the term refers to the dimensions of the net clear opening of a window or door (the horizontal clear distance, vertical clear distance and the net clear opening are established by local building codes). The reason for establishing minimum egress dimensions is to insure that a person attempting to leave a building in an emergency situation will have room to maneuver. Also, proper egress will allow a firefighter to enter a home while wearing emergency equipment. In 2001, the minimum egress dimensions required by most codes are 20" horizontally, 24" vertically, 5.0 square feet net clear opening for first floor applications and 5.7 square feet net clear opening for second floor applications. Some areas of the country use different dimensions.
Egyptian blue  4 A synthetic material, copper calcium tetrasilicate, with a distinctive blue color. In antiquity, Egyptian blue was made by heating together silica, lime, and a copper-containing ingredient. It is often confused with faience and misleadingly called frit. 
Electrochromics 3 Glazing with optical properties that can be varied continuously from clear to dark with a low-voltage signal. Ions are reversibly injected or removed from an electrochromic material, causing the optical density to change.
Electromagnetic spectrum 3 Radiant energy over a broad range of wavelengths.
ELEVATION 1 The front view or views from the street as shown in the blueprint plans of a home. 
ELONGATED OCTAGON 1 A fixed lite window shaped in the form of an extended octagon.
Emergency exit window 3 Fire escape window (egress window) large enough for a person to climb out. In U.S. building codes, each bedroom must be provided with an exit window. The exact width, area, and height from the floor are specified in the building codes.
Emissivity 2 The measure of surface's ability to absorb or reflect far-infrared radiation. The lower the emissivity rating, the better the insulating qualities of the window film/glass system.
Emittance 3 The ratio of the radiant flux emitted by a specimen to that emitted by a blackbody at the same temperature and under the same conditions.
Enamel  4 A vitreous substance made of finely powdered glass colored with metallic oxide and suspended in an oily medium for ease of application with a brush. The medium burns away during firing in a low-temperature muffle kiln (about 965°-1300° F or 500°-700° C). Sometimes, several firings are required to fuse the different colors of an elaborately enameled object. 
Engraving 4 The process of cutting into the surface of an annealed glass object either by holding it against a rotating copper wheel fed with an abrasive or by scratching it, usually with a diamond. See also carving, cutting, stippling. 
ENTRY DOOR 1 A door, usually swinging or hung, that leads to the outside of a structure
Evacuated glazing 3 Insulating glazing composed of two glass layers, hermetically sealed at the edges, with a vacuum between to eliminate convection and conduction. A spacer system is needed to keep the panes from touching.
EXFILTRATION 1 The escape of air from a structure. The opposite of infiltration.
EXPOSED POCKET DOOR 1 A sliding glass door style whereby the door panels stack up onto the exterior of a wall.
EXTERIOR TRACK SLIDING GLASS DOOR 1 A sliding glass track style that is used for exterior applications and is available in various riser heights to protect against water infiltration.
Exterior stop 3 The removable glazing bead that holds the glass or panel in place when it is on the exterior side of the light or panel, in contrast to an interior stop located on the interior side of the glass.
EXTRUSION 1 The act of forcing a material through a die to form a part that has a cross section similar to the opening in the die. In the window industry, the resulting part obtained from the extrusion process makes up the structural members of a window or door. This part is usually aluminum or a vinyl. Vinyl parts are sometimes called "Profiles" and aluminum parts are sometimes called "Shapes" or "Extruded Shapes". As an example, when toothpaste is squeezed from a tube, the portion of paste squeezed out is an extrusion that has a cross section similar to the opening of the tube. If the tube has a round opening then the paste is cylindrical, but if the tube were to have a square opening, the paste would have a cross section with four straight sides.
Extrusion 3 The process of producing vinyl or aluminum shapes by forcing heated material through an orifice in a die. Also, any item made by this process.
EYEBROW 1 A fixed lite window with a gently arched head similar in appearance to one's eyebrow and has jambs of equal height.
Eyebrow windows 3 Low, inward-opening windows with a bottom-hinged sash. These attic windows built into the top molding of the house are sometimes called "lie-on-your-stomach" or "slave" windows. Often found on Greek Revival and Italianate houses.
EYELID 1 A fixed lite window with a gently arched head similar in appearance to one's eyelid. Similar to an eyebrow but the eyelid has no jambs.

Faceting 4 The process of grinding and polishing an object to give the surface a pattern of planes or facets. 
Façon de Venise (French, "style of Venice") 4 Glass made in imitation of Venetian products, at centers other than Venice itself. Façon de Venise glass was popular in many parts of Europe in the 16th and 17th centuries. 
Faience 4 A fired silica body containing small amounts of alkali, and varying greatly in hardness depending on the degree of sintering. It is covered with a glaze, which may also be present interstitially among the quartz grains within the body. The term "glassy faience" is often used to describe a faience in which the reactions have proceeded to such an extent that the glass phase defines the visual appearance of the material. 
Fake 4 A genuine object that has been altered or "improved" for the purpose of enhancing its value (not to be confused with a forgery). 
Favrile glass  4 A type of glass with an iridescent surface, patented by Louis Comfort Tiffany (1848–1933) in 1894. 
Fanlight 3 A half-circle window over a door or window, with radiating bars. Also called circle top transom.
Fenestration 3 The placement of window openings in a building wall, one of the important elements in controlling the exterior appearance of a building. Also, a window, door, or skylight and its associated interior or exterior elements, such as shades or blinds.
FER (Forced Entry Resistant) 1 A requirement of some codes that a locked window or door meet certified tests that determine if the product is resistant to entry from the outside using normal hand tools. Also, that any attempt to enter the locked door or window will show definite signs of the attempt. FER does not mean "burglar proof". Any structure can be entered with enough time, privacy and effort. 
Fiberglass 3 A composite material made by embedding glass fibers in a polymer matrix. May be used as a diffusing material in sheet form, or as a standard sash and frame element.
FIELD GLAZE 1 The glazing of a window after the frame has been installed in the structure. (See OPEN)
Finial 4 An ornamental knob. 
FIN SEAL 1 A trade name for a type of wool pile weather strip employing a strip of rigid plastic material running lengthwise, greatly reducing air infiltration.
FINISH 1 The preparation of the surface of an aluminum window that adds color or protection to the aluminum. Mill finish is the unfinished surface of aluminum just as it comes from the mill. Painted finishes are factory applied to the aluminum extrusions before the assembly of the final product. Painted finishes come in many colors most commonly bronze (or brown), white, or beige. In rare instances and by special order, gray, blue, red or any color can been used. Anodized finishes are sometimes used, but mainly in architectural applications because of the expense. Clear lacquer finishes are called for on mill finish surfaces for protection during construction. (See ANODIZE)
Finishing 4 The process of completing the forming or decoration of an object. Finishing may take the form of manipulating the object into its final shape while it is hot, of cracking off prior to annealing, or of grinding, cutting or polishing. 
Fire clay  4 Clay capable of being subjected to a high temperature without fusing, and therefore used for making crucibles in which glass batches are melted. Fire clay is rich in silica, but contains only small amounts of lime, iron, and alkali. 
Fire polishing 4 The reintroduction of a vessel into the glory hole to melt the surface and eliminate superficial irregularities or dullness. 
Firing 4 The process of (1) heating the batch in order to fuse it into glass by exposing it to the required temperature in a crucible or pot, (2) reheating unfinished glassware while it is being worked, or (3) reheating glassware in a muffle to fuse enamel or guilding. The melting of the batch may require a temperature of about 2040°–2575°F (1300°–1500°C), whereas the muffle kiln may require a temperature of only about 960°–1320°F (500°–700°C). 
Firing glass 4 A drinking glass with a bowl, a short stem, and a thick foot. On ceremonial occasions, firing glasses were rapped loudly on the table, making a noise that resembled a volley of gunfire. 
FIXED FRAME 1 A type of window with no operating parts, just simply, a frame and glass. Also, referred to as a Picture Window.
Fixed light 3 A pane of glass installed directly into non-operating framing members; also, the opening or space for a pane of glass in a non-operating frame.
FIXED LITE 1 A light of glass in a window or door that does not operate. It is usually the upper light of a single hung window. Sometimes the same as a picture window or fixed frame window.
FIXED PANEL 1 The non-operating panel of a sliding glass door.
Fixed panel 3 An inoperable panel of a sliding glass door or slider window.
Fixed window 3 A window with no operating sashes.
FIXED VENT 1 The non-operating sash, lite, or panel of a sliding window or door.
Flameworking 4 The technique of forming objects from rods and tubes of glass that, when heated in a flame, become soft and can be manipulated into the desired shape. Formerly, the source of the flame was an oil or paraffin lamp used in conjunction with foot-powered bellows; today, gas-fueled torches are used. 
FLANGE 1 A term used for masonry construction, it is a window frame with a head, jamb, and sill exterior perimeter leg _” longer than the interior perimeter leg.
Flashing 3 Sheet metal or other material applied to seal and protect the joints formed by different materials or surfaces.
Flashing 4 The application of a very thin layer of glass of one color over a layer of contrasting color. This is achieved by dipping a gather of hot glass into a crucible containing hot glass of the second color. The upper layer may be too thin to be worked in relief. "Flashing" is sometimes used (erroneously) as a synonym for casing. 
FLAT GRID 1 A rectangular shaped grid applied to the exterior side of a light.
Float glass 3 Glass formed by a process of floating the material on a bed of molten metal. It produces a high-optical-quality glass with parallel surfaces, without polishing and grinding.
FLOATING MUNTIN 1 A type of muntin that actually separates lights of glass in a window but is not attached to the frame itself. (See MUNTIN and DIVIDED LIGHT)
Flux  4 A substance that facilitates fusion (by lowering the melting temperature of another substance). For example, a flux is added to the batch in order to facilitate the fusing of the silica. Fluxes are also added to enamels in order to lower their fusion point to below that of the glass body to which they are to be applied. Potash and soda are fluxes. 
Fogging 3 A deposit of contamination left on the inside surface of a sealed insulating glass unit due to extremes of temperatures or failed seals.
Folded rim 4 A rim that has been folded to double its thickness and thereby increase its strength. 
Foot-ring 4 A separate ring of glass added to the base after the body of the vessel is formed. 
Forest glass 4 Glass made in the rural glasshouses of central and northern Europe in the late Middle Ages and the early modern period. Most forest glass was fluxed with potash derived from the wood with which the furnaces were fueled. It is green because of iron impurities in the sand from which it was made. The German term for forest glass is Waldglas. 
Former mold 4 A mold with the same shape as the desired object, usually a vessel. Flat glass blanks are made into vessels by sagging them over or into former molds. 
Founding 4 The initial phase of melting batch. For many modern glasses, the materials must be heated to a temperature of about 2450° F (1400° C). This is followed by a maturing period, during which the molten glass cools to a working temperature of about 2000° F (1100° C). 
FRAME 1 The outer members of a window or door. The frame includes the head, sill or threshold, the two jambs and the meeting rail of a window.
Frame 3 The fixed frame of a window which holds the sash or casement as well as hardware.
Free-blown (off-hand blown) glass 4 Glassware shaped solely by inflation with a blowpipe and manipulation with tools. 
FRICTION BALANCE 1 A type of balance that holds a sash in position by friction. The friction balance usually has an adjustment device. This is a low cost substitute for other types of balances and is often not accepted by many building codes. 
Frigger 4 An object made by a glassworker on his own time. Most friggers were made from the molten glass that remained in the pot at the end of the day. Such glass was considered to be a worker's perquisite. 
Frit, fritting 4 Batch ingredients such as sand and alkali, which have been partially reacted by heating, but not completely melted. After cooling, frit is ground to a powder and melted. Fritting (or sintering) is the process of making frit. 
Frosting 4 (1) A matte finish produced by exposing the object to fumes of hydrofluoric acid; (2) a network of small surface cracks caused by weathering. 
Furnace 4 An enclosed structure for the production and application of heat. In glassmaking, furnaces are used for melting the batch, maintaining pots of glass in a molten state, and reheating partly formed objects at the glory hole. 
Fusing 4 (1) The process of founding or melting the batch; (2) heating pieces of glass in a kiln or furnace until they bond (see casting and kiln forming); (3) heating enameled glasses until the enamel bonds with the surface of the object. 

Gadget 4 A metal rod with a spring clip that grips the foot of a vessel and so avoids the use of a pontil. Gadgets were first used in the late 18th century.  
Gadroon 4 A flutelike decorative motif, usually short in proportion to its width, that often approaches an oval form. 
Gas fill 3 A gas other than air, usually argon or krypton, placed between window or skylight glazing panes to reduce the U-factor by suppressing conduction and convection.
GASKET 1 Any of a large class of materials with highly variable mechanical and optical properties that solidify from the molten state without crystallization. They are typically based on silicon dioxide (sand), boric oxide, aluminum oxide, or phosphorus pentoxide, generally transparent or translucent, and are regarded physically as supercooled liquids rather than true solids. (From The American Heritage Dictionary)
Gather 4  (Noun) A mass of molten glass (sometimes called a gob) collected on the end of a blowpipe, pontil, or gathering iron; (verb) to collect molted glass on the end of a tool. 
Gathering iron 4 A long, thin rod used to gather molted glass. 
Gilding 4 The process of decorating glass by the use of gold leaf, gold paint, or gold dust. The gilding may be applied with size, or amalgamated with mercury. It is then usually fixed to the glass by heat. Gold leaf may be picked up on a gather of hot glass. 
GLASS 1 Any of a large class of materials with highly variable mechanical and optical properties that solidify from the molten state without crystallization. They are typically based on silicon dioxide (sand), boric oxide, aluminum oxide, or phosphorus pentoxide, generally transparent or translucent, and are regarded physically as supercooled liquids rather than true solids. (From The American Heritage Dictionary)
Glass 3 An inorganic transparent material composed of silica (sand), soda (sodium carbonate), and lime (calcium carbonate) with small quantities of alumina, boric, or magnesia oxides.
Glass 4 A homogeneous material with a random, liquidlike (non-crystalline) molecular structure. The manufacturing process requires that the raw materials be heated to a temperature sufficient to produce a completely fused melt, which, when cooled rapidly, becomes rigid without crystallizing. 
GLAZE 1 The act of installing glass or other glazing materials, such as plastic, into a window or door. (See REGLAZE)
Glazier 4 A craftsman who paints and/or assembles glass windows. 
Glazing 3 The glass or plastic panes in a window, door, or skylight.
GLAZING BEAD 1 A part used to trim around the edge of the glass after it has been installed in a window. Glazing bead can be made from vinyl, aluminum extrusion, or aluminum formed sheet. The glazing bead either is screwed in place or snapped into grooves in the sash member.
Glazing bead 3 A molding or stop around the inside of a window frame to hold the glass in place.
GLAZING COMPOUND 1 A pliable material placed between the glazing leg of a window or door and the glass around its edges to seal the unit against air and water infiltration and to help hold the glass in place.
GLAZING LEG 1 A flat surface in frame members parallel with the glass, to which the glass is affixed using a glazing compound and glazing bead.
GLAZING TAPE 1 A tape with adhesive on both sides used to glaze glass to the glazing leg of a sash member.
Glory hole 4 A hole in the side of a glass furnace, used to reheat glass that is being fashioned or decorated. The glory hole is also used to fire-polish cast glass to remove imperfections remaining from the mold. 
Gold glass 4 The term applied to several types of Hellenistic and ancient Roman glass objects decorated with designs cut and/or engraved in gold leaf, which is sandwiched between two fused layers of glass. Hellenistic gold glass was made by sandwiching the decoration between two closely fitting, cast, ground, and polished vessels, which were then fused. Many Roman gold glasses apparently were made by applying the gold leaf to the surface of an object, reheating it, and inflating a parison against the decorated surface. 
Gold ruby 4 Deep red glass colored by the addition of gold chloride to the batch. The method of making gold ruby glass was perfected by Johann Kunckel (about 1630-1703) in Potsdam shortly before 1679. 
Gold-band mosaic glass  4 A variety of ribbon glass, which includes canes composed of bands of gold foil laminated between two layers of colorless glass. Gold-band mosaic glass was made in parts of the Roman world in the first century A.D. 
Graal glass 4 A type of decorative glass developed by Orrefors of Sweden in 1916. The design is carved, engraved, or etched on a parison of colored glass, which is then reheated, encased in a thick layer of transparent glass of a different color, and inflated. 
GREEN HOUSE WINDOW (Garden Vu) 1 A five-sided window unit that protrudes out from the exterior wall of a structure. The unit acts as, and somewhat resembles, a greenhouse. The unit contains shelves and has ventilating apparatus.
Greenhouse window 3 A three-dimensional window that projects from the exterior wall and usually has glazing on all sides except the bottom, which serves as a shelf.
Grisaille (French gris, "gray")  4  (1) A method of decorative painting in monochrome gray especially, but not exclusively, on stained glass windows; (2) brown paint made from iron oxide, which, when fused to the glass, defines details in a stained glass window. 
GRID 1 A removable muntin pattern applied to a single light of glass. Whereas a true divided light actually separates the pieces of glass, a grid only appears to divide the glass into smaller lights. A grid is applied to the exterior side of glass.
Grozing  4 The process of breaking away the edge of a glass object with a grozing iron or pliers in order to shape it. 
GULFSTREAM SCREEN 1 A sliding glass door screen framed with panel extrusion material

HANDING 1 A term describing the way a sliding glass door opens or on which side of a hung (swinging) door the hinges and locks are located. (See OX, OXO, XO) 
Hand cooler  4 A solid, egg-shaped piece of glass or decorative stone, said to have been used to cool the palms of a woman's hands. 
Hand press  4 A tool shaped like a pair of pliers, with flat jaws containing molds. Hand presses were used extensively in Europe for making chandelier parts. Later, they were introduced in the United States for pressing stoppers and bases. 
Head track 3 The track provided at the head of a sliding glass door. Also, the head member incorporating the track.
HEAD 1 The top or uppermost horizontal member or of the frame of a window or door. Sometimes called a header.
Header 3 The upper horizontal member of a window frame. Also called head.
HEADER 1 The structural member in a building that spans the upper portion of a window or door opening. (See HEAD)
HEAT-STRENGTHENED GLASS 1 This glass is produced in much the same way as tempered glass, but with lower levels of surface compression, 3500-7500 psi.  The final product is two times stronger than annealed glass.  The break pattern varies with level of surface compression with lower levels having a break pattern similar to annealed glass.  And higher levels resulting in patterns similar to tempered glass.
Heat-strengthened glass 3 Glass that is reheated, after forming, to just below melting point, and then cooled, forming a compressed surface that increases its strength beyond that of typical annealed glass.
HEAT ABSORBING GLASS 1 Types of glass containing minute particles of metal that absorbs solar heat and is primarily used in commerical applications.
Heat-absorbing glass 3 Window glass containing chemicals (with gray, bronze, or blue-green tint) which absorb light and heat radiation, and reduce glare and brightness. See also Tinted glass.
HEAT LOSS 1 Heat escaping from a structure.
Heat loss 3 The transfer of heat from inside to outside by means of conduction, convection, and radiation through all surfaces of a house.
HEAT GAIN 1 Heat entering a structure.
Heat gain 3 The transfer of heat from outside to inside by means of conduction, convection, and radiation through all surfaces of a house.
Heating degree day 3 Term used by heating and cooling engineers to relate the typical climate conditions of different areas to the amount of energy needed to heat and cool a building. The base temperature is 65 degrees Fahrenheit. A heating degree day is counted for each degree below 65 degrees reached by the average daily outside temperatures in the winter. For example, if on a given winter day, the daily average temperature outdoors is 30 degrees, then there are 35 degrees below the base temperature of 65 degrees. Thus, there are 35 heating degree days for that day.
HEXAGON 1 A six-sided fixed lite window with opposite sides parallel but not necessarily with all sides of equal length
HINGED WINDOW 1 A operable window that is hinged on one side and is primarily used to meet egress requirements.
Hinged windows 3 Windows (casement, awning, and hopper) with an operating sash that has hinges on one side. See also Projected window.
HOLLOW SHAPE 1 A class of extrusion with a cross section enclosing an open area. A tube is a hollow shape. It is a stronger and more rigid part than a solid shape. In other words, a channel extrusion of the same height, width and wall thickness will not be as strong as a square tube. Hollow shapes are generally more expensive than solid shapes and are used mostly in meeting rails, sash heads, and sash sill or bottom rails.
Hookah (Arabic huqqa)  4 A bell-shaped or globular bottle that is part of the water pipe used in the Islamic world and India for smoking tobacco. The smoke passes through the water-filled bottle before the smoker inhales it. 
Hopper 3 Window with sash hinged at the bottom.
HORIZONTAL ROLLER (Horizontal Slider) 1 A common type of window with a horizontal rolling or sliding sash. (See PICTURE SLIDER, PICTURE WINDOW SLIDER, and SLIDER) 
Horizontal slider 3 A window with a movable panel that slides horizontally.
Hot-formed, hot-worked 4 The generic term for glass that is manipulated while it is hot. 
Humidor 4 A closed container in which the air is kept appropriately humidified (for example for keeping cigars). 
HUNG 1 A type of window with one or more vertically moving sashes that employs balances. (See BALANCE, DOUBLE HUNG, SINGLE HUNG, and TRIPLE HUNG) Also refers to a type of door with hinges on one jamb. A hung door is a swinging door as opposed to a sliding door.
Hybrid Film 2 Window film that is made up of a combination of metallic film and dyed film to achieve the qualities and look of tinted film.
Hydrofluoric acid 4 A highly corrosive acid that attacks silicates such as glass. Pure hydrofluoric acid dissolves glass, leaving a brilliant, acid-polished surface. 

ICC 3 International Code Council. A national organization that publishes model codes for adoption by states and other agencies. Codes include the International Building Code (IBC) and the International Energy Conservation Code (IECC).
IECC 3 International Energy Conservation Code published by the ICC. The successor to the Model Energy Code, which is cited in the 1992 U.S. Energy Policy Act (EPAct) as the baseline for residential Energy Codes in the United States.
Ice glass 4 A decorative effect that causes the surface of the glass to resemble cracked ice. This is achieved by plunging a parison of hot glass into cold water and withdrawing it quickly. The thermal shock creates fissures in the surface, and these impart a frosted appearance after the parison has been reheated to allow the forming process to continue. 
IMPACT RESISTANT GLASS 1 A dual lamination of glass and plastic that is designed to resist penetration from flying debris.
Inclusions 4 A collective term for bubbles, metal and glass particles, and other foreign materials that have been added to the glass for decorative effects. 
Infrared Light 2 A form of electromagnetic radiation with wavelengths between 0. 7 micrometres (0.0007 millimetres) and 1 millimetre. These wavelengths are longer than those of visible light, but shorter than those of microwaves. (The prefix 'infra' means 'below; infrared refers to radiation below the frequency of red light.) Infrared light is primarily thermal radiation, and we can think of this as being heat. 
INFILTRATION 1 The air or moisture that leaks through the cracks of a window or door from outside of a structure. A tight window (low infiltration rate) will prevent the loss of energy more than any other single factor. (See EXFILTRATION)
Infiltration 3 See air leakage.
Infrared radiation 3 Invisible, electromagnetic radiation beyond red light on the spectrum, with wavelengths greater than 0.7 microns.
Inlay 4 Any object embedded in the surface of a larger object. See also Marquetry. 
INSULATED GLASS 1 A light of glass made up of two sheets of glass, a spacer bar filled with a desiccant material placed between the two sheets at the perimeter, and a sealant applied around the entire perimeter of the assembly. This assembly creates an envelope of dead air which when used in a window or door, greatly reduces the passage of heat through the glass, thereby producing a savings at an increased material cost.
Insulating glass 3 Two or more pieces of glass spaced apart and hermetically sealed to form a single glazed unit with one or more air spaces in between. Also called double glazing.
Insulated shutters 3 Insulating panels that cover a window opening to reduce heat loss.
Insulating value 3 See U-factor.
Insulation 3 Construction materials used for protection from noise, heat, cold or fire.
Intaglio (Italian, "engraving")  4 A method of engraving whereby the ornamentation is cut into the object and lies below the surface plane. The German name for this technique is Tiefschnitt. 
Intarsia glass (from Italian intarsiatura, "marquetry") 4 A type of glass developed by Frederick Carder (1863-1963) about 1920. A design of colored glass was applied to a parison of a different color, then flashed with a second parison of the same color as the first. 
INTEGRAL FIN WINDOW 1 A window with a nailing fin, it is primarily used in wood frame construction. (See NAILING FIN)
Intercalaire (French, "inserted") 4 The process of applying two layers of decoration, the first being covered with a skin of glass that serves as the surface of teh second. 
INTERIOR TRACK SLIDING GL 1 Also known as a flush track, it has no riser to protect against water infiltration.
INTERLOCK 1 A design feature of a window or door that provides a hooking action between the sash rail and the mid-rail, sill or jamb. This action reduces air infiltration and increases security to the unit.
Interlocker 3 An upright frame member of a panel in a sliding glass door which engages with a corresponding member in an adjacent panel when the door is closed. Also called interlocking stile.
INTERMEDIATE JAMB 1 A vertical member in a window or door, with three or more panels, that is located in the central area of the unit, and acts as a jamb in receiving the moving panel.
INTERNAL MUNTINS 1 Muntin bars located between the sheets of glass in an insulated glass unit. These muntins are purely decorative and only give the appearance of a divided light window. (See MUNTINS)
Iridescence  4 The rainbowlike effect that changes according to the angle from which it is viewed or the angle of incidence of the source of light. On ancient glass, iridescence is caused by interference effects of light reflected from several layers of weathering products. On certain 19th- and 20th-century glasses, iridescence is a deliberate effect achieved by the introduction of metallic substances into the batch or by spraying the surface with stannous chloride or lead chloride and reheating it in a reducing atmosphere. 

Jacks  4 A tool with two metal arms joined at one end by a handle. The distance between the arms is controlled by the glassworker, who uses jacks, or pucellas, to form the mouths of open vessels. 
Jacobite glass  4 A 17th-century English drinking vessel used for toasting Prince Charles Edward Stuart ("Bonnie Prince Charlie"). The Jacobites were supporters of the exiled King James II, who abdicated in 1698, and of his descendents James Edward Stuart (the "Old Pretender") and his son Charles Edward Stuart (the "Young Pretender"). Before the defeat of the Young Pretender in 1746, Jacobite glasses were usually engraved with the English rose, representing the Crown, and an optimistic motto such as "Redeat" ( Latin, "May he return"). After 1746, glasses at first bore cryptic symbols and messages, but later secrecy was abandoned. See also Williamite glass. 
Jalousie 3 Window made up of horizontally-mounted louvered glass slats that abut each other tightly when closed and rotate outward when cranked open.
JAMB 1 The sides or outermost vertical side members of a window or door frame. (See INTERMEDIATE JAMB)
Jelly glass  4 A vessel for serving jelly and other desserts. Jelly glasses usually have an inverted conical bowl, a square stem, and a foot. They may have one or two handles. 

KD 1 Abbreviation for Knocked Down or not assembled. All of the parts of a window or door are ready for assembly.
KEEPER 1 A part of a locking device attached to the frame or mid-rail of a window or door that accepts the mating part of the lock. (See STRIKE)
Kick 4 An oven used to process a substance by burning, drying, or heating. In contemporary glassworking kilns are used to fuse enamel and for kiln forming processes such as slumping. 
Kiln forming 4 The process of fusing or shaping glass (usually in or over a mold) by heating it in a kiln. See Slumping. 
Knop 4 A component, usually spherical or oblate, of the stem of a drinking glass, hollow or solid, used either singly or in groups, and placed contiguously or with intermediate spacing; also the finial at the center of a lid. 
Krypton 3 An inert, nontoxic gas used in insulating windows to reduce heat transfer.
KWH 3 KiloWatt Hour. Unit of energy or work equal to one thousand watt-hours.

Lacy-pattern glass  4 Nineteenth-century pressed glass whose patterns included extensive stippling to produce a bright, lacelike effect that conceals wrinkles caused when the cold plunger of the pressing machine came into contact with the hot glass. 
LAMINATED GLASS 1 A type of safety glass composed of a plastic film with adhesive sandwiched between two sheets of glass. This type of glass is used in windows, doors, skylights and automobile windshields.
Laminated glass 3 Two or more sheets of glass with an inner layer of transparent plastic to which the glass adheres if broken. Used for safety glazing and sound reduction.
LATCH 1 The locking device on a door or window.
Lathe cutting 4 The technique whereby a blank in the general shape of the finished object is mounted on a lathe and (in antiquity) turned with the aid of a bow or handled wheel, while a tool fed with abrasive is held against the surface in order to polish it, modify the profile, or cut it. 
Latticino, latticinio (from Italian latte, "milk") 4 A term formerly used to describe filigrana glass. It has now been abandoned. 
Lattimo (from Italian latte, "milk") 4 Opaque white glass, usually opacified by tin oxide or arsenic. 
Laub- und Bandelwerk (German, "leaf and strapwork") 4 A type of interlaced ornament consisting of foliage and strapwork, popular in Germany and Bohemia in the 18th century. 
Lead glass 4 Glass that contains a high percentage of lead oxide (at least 20 percent of the batch). In modern times, glass of this type was first used by George Ravenscroft (1632-1683) about 1676. It is relatively soft, and its refractive index gives a brilliance that may be exploited by covering the surface with polished wheel-cut facets. 
Lift 3 Handle for raising the lower sash in a double-hung window. Also called sash lift. 
LIGHT 1 A piece of glass in a window or door. (See LITE)
Light 3 A window; a pane of glass within a window. Double-hung windows are designated by the number of lights in upper and lower sash, as in six-over-six. Also spelled informally lite.
Light-to-solar-gain ratio 3 A measure of the ability of a glazing to provide light without excessive solar heat gain. It is the ratio between the visible transmittance of a glazing and its solar heat gain coefficient. Abbreviated LSG.
LIGHT AREA 1 The area of a window or door, expressed in square feet, that allows exterior light to enter a structure.
LIGHT (LITE) PATTERN 1 The arrangement of muntin bars in a window. • A single or double hung window with one horizontal muntin in each the upper and lower sash would have a light pattern designated as 2/2, which is called "two over two". A similar window with two horizontal muntins and three vertical muntins in the upper sash, and one horizontal muntin and three vertical muntins in the lower sash would be designated 12/8 which is called "twelve over eight". A similar window with no muntins in either sash is a 1/1 called "one over one".  • A horizontal sliding window or door with no muntins would be designated 1 x 1, which is called "one by one". Windows or doors with muntins are designated by the number of individual lights in each sash or panel. For instance a window with one vertical muntin and two horizontal muntins in each sash would be designated as 6 x 6 or called "six by six".  • A non-operating window (Picture Window) with no muntins is designated as 1 light. A Picture Window with no two vertical and three horizontal muntins would be either a 12 light unit or sometimes a 3 x 4 unit. Windows with diagonal muntins are referred to as "Diamond Light" units. (See DIVIDED LIGHT or COLONIAL LITE)
LINTEL 1 A structural member, usually a steel angle or channel, designed to support the wall or siding above a window or door.
Lintel 3 A horizontal member above a window or door opening that supports the structure above.
Lipper 4 A glassworker's tool made of wood in the shape of a cone with a handle. It is used to form the lip at the mouth of a vessel. 
Liquid crystal glazing 3 Glass in which the optical properties of a thin layer of liquid crystals are controlled by an electrical current, changing from a clear to a diffusing state.
LITE 1 Another term for a pane of glass used in a window. Frequently spelled "lite" in the industry literature to avoid confusion with light as in "visible light".
LOCK 1 The device on a window or door that secures it in a closed position. This can either be a keyed lock, a sliding bolt, a spring-loaded catch or a pivoting part that engages a keeper or strike.
LOCKSTILE 1 The vertical rail in a sliding glass door panel containing the lock.
Long-wave infrared radiation 3 Invisible radiation, beyond red light on the electromagnetic spectrum (above 3.5 micro meters), emitted by warm surfaces such as a body at room temperature radiating to a cold window surface.
Lost wax casting 4 A technique adapted from metalworking. The object to be fashioned in glass is modeled in wax and encased in clay or plaster that is heated. The wax melts and is released through vents or "gates," also made of wax, which have been attached to the obj ect before heating; the clay or plaster dries and becomes rigid. This then serves as a mold, into which molten or powdered glass is introduced through the gates. If powdered glass is used, the mold is heated in order to fuse the contents. After annealing the mold is removed from the object, which is then finished by grinding, fire polishing, or acid etching. 
Lotus-bud beaker 4 A first-century A.D. Roman mold-blown vessel decorated with rows of oval or almond-shaped bulges. Although the bulges are usually described as lotus buds, they are probably derived from representations of knotholes in the club of the mythical hero Hercules. 
Low-conductance spacers 3 An assembly of materials designed to reduce heat transfer at the edge of an insulating window. Spacers are placed between the panes of glass in a double- or triple-glazed window.
LOW-E GLASS 1 Stands for low emissivity glass, it is a glass type with a transparent coating applied to its’ surface that helps keeps your house cooler in the summer and warmer in the winter.
Low-emittance (Low-E) coating 3 Microscopically thin, virtually invisible, metal or metallic oxide layers deposited on a window or skylight glazing surface primarily to reduce the U-factor by suppressing radiative heat flow. A typical type of low-E coating is transparent to the solar spectrum (visible light and short-wave infrared radiation) and reflective of long-wave infrared radiation.
Luster 4 (1) A shiny metallic effect made by painting the surface with metallic oxides that have been dissolved in acid and mixed with an oily medium. Firing in oxygen-free conditions at a temperature of about 1150° F (600° C) causes the metal to deposit in a thin film that, after cleaning, has a distinctive shiny surface. (2) A glass lighting device, such as a candelabrum or candlestick, decorated with hanging prismatic drops. 

Marquetry  4 A decorating technique whereby pieces of hot glass are applied to still molten glass and marvered into the surface, creating an inlaid effect. After the glass is cooled, it is possible to further emphasize these areas by carving and engraving. See also Inlay. 
MARINE GLAZING 1 The term comes about because this type of glazing is often used in boats and other marine applications. (Same as CHANNEL GLAZING or WRAP AROUND GLAZING)
Marver (French marbre, "marble") 4 A smooth, flat surface, on which softened glass is rolled when attached to the blowpipe or pontil in order to smooth it or to consolidate applied decoration. 
Masonic glass  4 A glass object decorated with emblems or inscriptions associated with Freemasons. 
MASONRY OPENING 1 The opening size in a concrete block wall where a window will be installed. It is measured block to block.
Matsu-no-ke  4 A design developed by Frederick Carder (1863-1963) and registered by Stevens & Williams of England in 1884. Its distinctive feature is the presence of applied and tooled sprays of blossoms influenced by Japanese designs. Carder also used the design at Steuben Glass Works in Corning, New York, in the 1920s. 
Matte finish  4 A non-shiny finish made by grinding, sandblasting, or exposing the surface to fumes of hydroflouric acid. See Frosting. 
MEETING RAIL 1 A cross member of a window or sliding glass door where the sash comes together with an interlocking action. (Same as MID-RAIL)
Meeting rail 3 The part of a sliding glass door, a sliding window, or a hung window where two panels meet and create a weather barrier.
Melt  4 The fluid glass produced by melting a batch of raw materials. 
Metal-clad windows 3 Exterior wood parts covered with extruded aluminum or other metal, with a factory-applied finish to deter the elements.
Metal  4 A term frequently used as a synonym for glass. It is misleading because glass is not a metallic substance, and its use is discouraged. 
Metal oxide 4 The oxide of a metal. Oxides may be used to color glass and enamel, or to produce lustered or iridized surfaces. The resultant color depends primarily on the oxide used, but it can be affected by the composition of the glass itself and the presence or absence of oxygen in the furnace. See Iridescence and Luster. 
Mercury bottle 4 A type of ancient Roman mold-blown bottle with a tall body of square or polygonal cross-section, the underside of which bears a representation in relief of the god Mercury. Mercury, the messenger of the gods, was associated with commerce. 
Metallic Film 2 Window film that uses either a sputtering process or deposition process to deposit metals onto its surface to achieve the qualities and look of tinted film
Mezza-forma (Italian, "half-mold") 4 A term applied to the process of making vertical ribs on the lower part of a blown glass object by inflating the parison in a dip mold. 
Micron 3 One millionth (10-6) of a metric meter.
MID-RAIL 1 Same as Meeting Rail.
Mil 3 One thousandth of an inch, or 0.0254 millimeter.
MILL FINISH 1 Uncoated aluminum as it comes from the mill. (See FINISH)
MODULAR 1 The national industry standard method of determining standard window opening sizes.
Model Energy Code (MEC) 3 The Model Energy Code is cited in the 1992 U.S. Energy Policy Act (EPAct) as the baseline for residential Energy Codes in the United States. It has been succeeded by the International Energy Conservation Code (IECC) published by the International Code Council (ICC).
Mold 4 A form, normally made of wood or metal, used for shaping and/or decorating molten glass. Some molds (e.g., dip molds) impart a pattern to the parison, which is then withdrawn, and blown and tooled to the desired shape and size; other molds are used to give the object its final form, with or without decoration. 
Mold blowing 4 Inflating a parison of hot glass in a mold. The glass is forced against the inner surfaces of the mold and assumes its shape, together with any decoration that it bears. 
Mold pressing 4 Forcing hot glass into an open or multi-part mold by means of a plunger. 
Mosaic 4 A surface decorated with many small, adjoining pieces of varicolored materials such as stone or glass. 
Mosaic glass 4 Objects made from preformed elements placed in a mold and heated until they fuse. The term "mosaic glass" is preferable to "millefiori," except in the case of Venetian or façon de Venise glass. 
Moss Agate glass 4 A variety of Art Glass developed by John Northwood (1836-1902) and Frederick Carder (1863-1963) in England in the late 1880s. It was made by casing a parison of soda-lime glass with colorless lead glass, then covering it with a powdered glass of several colors, and casing it again with lead glass. The object was shaped and reheated, after which cold water was injected into it, causing the soda-lime glass to crackle. 
MOVING VENT 1 The operating sash of a window or the operating panel of a sliding glass door
Muffle 4 A fire-clay box in which glass (or porcelain) objects are enclosed, when placed in the muffle kiln, to protect them from the flames and smoke while being subjected to low-temperature firing, especially in the process of firing enamels and gilding at temperatures of about 950-1320°F (500-700°C). 
Muffle kiln 4 A low-temperature kiln for refiring glass to fuse enamel, fix gilding, and produce luster. See Kiln. 
MULL 1 A shorten version for Mullion. Also used as a verb, as in "to mull” two windows together.
MULLION 1 A horizontal or vertical member that holds together two adjacent lights of glass or windows or sections of curtain wall. 
Mullion 3 A major structural vertical or horizontal member between window units or sliding glass doors.
MUNTIN 1 A part of a window that divides a light of glass into smaller sections. A true muntin (the first "n" in "muntin" is silent) actually separates the pieces of glass. Insulated glass usually uses internal muntins, which only appear to divide the glass into smaller lights. Muntins are normally either vertical or horizontal although diagonal and curved are also used. (See DIVIDED LIGHT)
Muntin 3 A secondary framing member (horizontal, vertical, or diagonal) to hold the window panes in the sash. This term is often confused with mullion.
Muntin grilles 3 Wood, plastic, or metal grids designed for a single-light sash to give the appearance of muntins in a multilight sash, but removable for ease in cleaning the window.

NFRC 3 National Fenestration Rating Council.
NAILING FIN 1 A protruding portion of the frame of a window or door that allows the unit to be secured in a structure by driving nails (or screws) through it and into the framing of the structure. (See INTEGRAL FIN WINDOW)
Nailing fin 3 An integral extension of a window or patio door frame which generally laps over the conventional stud construction and through which nails are driven to secure the frame in place.
Newel 4 Usually, the post at the head and the foot of a stair, supporting the handrail. In the 19th century, glass finials were sometimes used to adorn newel posts. 
Nipt-diamond-waies 4 The technique of pincering adjacent vertical ribs to form a diamond pattern. "Nipt-diamond-waies" was the term used by the English glassmaker George Ravenscroft (1632-1683) in a 1677 advertisement for his new lead glass. 
NOMINAL SIZE 1 The name of the size of a door. (See CALL OUT SIZE)
NUVIEW 1 A window style where the fixed lite is larger than the operable lite.

O 1 The designation for a door panel or window vent that is fixed in place.
OBSCURE GLASS 1 A type of glass with one surface roughened in such a way as to reduce visibility but yet allow light to enter a structure. This type of glass is often used in bathroom windows. Also referred to as translucent glass.
Obscure glass 3 Any textured glass (frosted, etched, fluted, ground, etc.) used for privacy, light diffusion, or decorative effects.
Obsidian  4 A volcanic mineral that was the first form of natural glass used by humans. It is usually black, but it can also be very dark red or green; its splinters are often transparent or translucent. 
OCTAGON 1 A type of fixed window with eight sides whereby opposite sides are parallel but not necessarily equal in length. 
OFFSET 1 A measurement in a bow or bay window specifying the distance from the outer edge of the floor plate to the nailing fin line of the window unit furthermost from the floor plate.
ONE OVER ONE (1/1) 1 A hung window with no muntins in either sash. (See LIGHT PATTERN)
Opal glass  4 Glass that resembles an opal, being translucent and white, with a grayish or bluish tint. 
Opalescent glass  4  (1) A type of late 19th-century Art Glass, made by covering a gather of colored glass with a layer of colorless glass containing bone ash and arsenic. The parison was inflated in a mold to produce raised decoration. When the parison was reheated, the raised areas became opalescent. (2) A type of glass resembling the iridescent gemstone opal, which was developled by Frederick Carder (1863-1963) at Steuben Glass Works in Corning, New York. 
Openwork  4 Work that is perforated. Openwork in glass objects may be made by creating a network of trails, by casting (see Diatreta), or by cutting (see Cage cup). 
OPEN 1 A window frame with no glass installed. Sometimes an open frame is installed in a structure and glazed later. This is done to prevent construction damage to special glass that is very expensive or difficult to replace. (See FIELD GLAZING)
OPERABLE WINDOW 1 A window that can be opened for ventilation.
Operable window 3 Window that can be opened for ventilation.
Operator 3 Crank-operated device for opening and closing casement or jalousie windows.
Optic mold  4 An open mold with a patterned interior in which a parison of glass is inserted, then inflated to decorate the surface. 
Optical glass  4 Glass of extreme purity and with well-defined optical properties, which was originally created for making lenses and prisms. 
OVAL 1 A fixed lite window in the shape of an oval.
Overlay  4 A layer of glass that covers a layer of different color, often as the result of casing or flashing. 
Overblow  4 A by-product of the mold-blowing process, this is the portion of the parison that remains outside the mold. The overblow, or moil, is usually removed by cracking off. 
OX 1 The designation for a two-panel sliding window or door with the right hand panel, as viewed from the exterior of the structure, the movable panel.
OXO 1 The designation for a three-panel sliding window or door with the center panel operable and the two end units fixed (non-moving).
OXXO 1 The designation of a four-panel sliding glass door with the two center panels operable. One sliding panel must lock against the other. This type door gives a larger opening.

Pallet 4 A glassworker's tool consisting of a square piece of wood or metal and a handle. It is used to flatten the bases of vessels. 
PAINTED FINISH 1 After aluminum extruded shapes have been anodized (See ANODIZE), a coating of paint is applied, usually electrostatically and then oven dried. This coating is available in many colors (most commonly dark brown, white or tan) and helps protect the metal, as well as, add beauty to a window or door.
PANE 1 A lite of glass.
Pane 3 One of the compartments of a door or window consisting of a single sheet of glass in a frame; also, a sheet of glass.
Pane  4 A piece of flat sheet glass used for glazing windows
PANEL 1 A part of a door, or sometimes a window, composed of a light of glass and surrounded by a frame. Panels can be fixed in place or movable. It is similar to a sash or vent.
Panel 3 A major component of a sliding glass door, consisting of a light of glass in a frame installed within the main (or outer) frame of the door. A panel may be sliding or fixed.
Panning 3 In replacement window work, the outside aluminum trim that can extend around the perimeter of the window opening; used to cover up the old window material. Panning can be installed in the opening before the window, or can be attached directly to the window before installation.
Pâte de verre (French, "glass paste") 4 A material produced by grinding glass into a fine powder, adding a binder to create a paste, and adding a fluxing medium to facilitate melting. The paste is brushed or tamped into the mold, dried, and fused by firing. After annealing, the object is removed from the mold and finished. 
Particle dispersed glazing 3 Glazing in which the orientation of small particles between two sheets of glass is controlled electrically, thus changing its optical properties.
Parting stop 3 A narrow strip, either integral or applied, that holds a sash or panel in position in a frame.
PASS-THRU WINDOW 1 A single-hung window without a sill that is used for counter-top applications
PATIO DOOR 1 A sliding glass door used in a patio area.
PATIO DOOR SCREEN 1 A rolling screen for a patio sliding glass door.
Peachblow glass 4 A type of Art Glass made by several American factories in the late 19th century. It resembled the peach bloom glaze on the 17th- to 18-century Chinese porcelain such as the celebrated Morgan Vase. Most Peachblow glass had a surface that shaded from opaque cream to pink or red, sometimes over opaque white. Similar glass was made in England by Thomas Webb & Sons and Stevens & Williams. 
Peak load 3 The maximum thermal load to be provided by a heating or cooling system in a house.
Pegging 4 The process of pricking molten glass with a tool that leaves small, air-filled hollows. When the glass is covered with a second gather, the hollows become air traps. 
Photochromics 3 Glazing with the optical properties that change in response to the amount of incident light.
Pick-up decoration 4 A technique whereby a hot parison is rolled in chips of glass, which are picked up, marvered, and inflated. 
PICTURE SLIDER 1 A horizontal sliding window with two moving sash, one each located on either side of a fixed panel to make up a three-panel window. (See PICTURE WINDOW SLIDER)
PICTURE WINDOW 1 A non-operating window consisting only of frame and glass.
Picture window 3 A large, fixed window framed so that it is usually, but not always, longer horizontally than vertically to provide a panoramic view.
Piece mold 4 A mold made of two or more parts. 
Pillar-molded glass 4 A term used by 19th-century English glassmakers to describe vessels with mold-blown vertical ribs, but no corresponding indentations on the interior. This effect was achieved by partly inflating the gather, allowing it to cool sufficiently to become somewhat rigid, and then gathering an outer layer of glass around it. The parison was then further inflated in a ribbed dip mold, which shaped the soft outer layer without affecting the inner layer. The term is frequently but incorrectly applied to ancient Roman ribbed bowls, which were made in a different manner. 
Pincers 4 A glassworker's tool used for decorating objects by pinching the glass while it is hot. 
Pivot window 3 A window with a sash that swings open or shut by revolving on pivots at either side of the sash or at top and bottom.
Plastic film 3 A thin plastic substrate, sometimes used as the inner layers in a triple- or quadruple-glazed window.
Plastics 3 Artificial substances made of organic polymers that can be extruded or molded into various shapes including window frames and sashes.
Plastic 4 Susceptible to being modeled or shaped. Glass is plastic when it is in a molten state. 
Plate glass 3 A rolled, ground, and polished product with true flat parallel plane surfaces affording excellent vision. It has been replaced by float glass.
POCKET DOOR 1 A sliding door that has the moving panels slide into (interior) or onto (exterior) a wall when opened.
Polishing 4 Smoothing the surface of an object when it is cold by holding it against a rotating wheel fed with a fine abrasive. Glass can also be polished with hand-held tools. 
Polyester Film 2 Polyesters are made from chemical substances found mainly in petroleum and are manufactured in fibers, films, and plastics. Polyester film (PETF) is a semi-crystalline film used in many applications such as videotape, high quality packaging, professional photographic printing, X-ray film, floppy disks, etc. 
Pomona 4 A type of Art Glass developed by Joseph Locke at the New England Glass Company and patented in 1885. Made of colorless glass, it was mold-blown repeatedly, partly etched and stained amber or rose, and decorated with blue and amber garlands of flowers and fruits. 
Pontil, pontil mark 4 The pontil, or punty, is a solid metal rod that is usually tipped with a wad of hot glass, then applied to the base of a vessel to hold it during manufacture. It often leaves an irregular or ring-shaped scar on the base when removed. This is called the "pontil mark." 
Potassium-lime glass 4 A form of glass containing three major compounds in varying proportions: silica (usually about 60-75 percent), potash (12-18 percent), and lime (5-12 percent). Forest glass is a common type of potassium-lime glass. 
Pressed glass 4 Glassware formed by placing a blob of molten glass in a metal mold, then pressing it with a metal plunger or "follower" to form the inside shape. The resultant piece, termed "mold-pressed," has an interior form independent of the exterior, in contrast to mold-blown glass, whose interior corresponds to the outer form. The process of pressing glass was first mechanized in the United States between 1820 and 1830. 
PRIMARY WINDOW 1 A window installed into the wall of a structure. Storm windows, which attach to or over a prime window, are called secondary windows.
Prince Rupert's drop 4 A hollow glass object, about two inches long, with a bulbous end and a narrow, curving "tail." It is made by dropping a blob of glass into cold water and leaving it there until it has cooled. The rounded end resists a blow, but because of internal stress, the tail shatters into numerous fragments if it is broken or scratched. These objects, which have aroused great curiosity, were introduced into England by Prince Rupert (1619-1682), nephew of Charles II. Samuel Pepys described them in his diary on January 13, 1662. 
Prismatic cutting 4 A decorative pattern of long, mitered grooves, cut horizontally in straight lines so that the top edges of each groove touch the edges of the adjoining grooves. Prismatic cutting is usually found on the necks of pitchers and decanters. 
PROFILE 1 The term used to designate a vinyl extrusion (See EXTRUSION or EXTRUDED SHAPE)
Projected window 3 A window fitted with one or more sashes opening on pivoted arms or hinges. Refers to casements, awnings, and hoppers.
Prunt 4 A blob of glass applied to a glass object as decoration, but also to afford a firm grip in the absence of a handle. 
PVC (Polyvinyl Chloride) 1 A material used to make vinyl window parts, weather strip and glazing bead.
Polyvinylchloride (PVC) 3 An extruded or molded plastic material used for window framing and as a thermal barrier for aluminum windows.

Quarry 4 A small, square- or diamond-shaped pane. 
QUARTER CIRCLE 1 A fixed special non-operating window shaped of one quarter of a full circle.

R-FACTOR 1 A number indicating a body's resistance to transferring heat. (See U-FACTOR)
R-value 3 A measure of the resistance of a glazing material or fenestration assembly to heat flow. It is the inverse of the U-factor (R = 1/U) and is expressed in units of hr-sq ft-°F/Btu. A high-R-value window has a greater resistance to heat flow and a higher insulating value than one with a low R-value.
Radiation 3 The transfer of heat in the form of electromagnetic waves from one separate surface to another. Energy from the sun reaches the earth by radiation, and a person's body can lose heat to a cold window or skylight surface in a similar way
RAIL 1 The outer members of a sash. (See STILE)
Rail 3 Horizontal member of a window sash.
RAISED GRID 1 A dimensional grid applied to the exterior side of a light simulating the same look of a true divided light when used with a backer. The shape resembles a modified triangle.
Raised diamond cutting 4 An allover pattern of raised four-sided diamonds of pyramidal form, each with a sharp apex, cut with a mitered wheel. It was produced by English and Irish glass cutters between about 1780 and 1825. 
Reactive glass 4 A type of glass, made by Louis Comfort Tiffany (1848-1933), that changed color when it was reheated. 
RECTANGULAR SHAPED WIN 1 A fixed lite window that can be used as a sidelite or transom. (See SIDELITE or TRANSOM)
Reflectance 2 The amount that is bent or sent back by a medium.
REFLECTANCE 1 A coefficient that indicates the capability of glass to reflect sunlight.
Reflectance 3 The ratio of reflected radiant energy to incident radiant energy.
REFLECTIVE GLASS 1 A type of glass with a mirror-like surface that reduces the transmittance of sunlight through a window.
Reflective glass 3 Window glass coated to reflect radiation striking the surface of the glass.
Refraction 3 The deflection of a light ray from a straight path when it passes at an oblique angle from one medium (such as air) to another (such as glass).
REGLAZE 1 To glaze a window or door again or to replace broken or defective glass or other glazing material in a window or door. (See GLAZE)
Relative humidity 3 The percentage of moisture in the air in relationship to the amount of moisture the air could hold at that given temperature. At 100 percent relative humidity, moisture condenses and falls as rain.
Relief Cutting 4 A type of cut glass with decoration in high relief, made by removing the background. 
REMOVABLE SASH 1 Any sash in a window that can be easily removed without tools or by a major disassembly of the window or door.
RESFEN 3 A computer program used to calculate energy use based on window selection in residential buildings.
Retrofitting 3 Adding or replacing items on existing buildings. Typical retrofit products are replacement doors and windows, insulation, storm windows, caulking, weatherstripping, vents, landscaping.
RETURN 1 A channel formed in the outer frame of a window or door that accepts sheet rock or some other wall covering. This channel allows for a neat and inexpensive way of finishing. Also the distance from the inside edge of a window or door to the inside surface of the wall into which the window or door is installed measured perpendicular to the wall.
REVEAL 1 A protrusion on the head and jambs of a window frame, parallel to the wall of the structure allowing room for final trim within the opening in the wall.
Reverse foil engraving 4 A decorative technique in which gold or silver leaf is applied to the back side of a piece of glass, engraved and protected by varnish, metal foil, or another piece of glass. See also Verre églomisé. 
Reverse painting 4 The term applied to a number of decorative techniques, all of which involve painting on the back side of the glass a design that is viewed from the front (that is, through the glass). Because of this, the painter must apply the pigments in the reverse of the normal order, beginning with the highlights and ending with the background. 
Ribbon glass 4 (1) A type of first-century A.D. Roman mosaic glass that consists of ribbonlike canes arranged in parallel rows or geometric patterns; (2) a type of vetro a reticello made in Venice and at other places where façon de Venise glass was produced. 
RIGID VINYL 1 A type of polyvinyl chloride (PVC) used as glazing bead or weather strip in a window or door. This vinyl is firmer than soft vinyl, which is also used as weather strip.
RISE 1 In a window with a curved head, the vertical distance from the uppermost point of the curve to the top of the shorter jamb, if the jambs are different heights. (See EYEBROW)
ROLLERS 1 Wheels attached to the bottom of the sash or panel of a window or door that allows it to slide easily.
Roof window 3 A fixed or operable window similar to a skylight placed in the sloping surface of a roof.
Rotary polishing 4 The process of polishing an object with tools and an abrasive, while turning it on a lathe. 
ROUGH OPENING 1 The space in the wall of a structure into which a window or door is to be installed. This space is slightly larger than the actual buck size of the window.
Rough opening 3 The opening in a wall into which a door or window is to be installed.

SAFETY GLASS 1 A type of glass designed to prevent injury if it is broken. (See LAMINATED GLASS and TEMPERED GLASS) 
Safety glass 3 A strengthened or reinforced glass that is less subject to breakage or splintering.
Sand casting, sand molding 4 A glassforming technique in which molten glass is poured or ladled into a mold of compacted sand. A roughly textured granular surface results where the glass comes into contact with the sand. 
Sandblasting 4 The process of removing glass or imparting a matte finish by bombardment with fine grains of sand that are propelled by compressed air. 
SASH 1 Normally the moving segment of a window, although sash is sometimes referred to as fixed sash. (See PANEL and VENT)
Sash 3 The portion of a window that includes the glass and the framing sections directly attached to the glass, not to be confused with the complete frame into which the sash sections are fitted.
SASH GUIDE 1 A part of the sash of a window usually made from some type of plastic, which allows the window to move freely within the frame.
SASH HEAD 1 The uppermost horizontal member of the sash.
SASH JAMB 1 The outermost vertical members of a sash. (See SIDE RAIL)
SASH SILL 1 The bottom member or rail of a sash. Also known as a lift rail.
SASH STOP 1 A device placed near the top of the jambs of a hung window to prevent the sash from striking the head of the window.
Satin glass 4 A 19th-century term for glass with a matte finish. 
SCREEN 1 A product used with a window or door, consisting of a four-sided frame surrounding a mesh of wire or plastic material used to keep out insects. The screen can be fixed in place or it can be rolled side to side as on a sliding glass door. 
Screen 3 Woven mesh of metal, plastic, or fiberglass stretched over a window opening to permit air to pass through, but not insects.
SCREEN CLOTH 1 The mesh of wire or plastic used in a screen. (See SCREEN)
SCREEN SPLINE 1 A thin strip of plastic used to hold screen cloth into a screen frame.
SCREW BOSS (Also SCREW SLOT) 1 A "C" shaped groove in an extrusion that will accept a screw parallel to the extrusion when forming a joint of two parts perpendicular to each other.
Schmelzglas (German, "enamel glass") 4 A term applied to several types of decorative glassware, including calcedonio and opaque white glass with a red overlay applied by flashing. It does not refer to glass decorated with enamel. 
Schwarzlot (German, "black lead") 4 A sepia enamel first used in painting stained glass and later applied to glass vessels, either by itself or in combination with other enamels or gold. 
Seal 4 Its many meanings include an emblem impressed on wax or some other plastic substance as evidence of ownership or authenticity. Since the 17th century, many bottles have borne stamped glass seals that identify the producer of the contents, the tavern in which they were used, or the individual for whom the contents were bottled. 
SEALANT 1 A compound used to fill and seal a joint or opening, as contrasted to a sealer, which is a liquid used to seal a porous surface. Also, the material used to seal the edges of insulated glass.
Sealant 3 A compressible plastic material used to seal any opening or junction of two parts, such as between the glass and a metal sash, commonly made of silicone, butyl tape, or polysulfide.
Seam mark 4 A slight, narrow ridge on a glass object, which indicates that it has been made by molding. The seams appear where gaps in the joints between parts of the mold have permitted molten glass to seep during formation. On well-made pieces, the seam marks are usually smoothed away by grinding or fire polishing. 
SECONDARY LOCK 1 A lock on a window or door in addition to the primary locking device. This lock is required by some building codes for additional security.
Seeds 4 Minute bubbles of gas, usually occurring in groups. 
SETTING BLOCK 1 A small block of material, usually a rubber-like product but sometimes wood, placed between the edge of insulating glass and the glazing leg to cushion the glass. These blocks are placed at the sill but sometimes at the jambs and head.
Shade screen 3 A specially fabricated screen of sheet material with small narrow louvers formed in place to intercept solar radiation striking a window; the louvers are so small that only extremely small insects can pass through. Also called sun screen. Also, an awning with fixed louvers of metal or wood.
SHADING COEFFICIENT 1 A number expressed as a percentage, indicating the amount of sunlight that passes through a piece of glass relative to another piece of glass used as a standard.
Shading Coefficient 2 The ratio of solar heat gain passing through window film to the solar heat gain that occurs under the same conditions if the window were made of clear, unshaded double strength window glass. The lower the number, the better solar shading qualities of the window film/glass system.
Shading coefficient (SC) 3 A measure of the ability of a window or skylight to transmit solar heat, relative to that ability for 1/8-inch clear, double- strength, single glass. It is being phased out in favor of the solar heat gain coefficient, and is approximately equal to the SHGC multiplied by 1.15. It is expressed as a number without units between 0 and 1. The lower a window's solar heat gain coefficient or shading coefficient, the less solar heat it transmits, and the greater is its shading ability.
SHAPE 1 The same as an Extrusion.
Shears 4 A tool used to trim excess hot glass from an object in the course of production. 
Shearings (cuttings, clippings) 4 Slivers of waste glass formed by trimming glassware during manufacture. 
Sheet glass 3 A transparent, flat glass found in older windows, now largely replaced by float glass.
Short-wave infrared radiation 3 Invisible radiation, just beyond red light on the electromagnetic spectrum (between 0.7 and 2.5 microns), emitted by hot surfaces and included in solar radiation.
SIDE RAIL 1 The same as a Sash Jamb.
SIDELITE 1 A fixed lite rectangular shaped window that is placed next to a door for ornamentation and/or to allow light to pass through.
Sidonian glass 4 A popular generic name for numerous first-century A.D. Roman mold-blown vessels. It is not known how many of these objects were actually made at Sidon, a city on the coast of Lebanon
Silica 4 Silicon dioxide, a mixture that is the main ingredient of glass. The most common form of silica used in glassmaking has always been sand. 
SILICONE 1 A plastic type material used for sealing cracks in window frames, and is used sometimes as a glazing compound.
SILL 1 The threshold or lowest horizontal member of the frame of a window or door.
Sill 3 The lowest horizontal member in a door, window, or sash frame.
Sill track 3 The track provided at the sill of a sliding glass door. Also, the sill member incorporating such a track.
Silver stain 4 A deep yellow stain made by painting the surface of the glass with silver sulfide and firing it at a relatively low temperature. 
Silvered glass 4 A type of 19th-century glassware with an allover silver appearance, made by applying a solution of silver nitrate between the walls of a double-walled vessel. The solution was introduced through a hole in the base, which was then sealed to prevent the silver from oxidizing. Silvered glass is sometimes known, mistakenly, as "mercury glass." 
Simulated divided lights 3 A window that has the appearance of a number of smaller panes of glass separated by muntins, but actually is a larger glazing unit with the muntins placed between or on the surfaces of the glass layers.
SINGLE GLAZED 1 A window or door that is glazed with a single sheet glass, as opposed to multiple glazing (insulated glass) which uses two or more sheets of glass.
Single glazing 3 Single thickness of glass in a window or door
SINGLE HUNG 1 A type of hung window with only the lower sash being operable. (See DOUBLE HUNG and TRIPLE HUNG)
Single-hung window 3 A window consisting of two sashes of glass, the top one stationary and the bottom movable.
SINGLE STRENGTH GLASS 1 Glass that is approximately 3/32” (2.5mm) thick. (SSB)
Single-strength glass 3 Glass with thickness between 0.085" and 0.100" (2.16­2.57 mm).
Size 4 In glassworking, the name applied to several glutinous materials, such as glue and resin, used to affix color or gold leaf. 
SKYLIGHT 1 A type of window installed in the roof of a structure to allow admittance of sunlight. These units can be fixed in placed or they can be of a type that opens for ventilation. The glazing, either plastic or tempered, can be a single sheet or multiple and can be clear or tinted.
Skylight (operable or pivot) 3 A roof window that gives light and ventilation.
SLIDING GLASS DOOR 1 A type of door with one or more horizontally sliding glass panels. This type of door acts as a window, as well as, a door. It is commonly used for access to patios and may be called a Patio Door.
Sliding glass door 3 A door fitted with one or more panels that move horizontally on a track and/or in grooves. Moving action is usually of rolling type (rather than sliding type). Also called gliding door, rolling glass door, and patio sliding door.
Sliding window 3 A window fitted with one or more sashes opening by sliding horizontally or vertically in grooves provided by frame members. Vertical sliders may be single- or double-hung.
SMALL VENT AWNING WIND 1 An Awning window style in which the vent(s) are thinner in height than in a standard vent. Therefore, a Standard Vent 25 Awning window has 4 vents and a Small Vent 25 Awning window has 5 vents.
Smalt 4 Colored glass, often deep blue glass colored with cobalt oxide. Smalts are finely ground to use as colorants for glass and enamel. 
Smart window 3 Generic term for windows with switchable coatings to control solar gain.
Soda 4 Sodium carbonate. Soda (or alternatively potash) is commonly used as the alkali ingredient of glass. It serves as a flux to reduce the fusion point of the silica when the batch is melted. 
Soda-lime glass  4 Historically, the most common form of glass. It contains three major compounds in varying proportions, but usually silica (about 60-75 percent), soda (12-18 percent), and lime (5-12 percent). Soda-lime glasses are relatively light, and upon heating, they remain plastic and workable over a wide range of temperatures. They lend themselves, therefore, to elaborate manipulative techniques. 
SOFT VINYL 1 A type of PVC (Polyvinyl Chloride) material used for glazing bead or weather strip in a door or window that is more flexible than rigid vinyl.
Solar control coatings 3 Thin film coatings on glass or plastic that absorb or reflect solar energy, thereby reducing solar gain.
Solar Heat Gain Coefficient 2 The ratio of total solar heat passing through a given window product relative to the solar heat incident on the projected window surface at normal solar incidence (I.E. perpendicular to the glazing surface). The lower the coefficient number for a particular window film/glass system, the better it is able to reduce heat.
SOLAR HEAT GAIN COEFFICIENT 1 The SHGC is the fraction of incident solar radiation admitted through a window and is expressed as a number between 0 and 1. The lower a window’s solar heat gain coefficient, the less solar heat it transmits.
Solar heat gain coefficient 3 The fraction of solar radiation admitted through a window or skylight, both directly transmitted, and absorbed and subsequently released inward. The solar heat gain coefficient has replaced the shading coefficient as the standard indicator of a window's shading ability. It is expressed as a number between 0 and 1. The lower a window's solar heat gain coefficient, the less solar heat it transmits, and the greater its shading ability. SHGC can be expressed in terms of the glass alone or can refer to the entire window assembly.
Solar Absorptance 2 The percent of incident solar radiation that is absorbed by the window film/glass system. The lower the number, the less solar radiation absorbed.
Solar screen 3 A sun shading device, such as screens, panels, louvers, or blinds, installed to intercept solar radiation.
Solar radiation 3 The total radiant energy from the sun, including ultraviolet and infrared wave lengths as well as visible light.
Solar Reflectance 2 The percent of incident solar radiation that is reflected by the window film/glass system. The lower the number, the less solar radiation reflected.
Solar spectrum 3 The intensity variation of sunlight across its spectral range.
Solar Transmittance 2 The percent of incident solar radiation that is transmitted through the window film/glass system. The lower the number, the less the solar radiation transmitted.
Sound Transmission Class 3 The sound transmission loss rating of a material over a selected range of sound frequencies. The higher the number, the less sound transmitted
SOLID SHAPE 1 An extrusion that has no enclosed voids, as opposed to a hollow shape. (See HOLLOW SHAPE and EXTRUSION)
SPACER BAR 1 A hollow tube with flat sides used around the perimeter of insulated glass to separate the sheets of glass and provide for a dead air space. The tube is vented to the interior of the piece of insulated glass and is normally filled with a desiccant to absorb any moisture that might have been present during the manufacture of the insulated glass. The tube is usually made of roll formed thin aluminum sheet, although other materials such as plastic are also used. The first insulated glass used wood strips. (See INSULATED GLASS)
SPECIAL WINDOW 1 A group of windows that are not listed in a manufacturers standard catalog. These windows can include shapes such as trapezoid, diamond, hexagon, triangle, circular or nonrectangular configurations. Special windows may also have nonstandard glass types, muntin bar arrangements, unusual finishes, or nonstandard locking devices.
Spectrally selective coating 3 A coated or tinted glazing with optical properties that are transparent to some wavelengths of energy and reflective to others. Typical spectrally selective coatings are transparent to visible light and reflect short-wave and long-wave infrared radiation.
Sputtering Process 2 A form of physical vapor deposition (PVD) often used for deposition of metal films. Sputtering involves knocking metal atoms off a disc of pure metal with charged, energetic, chemically inactive atoms called ions (from a plasma). The metal atoms will re-deposit and build on top of polyester film .
SQUARE 1 A fixed lite window in the shape of a square.
SSB 1 This symbol represents Single Strength “B quality” sheet glass, which is approximately 3/32" (2.5mm) thick. (See DOUBLE STRENGTH GLASS, DSB, SINGLE STRENGTH GLASS)
STACK 1 A condition where one or more windows are attached above another window or door that is to be installed in a structure. Also refers to the total thickness of an insulated glass unit.
Stained glass 4 The generic name for decorative windows made of pieces of colored glass fitted into cames and set in iron frames. Strictly speaking, the term is inaccurate because, in addition to glass colored by staining, glaziers used, and continue to use, glass colored throughout by metallic oxide, glass colored by flashing, and glass decorated with enamel. 
Staining 4 In glassworking, the process of coloring the surface of glass by the application of silver sulfide or silver chloride, which is then fired at relatively low temperature. The silver imparts a yellow, brownish yellow, or ruby-colored stain, which may be painted, engraved, or etched. 
STANDARD LIGHT (2/2, 3/2) 1 A designation for a window with horizontal but no vertical muntins, with a light pattern of either 2/2 or 3/2. (See LIGHT PATTERN)
STEP SILL 1 A condition in the sill of a door or window that employs a "step like" configuration to act as a dam against the infiltration of water.
STICK BUILT 1 A slang term for a prefab structure with a framework made of wood. 
STILE 1 Another name for the vertical side rails of a sash or a sash jamb.
Stile 3 The upright or vertical edges of a door, window, or screen.
Stippling 4 (1) The technique of tapping the surface of a glass object with a pointed tool, often with a diamond or tungsten-carbide tip. Each tap produces a mark, and the decoration is composed of many hundreds or thousands of marks. (2) On lacy-pattern pressed glass, the stippling is part of the decoration of the mold. 
STOOL 1 The part of the framing around a window located at the bottom of the window opening and either under or next to the window's sill.
Stool 3 The shelf-like board of the interior part of the window sill, against which the bottom rail of the sash closes.
Stop 3 The molding on the inside of a window frame against which the window sash closes; in the case of a double-hung window, the sash slides against the stop. Also called bead, side stop, window stop, and parting stop.
Storm windows 3 A second set of windows installed on the outside or inside of the primary windows to provide additional insulation and wind protection.
STRIKE 1 A part of a locking device into which the moving portion of the latch engages. The moving parts to the lock are usually located on the sash or panel of a window or door, while the strike is located on the jamb or meeting rail.
Striking 4 The process of reheating glass after it has cooled, in order to develop color or an opacifying agent that appears only within a limited range of temperatures. 
Studio glass 4 A term popularized in the 1960s for unique or limited-edition objects designed and made in a studio rather than a factory, often, but not necessarily, by the same person
Studio Glass Movement 4 A movement that began in the United States in the 1960s and has spread all over the world. It is characterized by the proliferation of glass artists who are not affiliated with factories, but work with hot glass in their own studios. The emergence of independent glass artists was made possible by Harvey Littleton and Dominick Labino's development in 1962 of a small furnace and easy-to-melt glass. 
Sun control film 3 A tinted or reflective film applied to the glazing surface to reduce visible, ultra-violet, or total transmission of solar radiation. Reduces solar heat gain in summer and glare. Some can be removed and reapplied with changing seasons.
Superwindow 3 A window with a very low U-factor, typically less than 0.15, achieved through the use of multiple glazings, low-E coatings, and gas fills.
SWIGGLE 1 The trade name for Tru-Seal, which is utilized in the manufacture of insulated glass.
Swirled ribbing 4 A pattern of spirialing vertical ribs made by inflating the parison in a dip mold with vertical ribs, withdrawing it, and twisting it before continuing the process of inflation. The pattern is also described as wrythen. 
Switchable glazings 3 Glazings with optical properties that can be reversibly switched from clear to dark or reflective

TAB CORNER 1 A type of joinery in a window or door frame, that uses a tab on one part that fits into a slot on the part to be joined to, and then the tab is bent over to secure it, such as awning vents.
TAB LOCK 1 A type of joint, in the corner of a sash of a window or door, that employs a protrusion on one part that fits into a groove on the other part, and tends to keep the corner square. This corner usually is also screwed together.
TAPE BALANCE 1 A type of balance using a spring retractable strip of steel that resembles a retractable steel tape measure. (See BALANCE)
Teardrop 4 A drop-shaped air bubble enclosed in glass, usually in the stem. 
TEMPERED GLASS 1 A type of safety glass that has been heat treated so when it breaks it separates into very small pieces that reducing the possibility of injury. Tempered glass is used in doors, windows located near doors, and other locations where safety is critical. Glass tempering is achieved by heating annealed glass to near it's softening point, rapidly cooling the surface and allowing the inner core to cool naturally. The result is layers of high compression at the surfaces balanced by a high-tension layer through the center of the glass making it much stronger than annealed glass. Once tempered, the glass will fracture if cut.
Tempered glass 3 Treated glass that is strengthened by reheating it to just below the melting point and then suddenly cooling it. When shattered, it breaks into small pieces. Approximately five times stronger than standard annealed glass; is required as safety glazing in patio doors, entrance doors, side lights, and other hazardous locations. It cannot be recut after tempering.
Tessera (Latin, "small square tablet or block") 4 A small piece of glass or other suitable material, used in the formation of mosaics
THERMAL BREAK 1 A type of window that employs an insulating material in the sash and frame members to reduce the flow of heat either inward or outward. The outer portion of the frame and sash are separated from the inner portion. This type of frame is mostly used in colder climates because it saves energy and reduces condensation on the inner surfaces of the window.
Thermal break 3 An element of low conductance placed between elements of higher conductance to reduce the flow of heat. Often used in aluminum windows.
Thermal expansion 3 Change in dimension of a material as a result of temperature change.
Thermal mass 3 Mass in a building (furnishings or structure) that is used to absorb solar gain during the day and release the heat as the space cools in the evening.
Thermochromics 3 Glazing with optical properties that can change in response to temperature changes.
Thermogram 3 An image of an object taken with an infrared camera that shows surface temperature variations.
Threshold 3 The member that lies at the bottom of a sliding glass door or swinging door; the sill of a doorway.
Tilt window 3 A single- or double-hung window whose operable sash can be tilted into the room for interior washability.
TINTED GLASS 1 A special type glass with additives, usually metallic particles that reduce the passage of sunlight. Tinted glass can be bronze, gray, green or blue as well as other more exotic colors.
Tinted glass 3 Glass colored by incorporation of a mineral admixture. Any tinting reduces both visual and radiant transmittance.
Tool 4  (Noun) Any instrument used by glassworkers to develop and shape an object. Glassworkers' tools include the blowpipe, pontil, gathering iron, pucellas, shears, clapper, pallet, block, pincers, battledore, lipper, and crimper. (Verb) To alter an object with a tool. 
Total Solar Energy Rejected 2 The percent of total solar energy (heat) rejected by the window film/glass system. The higher the number, the more total solar energy (heat) rejected.
Trail 4 A strand of glass, roughly circular in section, drawn out from a gather. 
Trailing 4 The process of applying trails of glass as decoration on the body, handle, or foot of a vessel. It is done by laying or winding softened threads onto a glass object. See also Combed decoration. 
TRANSOM 1 A fixed lite rectangular window that is placed over a door.
Transom 3 A horizontal transverse beam or bar in a frame; a crosspiece separating a door or the like from a window or fanlight above it. Also, a window above a door or other window, built on and commonly hinged to a transom.
Transom window 3 The window sash located above a door. Also called transom light.
Transmittance 2 The amount that is allowed to pass through a medium.
Transmittance 3 The percentage of radiation that can pass through glazing. Transmittance can be defined for different types of light or energy, e.g., visible light transmittance, UV transmittance, or total solar energy transmittance.
TRAPEZOID 1 Another name for an Angle Top or Rake Head window.
TRIANGLE 1 A fixed lite window in the shape of a triangle. Can be a right, equilateral, or isosceles shape
Trick glass 4 A glass, usually for wine and often of extraordinary shape, designed to be as difficult as possible to drink from without spilling the contents. In drinking competitions, any drinker who spilled wine was required to start again with a full glass. 
TRIPLE 1 Three windows mulled together horizontally in the same plane to form one unit.
TRIPLE HUNG 1 A hung window with three operable sash each in it's own track and with it's own balances.
Triple glazing 3 Three panes of glass or plastic with two air spaces between.
TRUE COLONIAL 1 A pattern of muntin bars using horizontal and vertical members to form a "tic tac toe" design on a light of glass by dividing a single glazed light into smaller individual pieces.
TWIN 1 Two windows mulled together in the same plane to form one unit.
Twist 4 A type of decoration in the stems of 18th-century and later drinking glasses, made by twisting a glass rod embedded with threads of white or colored glass, columns of air (air twists), or a combination of all three. 

UBC 3 Uniform Building Code
U-FACTOR 1 The number of BTU's that will pass through each square foot of area of a window or door per hour, per degree Fahrenheit difference from one side of unit to the other. For example, a 3050 window (15 sq. ft.) with a U-factor of 1.0 will allow 150 BTU's to escape every hour if the outside temperature is 55 degrees and the inside temperature 65 degrees (a difference of 10 degrees). The lower the U-factor the better the unit is at conserving energy. The U-factor of a window or door is an indication of how much heat will be lost while the R-factor indicates a body's resistance to losing heat. The R-factor is used when referring to a single construction material, while the U-factor is used when there are several materials involved such as aluminum, glass and plastic. The U-factor divided into 1.0 will equal the R-factor.
U-factor (U-value) 3 A measure of the rate of non-solar heat loss or gain through a material or assembly. It is expressed in units of Btu/hr-sq ft-°F (W/sq m-°C). Values are normally given for NFRC/ASHRAE winter conditions of 0° F (18° C) outdoor temperature, 70° F (21° C) indoor temperature, 15 mph wind, and no solar load. The U-factor may be expressed for the glass alone or the entire window, which includes the effect of the frame and the spacer materials. The lower the U-factor, the greater a window's resistance to heat flow and the better its insulating value.
 U-Value 2 The ability for heat to transfer through 1 square foot of window film for each 1° Fahrenheit difference in temperature. It is dependent upon the local climate or environment that the window is located in effects the level of heat transfer and the rate; in summer, heat transfers from the outdoor air to indoor air. In winter, heat transfers from indoor air to outdoor air. The lower the U-Value, the better insulating qualities of the window film/glass system.
Ultraviolet Light 2 Light having a shorter wavelength and higher energy than visible light. Ultraviolet light is potentially damaging to library, archive and museum objects. Removing UV light can reduce the rate of deterioration. Certain acrylic sheets have UV filtering chemicals built into them. 
Ultraviolet light (UV) 3 The invisible rays of the spectrum that are outside of the visible spectrum at its short-wavelength violet end. Ultraviolet rays are found in everyday sunlight and can cause fading of paint finishes, carpets, and fabrics.
Ultraviolet Transmittance 2 The percent of ultraviolet light (UV) that is transmitted by the window film/glass system. The lower the number, the less ultraviolet transmitted.
Undercutting  4 The technique of decorating glass in high relief by cutting away part of the glass between the body of an object and its decoration (e.g., on a cage cup). 
UNITED INCHES 1 Total of one width and one height of a window or lite of glass in inches.
Uranium glass  4 Glass colored with uranium oxide. This brilliant yellow-green glass was first made in the 1830s. 

Vapor retarder 3 A material that reduces the diffusion of water vapor across a building assembly.
VENT 1 Another word for a sash or panel of a window or door.
Vent 3 The movable framework or sash in a glazed window that is hinged or pivoted to swing open.
VENT AREA 1 In a fully opened door or window, the area of the opening that will allow passage of air in or out. Some building codes require a minimum vent area in a structure, which is usually a percentage of the floor area or the wall area. 
Vetro a fili (Italian, "glass with threads") 4 A type of blown glass made with canes that form a pattern of parallel lines. 
Vetro a reticello (Italian, glass with a small network") 4 A type of blown glass made with canes laid in a crisscross pattern to form a fine net, which may contain tiny air traps. 
Vetro a retorti (Italian, "lace glass") 4 A term loosely applied to various types of vetro a reticello. 
VINYL 1 A shortened form for polyvinyl chloride or PVC. (See PVC)
Vinyl 3 Polyvinyl chloride material, which can be both rigid or flexible, used for window frames.
Vinyl-clad window 3 A window with exterior wood parts covered with extruded vinyl.
Visible Light 2 Electromagnetic radiation at wavelengths which the human eye can see. We perceive this radiation as colors ranging from red (longer wavelengths; ~ 700 nanometers) to violet (shorter wavelengths; ~400 nanometers).
Visible light 3 The portion of the electromagnetic spectrum that produces light that can be seen. Wavelengths range from 380 to 720 nanometers.
Visible Light Absorptance 2 The percent of total visible light that is absorbed by the window film/glass system. The lower the number the less visible light absorbed.
Visible Light Reflectance 2 The percent of total visible light that is reflected by the window film/glass system. The lower the number the less visible light reflected.
VISIBLE LIGHT TRANSMITTA 1 Visible Light Transmittance indicates the amount of available visible light energy that is allowed to pass through a transparent or translucent material. This measurement is noted as a percentage figure and the higher the percentage, the more visible light is transmitted through the material.
Visible Light Transmittance 2 The percent of total visible light that is transmitted through the window film/glass system. The lower the number the less visible light transmitted.
Visible transmittance (VT) 3 The percentage or fraction of the visible spectrum (380 to 720 nanometers) weighted by the sensitivity of the eye, that is transmitted through the glazing.

Warm-edge technology 3 The use of low-conductance spacers to reduce heat transfer near the edge of insulated glazing.
WEATHER STRIP 1 A part of a window or door, used to seal the cracks around moving sash or panels against the passage of air or water, when the door or window is in the closed position. Weather strip can be made of metal, vinyl, wool pile or other materials.
Weathering 4 Changes on the surface of glass caused by chemical reaction with the environment. Weathering usually involves the leaching of alkali from the glass by water, leaving behind siliceous weathering products that are often laminar. 
Weatherstripping 3 A strip of resilient material for covering the joint between the window sash and frame in order to reduce air leaks and prevent water from entering the structure.
WEEPHOLE 1 An opening at the sill of a window or door allowing moisture to drain free.
Weep hole 3 A small opening in a wall or window sill member through which water may drain to the building exterior.
Wheel engraving 4 A process of decorating the surface of glass by the grinding action of a wheel, using disks of various sizes and materials (usually copper, but sometimes stone). An abrasive in a grease or slurry is applied to a wheel, as the engraver holds the object against the underside of the rotating wheel. See Copper-wheel engraving. 
Williamite glass 4 A 17th-century English drinking vessel engraved with a toast, a symbol (an orange tree, for example), or a motto supporting King William III, or with his portrait. William III, who was the hereditary prince of Orange, came to the English throne in 1689. His political opponents were the Jacobites; see Jacobite glass
WINDOW 1 An opening constructed in a wall or roof and functioning to admit light or air to an enclosure, usually framed and spanned with glass mounted to permit opening and closing. (From the Old Norse word "vindauga", which is an eye for the wind" or "wind eye".)
Window 3 A glazed opening in an external wall of a building; an entire unit consisting of a frame sash and glazing, and any operable elements.
WINDOWORKS 1 NuAir’s component system for mulling windows together.
Window hardware 3 Various devices and mechanisms for the window including catches, fasteners and locks, hinges, pivots, lifts and pulls, pulleys and sash weights, sash balances, and stays.
WOOL PILE 1 A type of weather strip material used to reduce the passage of air or water around sash members of a window or door.
WRAP AROUND GLAZING 1 The same as Channel Glazing or Marine Glazing.

XO 1 The designation for two-panel sliding window or door with the left hand panel, as viewed from the exterior of the structure, operable.
XX 1 The designation for two-panel window or door with both panels operable.
XXX 1 The designation for three-panel sliding window or door in which all three panels are operable. 





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