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Glossary

Glossary

  • Adhesion  - The property of a coating or sealant to bond to the surface to which it is applied.
  • Annealed Glass- Float glass that has not been toughened or heat strengthened is annealed glass. Annealing float glass is the process of controlled cooling to prevent residual stress in the glass and is an inherent operation of the float glass manufacturing process. Annealed glass can be cut, machined, drilled, edged and polished.
  • Annealing Lehr  - An in-line, controlled heating/cooling apparatus located after the tin bath and before the cooling conveyor of a float glass production line. Its purpose is to relieve induced stress from the flat glass product to allow normal cold end processing.
  • Anti-Walk Blocks - Elastomeric blocks that limits lateral glass movement in the glazing channel, which may result from thermal, seismic, wind load effects, building movement, and other forces that may apply.
  • Aspect Ratio  - The quotient of the long side of a glazing lite over the short side of that lite.
  • Autoclave  - A vessel that employs high-pressure and heat. In the glass industry, used to produce a bond between glass and PVB or urethane sheet, creating a laminated glass product.
  • Bay window  - 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  - An applied sealant in a joint irrespective of the method of application, such as caulking bead, glazing bead, etc. Also a molding or stop used to hold glass or panels in position.
  • Bedding of Stop  - In glazing, the application of compound or sealant at the base of the channel, just before the stop is placed in position, or buttered (see Buttering) on the inside face of the stop.
  • Bent Glass  - Flat glass that has been shaped while hot into curved shapes.
  • Bevel of Compound Bead  - In glazing, a bead of compound applied to provide a slanted top surface so that water will drain away from the glass or panel.
  • Beveling  - The process of edge finishing flat glass to a bevel angle.
  • Bite  - The dimension by which the framing system overlaps the edge of the glazing infill.
  • Bleeding  - A migration of a liquid to the surface of a component or into/onto an adjacent material.
  • Block  - Rectangular, cured sections of EPDM, neoprene, silicone or other suitable material, used to position the glass product in the glazing channel.
  • Bow (and Warp)  - A curve, bend or other deviation from flatness in glass.
  • Bullet Resistant Glass  - A multiple lamination of glass or glass and plastic that is designed to resist penetration from medium-to-super-power small arms and high-power rifles.
  • Butt Glazing  - The installation of glass products where the vertical glass edges are without structural supporting mullions.
  • A compound used for sealing that has minimum joint movement capability; sometimes called low performance sealant.
  • Casement  A window sash that swings open on side hinges
  • Channel (pocket)  The measurement between stationary stops (or stationary stop and removable stop) in a U-shaped channel.
  • Channel Glazing -  The installation of glass products into U-shaped glazing channels. The channels may have fixed stops; however, at least one glazing stop on one edge must be removable.
  • Channel Width -  The distance between opposing glazing stops.
  • Chemically Strengthened Glass  -  Glass that has been strengthened by ion-exchange to produce a compressive stress layer at the treated surface.
  • Chipped Edge  -  An imperfection due to breakage of a small fragment from the cut edge of the glass. Generally this is not serious except in heat absorbing glass.
  • Clips  -  Wire spring devices used to hold glass in rabbeted sash, without stops, and face glazed.
  • Coated Glass - Thin layers of material are applied to the surface of the glass to add properties to the glass including reduced light transmission, increased solar energy elimination, colour and aesthetic properties. Examples of coated glass include mirrors, spectrally selective glass and the SolarVue and Solarshield ranges.
  • Cohesive Failure  -Internal splitting of a compound resulting from over-stressing of the compound.
  • Compatibility  - The ability of two or more materials to exist in close and permanent association for an indefinite period with no adverse effect of one on the other.
  • Compound  - A chemical formulation of ingredients used to produce a caulking, elastomeric joint sealant, etc.
  • Compression Gasket  - A gasket designed to function under compression.
  • Compression Set  - The permanent deformation of a material after removal of the compressive stress.
  • Condensation  - The appearance of moisture (water vapor) on the surface of an object caused by warm moist air coming into contact with a colder object.
  • Cut Sizes  - Glass cut to specified width and length.
  • Curtain Wall  - An exterior, non-load-bearing wall system that utilizes glass  either transparent or spandrel, or both  and vertical and horizontal mullions acting as structural members to transfer wind and gravity forces to the building structure. The system is anchored to, and supported by, the structural members of the the building. There are two types of curtain wall systems: stick and unitized.
  • Stick Curtain Wall  - A curtain wall system in which the mullions are installed first, and then the glass panels are inserted into the mullion framing in the field.
  • Unitized Curtain Wall  - A factory-assembled and glazed curtain wall system. The mullions are fabricated with the glass panels in place, and then erected as panels.
  • - A method of securing g in a frame that uses preformed, resilient gaskets instead of a wet sealant or glazing compound.
  • Cutting  - Scoring glass with a diamond, steel wheel or other hard alloy wheel and breaking it along the score. Other methods of cutting glass include water jet and laser.
  • Design Pressure  - Specified pressure a product is designed to withstand.
  • Diffusing  - Scattering, dispersing, as the tendency to eliminate a direct beam of light.
  • Distorton  -Alteration of viewed images caused by variations in glass flatness or inhomogeneous portions within the glass. An inherent characteristic of heat-treated glass.
  • Divided light  - A window with a number of smaller panes of glass separated and held in place by muntins.
  • Double Glazing  - In general, any use of two lites of glass, separated by an air space, within an opening, to improve insulation against heat transfer and/or sound transmission. In insulating glass units the air between the glass sheets is thoroughly dried and the space is sealed, eliminating possible condensation and providing superior insulating properties.
  • Double-hung window - 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 Strength  -In float glass, approximately 1/8" (3 mm) thick.
  • Dry Glzing  -Also called compression glazing, a term used to describe various means of sealing monolithic and insulating glass in the supporting framing system with synthetic rubber and other elastomeric gasket materials.
  • Dry Seal  -Accomplishment of weather seal between glass and sash by use of strips or gaskets of Neoprene, EPDM, silicone or other flexible material. A dry seal may not be completely watertight.
  • Ethylene Propylene Diene Monomer  - a synthetic rubber.
  • Edge Block (See Anti-walk Block)
  • Edge Clearance  -Nominal spacing between the edge of the glass product and the bottom of the glazing pocket (channel).
  • Edging  -Grinding the edge of flat glass to a desired shape or finish.
  • Elastomer  -An elastic, rubber-like substance, such as natural or synthetic rubber.
  • Elastomeric  -(adj) Having the property of returning to its original shape and position after removal of load.
  • (n) An elastic rubber like substance.
  • Emissivity  -The measure of a surface ability to emit long-wave infrared radiation.
  • Etch  -To alter the surface of glass with hydrofluoric acid or other caustic agents. Permanent etching of glass may occur from alkali and other runoff from surrounding building materials.
  • Exterior Glazed  -Glazing infills set from the exterior of the building.
  • Exterior Stop  -The molding or bead that holds the lite or panel in place when it is on the exterior side of the lite or panel.
  • -The whole exterior side of a building that can be seen at one view; strictly speaking, the principal front. Commonly used as reference to the exterior skin of a building.
  • Face Glazing  -A system having a triangular bead of compound applied with a putty knife, after bedding, setting and clipping the glazing infill in place on a rabbetted sash.
  • Fenestration  -Any glazed panel, window, door, curtain wall or skylight unit on the exterior of a building.
  • Fillet Bead  -Caulking or sealant placed in such a manner that it forms an angle between the materials being caulked.
  • Fire-Polish -To make glass smooth or glossy by the action of fire or intense heat.
  • Fire-Protection Rating -The period of time that an opening protective assembly will maintain the ability to confine a fire as determined by tests NFPA 252/ NFPA 257/UL 9/UL 10c/ASTM E 2010/ASTM E 2074.
  • Fire-Resistance - That property of materials or their assemblies that prevents or retards the passage of excessive heat, hot gases or flames under conditions of use.
  • Fire-Resistance Rating -The period of time a building element, component or assembly maintains the ability to confine a fire, continues to perform a given structural function, or both, as determined by tests NFPA 251/ASTM E 119/UL 263 (wall assemblies).
  • Flare  -A protrusion on the edge of a lite of glass.
  • Flat Glass  - A general term that describes float glass, sheet glass, plate glass and rolled glass.
  • Float Glass  -Glass formed on a bath of molten tin. The surface in contact with the tin is known as the tin surface or tin side. The top surface is known as the atmosphere surface or air side.
  • Flush Glazing (Pocket Glazing)  -The setting of a lite of glass or panel into a four-sided sash or frame opening containing a recessed "U" shaped channel without removable stop on three sides of the sash or frame and one channel with a removable stop along the fourth side.
  • Frosted Finish  - A surface treatment for glass, consisting of an acid etching of one or both surfaces that diffuses transmitted light and reduces glare.
  • Fully Tempered Glass  - Flat or bent glass that has been heat-treated to have either a minimum surface compression of 10,000 psi (69 MPa) or an edge compression not less than 9,700 psi (67 MPa) in accordance with the requirements of ASTM C 1048, kind FT or meet the requirements of ANSI Z97.1 or CPSC 16 CFR 1201. Outside of North America, sometimes called "toughened glass."
  • - Insulating glass units with a gas other than air in the air space to decrease the unit thermal conductivity (U-value) or to increase the units sound insulating value.
  • Gaskets  - Pre-formed shapes, such as strips, grommets, etc., of rubber or rubber-like composition, used to fill and seal a joint or opening either alone or in conjunction with a supplemental application of a sealant.
  • Girth  - In bent glass, the distance around the concave or convex surface measured perpendicular to the height, including any flats.
  • Glass  - A hard brittle substance, usually transparent, made by fusing silicates, under high temperatures, with soda, lime, etc.
  • Glass Clad Polycarbonate  - One or more lites of flat glass bonded with an aliphatic urethane interlayer to one or more sheets of extruded polycarbonate in a pressure/temperature/vacuum laminating process.
  • Glass Fines  - Minute glass particles typically resulting from glass fabrication processes (i.e. cutting, grinding, polishing, drilling, edging, etc.)
  • Glass Quality (Flat)  - Defined by ASTM C 1036 on the basis of end use and allowable blemishes.
  • Glazing  - (n) A generic term used to describe an infill material such as glass, panels, etc.  
  • (v) The process of installing an infill material into a prepared opening in windows, door panels, partitions, etc.
  • Glazing Bead  -  A strip surrounding the edge of the glass in a window or door, which holds the glass in place.
  • Glazing Channel  -  A three-sided, U-shaped sash detail into which a glass product is installed and retained.
  • - Glass that absorbs an appreciable amount of solar energy.
  • Heat-Resisting Glass - Glass able to withstand high thermal shock, generally because of a low coefficient of expansion.
  • Heat-Strengthened Glass - Flat or bent glass that has been heat-treated to have a surface compression between 3,500 and 7,500 psi (24 to 52 MPa) and meet the requirements of ASTM C 1048, kind HS. Heat-strengthened glass is not a safety glazing material and will not meet the requirements of ANSI Z97.1 or CPSC 16 CFR 1201.
  • Heat-Treated  - Term used for both fully tempered glass and heat-strengthened glass.
  • Heel Bead  - Sealant applied at the base of a channel, after setting the lite or panel and before the removable stop is installed; one of its purposes being to prevent leakage past the stop.
  • High-Transmission Glass - Glass, which transmits an exceptionally high percentage of visible light.
  • Insulating glass  - 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.
  • -Two or more lites of glass spaced apart and hermetically sealed to form a single-glazed unit with an air space between each lite. (Commonly called IG units.)
  • Interior Glazed  -Glazing infills set from the interior of the building.
  • Interior Stop  -The removable molding or bead that holds the lite in place when it is on the interior side of the lite.
  • Interlayer  -Any material used to bond two lites of glass and/or plastic together to form a laminate. The interlayer imparts additional properties to the glass including safety, security, solar control, light control, UV control, color and sound absorption.
  • -The vertical frame members at the perimeter of the opening.
  • Joint  -The space or opening between two or more adjoining surfaces.
  • -Two or more lites of glass permanently bonded together with one or more interlayers.
  • Laminated Plastics (Plastic Laminates)  -Two or more lites (or sheets) of polycarbonate (or acrylic) with an aliphatic urethane interlayer between polycarbonate or acrylic bonded together under heat and pressure.
  • Lehr  -A long, tunnel-shaped oven for annealing glass, usually by a continuous process.
  • Lite  -Another term for a pane of glass. Sometimes spelled "light" in the industry literature, but spelled "lite" in this text to avoid confusion with light as in "visible light".
  • Low-emissivity (or low-e) -A low rate of emitting (radiating) absorbed radiant energy. The radiant energy (heat), i.e. long wave infrared, is in effect, reradiated back toward its source.
  • Luminous Efficacy (Light-to-Solar Gain Ratio) -The visible transmittance of a glazing system divided by the solar heat gain coefficient (or shading coefficient). This ratio is helpful in selecting glazing products for different climates in terms of those that transmit more heat than light and those that transmit more light than heat.
  • -Descriptive of heavy-consistency compounds that may remain adhesive and pliable with age.
  • Migration  -Spreading or creeping of a constituent of a compound onto/into adjacent surfaces. See bleeding.
  • Mullion  -A horizontal or vertical member that supports and holds such items as panels, glass, sash, or sections of a curtain wall.
  • Multiple-Glazed Units -Insulating glass units with three or more lites of glass.
  • Muntins  -Horizontal or vertical bars that divide the sash frame into smaller lites of glass. Muntins are smaller in dimensions and weight than mullions.
  • Noise Control ISO rating/STC  -A single-number weighted average used to define the sound insulation caused by glass. The number can be used to compare two pieces of glass (or InsulVue units) but must not be used to design or predict sound levels within a space.
  • Non-Sag -A sealant formulation having a consistency that will permit application in vertical joints without appreciable sagging or slumping. A performance characteristic, which allows the sealant to be installed in a sloped or vertical joint application without appreciable sagging or slumping.
  • Non-Staining -Characteristic of a compound, which will not stain a surface.
  • Nozzle  -The tubular tip of a caulking gun through which the compound is extruded.
  • OITC (Outside-Inside Transmission Class)A rating used to classify the performance of glazing in exterior applications. (For more information see ASTM E 1332 and ASTM E 1425.)
  • Obscure Glass (See Patterned Glass)
  • Operable window.  Window that can be opened for ventilation.
  • -One type of rolled glass having a pattern impressed on one or both sides. Used extensively for light control, bath enclosures and decorative glazing. Sometimes called "rolled," "figured" or "obscure" glass.
  • Permanent Set  -The amount by which a material fails to return to its original dimensions after being deformed by an applied force or load.
  • Pocket (Channel)  -  A three-sided, U-shaped opening in a sash or frame to receive glazing infill. Contrasted to a rabbet, which is a two-sided, L-shaped section, as with face glazed window sash.
  • Pocket (Channel) Depth -The inside dimension from the bottom of the pocket to the top. Pocket depth equals the bite plus the edge clearance.
  • Pocket Glazing (See Flush Glazing)
  • Pocket (Channel) Width  -The measurement between stationary stops (or stationary stop and removable stop) in a U-shaped channel.
  • Points  -Thin, flat, triangular or diamond shaped pieces of zinc used to hold glass in wood sash by driving them into the wood.
  • Polished Wired Glass  -  Wired glass that has been ground and polished on both surfaces.
  • Polyisobutylene  -Typically the primary seal in a dual seal IG unit and the key component in restricting moisture vapor transmission.
  • Polymer  -A chemical structure consisting of long chains of molecular units.
  • Polyurethane Sealant  -An organic compound formed by the reaction of a glycol with an isocyanate.
  • Polyvinyl Chloride (PVC)  -Polymer formed by polymerization of vinyl chloride monomer. Sometimes called vinyl.
  • Pre-Shimmed Tape Sealant  -A sealant having a pre-formed shape containing solids or discrete particles that limit its deformation under compression.
  • Primer  -A coating specifically designed to enhance the adhesion of sealant systems to certain surfaces, to form a barrier to prevent migration of components, or to seal a porous substrate.
  • Priming  -Sealing of a porous surface so that compound will not stain, lose elasticity, shrink excessively, etc., because of loss of oil or vehicle into the surround. A sealant primer or surface conditioner may be used to promote adhesion of a curing type sealant to certain surfaces.
  • Pyrolytic Deposition  -A process for applying a thin metallic coating to the surface of flat glass during the float glass manufacturing process.
  • Racking  -A movement or distortion of sash or frames causing a change in angularity of corners.
  • Reflective Glass  -Glass with a metallic coating to reduce solar heat gain. (See also Solar Control Glass).
  • Relative Heat Gain  -The amount of heat gain through a glass product taking into consideration the effects of solar heat gain (shading coefficient) and conductive heat gain (U-value). The value is expressed in Btu/hr/ft2 (W/m2).
  • The relative heat gain is calculated as RHG =  (Summer U-value x 14oF) + (Shading Coefficient x 200). The lower the relative heat gain, the more the glass product restricts heat gain.
  • Removable Double Glazing (RDG)  -A removable glazed panel or sash on the inside or outside of an existing sash or window, such as a storm panel, used for additional insulation and protection against the elements.
  • Rolled Glass  -Glass formed by rolling, including patterned and wired glass.
  • Rough Opening  -The opening in a wall into which a door or window is to be installed.
  • Rub  -A series of small scratches in glass generally caused during transport by a chip lodged between two lites.
  • R-Value -The thermal resistance of a glazing system expressed ft2/hr/oF/Btu (m2/W/oC). The R-value is the reciprocal of the U-value. The higher the R-value, the less heat is transmitted throughout the glazing material.
  • -A single number rating derived from individual transmission losses at specified test frequencies (for more information see ASTM E 90 and ASTM E 413). It is used for interior walls, ceilings and floors and in the past was also used for preliminary comparison of the performance of various glazing materials.
  • STL (Sound Transmission Loss)  -The reduction of the amount of sound energy passing through a wall, floor, roof, etc. It is related to the specific frequency (Hz) at which it is measured and it is expressed in decibels (dB). Also called "Transmission Loss (TL)."
  • Sandblasted Finish  -A surface treatment for flat glass obtained by spraying the glass with hard particles to roughen one or both surfaces of the glass. The effect is to increase obscurity and diffusion, but it makes the glass weaker and harder to clean.
  • Sash  -The window frame, including muntin bars if used, to receive the glazing infill.
  • Score  - To penetrate the surface of a lite of glass by means of a cutting device, e.g. a glass cutter, along a predetermined line in order to produce a lite of glass of a specific size and/or shape.
  • Screened Glass  -Glass which has had a pattern applied to it using the silkscreen process. The screen is fired into the glass during the toughening process.
  • Screw-On Bead (or Applied Stop) -Stop, molding or bead fastened by screws as compared with those that snap into position without additional fastening.
  • Sealant  -An elastomeric material with adhesive qualities, applied between components of a similar or dissimilar nature to provide an effective barrier against the passage of the elements.
  • Sealed Insulating Glass Units (See Insulating Glass Unit)
  • (verb)  -To grind, usually with an abrasive belt, wet or dry, the sharp edges of a piece of glass.
  • Setting  -Placement of lites or panels in sash or frames. Also action of a compound as it becomes more firm after application.
  • Setting Blocks  -Generally rectangular, cured extrusions of neoprene, EPDM, silicone, rubber or other suitable material on which the glass product bottom edge is placed to effectively support the weight of the glass.
  • Shading Coefficient  -The ratio of the solar heat gain through a specific glass product to the solar heat gain through a lite of 1/8" (3mm) clear glass. Glass of 1/8" (3mm) thickness is given a value of 1.0; therefore, the shading coefficient of a glass product is calculated as follows:
  • Solar Heat Gain of the Glass in Question  = S.C.
  • Solar Heat Gain of 1/8" Clear Glass
  • Simulated divided lights.  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 glazing.  Single thickness of glass in a window or door.
  • Single-hung window.  A window consisting of two sashes of glass, the top one stationary and the bottom movable.
  • Single-strength glass.  Glass with thickness between 0.085" and 0.100" 
  • Skylight (operable or pivot).  A roof window that gives light and ventilation.
  • Sliding glass door.  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.
  • Simulated Divided Lites (SDLs):  Muntins permanently adhered to the interior and exterior of the glass.
  • Sliding window  -  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.
  • Smart window  -  Generic term for windows with switchable coatings to control solar gain.
  • Solar control coatings  -  Thin film coatings on glass or plastic that absorb or reflect solar energy, thereby reducing solar gain.
  • Sidelite  -  A stationary glass panel mulled to or installed next to a door.
  • Silicone Sealant  -  A sealant having as its chemical composition a backbone consisting of alternating silicon-oxygen atoms.
  • Sloped Glazing  -  Any installation of glass that is at a slope of 15 degrees or more from vertical.
  • Solar Control Glass  -  Tinted and/or coated glass that reduces the amount of solar heat gain transmitted through a glazed product.
  • Solar  All energy received from the sun on the surface of the earth. This includes the energy from the ultraviolet, visible and infrared segments of the solar spectrum. For reasons of standardization solar energy is measured between the wavelengths 280 nm to 2500 nm.
  • Solar Energy Reflectance  -  In the solar spectrum, the percentage of solar energy that is reflected from the glass surface(s).
  • Solar Energy Transmittance -  The percentage of ultraviolet, visible and near infrared energy within the solar spectrum (300 to 2100 nanometers) that is transmitted through the glass.
  • Solar Energy Absorption  -  The higher the absorption the higher the thermal stress and the more likely a glass is to crack if incorrectly glazed.
  • Solar Heat Gain Coefficient  -  The ratio of the solar heat gain entering the space area through the fenestration product to the incident solar radiation. Solar heat gain includes directly transmitted solar heat and absorbed solar radiation, which is then reradiated, conducted, or convected into the space.
  • Solarization  -  Change in transmission, and sometimes color, of plastics as a result of exposure to sunlight or other radiation.
  • Sound Transmission Class (See STC)
  • Sound Transmission Loss (See STL)
  • - Small blocks of neoprene, EPDM, silicone or other suitable material, placed on each side of the glass product to provide glass centering, maintain uniform width of sealant bead and prevent excessive sealant distortion.
  • Spandrel  - The panel(s) of a wall located between vision areas of windows, which conceal structural columns, floors and shear walls.
  • Spectrally Selective Glass  -  Tinted and/or coated flat glass that reduces the amount of solar heat gain transmitted through a glazed product.
  • Stop  -  Either the stationary lip or the removable molding of the rabbet, serving to hold the glazing infill in the sash or frame, with the help of spacers.