Glossary

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AAMA

American Architectural Manufacturers Association. A national trade association that establishes voluntary standards for the aluminum window, door and skylight industry.

Acrylic

(Plastic) A non-crystalline thermoplastic with good weather resistance, shatter resistance, and optical clarity; sometimes used for glazing.

Adhesion

That property of a coating or sealant which measures its ability to stick or bond to the surface to which it is applied.

Adhesive Failure

Failure of a compound by pulling away from the surface with which it is in contact (see cohesive failure).

Air Infiltration

The amount of air leaking in and out of a building through cracks in walls, windows and doors.

Air Pockets

Bubbles of air formed within a compound or between two adjacent beads of compound applied successively in a joint.

Angle Bead or Joint

A bead of compound whose cross-section is triangular shaped with the hypotenuse side exposed.

Annealed Glass

Standard float glass.

Annealing

To heat above the critical or re-crystallization temperature, then controlled cooling metal, glass or other materials to eliminate the effects of cold-working, relieve internal stresses or improve strength, ductility or other properties.

Anodize

To provide an extremely hard non-corrosive oxide film on the surface of aluminum, by electrolytic action. The electrochemical process produces an anodic coating by conversion of aluminum into essentially aluminum oxide. Appearance depends upon both the alloy involved and the surface preparation. Anodic coatings may be transparent, of varying shades of silver, gray or brown, or colors may be incorporated by the use of dyes or pigments.

ANSI

American National Standards Institute. Clearing house for all types of standards and specifications.

ASHRAE

American Society of Heating, Air-conditioning and Refrigerating Engineers.

ASTM

American Society for Testing and Materials. A society of engineers which sets standards for testing of materials.

Batching

The first part of the glass making proces where the raw materials are offloaded on to a conveyer and sent to their respective storage silos. The actual batching begins when the raw materials are moved, weighed and mixed, and sent via a conveyor belt to the charging end of the melting furnace.

Bleeding

The absorption of oil or vehicle from a compound into an adjacent porous surface, and different from migration, which is the spreading or creeping of oil or vehicle from a compound out onto an adjacent non-porous surface.

BOCA

Building Officials and Code Administrators.

BTU

British Thermal Unit. The energy used for heating and cooling is measured by the number of BTU's needed to keep a building at a comfortable temperature. Scientifically, it is the amount of heat energy necessary to raise the temperature of one pound of water one degree Fahrenheit.

Butyl

A synthetic rubber prepared by co-polymerization of isobutylene with a small amount of isoprene (both ingredients are gaseous hydrocarbons). It can be used as a sealant and architectural glazing tape.

Catalyst

A material which markedly speeds up the cure or reaction of another substance when added in minor quantities.

Cavity Wall

A type of building wall construction consisting of an outer wall fastened to an inner wall separated by an air space.

CFM

Cubic feet per minute (written ft3/min.). Unit for air flow.

Channel

A three-sided, U-shaped opening in sash or frame to receive lite or panel, as with sash or frame units in which the lite or panel is retained by a removable stop. Contrasted to a rabbet, which is a two-sided L-shaped opening, as with face glazed window sash.

Channel Depth

The measurement from the bottom of the channel to the top of the stop, or measurement of sight line to base of the channel.

Channel Glazing

The sealing of the joints around lites of glass or panel set in a U-shaped channel employing removable or fixed stops.

Chemical Cure

A change in the properties of a material due to polymerization of vulcanization, which may be effected by heat, catalysts, exposure to the atmosphere, or combinations of these.

Clear glass

The most basic type of glass.

Clearance

The space or distance allowed for anchorage or erection purposes or to accommodate dimensional variations in a building structure.

Cohesive Failure

Failure of a compound when placed under a strain, in which - because of insufficient elasticity and elongation to absorb the strain - the compound splits and opens.

Color Properties

The color of the glass either looking through it (Transmittance) or at a 10 degree angle from normal (Reflectance) expressed using the 3 dimensional CIE L*a*b* color space. L* is an expression of lightness-darkness (higher L* is lighter or approaching white, lower L* is darker approaching black), a* is an expression of red-green color (+a* is more red, -a* is more green) and b* is an expression of yellow-blue color (+b* is more yellow, -b* is more blue). Neutral is considered 0,0 when comparing a*,b*.

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.

Condensation

When water vapor, which is present in all but the driest air, comes in contact with a surface that is below what is called the "dew point temperature," the vapor becomes liquid and is called condensation. An example is as follows condensation forms on a glass of ice water since the surface of the glass is down to the dew point temperature of the inside air.

Conduction

Process of heat transfer through a material from a warm surface to a cool surface.

Convection

Heat transfer by the movement of fluid or air.

CRF

Condensation Resistance Factor. Gives an indication of a window's ability to resist condensation. The higher the CRF, the less likely condensation is to occur.

Cullet

Crushed, recycled glass that is combined with batch materials and melted to form liquid glass.

Curing Time

The time required to complete the chemical reaction of a product to reach its final physical form as a result of chemical reaction.

Curtain Wall

An exterior building wall which carries no roof or floor loads and consists entirely or principally of metal, or a combination of metal, glass and other surfacing materials supported by a metal framework. There are two basic types:

  • Custom - Walls designed specifically for one project, and using parts and details specially made for this purpose
  • Standard - Walls made up principally of parts and details standardized by their manufacturer and assembled in accord with either the architect's design or the manufacturer's stock patterns.

Cut/drilled/notched glass

A type of glass fabrication. It must be done before heat processing.

Decibel

A unit for expressing the relative intensity of sounds on a scale from zero for average least perceptible sound to about 130 for the average pain level.

Decorative glass

Decorative glass is made when vision glass or spandrel glass is silk-screened, painted, patterned, sand-blasted or acid-etched for aesthetics or performance changes. Lines, dots and holes are the most popular types of glass decoration, but virtually any design is possible.

Degree-Day

A unit that represents a 1° F deviation from some fixed reference point (usually 65° F) in the mean, daily outdoor temperature.

Desiccant

An extremely porous crystalline substance used to absorb moisture from within the sealed air space or an insulating glass unit.

Dew Point

The temperature at which the condensation of water vapor in a space begins, at a given state of humidity and pressure, as the temperature is reduced. Used in testing sealed insulating glass. The lower the number, the higher the resistance to forming condensation.

Distributor (GLASS)

(Distributor) Buys glass from the primary manufacturer, stock and resells it to smaller glass shops and other outlets that install or sell to the ultimate consumer.

Double Glazing

In general, any use of 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.

Dry Glazing

A method of securing glass in a frame by use of a dry, preformed resilient gasket, without the use of a compound.

DSE Sealants

A sealant that exhibits properties of high structural strength and low moisture vapor transmission rates.

Dynamic Elongation Test

Elongation or stretching of a material under continuous movement.

Elasticity

Pliability, ability to take up an expansion and contraction; opposite of brittleness.

Elastomer

An elastic, rubber-like substance which may either occur naturally or be produced synthetically.

EPDM

A weathering compound with good resistance to ultra-violet radiation. Good memory and weathering characteristics.

Epoxy

A thermoplastic resin formed by combining epichlorohydrin and bisphenols. Requires a curing agent for room temperature or elevated temperature hardening. Has outstanding adhesion, strength and excellent chemical resistance.

Exterior Glazed

Glass set from the exterior of the building.

Exterior Stop

The removable molding or bead that holds the lite or panel in place when it is on the exterior side of the lite or panel as contrasted to an interior stop located on the interior side of the lite or panel.

Extrusion

The process of producing aluminum shapes by forcing heated metal through an orifice in a die by means of a pressure ram. Also, any item made by this process.

Fabricator (GLASS)

Buys glass from the glass manufacture and fabricates (tempering, laminating, insulating, etc.) to their customers' requirements.

Fading Factor

The measure of the ability of a glazing to reduce fading or damage to interior fabrics and materials. The ISO Damage Weighted Transmittance (Tdw-ISO) calculation assigns a specific damage weighted factor to each wavelength of UV or visible light (from 300nm to 680nm), based on its contribution to fading. Tdw-ISO is expressed as a number between 0 and 1. The lower the value, the lower the risk of fading to interior fabrics and materials.

Fining process

The bubbles that are formed during the melting process during the glass manufacturing process rise to the surface and escape into the chamber atmosphere. The glass then moves from the chamber through a canal into what is known as the bath.

Float Glass

Glass which has its bottom surfaces formed by floating on molten metal, the top surface being gravity formed, producing a high optical quality of glass with parallel surfaces and, without polishing and grinding, the fire-finished brilliance of the finest sheet glass. Float is replacing plate glass.

Fogging

A deposit of contamination left on the inside surface of the sealed insulating glass unit due to extremes of temperatures. Usually happens with failed SIG.

Glazier

Buys glass and installs it on a "contractor" basis. Examples Installing the Window system in large office buildings, shopping center malls, etc.

Glazing

The work of installing glass in a frame.

Heat Gain

The similar transfer of heat from outside to inside. Both heat loss and heat gain are measured in terms of the fuel consumption required to maintain a comfortable indoor temperature.

Heating Degree Day

Heating and cooling engineers have found a way to relate the typical climate conditions of different areas to the amount of energy needed to heat and cool a building. The term they use is "Degree Days" using a base temperature of 65° F. A heating degree day is counted for each degree below 65° reached by the average (between the highest and lowest) daily outside temperatures in the winter. For example, if on a given winter day the high is 40° and the low is 20° , the daily average temperature is 30°. This is 35° below the base temperature of 65° . So, on that day, you would have gone through 35° heating degree days.

Heat Loss

The transfer of heat from inside to outside by means of conduction, convection, and radiation through all surfaces of the house.

Heat-Strengthened Glass

Glass which is reheated, after forming, just below melting point and then cooled. A compressed surface is formed which increases its strength. Used for spandrel glass.

Hermetically Sealed Unit

An insulating glass unit made up of two lites of glass, separated by a roll formed aluminum spacer tube (at the full perimeter) which is filled with a moisture absorbing material. The unit is then completely sealed, creating a moisture-free, clean dead air space.

Humidity, Relative

The percentage of moisture in the air in relationship to the amount of moisture the air could hold at that given temperature. 100% relative humidity would be rain. The amount of degree of moisture in the air.

Hypalon

A synthetic, vulcanizable rubber manufactured by reacting polyethylene plastic with chlorine and sulphur dioxide.

IGCC

Insulating Glass Certification Council.

Inclusion

Presence of foreign matter in a finished material, such as glass.

Insulating Glass

Insulating glass refers to two pieces of glass spaced apart and hermetically sealed to form a single-glazed unit with an air space between. Heat transmission through this type of glass may be as low as half that without such an air space. It is also called Double Glazing.

Interior Glazed

Glass set from the interior of the building.

Interior Stop

The removable molding or bead that holds the lite, as contrasted to an exterior stop which is located on the exterior side of a lite or panel.

Kerf

A cut, notch, or groove in a material.

Kicker

Synonymous with the word activator or catalyst, and sometimes actually added as a third material in a three-part system.

Laminated Glass

Two or more sheets with an inner layer of transparent plastic to which the glass adheres if broken. Used for overhead, safety glazing, and sound reduction.

Laminator

Manufacturer of laminated glass, which consists of 2 or more layers of glass and/or plastic bonded together with a PVB or PVC interlayer.

Lear

Cools the glass at a controlled rate during the glass manufacturing process in order to ensure proper stresses are put into the glass so it can be cut easily and accurately.

Light-to-Solar Gain Ratio

The ratio of visible light to solar heat gain. LSG = VLT ÷ SHGC. Glass with higher LSG numbers are typically desired by architects because they offer superior solar control, with relatively high visible light transmittance.

Low-iron glass

Has as little as 10% of the iron content of regular glass, which allows it to transmit 91% of light and eliminates the greening effect associated with thicker glass panels.

Mill Finish

The original finish produced on aluminum by cold rolling or extruding.

Mirror Manufacturer

Manufacturer of mirrors. Involves a process called "Silvering", where glass is coated (sprayed) with silver, then copper, then a paint (protective) backing.

Mock-Up

A model of a section of a wall or its parts, built to scale or at full size, for purposes of studying its construction details, judging its appearance, and/or testing its performance.

Moisture Vapor Transmission Rate

The rate at which moisture diffuses through a substance. Generally given in the following units grams/meters2 x 24 hours. The lower the MVT rate, the greater the resistance of the sealant to moisture penetration.

Monomer

A substance or simple chemical compound that can be polymerized, yielding a much larger molecule called a polymer.

Mullion

An intermediate connecting member used to "marry" two or more windows or patio doors together in a single rough opening without sacrificing air or watertight performance. A mullion also can give added strength to the connection for structural stability.

Needle Glazing

Application of small bead of compound at the sight line by means of gun nozzle about 1/4" x 1/8" in opening size.

Neoprene

A synthetic rubber having physical properties closely resembling those of natural rubber but not requiring sulphur for vulcanization. It is made by polymerizing chloroprenes. The latter is produced from acetylene and hydrogen chloride.

Nitrile Rubber

A class of rubber-like co-polymers of acrylo nitrile with butadene. There are many types and a few of the trade names are Funa N, Butraprene, and Chemigum. It has high resistance to solvents, oils, greases, heat, and abrasion.

Non-Resilient Tape

A high solids content, mastic material furnished in varying thicknesses and widths, in roll form; easily deformed and permanently soft and tacky.

Non-Skinning

Descriptive of a product that does not form a surface skin after application. Usually remains tacky or sticky.

Non-Staining

Characteristic of a compound which will not stain a surface by bleeding or migration of its oils or vehicle content.

Non-Volatile

Any substance which does not evaporate or volatilize under normal conditions of temperature and pressure.

Nozzle

The tabular tip of a caulking gun through which the compound is extruded.

Opacified glass

Opacified glass is glazed with ceramic frit or silicone-based paint to make it opaque. It is most commonly used in spandrel glass to hide non-vision areas of a building, such as floor lines and columns.

Organic

Compounds which consist of carbon and generally hydrogen, with a restricted number of other elements, such as oxygen, nitrogen, sulphur, phosphorous, chlorine, etc.

Organic Coating

A coating such as paint, lacquer, enamel, or plastic film in which the principal ingredients are derived from animal or vegetable matter or from some compound or carbon (which includes all plastics).

OITC

Outdoor-Indoor Transmission Class (OITC) is measure that determines the amount of outside noise, like traffic, that will permeate a window.

Outside Casing

Wooden exterior framing of the window. 1. A pre-assembled section of wall, including framing (if any), window area, and solid area. 2. A solid filler or facing material, either of one piece or an assembly, or use with a surrounding frame. 3. S length of formed metal sheet, or an assembly of such sheets, usually with insulation between, as used for wall enclosure on industrial type buildings.

Peeling

The failure of a compound whereby the skin curls away from the remaining compound under the skin.

Permanent Set

The amount by which a material fails to return to its original form after being deformed by an applied force or load.

Permeability

The quality of permitting passage of water through openings without causing rupture or displacement.

Plate Glass

Polished plate glass is a rolled, ground and polished product with true flat parallel plane surfaces affording excellent vision. It has less surface polish than sheet glass and is available in thickness varying from 1/4" to 1-1/4". Now replaced by float glass.

Polybutene

A light colored liquid, straight chain aliphatic hydrocarbon polymer. Non-drying and widely used as a major component in sealing and caulking compounds. It is essentially non-reactive and inert.

Polyester

There are many types of polyester resins, and they are manufactured by reacting together two basic raw materials. These are dicarboxylic acid and a dihydroxy alcohol. Polyesters are used in one and two-part systems for coatings and molding compound. The manufacture of Dacron is well-known for polyester fiber.

Polyethylene

A straight chain plastic polymer of ethylene (gaseous hydrocarbon) used for containers, packaging, etc.

Polyisobutylene

Polymer manufactured from gaseous hydrocarbons. The polymer is a major portion of butyl rubber which also contains a small percent of isoprene.

Polymer

A material which has been polymerized from smaller molecules into longer molecules or chains. This can be done by addition or condensation reaction.

Polymerized

Treated by heating or cooking so that molecules of different substances unite into larger molecules of a different substance with individual characteristics.

Polymerization

The reaction occurring when two or more molecules of a compound are united to form a more complex compound with a larger molecular weight.

Polysulfide

Polysulfide liquid polymers (Thiokol) are mercaptan terminated, long chain aliphatic polymers containing disulfide linkages. They can be converted to rubbers at room temperatures without shrinkage upon addition of a curing agent.

Polyurethane

A synthetic rubber formed by the reaction of a glycol with an isocyanate. When used in sealants, yields a rubber-like material with excellent strength characteristics. Used as exterior sealant and sealed insulating glass sealant.

Pot Life Test

The time interval following the addition of an accelerator of curing agent before a chemically curing material will become too viscous to apply satisfactorily. Synonymous with working life.

Pre-Shimming

A preformed tape containing a built-in continuous elastomer rod to eliminate use of individual shims which can be inadvertently omitted.

Primer

A special coating designed to enhance the adhesion of sealant systems to certain surfaces or a final organic coating to a surface.

Priming

Sealing of a porous surface so that compound will not stain, lose elasticity, shrink excessively, etc., because of loss of oils or vehicle into the surface. Frequently the sign of inferior formulation when compound requires priming of surface before application.

PSF

Pounds per square foot (lbs/ft2). Abbreviation of pressure notation, used to describe wind velocity, barometric pressure.

PSI

Pounds per square inch (lbs/in2). As above.

Reflectance

Expressed as a % of reflectivity from the glass surface that is in a given spectrum range; Visible Out covers the reflectance on the exterior surface (surface 1 facing the elements) in the visible spectrum from 380 nanometers to 780 nanometers, Visible In covers the reflectance of the interior surface (facing the inside of the living space) in the visible spectrum from 380 nanometers to 780 nanometers and Total Solar Energy Out covers the reflectance of the exterior surface (surface 1 facing the elements) in the ultraviolet, visible and near infrared energy from 300 nanometers to 2100 nanometers.

Reflectivity

A measure of the ability of a surface to reflect radiation, equal to the reflectance of a layer of material sufficiently thick for the reflectance not to depend on the thickness.

Reglet

Any slot cut into masonry or formed into poured concrete or precast stone. May also be an open mortar joint left between two courses of bricks or stones, or a slot cut or cast into other types of building materials.

Relative Heat Gain (RHG)

A calculated relationship of heat gain (through a window system) that accounts for center-of-glass U-value and center-of-glass shading coefficient (SC) based on a standard inside and outside temperature. The lower the RHG, the more the glass product restricts heat gain.

Relative Humidity

See Humidity, Relative.

Retrofitting

Adding or replacing items to existing buildings. Typical retrofit products are replacement doors and windows, insulation, storm windows, caulking, weatherstripping, vents landscaping.

Roller wave

The periodic wave imparted to glass during heat-treatment, measured by the peak-to-valley distance.

R-Value

A measure of resistance to heat gain or loss (insulative ability). R-Values rather than thicknesses can be compared for different materials, since 6" of fiberglass (R-19) might compare with 12" of wood or 18' of stone.

SBC

Southern Building Code.

Sealant

Compound used to fill and seal a joint, as contrasted to a sealer which is a liquid used to seal a porous surface.

Setting Time

A term used rather loosely to describe a period when a material has either dried sufficiently through solvent release, or cured sufficiently through chemical reaction, to reach either a specified condition or a condition resulting from either of the two processes.

Shading Coefficient

The measure of the heat gain through glass from solar radiation. Specifically, the shading coefficient is the ratio between the solar heat gain for a particular type of glass and that of 3mm clear glass. The lower the number, the better the shading performance.

Shear

Strain put on a compound between two surfaces when there is a slipping movement of the two surfaces parallel to and in opposite directions along the length of the joint, such as occurs when an aluminum channel expands to a greater length than a glass panel when both are subjected to the same pronounced rise in temperature. This kind of strain tends to rub or knead the compound in opposite directions along the joint, as contrasted to other forms of strains which may try to pull the compound apart, by reason of the strain being at a right angle to the joint.

Sheet Glass

A transparent, flat glass whose surface has a characteristic waviness replaced by float glass. There were three basic classifications of sheet glass:

  1. single strength 3/32" thick
  2. double strength: 1/8" thick
  3. heavy sheet which has 3 thicknesses: 3/16", 7/32" and 1/4"

Shore "A" Hardness

Measure of firmness of a compound by means of a durometer hardness gauge. Range of 20-25 is about the firmness of an art gum eraser. Range of 40-50 is about the firmness of a rubber heel.

Sight Line

Imaginary line along the perimeter of lites or panels corresponding to the top edge of stationary or removable stops, and the line of which sealants contacting the lites or panels are sometimes finished off.

Single Glazing

The use of single thickness of glass in a window or door (as opposed to sealed insulating glass which offers far superior insulating characteristics).

Solar Heat Gain Coefficient (SHGC)

Measures how well a window blocks (or shades) the heat from sunlight. SHGC is the fraction of solar radiation transmitted through a window or skylight, as well as the amount that is absorbed by the glass and reradiated to the interior. SHGC is expressed as a number between 0 and 1. The lower a window's SHGC, the less solar heat it transmits and the greater its shading ability. The SHGC is similar to the SC, but also accounts for absorbed, convected, and inwardly radiated solar energy.

Sound Transmission Class

(STC) The sound transmission loss rating of a material over a selected range of sound frequencies. The higher the number, the better.

Spandrel Glass

Heat-treated float glass with a colored-ceramic coating adhered to the back by a heat-fusing process or with a colored water-based silicone coating. It is used as a fixed opaque colored glass on buildings in front of floor slabs and columns. Spandrel glass is available in a wide array of colors, but should be evaluated for thermal stress to determine the level of heat treatment needed.

Summer Day U-Value

The calculation of U-Value using Summer Daytime environmental conditions of a hot outside temperature and direct sunlight.

Tempered Glass

As with heat-strengthened glass, it is re-heated to just below the melting point, but suddenly cooled. When shattered it breaks into small pieces. It is approximately five times stronger than standard annealed glass. It must be used as safety glazing in patio doors, entrance doors, side lites, and other hazardous locations. It can't be re-cut after tempering.

Temperer

Manufacturer of tempered glass, which is heat treated either vertically or horizontally. Tempered glass, when shattered, breaks into rounded, smooth pieces of glass, rather than sharp, irregular pieces.

Therm

100,000 BTU's of energy or heat.

Thermal Break

An element of low conductivity placed between elements of higher conductivity in an effort to reduce the flow of heat and cold, i.e., insulation.

Tinted Glass

A mineral admixture is incorporated in the glass, resulting in a degree of tinting. Any tinting reduces both visual and radiant transmittance.

Tolerance

Permissible deviation from a nominal or specified dimension or value.

Transmittance

Expressed as a percentage of transmittance through the glass that is in a given spectrum range; Ultraviolet (UV) covers the ultraviolet spectrum for 300 nanometers to 380 nanometers, Visible light (VLT) covers the visible spectrum from 380 nanonmeters to 780 nanometers and Total Solar Energy covers ultraviolet, visible and near infrared energy within the solar spectrum from 300 nanometers to 2100 nanonmeters.

Trombe Wall

Glass covered concrete wall that collects and stores heat passively. Heat radiates back into the outdoors or into internal air or heating.

Tvis

The percentage of the visible spectrum of sunlight that is passing through a piece of glass, expressed as a value between 0 and 100. A glass with a Tvis of 0 would transmit no sunlight, while a glass with a Tvis of 100 would transmit all possible sunlight. Abbreviated from "transmittance visible" and synonymous with Visible Light Transmittance. See Visible Light Transmittance (VLT).

UBC

Uniform Building Code.

UL

Underwriters Laboratory.

Ultra-Violet

The invisible rays of the spectrum which are outside of the visible spectrum at its violet end. U.V. rays are found in everyday sunlight and can cause fading or chalking of dark paint finishes. Extreme U.V. exposure can cause certain plastic materials to distort.

Unit

Term normally used to refer to one single lite of insulating glass.

United Inches

The addition of the dimensions of one length and one width of a lite of glass. Example: A window that is 24" wide and 72 high is 96 U.I.

Urethane

Excellent insulator used in insulating panels with extremely high R-value (7.70 per inch of thickness) and U-value (.13 per inch of thickness).

U-Factor

Measures the insulation value of the whole window, including glazing, frame and spacers. The lower the U-factor, the better a window unit’s insulation value. It is the recommended measure by IECC, ASHRAE and NFRC.

U-Value

A measure of the insulating characteristics of the glass or how much heat gain or loss occurs through the glass due to the difference between indoor and outdoor temperatures. The lower the number, the better the insulating performance. This number is the reciprocal of the R-Value.

Vinyl Glazing

Holding glass in place with extruded vinyl channels or roll-in type.

Visible Light Transmittance (VLT)

The percentage of the visible spectrum of sunlight that is passing through a piece of glass. It is expressed as a figure between 0 and 100 – a glass with a VLT of 0 would transmit no sunlight whatsoever, while a glass with a VLT of 100 would transmit all of the sun’s light.

Wedge Glazing

Interior flexible continuous pressure fit gasket that insures a high compression seal between the glass and aluminum while applying pressure and seal to the outside architectural glazing tape.

Weephole

A small opening in a wall or window member through which water may drain to the building exterior.

Wet Glazing

A method of sealed glass in a frame by use of a knife or gun-applied glazing compound or sealant.

Window Wall

A metal curtain wall of the commercial type, in which windows are the most prominent element. Also refers to smallest fixed lites used with wall systems.

Winter Night U-Value

The calculation of U-Value using Winter Nighttime environmental conditions of a cold outside temperature and no sunlight.

Wire Glass

Polished or clear glass, 1/4" thick. Wire mesh is embedded within the glass such that the glass will not shatter when broken. The wire pattern is available in many types. It is frequently used in skylights, overhead glazing, and locations where a fire-retardant glass is required.

Work-Life

The time during which a curing sealant (usually two compounds) remains suitable to use after being mixed with a catalyst.


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Bent_Laminated_Glass Fun Glass Facts!

Established in 1883, PPG is the first commercially successful U.S. glass company.

Tempered glass is four times stronger than regular glass; heat strengthened is just two times stronger.

Pure glass is incredibly strong – it only scratches or breaks because of imperfections that can occur during the manufacturing process.

The first insulating glass units were developed in 1945 for the Pullman Car Company in Butler, PA.

If you see condensation on the outside of your low-e glass windows, it means the coating is working properly.

The word window comes from a Norse term translated "wind eye", for "eye on the weather."

A standard float tank can produce glass 24 hours/7 days a week for up to 15 years before it needs to be rebuilt.

Tempered glass deflects just as much as annealed glass. It also weighs the same.

Insulated Glass Units are made with two or more lites of glass with a hermetically sealed space filled with dry air or insulating gas.

Insulated glass units or double glazed units are a significantly more energy efficient glazing system than single glazing.

IGUs reduce the likelihood of interior condensation forming by providing a thermal barrier between the inside and the outside. The thermal barrier makes interior spaces more comfortable as it is easier to maintain a consistent indoor environment.

Thermal or insulation improvements achieved with an IGU work day and night in both summer and winter conditions, reducing heat entry and heat loss.

IGUs reduce sound transmission and provide quieter interior spaces.

Clear glass isn’t actually clear. It has a light green tint, which can be seen when held against a white background.

Due to the chemistry involved in the float glass process, all the colors of the rainbow are not possible. For example, orange, red, yellow and violet colored glasses cannot be produced using standard float technology.

How much does glass weigh?

Glass 6mm thick will weigh 2.9 lbs. per square foot.

What’s the difference between “float” glass and “flat” glass?

“Float” describes the process by which nearly all commercial “flat” glass is made, so “float” glass and “flat” glass are really the same thing.

Greater than 99 percent of the unused glass PPG manufactures is reutilized in production.

PPG ships the majority of its glass products on reusable steel racks, which has reduced the amount of disposable packaging that accompanies architectural glass products by 65 percent.