That portion of total incident radiation that is absorbed by the glass and subsequently re-radiated either outside or inside.
A wearing, grinding or rubbing away by friction.
The inherent ability of a coating or substrate to resist degradation or destruction by friction.
The process of decorating glass, which involves the application of hydrofluoric acid to the glass surface.
Sharpness of image.
Australian Fenestration Rating Council – the Australian body which manages the performance ratings of various glass types.
Australian Glass & Glazing Association – has been formed to bring together for the benefit of the Australian Flat Glass Industry, representatives of the main groups in the industry via glass merchants and glaziers, the local glass manufacturers, agents representing overseas glass manufacturers, industry suppliers and any other interested parties. Website: www.agga.org.au
The space in the cavity between two glass panes in an insulated glass unit.
The surrounding temperature existing at any given time.
Glass cooled gradually during manufacture in an annealing operation to reduce residual stresses and strains that can occur during cooling. Technically, the stress condition of ordinary glass which is glass that can be cut and processed. This is the normal cuttable glass that is generally available.
In the manufacturing of float glass and obscure glass, it is the process of controlled cooling done in a lehr to prevent residual stresses in the glass. Re-annealing is the process of removing objectionable stresses in glass by re-heating to a suitable temperature followed by controlled cooling.
An on-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 inherent in the flat glass product to allow normal cold end cutting and processing.
Temperature at which the viscosity of the glass is approximately 1013 Poises. At the annealing point of glass, internal stresses are substantially relieved in a matter of minutes.
A type of security glazing, typically laminated glass, designed to resist manual attack and to delay access to the protected space for a short period of time.
Glass with an uneven surface texture and bubbles inside, produced by using antique methods in order to obtain the appearance of glass made before the development of industrial processes.
Period of time during which a sealant can be effectively applied to a joint. The timing is from completion of mixing and could be affected by temperature, humidity or a combination of both. Also known as Working life.
An inert, non-toxic gas placed between glass panes in an insulated glass unit in order to improve the insulating properties of the unit.
A small bevel at an angle of approximately 45 degrees to the edge points of the glass, applied usually with a wet or dry belt, stone or machine.
The result of removing sharp edges.
The ratio of the longer side of a panel to its shorter side.
Material is asymmetric when it is composite and some of the components are of different thicknesses.
The reduction of sound intensity (or signal strength) with distance. Attenuation is the opposite of amplification, and is measured in decibels.
A now superseded trade name for the Viridian range of tinted float glass. Now known as VFloat.
A pressure tank vessel that employs high pressure and heat to produce bonding between glass and PVB or urethane sheet, creating a PVB laminated glass product.
Australian Window Association – has been formed to bring together for the benefit of window manufacturers. Website: www.awa.org.au
A polyethylene or polyurethane foam material installed under compression and used to control sealant joint depth, provide a surface for sealant tooling, serve as a bond breaker to prevent three-sided adhesion and provide an hourglass contour of the finished sealant bead.
Clearance Space between the surface of the glass and the back of the rebate.
That portion of the compound remaining between the back of the rebate and glass after the glass has been pressed into position in the bedding putty.
A vertical member supporting a handrail and forming part of a balustrade.
A framed or unframed barrier between handrail and floor level (see also handrail).
A surface defect that looks like hammered metal. Unless very heavy, it usually cannot be seen by the naked eye, although it can be clearly seen on the shadowgraph.
A strip of timber, aluminium or other suitable material secured to the rebate to retain the glass in place (sometimes referred to as a glazing bead).
Bed or Bedding
The glazing material used to seal between the glass and frame/bead.
Bedding or Stop
In glazing, the application of compound 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.
The process of manufacturing bent glass.
Glass produced by heating annealed glass to the point where it softens and which then can be pressed or sag-bent over formers. Bends can be created in one or two planes. Bending can be incorporated in the toughening process. Bent glass can also be laminated.
A sloping edge on a glass sheet commonly used on mirror glass.
The process of grinding and polishing a sloped angle on the face of the edge of flat glass which results in a decorative edge appearance to the glass.
Bevel Both Sides
The edges to both surface sides of the glass are bevelled to the usual standard bevel.
Bevel To Butt
The process of producing a small mitre bevel to butt edges typically on mirrors.
Also referred to as structural bite, is the width of silicone sealant that is applied to the panel of glass to adhere it to the frame.
Migration of colour from the coating film onto or into a surface with which it comes in contact.
An elongated bubble larger than seed.
A noticeable imperfection in or on the surface of the glass.
A profusion of bubbles or gaseous inclusions in glass. Small bubbles less than 2mm diameter are referred to as seeds.
A small piece of lead, wood, santoprene or rubber or other suitable material used to position glass in a frame. Refer setting blocks.
A surface film on glass resulting from atmospheric attack or deposition by smoke or other vapours.
A separation of glass and interlayer at or close to the edge of laminated glass caused by penetration of the autoclaving medium into the edge during laminating.
Body Tinted Glass
Glass produced by the addition of metal oxides to the molten glass which do not materially affect the basic properties except for the colour and solar energy transmission.
A curve, bend or other deviation from flatness in glass.
The resultant pattern formed by the cracks within an individual pane of glass when broken.
Breather Tube Units
An insulating glass unit with a tube factory-placed into the unit’s spacer to accommodate pressure differences for units being installed at high altitudes. These tubes must be sealed on the job site prior to unit installation.
A rainbow effect sometimes seen in double glazing caused by the light refraction from identical thicknesses of glass.
Decorative process in which designs are cut into glass with abrasive and polishing wheels.
British Thermal Units (BTUs)
The amount of energy (in imperial units) needed to raise one pound of water from 63°F to 64°F.
See tinted glass.
In float glass and obscure glass, a gaseous inclusion. In laminated glass, a gas pocket in the interlayer material or between the glass and the interlayer. Also called a blister or seed.
In float glass manufacture, the extreme lateral edge of the ribbon as floated down the line.
Bullet Resistant Glass
A multiple lamination of glass and plastic that is designed to resist penetration from medium-to-super-power small arms and high-power rifles.
A glass panel having a formed antique style circle in its centre for decorative effect. Originally the cut-out bottom of a mouth blown glass cylinder.
The rounding, in the form of a quarter circle, of half of the cut edge of the glass. The remaining surface edge is slightly rounded. Also known as half round.
The installation of glass products where the vertical glass edges are glazed with silicone and without structural supporting mullions.
Application of sealant or compound to the flat surface of some member before placing the member in position; for example, the buttering of a removable stop before fastening the stop in place.
Processing Computer Aided Design, the use of a computer to produce graphics.
The amount of energy needed to raise one gram of water from 14.5°C to 15.5°C.
The use of glass in a balustrade where it forms a structural enclosure or barrier. The glass is installed or cement fixed directly into channels or with fixings and the glass takes all loads directly back to its fixing point.
Capillary Tube Units
An insulating glass unit with a very small metal tube of specific length and inside diameter, factory-placed into the unit’s spacer to accommodate pressure differences encountered in shipping to high altitudes. (See also Breather Tubes).
A window, pivoted or opening on side hinges.
Cast-In-Place Lamination (CIP)
Lamination process where the interlayer is obtained by pouring a liquid between plies of glass or plastics glazing sheet material, which is then cured to produce the final product.
Glass produced by ‘casting’, in other words by pouring molten glass into a mould or by heating glass in a tank and extruding it through patterned rollers.
Central Area of Sheet
The area that forms an oval or circle centred on the sheet, whose axis or diameter does not exceed 80% of the overall dimension. This allows a fairly large area at the corners, which may have imperfections that are not allowed in the central area.
Residual tension stresses within the centre (core or zone) between the surface compression layers of thermally toughened and heat-strengthened glass.
A combination of crushed glass, metal oxide colourants and flux mixed in an oil or water medium and fused onto glass. Also known as ceramic ink.
The oxide of the rare earth group, used alone or together with other substances as a polishing agent for glass.
A fixed glazing bar or rigid push bar that provides protection from human impact. Also known as a crash rail.
The measurement from the sight line of the frame to the bottom of the channel.
A three-sided, U-shaped opening in sash or frame to receive light or panel. Also known as perimeter channel.
The distance between the fixed and removable beads at the widest point.
Very small cracks in flat glass, usually at the edge. Though small, these are cause for concern since they can be intensified under strain (See Edge Vents).
The lasting quality, both physical and chemical, of a glass surface. It is frequency evaluated after prolonged weathering or storage, in terms of physical and chemical changes in the glass surface (see Weathering).
Chemically Toughened Glass
Chemical strengthening of glass is brought about through a process known as ion-exchange. Glass is submersed in a molten salt bath at temperatures below the annealing range of the glass. In the case of soda lime silica glass, the salt bath consists of potassium-nitrate. During the submersion cycle, the larger alkali potassium icons exchange places with the smaller alkali sodium ions in the surface of the glass. The larger alkali potassium ions ‘wedge’ their way into the voids in the surface created by the vacating smaller alkali sodium ions. This ‘strengthened’ surface may penetrate to a depth of only a few microns. It is not a recognised safety glass.
A small shallow piece of glass which has become detached from the original glass edge or face or the void it has left.
An imperfection due to the breaking of a small fragment from the cut edge of the glass. Generally this is not serious except in heat absorbing glass.
A straight line (or measurement), joining ends of an arc.
CIP (Cast In Place)
Lamination process where the interlayer is a liquid poured between two plies of glass and then chemically or UV cured to produce the final laminated glass product.
Toughened or Heat strengthened glass usually painted or silk-screened using ceramic ink as a colouring agent for use in curtain walls or as a cover to columns and walls. (See also Spandrel).
Architectural clear glass is almost invariably of the soda-lime-silica type. Composition varies with manufacturer but is generally silica (SiO2) 70% to 74%, lime (CaO) 5% to 12% and soda (Na2O) 12% to 16%, with small amounts of magnesium, aluminium, iron and other elements.
Computer Numeric Control. This type of machinery enables the processing of sophisticated shapes and hole contours in glass.
Internal splitting of a sealant resulting from over stressing and insufficient elasticity and elongation to absorb the strain.
The frequency at which a glass panel vibrates in unison with the frequency of the incident sound pressure waves thus significantly reducing the sound insulating properties of the glass at that specific frequency.
Horizontal or vertical bars that divide a sash frame into smaller panels of glass. Colonial bars are smaller in dimensions and weight than mullions. They are sometimes surface fixed to glass.
A system that can be used to assign numbers to specify or describe the colour of glass or the colour of coating on glass.
Noticeable colour differences between glass panels, or within one panel of glass or coated glass.
Pressure exerted on the glazing compound sealant, tape or gasket by the glazing method.
The appearance of moisture (water vapour) on the surface of glass caused by warm moist air coming into contact with the colder surface of the glass.
Heat transfer in which there is a direct contact of molecules in a solid body, e.g. the passage of heat along a metal bar of which one end is inserted into a fire.
Degree of softness or firmness of a compound as supplied in the container and varying according to method of application, such as gun, knife, tool, and the like.
Heat transfer in which actual movement of the medium, gas or liquid occurs e.g. heated air from a convection heater.
(See Luminous Efficacy).
Attenuated glassy inclusions that possess optical and other properties differing from those of the surrounding glass. Cords are the result of non-homogeneity. Low intensity cords are called strings, wire lines or ream.
Section of glass remaining on or removed from the corner of a sheet, caused by the score mark not continuing right through to the traverse mark.
The perimetric area of the glass covered by the channel or sash when installed. Also known as edge cover.
A hole which has been ground out at the surface to receive a mechanical fixing, allowing the bolting or fixing of the glass panel.
A rail, together with its fixings, capable of withstanding a load of 750N per metre length, acting in any direction without contact with the glazing material.
Abbreviation for cut-to-size glass.
Broken glass , the excess glass from previous glass manufacture or edge trims off the cutting of glass to size. Cullet is an essential ingredient in the pre-melt raw glass mix as it facilitates the melting process.
One part of a two-part sealant, which, when added to the base, will cause the base to change its physical state by chemical reaction between the two parts.
A non load-bearing wall of metal sections, glass and infill panels, which is carried directly by the structure of a building. Extensively used in modern high-rise office buildings.
The removal of a section of a glass panel.
Any flat glass cut to specific dimensions. Also known as cut-to-size
(a) A person who cuts glass. (b) The tool used in cutting glass.
Scoring glass with a diamond, steel or hard alloy wheel and breaking along the score.
The measurement of the relative fading reduction over the whole solar spectrum, not just ultra violet. It is weighted to address the fact that fading results from a broad band of solar energy.
The clear height and width between frame members that admits light.
A specially prepared paper on which designs have been printed for the purpose of transferring to glass.
The process of producing a colourless appearance in glass.
Clear or patterned glass processed by craftsmen for decorative effect. Stained glass, leadlights and sand-blasted, acid-etched, embossed and printed glass fall into this category. Decorative interlayers can also be incorporated in laminated glass.
(a) Firing enamels onto glassware. (b) Applying designs to formed glassware by means of etching, sandblasting, cutting, engraving or similar methods.
Deflection (centre of glass)
The amount of bending movement of the centre of a glass panel, perpendicular to the plane of the glass surface under load (usually wind load).
A condition in which one or more of the glass plies of laminated glass loses the bond with the interlayer. Often it is a minor edge discolouration reaction from sealant.
Desiccant (Silica Gel)
Molecular sieve or extremely porous crystalline substance used to absorb moisture inside the air space of insulated glass units.
Design Wind Pressure
The specified pressure a product is designed to withstand.
Crystallization in glass.
The temperature at which condensation of moisture begins when air is cooled.
The more or less cubicle (cubic?) pattern of fracture of fully tempered glass, the edges of the dice being roughly equal to the thickness of the glass (see break pattern).
Multi-layered coatings that exhibit different colours by reflection and transmission as a function of viewing angle.
A flexible, electrically insulating coating suitable for application by spraying, dipping and syringe dispensing. NOTE: The range of performance available from the use of metallic coatings is limited because of the thickness of coating that has to be applied. The use of dielectric coatings, which produce interference effects, allows higher light transmission with increased selectivity; the range of colours is also increased.
The ratio of the electric energy of the field set up in a dielectric material to that set up in a vacuum. At a given frequency, it is the ratio of the capacitance of the capacitor with the glass material as the dielectric to the capacitance of the same capacitor with a vacuum as the dielectric.
Glass used in picture framing to avoid reflections and the glare of lighting.
Scattering, dispersing, as the tendency to eliminate a direct beam of light.
Deep, short scratches.
Diminishing Stop Bevel
A bevel in which only a portion of the surface edges is bevelled, the bevel running out on a small radius.
That portion of the sun’s emitted solar heat energy which is directly transmitted through the glazing.
Distance Piece (Shims)
Small blocks of resilient, non-absorbent material (such as extruded rubber) used to prevent the displacement of glazing compound or sealant by external loading. They are positioned opposite each other between the glass and rebate, and glass and bead.
Alteration of viewed images caused by variations in glass flatness and is an inherent characteristic of glass that has been heat treated.
The surface edge of the glass on the face that is bevelled, the bevel consisting of two intersecting planes.
In general, any use of two panels of glass, separated by an air space, within an opening to improve insulation against heat transfer and/or sound transmittance. 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
Refers to the direction of flow (or pull) of the glass during production of sheet glass. Float glass has eliminated this issue.
The vertical distance used from the horizontal centre-line of the maximum diameter of the impacting object when it is released, relative to the horizontal centre-line of the impacting object when it is at rest.
Also called compression glazing. This term is used to describe the glazing or sealing in of single glass or insulating glass in the supporting framing system without wet sealants using pre-formed and extruded materials such as glazing gaskets and wedges.
A weather seal between the glass and frame using foam tapes or gasket materials. Note: A dry seal may not be completely watertight.
Insulating Glass units manufactured with a primary seal and a secondary seal for maximum protection against moisture vapour transmission.
An instrument for measuring the relative hardness of materials such as rubber. Also, the term often used (loosely) as a synonym for relative hardness.