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Acid Etched Glass

Acid etched glass is glass that has been treated using a technique generally involving hydrofluoric acid. The acid is applied to the glass only on the specific areas where the glass. Typically, a stencil is used to ensure the acid does not seep into other parts of the glass.

This process of etching produces a smoother and more easily maintainable finish compared to sandblasting.

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A pile of acoustic interlayer.

Acoustic Interlayer

Acoustic interlayers refer to the use of a special polyvinyl butyral (PVB) – a resin-based plastic – as the plastic in laminated glass, which provides sound-reducing qualities in the glass. Acoustic interlayers can be found in vehicles, where laminated windshields are standard features and laminated side windows, also called sidelites, have become more common since 2007. Vehicles that have acoustic interlayers in the windshield or sidelites are said to block out more exterior noise than vehicles that don’t, which should offer occupants a quieter ride.


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Advanced Driver Assistance Systems (ADAS)

Technology that helps a driver avoid hazards on the road is considered advanced driver assistance systems. This technology can range from the most commonly known options such as electronic stability control and anti-lock brakes, to blind-spot monitoring, lane-change assistance, collision warnings or avoidance systems, such as automatic braking. ADAS technology is designed to either alert the driver of impending challenges or to override the driver input to prevent collisions. ADAS is available to varying degrees in commercial vehicles, but are the driving force behind autonomous vehicles.

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glass anchoring system diagram

Anchoring system

Where glass and glazing is concerned, anchoring systems are present in some safety and security glazing systems and attach window film to the glass or to the frame of the glazing. Anchoring systems can be wet glazed or mechanically attached.

A wet glaze attachment is where the manufactured seals on the glazing are removed and security or safety window film is applied all the way to the edge of the glass. A new sealant is applied, securing the film and glass in place in the frame.

A mechanically-attached anchoring system physically attaches the security or safety film to the frame. The film is applied to the interior surface of the glass with an overhang that is either screwed into the frame or that is held in place with an anchor that is glued to both the glass and the frame.

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shattered annealed glass

Annealed glass

Glass that is left to cool at a natural speed during the manufacturing process is annealed glass and, when broken, will break into large pieces afterward. The larger pieces of glass when broken often have very sharp edges and can cause significant injury to people or damage to property nearby.


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architectural glass

Architectural glass

Any glass used in buildings, both residential and commercial, as part of the design is architectural glass. The most commonly known application of architectural glass is windows and doors, but the phrase also applies to glass walls, building facades and spandrel glass.


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Athermic Windshield

Also called metalized windshields, athermic windshields have a very thin reflective coating that acts as a screen or filter to deflect most of the solar (infrared) rays of the sun while allowing visible light to pass through the glass. The coating, which is applied during the glass laminating process, is meant to reduce radiant heat transmitted into the car through the windshield. Athermic windshields may interrupt or block radar detectors, tollroad passes, and even some remote garage door openers, and now have areas that are left untreated to prevent device blockage, though the areas on the windshield vary from one car model or windshield manufacturer to the next.

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A white Autonomous car

Autonomous Vehicles

Also known as driverless cars or self-driving cars, autonomous vehicles are piloted by a combination of technologies, including radar, lasers lights, GPS, and computer vision and do not require human input behind the wheel.

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A red and white awning hanging from a white building.


An awning is an architectural addition made of cloth, aluminum, vinyl, or even wood, that extends outward from a building providing shade at the least and sometimes protection from precipitation. Awnings can be stationary or retractable, and differ from canopies due to their lack of column support. Awnings generally are made of framing that attach to the building without additional support.

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An awning window

Awning Window

An awning window is one that opens from the bottom and swings out and upward, to a position that mimics an awning.

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review look of the black glass of a BMW.


What most people commonly refer to as the “back windshield” or “back glass” of a vehicle is referred to within the auto glass industry as the backlite. Not all vehicles have backlites, but in those that do, it is often the largest or second largest piece of glass on a vehicle and is found at the rear of the seating compartment.

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sliding barn shower door

Barn Shower Doors

Similar to a sliding or bypass shower door, barn shower doors slide open left to right on a sliding mechanism along the top of the door, as they do not sit in a specific track. Barn doors—which open on a slide at the top—are gaining popularity in homes in general, as they don’t require as much floor space as a swing door, and have been seen as bathroom entry doors, among other uses. As a shower entry, barn shower doors can be a type of frameless shower door, as the sliding apparatus at the top serves as the connection to the shower or bath enclosure.

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A clean, simple bathroom. In the bathroom with a glass door shower, a white toilet, and a white vanity.

Bath Screen

A piece of glass made for use on the side of a bath space, providing a barrier between the water of the shower and the rest of the bathroom, without entirely enclosing the tub. Bath screens are generally at least as tall as the shower head and about half the length of the tub. They can be hinged, allowing for full access to the tub space, or they can be made of multiple pieces of glass, with one fixed and the others operational. Those operational pieces can be hinged so that they can fold in upon the set piece like bi-fold or tri-fold doors.

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Bay window, bow window, operable window, flankers

Bay Windows

Bay windows are similar to bow windows in that they extend outward from the flat plane of the building. However, bay windows usually have fewer windows—often only three—with the center window being a fixed window and flanked by two operable windows, appropriately referred to as “flankers.”

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large bent glass wall structure on building

Bent glass

When float glass comes off the manufacturing line it is a flat sheet. However, glass can be made to bend when the need — or design – calls for it. Bent glass is also called curved glass and can be found in vehicles (many windshields and some backlights are curved on the edges) as well as in architectural designs, from glass domes and hand rails to revolving doors and display cases. Due to the brittleness of glass, bending must happen while the glass is still warm enough to be manipulated but not so hot that it is molten. To bend glass, manufacturers place a piece of glass over a piece of metal made to simulate the curve needed for the glass. Both the metal and glass are placed into an oven and heated until the glass begins to soften, at which point both the glass and the metal form are removed from the heat. If left alone, gravity will pull the softened glass down and onto the shape of the intended curve, or an outside force can apply pressure to hasten the bending process.


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An open, wooden bi-fold leading into a shop.

Bi-fold Door

A door that is made of two slender panels with a hinge in the middle, bi-fold doors slide open in one direction, bending at the hinge. Bi-fold doors open in one direction and fold fairly flat, making them a space-efficient option for areas that don’t have as much room for a door that swings open. Consumers can find bi-fold doors in houses for the closet, patio, and shower doors

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blown glass, glassblowing

Blown Glass

Blown glass objects are those made through the process of glassblowing, wherein air is literally blown through a tube into molten glass, forming it into different shapes and pieces while still in its molten state. Blown glass objects are usually used as decorative glass but some pieces can be formed into functional items such as vases.

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bow window, bay window

Bow Windows

Bow windows are a specific architectural element that comprises multiple windows set at angles to one another so that the element in its entirety bends or bows outward from the flat plane of the building.

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bullet resistant glass with a bullet hole in it.

Bullet-proof glass

An industry-acknowledged misnomer, the phrase “bullet-proof glass” actually refers to what is really bullet-resistant glass. All glass will shatter and the thermoplastic can only absorb so much energy. While these elements, used in combination, can slow – and often stop – a bullet, it must be stressed that there is no such thing as bullet-proof glass. At least one member of the glass and glazing industry has previously said that the use of the phrase “bullet-proof” in relation to glass can create a false sense of security in those whose lives may depend on it.

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Shattered bulletproof glass

Bullet-resistant glass

One aspect of security glazing is bullet-resistant glass, which is designed specifically to minimize damage the glazing system might sustain if subjected to gunfire. Bullet-resistant glazing usually includes layers or multiple layers of laminated glass and thermoplastic. The laminated glass used for bullet-resistant glazing is nearly always tempered glass, which, when broken, will shatter into small pieces rather than large shards. The plastic interlayers that laminate the glass hold the fragments together when broken and the thermoplastic between the layers of laminated glass provide elasticity to absorb the bullet’s energy to slow and sometimes stop a bullet, depending on caliber and the distance from which it is fired.

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A glass bypass shower door.

Bypass Shower Door

The professional name for sliding glass shower doors, bypass doors slide past one another the same way sliding patio doors do. A bypass shower door may have a set pane with one side sliding on a track or both panels of glass can move. The track can either have manual rollers in it, or the sliding piece can just glide without extra support. Bypass or sliding glass shower doors are space-efficient, as they require no room to swing open.

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An open casement window with a yellow lab resting in the open section of the window.

Casement Window

A casement window has framing with a hinge that allows an architectural window to open outward from the building, swinging right or left as would a door.

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ceramic stove top


Most people use the word ceramic to refer to anything made of a nonmetallic mineral, such as clay, and permanently hardened by heat, though it can describe the manufacturing of those items as well (e.g. earthenware, porcelain, or brick).

Ceramic materials are brittle, hard and strong in compression (forces pushing or pressing on it) but weak in shearing (forces moving parallel to the surface, such as wind) and tension (forces pulling on it). They withstand chemical erosion that occurs in other materials subjected to acidic or caustic environments and can generally can withstand very high temperatures, up to 3,000°F (1,600°C).
Most ceramics are crystalline and good thermal and electrical insulators but poor conductors of electricity. Glass is not a ceramic because it is a non-crystalline matter, but there is overlap in the manufacturing processes and the mechanical properties of glass is similar to ceramic materials.
A glass-ceramic is made when cast or molded glass becomes partly crystalline during additional heat treatments after the initial fabrication. Glass-ceramic is most widely known for its use in cook-tops but also serves as a glass composite material for nuclear waste disposal.

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A man standing in a glass balcony over looking a city.

Chemically-Strengthened Glass

Giving glass a potassium salt bath just after it was manufactured but while it is still warm (post-production) makes chemically-strengthened glass. Though it is considerably stronger than standard annealed glass and does not break easily, chemically-strengthened glass is not considered safety glass, because when it does break, it breaks into long, sharp shards as does untreated annealed glass. For chemically-strengthened glass to qualify as safety glass, it would need to be laminated. Chemically-strengthening glass is primarily used for thin glass applications.

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Close-up of low-iron glass corner.

Clear Glass

Clear glass is what consumers think of when they think of glass: that with no visible tint or additives that make it anything but transparent. When float glass comes off the line, the presence of iron shows up as a green tint. Low-iron glass was developed to lessen the green tint and create more transparent, clear glass.

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glass coating, coating, Low-E, hard coat, soft coat


Glass coatings come in different varieties and serve different purposes, from strictly aesthetics (how the glass looks) to practical (how it performs), such as Low-E glass. Coatings can be applied during the float process, while the glass is warm, and those are referred to as hard coats; or a coating can be applied in post-production, via a vacuum process, which creates a soft coat.

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concave mirror

Concave Mirrors

Concave mirrors bend inward from a flat plane, bending into a middle point, like a hole – or cave entrance – extending away from the viewer. Reflections in a concave mirror can be real images, meaning they are projected outward, in front of the mirror, appear to be floating, and can be viewed even without looking into the mirror; or the images can be virtual and appear only inside the mirror. The kind of reflection the mirror provides depends on the distance between the object and the mirror. Concave mirrors are used in reflecting telescopes, spotlights, and laser construction.

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convex mirror

Convex Mirrors

Convex mirrors bend outward from a flat plane, like a bubble. The curvature of a convex mirror can distort images, making them smaller than they are or would typically be if viewed in a plane mirror. Convex mirror reflections also are always virtual and upright. These mirrors often are found where hallways of busy buildings intersect, such as hotels and hospitals, to allow people to see around corners. Convex mirrors are also found in car side-view mirrors, some of which contain the wording “Objects in mirror are closer than they appear,” in an acknowledgment of the distortion the curve, no matter how slight, will create in the reflection.

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curved glass

Curved glass

Also known as bent glass, curved glass is glass that has been reheated and shaped, usually over a metal mold, to a desired bend or curvature, and left to cool in that position. Curved glass can be found in vehicles (many windshields and some backlights are curved on the edges) as well as in architectural designs, from glass domes and hand rails to revolving doors and display cases.

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decorative glass

Decorative glass

Glass that is used for more than just a functional purpose—particularly if it is designed to be pretty or change the look of the space in which it is used—is decorative glass (also known as ornamental glass). Easily recognizable use of decorative glass might be frosted, colored or textured glass in doors, which can be found in residential as well as corporate buildings. Stained glass is also a type of decorative glass.

The use of decorative glass can range from doors (especially shower doors) to stairways and hand rails, desks, tables and walls. Furniture made of glass is classified as decorative glass, as are shelves and floors made of glass.

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Distorted Glass / Glass Distortion

The view looking through flat glass is generally expected to be crystal clear by the viewer. However, occasionally the view looks a little off. It might be warped or wavy. If it is, that’s an example of glass distortion. Glass gets distorted in a few different ways, most of which are during the manufacturing process, such as when heat-strengthened or tempered flat glass is being made. When the molten glass is spread, it can start to droop between the rollers that move it along the system. These small dips are then locked in place during the cooling process, creating what is known as roller wave distortion in the glass.

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Double glazing glass close up

Double glazing

The original and most common form of insulating glass, double glazing consists of two pieces of glass, separated by one spacer. The space created between the glass can be filled with noble gases, such as argon or krypton.

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A double Hung window

Double Hung Window

A double-hung window has two moving parts, or sashes, and can be opened from the bottom (a sash that moves upward) or the top (a sash that can slide down).

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A hand holding a smart phone while the other hand uses a finger to scroll on the phone screen.

Electrically conductive glass

Glass generally does not conduct electricity well, but special coatings designed to conduct electricity can be added in post-production that allow glass to do just that. The coatings, which are often made of tin oxide but also can be made of other metals, including gold, or combinations of other metals. The uses of electrically conductive glass include touch screens, electrochromic glass and thin film photovoltaics.

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Windshield reflecting a red leave covered tree.

Electrochromic Glass

A kind of variable transmittance glass, electrochromic glass works in a way similar to suspended particle devices (SPDs), but generally uses lithium ions instead of nano-particles, and does not require sustained voltage to maintain the change in the glass. When electrochromic glass is activated, a single burst of electricity is dispersed and the look of the glass changes, even after the electricity has dissipated. The glass will retain that specific look—be it transparent or translucent—after the electricity no longer is provided to the unit. A second burst of electricity is required to change the glass back to the original state. Electrochromic glass does not change instantly or evenly; the change is often first noticeable on the sides first and moves toward the center. The time it takes to complete the change from one look to the other can depend on the size of the glass and some electrochromic glass provides a certain amount of limited visibility in its darkened state.

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ENERGY STAR® is a program run by the Environmental Protection Agency and the Department of Energy, that promotes energy efficiency and encourages consumers to protect the environment while saving money.

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Entry doors, front doors, doors

Entry Doors

Any traditional opening door that allows access or entrance to a building from the outside.

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A trash can filled in the middle of tall green grasses.

Environmental Product Declarations

Environmental Product Declarations, or EPDs®, are statements that reflect what a product’s life cycle and its related impact on the environment will be. The statements are verified independently, usually through testing by a third-party company. They are registered and contain specific, clear information that can be compared with similar products. The most commonly recognized EPD for windows and glazing are ASTM ISO 14025 and EN15804. EPDs were introduced in 2002.

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Religious etched glass

Etched glass

A kind of decorative glass, etched glass is the result of a series of small cuts made to the glass, by acidic, caustic or abrasive substances, after the glass has been manufactured. The cuts normally appear white against the glass and can be made into patterns or images. Etched glass can be made by sandblasting, acid etching, using glass etching cream or even mold etching, where a mold is made with the design or image created in relief and molten glass is poured into the mold and left to cool.

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Black felt being held by two fingers.


This is a weatherstripping which runs along the inside of a window’s frame, against the glass. It helps seal out air, dirt and other contaminants.

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Worker laying fiberglass insulation.


Fiberglass, as most consumers understand it, is a glass composite. It’s made when glass filaments are woven or pressed together, and can be strengthened and/or molded in different ways with the addition of plastic resins. Technically, the word Fiberglass is a trademarked name—owned by Owens Corning—now a proprietary eponym, a brand name that, due to its popularity or significance, has become the generic name for the product it represents.

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one-piece fiberglass shower

Fiberglass Showers

Fiberglass, the glass filament composite, can be used to make shower and bath enclosures when polyester is added into the fiberglass mix. Mixing fiberglass with the resin allows the material to be molded by either spraying it or pouring it into a mold. In this case, the mold is the shape of a shower or bathtub enclosure. The mold is cured into a hard laminate that is long-lasting but less expensive than acrylic, ceramic, or tile shower and bath enclosures. Fiberglass shower enclosures, like those made of acrylic, are usually made in a single piece, without a seam that might weaken at a later time.

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fire-rated glass

Fire-rated glass

Fire-rated glass refers to glazing that employs the latest technology to prevent glass breakage when exposed to high heat, such as in a fire. Keeping a glass surface intact protects building or room occupants not only from fire but smoke that may accompany the fire. A newer, safer version of wired glass exists, as do other glazing alternatives that are clear and wire free. The actual fire ratings assigned to the glass refer to the length of time the glass can be exposed to heat before it fails. Ratings can be measured in minutes or hours.

Fire-rated glass is either fire protective or fire resistive. Both block smoke and flames but fire protective glazing can still transfer the heat of the fire to the other side of the glass, while fire restrictive glazing does not.

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window flashing, hail damage, skylight, insulating properties


Flashing refers to weatherproofing a window. The material itself, which can be metal – aluminum, copper, zinc, or steel – vinyl, or tape, is called flashing and is installed around the window to fill any gaps and prevent water from entering the building. Incorrectly installed window flashing, or a lack of flashing, can allow water into the wall cavity and lead to wood rot or insect infestation.

However, the act of installing it is also referred to as flashing. Videos and articles are available online on installing and flashing windows correctly.

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A view looking up of flat-glass windows

Flat glass

All glass goes through a molten (liquid) state and how it is cast (made into its final product) determines its shape. When molten glass is spread out in sheets on a metal plane, it makes flat glass. The glass is flat like sheets of paper. It is also sometimes called sheet glass and plate glass.

The most common use of flat glass is in windows, doors, automotive glass, mirrors and in solar panels. Flat glass is made by melting sand and other materials into a liquid, spreading the liquid (molten) glass to a desired thickness, and cooling into the final product.

Flat glass has a different chemical make-up from container glass, which is used for bottles, jars, cups, and glass fibers used for thermal insulation, in fiberglass composites, and optical communication.
Most flat glass is soda-lime glass and is most frequently made via the float glass process, though it can also be rolled or made by broad sheet. Flat glass can be bent after it’s made, for architectural and automotive applications

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A machine arm holding a flat piece of glass.

Float Glass

Float glass uses the manufacturing process of flat glass. Molten glass is literally floated on a bed of metal, usually tin. A couple of float glass applications include the making of windows and glass doors. Float glass can be manufactured clear or colored and is one of the less expensive methods of producing flat glass, as previous methods required more space and time. The float manufacturing process was introduced in the 1950s and is currently the most common way of making flat glass.

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Man inspecting a windshield

Flush Mount

When an object is mounted, if it is set into the surface, into a hole cut to fit it, where it becomes part of the flat plane. This means that the object itself is flush with its surrounding and not sticking out or above the plane into which it is placed (in contrast to surface mounting). In auto glass, windshields or backlites are flush mounted, particularly in older model hot rods and the newer model cars that do not have a windshield moulding.

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Foxed Mirrors

A foxed mirror is an old mirror that is starting to deteriorate. It may have spots and browning that cannot be removed with regular cleaning and it may be less reflective. Popular now as part of the shabby-chic decorating style, mirrors can be intentionally foxed with chemicals applied to the surface after manufacturing.

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framed shower doors

Framed Shower Doors

Framed shower doors have glass that sits inside a metal frame, through which the door is attached to the shower or bath enclosure.

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frameless shower doors

Frameless Shower Doors

Glass shower doors that do not attach to the rest of the shower enclosure via a metal frame are frameless shower doors. These shower doors usually only have hinges attaching them to the shower enclosure but no other connection.

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The black band and accompanying black dots at the top, bottom, and/or sides of a windshield is the windshield frit, which serves a couple of different purposes. Made of ceramic that is baked into the edges of the glass, the frit provides a different texture to the inside of the glass to allow the urethane (the glue) to bond to the windshield for installation. The frit that faces the outside of the glass provides a shade or shield against the sun and ultraviolet light, either to protect the urethane during the installation process, or the occupants of the vehicle, depending on the location of the frit and how far into the windshield it extends.

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An outside view of a full glass window wall.


A ubiquitous building material, glass is a hard, brittle and transparent solid material that is used in a variety of ways across different industries, from architecture and building to science and technology.
Glass is made by melting together a silicate (e.g. silicon oxide or quartz) and an alkali (soda, lime, etc.). The resulting matter is a non-crystalline structure. The most common kind of glass is silicate glass, which consists mainly of silica or silicon dioxide (SiO2). Silicon dioxide is the chemical makeup of sand, which is why many people say that glass is made from sand—it is a primary component.
Other substances can be added to make different kinds of glass. Boron oxide added to the mixture will make a tougher glass that remains solid at high temperatures, such as the glass used in kitchens and laboratories. Iron alters optical properties of glass and can be found in decorative glass applications. Glass can be colored by adding metallic salts, and can also be painted after manufacturing.
Glass both reflects and refracts light. Cutting and polishing glass in certain ways enhance these qualities and create optical lenses, prisms, fine glassware, and optical fibers for high speed data transmission by light.

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Glass brick wall

Glass block

Glass that is made generally smaller and significantly thicker than traditional windows and look like building blocks are called glass blocks. They can be anywhere from 2- to 3-inches thick or more and they offer light transmittance but not usually the same optical clarity as regular windows. Glass blocks, which are sometimes called glass bricks, are often squares, though they can be made into other three-dimensional shapes, such as hexagons and end blocks for curves. Glass blocks are most frequently used in wall fabrications (especially bathroom installations) and decorative windows, though they can also be used in flooring and some furniture building.

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A look up view of a ceiling of glass canopies.

Glass Canopies

Architectural canopies, freestanding or not, provide a cover over a space without the benefit of walls. Glass canopies are simply that—canopies made of glass. Glass canopies can be supported by a building to which they are attached, or they can be free standing, with different kinds of support.

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Glass Deflection

Glass deflection is the amount that a piece of glass bends, or flexes, at its center point when a force, such as wind load or snow load, is applied. Extreme amounts of deflection can lead to distortion. Therefore, The International Building Code (IBC) has established deflection limit standards for glass wall systems.

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glass ornament, ornamental glass

Glass Ornaments

Glass ornaments can be any piece of ornamentation made of glass, whether a holiday ornament such as a Christmas tree ornament, or a decorative piece that adds to the décor of a room. Glass ornaments could be considered a type of decorative glass and can be made of nearly any kind of glass, from clear, annealed glass, to crystals or blown glass pieces.

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A man grinding a piece of wood. He is being protected by a glass shield.

Glass Shield for Equipment

Occasionally, production machinery requires a safety shield to protect the operator from aspects of the production process that may include flying pieces of raw material. The operator still needs to see the production process and glass shields provide clear visibility and protection. Glass shields can be cleaned regularly, and will not be as susceptible to abrasions and contaminants that could cloud plastic. Different types of glass, in conjunction with ceramics, can provide strength and heat resistance during the production process.

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Upper view of a window spacer.

Glass Spacer

Glass spacers—sometimes simply called spacers—are used in insulating glass units (IGUs) to create a space that physically separates the lites of glass. That space it creates is sometimes filled with inert gases that add to the insulating properties of the IGU. Spacers can be made of different materials (plastic, metals, composites) and depending on the material and the IGU, they play different roles in addition to creating the space. Warm edge spacers create an additional layer to heat loss through the windows; some spacers may help absorb moisture.

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A sliver pan sits on a glass stove top filled with cut up yellow and red peppers.

Glass Stove Top

The glass stove top is made of a glass-ceramic blend that provides the stove top with the strength and heat-resistance needed to sit atop heating elements. The glass in the stove top is cooled before undergoing a special heat treatment to partially crystalize the glass. The end result is a piece that can expand and contract with the heat, as need be, without being as porous as traditional ceramic.

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blown glass, glassblowing


Glassblowing refers to the act of manipulating molten glass into artistic pieces. Many people recognize a form of glassblowing called free-blowing, which is the blowing of air through a tube into a blob of molten glass at the end of the tube. Free-blowing creates orbs of glass that can be formed into other shapes while the glass remains warm. Mold-blowing is similar to free-blowing, but includes placing the molten blob of glass into a shape mold and blowing the glass to fill the mold.

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Glazier Points

A type of glass stop, glazier points keep glass in a sash or wood frame and are commonly used in picture and mirror framing. Glazier points usually are flat pieces of metal, with a point on one end that wedges into the frame, and two small bits that sit at a 90-degree angle to create a ledge behind which the glass sits, keeping it flush to the frame.

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Gorilla Glass

Gorilla Glass®

Corning Glass has a line of ceramic-hybrid glass with the registered name Gorilla Glass. Described as thinner, and lighter weight than other glass, Gorilla Glass is also reported to be harder than other glass and equal hardness to that of a sapphire. Gorilla Glass is subjected to a chemical process called ion exchange, which is what gives the glass the hardness for which it is known. According to the Corning website, the science behind Gorilla Glass was created in the 1960s but the product created then is compositionally different from the various incarnations of Gorilla Glass available today (there are four kinds of Gorilla Glass on the market). Gorilla Glass frequently can be found on electronic devices such as smart phones and tablets, and the company states that it can be used in automotive applications.

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A diagram of head up technology of a BMV E60.

Heads-up Display (HUD)

Automotive technology that projects information onto the windshield of a vehicle in front of the driver, allowing the driver to keep their head up instead of looking down onto the dash for the same data.

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Health Product Declaration

Health Product Declarations

Similar to an EPD, a health product declaration (HPD) is an independently-verified document that presents specific information regarding the materials used in the product and how those materials may affect human health or local ecology. Like an EPD, an HPD statement should be clearly written in such a way that the product can be compared against similar products. HPDs were first initiated in 2010.

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A car sideview mirror reflecting a sunset.

Heat Mirror®

A proprietary brand by Eastman Chemical, Heat Mirror is the registered name of a line of insulating glass units that the company says insulates a building as well as a traditional wall.

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Heat Soaking

Heat soaking is a method of making thermally toughened glass to decrease the chances of spontaneous breakage. Because spontaneous breakage can happen when nickel sulfide

is in the glass, heat soaking is done in a chamber and exposes the glass to higher levels of heat than the nickel sulfide can withstand, allowing the piece to break in a safe environment rather than during installation or while in the end customer’s possession.

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window film, window tint, tint, solar control

Heat-Absorbing Tint or Film

Windows and other glass elements in architecture can have the potential to allow heat to escape from a building during the winter and allow heat into a building during warmer months. Unless the windows are made to prevent that heat transfer, a building would require more energy for heating and cooling the interior. One way to prevent heat transfer is with heat-absorbing tint or window film. Often an aftermarket application, window tint—a type of window film made specifically to darken the glass or reflect light—will reduce glare and absorb solar heat from the outside. Certain colors, particularly bronze, green, or gray tint will lower heat transfer (prevent heat from entering or leaving through a closed window) by up to 45 percent. Lowering the heat transfer reduces the energy costs for keeping the building interior stable. While heat-absorbing films are made to be practical, they also do offer a certain decorative element, though not on the scale that decorative window film provides. Decorative film does not generally provide heat-absorbing properties.

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Glass skyscraper.

High performance glass

The phrase high performance glass is a broad description that can encompass any added benefit the glass provides, other than a general, practical component. High performance glass is most commonly applied to glass that provides (additional) energy efficiency. However, the phrase is technically broad enough that impact resistant glass – both security glazing and safety glazing – and glass with electrically charged interlayers can be considered high performance glass.

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Two large hinged doors are open, leading to an opened glass door, into a restaurant.

Hinged Door

A hinged door normally has two or three hinges on one side that allow the door to open in one direction (inward or outward). Some hinged doors will be able to open only 90 degrees, while others – with enough room – can open to 180 degrees. Hinged doors can be found in almost any residential or commercial building, including entry doors, closet doors, and shower doors.

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An exterior view of an open hopper window.

Hopper Windows

The opposite of the awning window, which tilts outward from the bottom like a building awning, a hopper window tilts inward from the top. Hopper windows are frequently used in basements.

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Inside a building with tall open ceiling. Looking out is a giant glass wall that looks out to a body of water with palm trees.

Hurricane resistant glass

A type of security glass, hurricane-resistant glass and the accompanying components that make up the glazing system (window or door) are designed to withstand the high winds and high-velocity projectiles associated with hurricanes.

Like bullet-resistant glass, hurricane resistant glass starts with laminated glass and can be set in a frame that is also designed to be stronger and withstand the elements. The glass and frame system can also be part of a bigger system that is anchored into the wall.

Hurricane resistant glazing is meant to help protect the interior of a building from the high winds, strong rain and projectiles that form when a hurricane makes landfall. If a window or door is breached during a hurricane, wind and rain can penetrate the building and cause structural damage to the building. Hurricane resistant glazing is frequently measured against the Miami-Dade County Hurricane Code, considered by the building industry to be one of the most stringent in the nation.

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Inside view of a car windshield covered in soapy water.

Hydrophilic Glass

A type of self-cleaning glass, the coating on hydrophilic glass makes water run in sheets, rather than single drops. Hydrophilic glass is almost the opposite of hydrophobic glass, in that the water is attracted to the coating and spreads out. Like hydrophobic glass, the hydrophilic glass coating plays a part in the self-cleaning aspect, but rather than preventing substances from adhering to the glass, hydrophilic glass coating breaks down organic matter when exposed to UV light. After a day in the sun, dirt and organic matter can be washed away when rain or other water applied to the surface runs flat and quickly across the surface of the glass.

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Water droplets on glass.

Hydrophobic glass

A type of self-cleaning glass, the coating on hydrophobic glass essentially repels water. It also prevents most dirt and contaminants from bonding to the glass. The water drops roll together into larger beads (which take up less surface area) and are able to pick up more dirt (both organic and inorganic) as they roll off the glass. The most commonly recognized hydrophobic glass coating is sold directly to consumers as Rain-X®.

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Insulated Glass Unit

An insulated glass unit (IGU) is a window that consists of two or more panes of glass with a sealed air gap between the panes. The air gap acts as insulation and can either be vacuum sealed or filled with an inert gas such as argon or krypton. The inert gas filling reportedly helps increase the insulating properties.

Most insulated glass units are double-pane, but some areas of the country require further insulation using triple-pane units or even quadruple pane units. Insulated glass units are also known as insulating glass units.

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Double glazing insulated glass

Insulating glass

Insulating glass refers to glass that is made to prevent significant heat transfer into or out of a building through glass. It consists of multiple pieces of glass separated by spacers made of either metal, such as aluminum, or structural foam. The space between the glass is sometimes filled with a noble gas, such as argon or krypton. Insulating glass is often abbreviated IG and is sometimes called double-glazed or double-pane glass. More recently, with additional lites of glass being added, it now can also be triple-paned or quadruple-paned glass.

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Insulating glass unit

Insulating glass units

Insulating glass is comprised of several pieces: multiple pieces of glass, materials that create and maintain space between the glass and any gas added to the space between the glass. All of these pieces are assembled into a single, sealed unit that holds the entire system together and prevents changes, especially to the air (or gas) between the glass. These complete units are called Insulating Glass Units, or IGUs.

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A man inspecting a cracked windshield.


The interlayer is the plastic used in between pieces of glass to make laminated glass.[/caption]The plastic used in between pieces of glass to make laminated glass is the interlayer.

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Shattered glass close-up.

Laminated glass

The practice of sandwiching a thin film of plastic between two pieces of glass creates laminated glass, a common component both safety and security glazing. The plastic sheeting, usually made of polyvinyl butryl (PVB), holds the glass together when it is broken, preventing the glass from flying and causing injuries or damage. Laminated glass consists of at least two pieces of glass and one plastic interlayer, though it can be made with more layers if needed.

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Broken laminated tempered glass with a chunk missing.

Laminated tempered glass

Glass that is cooled very quickly during the manufacturing process (tempered) and then paired with another piece of glass and a thin plastic film (usually polyvinyl butryl) in between makes laminated tempered glass. In short, a piece of tempered glass has been laminated, merging the two most common ways of keeping people safe from glass breakage. The resulting glass, if broken, will shatter into very small pieces that are held together by the plastic interlayer. The lamination prevents those tiny shards of glass from flying if, for example, the glass were to be hit by an object that, under normal circumstances, would propel them with some force.

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Layered Glass / Multi-Layered Glass

Layered or multi-layered glass gets its name from the process of layering glass, sometimes of different colors, together into one piece usually of substantial size. Layered or multi-layered glass, while decorative on its own, can be carved or etched for additional decorative looks and can be combined with or used as functional pieces.

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A narrow, wooden hallway with a glass railing. Surrounded by green lights.

LED glass

Light Emitting Diodes, or LEDs, are considered a more energy efficient lighting source than traditional incandescent or even florescent light bulbs. They are frequently smaller and seem brighter than incandescent or florescent bulbs and they can be incorporated into glass.

By incorporating LEDs into glass, particularly during the fabrication process, companies can create specific looks – both practical and decorative – to meet a customer’s needs. LED glass can be used in nearly any application that decorative glass might be used that would also benefit from proper lighting, such as display cases or counters at a store, around skylights or on surfaces onto which a company might want to project or display a logo with light so that it may be seen at night.

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Life cycle analysis

Life Cycle Analysis

A life cycle analysis (LCA) is a study of all aspects of a glass product, starting with the collection of raw material, and the impact the product has on the environment, including what it takes to manufacture the product and what the product does once it is finished and in use. An LCA can include information about the resources needed to maintain and repair the product, as well as recycling and/or disposal of the product when it can no longer be repaired.

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Light Transmittance

Light Transmittance, also referred to as Solar Transmittance or Visible Transmittance, is the measurement of visible light passing through a piece of glass. Light transmittance can be altered by the addition of glass coatings, etchings, solar films, and more. It is measured as a percentage where 100% would be completely clear and transmit all the light, while 50% would only let half the light through.

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low-e diagram

Low-Emissivity glass

Commonly referred to as Low-E glass, this kind of glass has a coating that reduces the ultraviolet and infrared light that passes through a window. It helps regulate temperature (and energy consumption) within a building by redirecting heat back in the direction from which it is coming. Low-E coatings are made of microscopically thin coatings of materials that reflect heat much better than it absorbs or emits it (e.g. silver and/or a metal oxide). These coatings are applied to glass either during the manufacturing process (a pyrolytic application) while the glass is still hot and forms what is called a “hard coat” as the glass cools, or after the glass has been cooled and cut, via a vacuum process called sputtering, which results in a “soft coat.”

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Close-up of low-iron glass corner.

Low-iron glass

As the name implies, low-iron glass is glass that has less iron in it than what most people think of when they think of glass. Clear float glass, as it is normally made, has a greenish tint, which is evidence of the iron content. By reducing the amount of iron in the glass, the tint that would naturally be found in the glass is reduced as well. Low-iron glass can be treated the same way as clear float glass, being tempered during manufacturing or laminated afterward. It can be used the same way as clear float glass and is frequently found in applications where clarity is important, such as display cases and shop windows, as well as in shower doors and bath enclosures, among others.

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Metalized Windshield

Also called athermic windshields, metalized windshields have a transparent reflective coating that helps to deflect most solar (infrared) rays of the sun. The coating is applied during the manufacturing process during the laminating stage. Metalized windshields may interrupt or block radar detectors, tollroad passes, and even some remote garage door openers. Newer versions typically have untreated areas to prevent device blockage, though the areas on the windshield vary from one car model or windshield manufacturer to the next.

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Mirrored glass.


Anything that, under the right lighting conditions, serves as a reflecting surface can be considered a mirror. What most people today consider a mirror was traditionally a piece of metal polished until it reflected but modern mirrors are nearly always glass with a metallic backing, which causes the light to reflect back toward the direction it came, rather than passing through.

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A cat with green eyes looking from behind a glass wall.

Mirrored glass

Mirrored glass is another phrase used for reflective glass. It is glass that has been treated with a metallic substance and offers mirror-like properties. The phrase mirrored glass can apply to products made specifically to serve as mirrors as well as glass that is reflective but made for architectural or decorative purposes, such as facades or table tops.

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A white multi-fold door in an office area.

Multi-Fold Door

Multi-fold doors follow the same idea and layout as bi-fold and tri-fold doors, with multiple panels, connected by hinges each set opposite the hinges on the next door, allowing the panels to fold in on one another like an accordion when opened.

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Bronze Multi-point lock

Multi-Point Lock

As the name implies, a multi-point lock is one that has more than one mechanism to secure a door in place. Multi-point locks usually have a deadbolt and can have nearly any combination of live bolts/latches and hook or compression bolts. Keys are required to operate a multi-point lock.

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nhtsa logo

National Highway Traffic Safety Administration

A division of the U.S. Department of Transportation, the National Highway Traffic Safety Administration (NHTSA) works with state and local governments to enforce vehicle performance standards and reduce motor vehicle related deaths, injuries, and economic losses. Its stated mission is to save lives, prevent injuries and reduce economic costs due to road traffic crashes, through education, research, safety standards and enforcement activity, and its website states that it is responsible for keeping people safe on America’s roadways. The general public is most familiar with NHTSA rating systems such as the 5-star vehicle rating system, as well as ratings systems for car seats as well as tires, but the administration also tracks consumer complaints about vehicle problems and requires manufacturers to recall vehicles and equipment’s that have safety-related defects.

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A glass shower.

Neo-Angle Shower Door

Made for corner showers—those that take up a corner of the bathroom – neo-angle shower doors are more than just the doors. They comprise two pieces of glass, each anchored perpendicularly to the walls of the shower, with a shower door connecting the two side pieces of glass. Neo-angle shower doors can be hinged or pivot doors, and the three parts of the glass meet to form distinct angles. The footprint of a corner shower with a neo-angle door looks a bit like a cut diamond or a bow window.

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Obscure Glass

Obscure glass is glass which is not completely transparent, but rather has some level of distortion which can be created using texture or patters. Common methods used to distort glass include sandblasting and acid etching to create frosted glass. Obscure glass is typically used in bathrooms, or anywhere else that privacy is needed.

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Ford windshield

Original Equipment Manufacturer (OEM)

The company that was responsible for manufacturing a part or parts, which originally were installed on a vehicle at the time of assembly. Replacement or additional parts made by other companies are aftermarket equipment.

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Paint Seal

Windows that won’t open in older homes may be paint sealed, meaning they were painted shut. Someone painted the window frame (and maybe the sash as well) while the sash was closed and the paint sealed the sash to the frame. Opening a paint sealed window may require a professional.

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A small paint brush painting a piece of glass with etched flowers.

Painted glass

As the words imply, putting paint on any glass surface results in painted glass. One way of achieving a certain aesthetic is to paint the glass; however, painted wine glasses differ from painted architectural glass. While both may be hand painted by individual artists projecting a specific image, architectural glass frequently is painted on the back of the glass, so that the color (and/or image) is viewed through the glass from a particular side. In general, those viewing the painted glass would not be able to access the paint itself. Painted architectural glass can range from a single, solid color to different colors and patterns or images, depending on application, and placement. If painted architectural glass includes a specific image, that image would be applied in layers opposite of traditional painting as each successive layer has to be seen through the glass and the last layer cannot be smaller than the first layer applied.

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sunroof, panoramic

Panoramic Sunroof

Glass in a vehicle roof that allows occupants to see the sky are referred to as sunroofs. A panoramic sunroof is one that spans nearly the entire roof of the vehicle, from front to back. Panoramic sunroofs can be made in a single piece or in multiple panels. Those that are made in panels are often operated by controls within the vehicle, rather than manually, and with at least one panel sliding over or under the other, though some do tilt to open

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Partition Glass

Partitions are non-load-bearing structures used to separate a room into smaller spaces. One made of glass is a glass partition, which allows those using the space to create separate areas without losing light or the feeling of floor space.

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Patio doors, exit doors, doors

Patio Doors

Doors that allow entry to a residential building, that is not the main entryway to the house and usually open to a patio or other outdoor area. These doors often are more decorative and common types of patio doors include sliding doors, French doors, and even folding doors.

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A white picture window from the exterior of a white brick home.

Picture Windows

A type of fixed window, picture windows utilize larger panes of glass that work as a design element, both to let in light and offer a picturesque view from that vantage point in the room or house.

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Glass pivot doors lead from inside to an outdoor patio.

Pivot Door

A pivot door is one that opens on a pivot hinge located at the top and bottom of the door. Unlike the hinge on a hinged door, a pivot hinge allows a door to open in either direction, swinging inward or outward as desired.

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Pivot Shower Door

A pivot shower door is a swinging shower door that opens both inward and outward. The pivot hinge allows the user to choose which way to open the door. This can be helpful by allowing the user to swing the door outward to enter the shower, then inward to exit the shower, which helps prevent water from dripping outside the shower.

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Plane Mirrors

Mirrors that are completely flat are plane mirrors. They do not deviate from the flat plane. Reflections in a plane mirror are the same size and orientation as the object they are reflecting, and are always virtual, meaning they appear to be behind the mirror and can only be seen in the mirror.

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plate glass

Plate Glass

Plate glass is a type of flat glass that was once commonly used in glass doors, mirrors, and windows.

So, how is plate glass made? The first way of creating truly flat glass was done by pouring molten glass onto metal tables or plates and rolling it flat before leaving it to cool. This method made the plates of glass for which plate glass is named and was the traditional way of manufacturing windows and mirrors. Plate glass could be made in various weights or thicknesses. Today, flat glass is primarily made through the float process, which requires less space. While many consumers still use the phrase plate glass, especially to refer to large windows (e.g. in storefronts) or doors, the float process – which makes float glass – all but replaced the plate glass manufacturing process by the 1950s.

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colorful polycarbonate laying on top of one another


Polycarbonate is a particularly strong but lightweight and clear plastic. Though it is used in many different applications in daily life, is used most frequently in architecture for bullet-resistant glazing and in headlights for the automotive industry.

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sunroof, moon roof, pop up

Pop-Up Sunroof

A sunroof that opens by tilting upward is a pop-up sunroof. Pop-up sunroofs are operated electronically or manually and some can be completely removed. They can also be installed as an aftermarket feature.

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A diagram of U-factor graph and a clipart home.


The opposite measurement of the U-Factor, the R-value of a window also measures the insulating properties, specifically measuring how much heat is retained. The numbers of an R-value are directly opposite of the U-Factor. A low U-factor equates to a high R-value, and both mean the window offers good insulating properties. (A high U-factor would mean a low R-value, and both indicate the window allows a lot of heat to escape the building.)

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reflective glass

Reflective glass

The term reflective glass does not refer to mirrors only, though such glass can provide mirror-like qualities. Reflective glass has a metallic coating to help reflect heat, which in turn lowers energy costs for the building, as it takes less energy to regulate the building’s interior temperature. Reflective glass can give the appearance of a one-way mirror, providing added privacy for building occupants. Reflective glass uses consist of forming building facades and interior design pieces.

The metal coating on reflective glass can be added to the hot glass during the float process. This kind of coating is called a hard coat and reflective glass with a hard coat can be cut, heat strengthened or toughened (tempered). The other way of adding a metal coating to glass is by adding it via a vacuum after the glass has been finished. This is called a soft coat. A soft coat is more susceptible to scratches and other damage, so is usually applied to the inside surface of a glass pane as part of a double-glazed system.

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Round shower with a glass door.

Round Shower Door

Similar to neo-angle shower doors, round shower doors enclose a corner shower unit with two pieces of glass attached perpendicularly to the bathroom walls and connected with a door; however with round shower doors, all the glass in the enclosure is bent glass, creating a rounded area and providing a bigger space inside the enclosure.

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A close-up of shattered glass

Safety glazing

Similar to security glazing, safety glazing mostly refers to the window and door units with glass that has been reinforced to resist or mitigate damage. Tempered glass is the most basic form of safety glazing, but within the industry, the phrase usually refers to more involved methods that help retain broken glass and protect building occupants. Both safety and security glazing options employ similar solutions, including but not limited to combinations of laminated glass and other systems, but safety glazing is designed to withstand sustained high winds and objects that have become projectiles via those winds.

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sandblasted glass

Sandblasted glass

Sandblasting is one way of etching glass that creates a look associated with frosted glass. Sand is naturally abrasive and when combined with fast moving air, will wear away at a surface. The longer the sandblasting technique is applied to an area, the more the sand will wear away at the surface and the deeper the cut.

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Security Film

A type of window film made to help slow down intrusions into a building through a door or window, security film is one aspect of security glazing. Security film is typically an after-market addition. It can be added only to the glass and held in place with sealant, or installers can attach it to the frame of the window or door. If the window that the film is applied to becomes broken, the film provides an extra layer of polyvinyl that will both hold broken glass together and, in those latter installations, it can hold the broken glass in the frame, which would slow or even prevent someone who is attempting to gain entry.

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A glass door with shattered glass.

Security glazing

Glass used in doors and windows can be modified, either during production or afterward, to make it stronger and take longer to break. Security glazing is designed to specifically resist human efforts to assault a building, whether to gain entry or to inflict damage to the building and injury to the building occupants. Security glazing generally differs from safety glazing in that security glazing is designed to withstand large blasts or direct hits for a short duration. Options for security glazing range in complexity from laminated glass to window film and anchoring systems.

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A front view from inside the vehicle with a soapy water covered windshield.

Self-Cleaning Glass

Glass billed as being “self-cleaning” has a coating that hastens how quickly water runs down the glass. The way the water runs down the glass also changes how much dirt and other substances it can remove from the glass. The theory is that with the water washing away the dirt and grime from the glass, consumers won’t need to clean the windows with soap or glass cleaner as frequently as one would without the specialty coating.

There are two different kinds of “self-cleaning” glass: hydrophilic and hydrophobic. Self-cleaning glass coatings are not particularly popular among members of the glass repair industry, as the coating and its ability to transform how water reacts to glass can make the repair process more difficult.

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semi-frameless shower door

Semi-Frameless Shower

A shower enclosure composed of glass with a metal frame around the enclosure itself but not around the door, or has a frame on less than four (4) sides of the glass paneling.

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Shear Wind Load

Shear wind load is a type of wind load that describes the amount of horizontal force a structure can endure before damage begins to occur to the glass and other building components.

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Sheet Glass

Sheet glass is a type of flat glass. It is created by drawing a molten mix of glass out of a tank. The glass is drawn out vertically using a series of rollers and then turned horizontally to cool. Sheet glass has limitations when it comes to thickness, overall dimensions, and clarity, but was historically cheaper to manufacture.

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A side view of a beige Escalade.


Automotive glass sidelites

The windows in a vehicle that are not the windshield or backlight are also called sidelites. Some people refer to these windows as the roll-downs (or roll-ups), as these are the windows that can be opened and closed by a mechanism that allows them to slide up and down. The windows that don’t open and that are located immediately in front or behind the operational windows are called the quarter glass.

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An exterior view of a single hung window on a red brick home.

Single Hung Window

A single-hung window has only one moving part, referred to as the sash. Depending on how it is installed it can be opened from the bottom (a sash that moves upward) or the top (a sash that can slide down) but only that one piece will be operable.

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Slider Windows

Operable windows that slides horizontally (left and right) to open are slider windows. They operate in the same manner as a sliding glass door.

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An outside look of a glass, patio sliding door.

Sliding Glass Door

Sliding glass doors are two panes of glass with at least one pane set on a track, allowing it to slide in one direction to open. While some sliding glass doors have one set pane and one movable pane, other sliding glass doors have two movable panes, each sitting in adjacent tracks, allowing the panes to move past each other. Sliding glass doors are common patio entryways, and those are sometimes referred to as sliding patio doors.

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A glass bypass shower door.

Sliding Shower Door

A sliding shower door, also known as a bypass door, is the same concept as a sliding glass patio door, just used in a shower or bath enclosure. A sliding shower door may have a set pane with one side sliding on a track or both panels of glass can move. The track can either have manual rollers in it, or the sliding piece can just glide without extra support. Bypass or sliding glass shower doors are space-efficient, as they require no room to swing open.

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Snow Load

Snow load is the downward force of pressure from snow that is placed upon a non-vertical structure. It is typically measured in pounds per square foot and applies to the roof of a building.

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Temperature gauge in a blue sky.

Solar Heat Gain Coefficient

The solar heat gain coefficient (SHGC) is the measurement of how much solar radiation passes through the glass in a window or skylight. Ratings based on the solar heat gain coefficient help determine the energy efficiency of the window or skylight. The lower the SHGC, the less heat the window (or skylight) allows to pass through it.

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Solar Transmittance

Solar transmittance, also referred to as light transmittance or visible transmittance, is the measurement of visible light passing through a piece of glass. Solar transmittance can be altered by the addition of glass coatings, etchings, solar films, and more. It is measured as a percentage where 100% would be completely clear and transmit all the light, while 50% would only let half the light through.

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Also called a sunroom, a solarium is a room with particularly large or numerous windows to allow considerable amounts of natural light.

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A women sits on one side of a piece of a soundproof glass. As man sits on the other side with headphones on, smiling at the girl.

Soundproof Glass

There is really no such thing as “soundproof” glass, though there are glasses that can mitigate sound waves substantially. “Soundproof glass” is made specifically to reduce sound traveling through a window. Soundproof glass may be manufactured with thicker glass, spacers, laminated glass, or any combination thereof. A soundproof window can be installed in front of an existing window to increase noise reduction beyond what the original window offers. Despite the name, soundproof glass does not block sound in its entirety, though some window dealers advertise their wares as able to reduce noise up to 90 or 95 percent.

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spandrel glass

Spandrel glass

In multi-story buildings the sections between floors, where building components are held, is called spandrel. When a building has a full glass facade with a seamless appearance, the glass covering the spandrel areas is referred to as spandrel glass. Spandrel glass has both interior and exterior applications, though spandrel glass used on the exterior of a building usually is heat treated and insulated, to ensure it provides the properties similar to that which an actual wall would provide. Interior spandrel glass does not need to meet the same criteria. Spandrel glass often is also reflective, which helps it to mask the space behind it.

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Closeup of glass breakage

Spontaneous Breakage

Sudden glass breakage without warning and seemingly for no reason is spontaneous breakage. It happens primarily to tempered glass, and can be caused by a variety of reasons, few of which are predictable or noticeable. Some causes of spontaneous breakage includes defects in the glass during production, particularly if the glass becomes contaminated with nickel sulfide occlusions; minor damage to the glass, especially the edge of the glass (often during installation) that weakens the piece; stress on the glass created when incorrect biding on the frame does not allow room for proper expansion and contraction of the glass and the frame; thermal stress on the glass when the outside glass on an insulating glass unit heats faster than the inside glass; and the wrong size or thickness of glass being used for high wind loads.

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Stained glass.

Stained glass

Glass can be manufactured in different colors by adding different metals into the initial mix. When glass of different colors are pieced together to make a larger unit, it is referred to as stained glass. A form of decorative glass, the most commonly recognizable use was as windows in places of worship, though it can also be found in other structures as well, including restaurants. Stained glass can replicate specific images or offer more abstract designs. More recently, it has also been used in three-dimensional artwork by some glass artisans. In traditional stained glass windows, the colored glass pieces are held together by lead framework.

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stationary window, fixed window

Stationary Windows

Stationary windows are the same as a fixed window. They are sometimes used in conjunction with operable windows for a specific look or design on a building.

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A glass steam shower unit.

Steam Shower Door

Turning a bath enclosure into a personal sauna or steam room is possible with steam shower doors. With an enclosure that runs floor to ceiling, a steam shower door completes the enclosure and is sealed, along with any other glass components, to prevent steam from escaping, though the enclosure will likely also have movable transoms that can be opened to vent the space as needed.

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Glass stops hold the glass in a door or window in place. They can be made of wood or rubber, which becomes part of the decorative molding. Inside a window or door, the glass can be seated in a glass stop or it can be sandwiched between the glass stop and the frame.

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Sun Room

A room made primarily of, or featuring, large or numerous windows to allow in a considerable amount of natural light into a space. Also called a solarium.

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suspended particle devices, veri variable transmittance glass

Suspended particle devices

A kind of variable transmittance glass, suspended particle devices (SPDs) operate with nano-scale particles that are suspended in a liquid. All of this is done in the scale of thin-film, and attached to glass. Controlled by electricity, this kind of switchable glass is opaque when turned “off,” and the particles are in disarray– providing very little light transmittance and a considerable amount of privacy. When electricity (voltage) is applied to the glass, usually via a switch or control panel, the particles line up, light is able to pass through and the glass becomes transparent. The presence of electricity must be constant for SPD to maintain its particle alignment, the same way electricity must continuously flow to a light bulb to keep it lit. Once the electrical flow is interrupted, the particles disperse again and the glass becomes opaque, the way a light bulb goes out. In this way, SPDs differ from electrochromic glass, which works under the same principles but requires only a single burst of electricity to change from one finish to the other.

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Shattered tempered glass on a black cloth.

Tempered glass

Glass that is cooled very quickly during the manufacturing process to increase the strength of the glass is called tempered glass. In a way, it is the most basic form of safety glass. Tempering changes the property of the glass so that it shatters into pellets when broken, rather than shards, the sharp edges of which can cause significant injury to people and damage to property. Tempered glass is the opposite of annealed glass.

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thin glass

Thin glass

Where architectural glass is measured in fractions of inches (e.g. ¼-inch glass), glass classified as thin glass, is measured in smaller increments, such as millimeters and even micrometers. Thin glass is used for very technical applications such as for parts of telescopes in astronomy and microscopes for the medical and scientific fields, as well as for very specific, sensitive products such as sensor covers and lithium batteries with solar cells.

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Third Party Administrator, TPA, Insurer, Auto Glass Claim

Third-Party Administrator (TPA)

A company or organization that processes an auto glass insurance claim jobs on behalf of an insurance company. The TPA connects the insured with a glass replacement company and facilitates the glass replacement.

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Shattered glass pieces on a concert floor.

Toughened Glass

The phrase toughened glass is another name for tempered glass, that which has been cooled very quickly during the manufacturing process. Toughened glass has a different composition compared to standard (annealed) glass that makes it withstand daily stresses better than annealed glass does. Once toughened (tempered) glass does break, the different tensions and compressions within the glass make it break into small pellets, rather than the large, dangerous shards into which annealed glass breaks.

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A wooden door.

Transom glass

One architectural feature that many people might see, especially on houses, is to have a horizontal window, usually fairly narrow, above a door or window, sometimes in addition to narrow vertical windows, or sidelites, alongside a door. That horizontal (transverse) window above the door is called as a transom window and glass used in any such design can be referred to as transom glass.

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Three wooden trim-fold doors are opening leading to two different rooms.

Tri-Fold Door

Three door panels connected by alternating hinges that can fold in upon one another like an accordion are tri-fold doors. They can be used in nearly any interior application, including closet doors and bath screens, as well as some exterior doors, usually patio doors.

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Triple Glazing.

Triple glazing

Insulating glass comprises multiple pieces of glass, separated by a spacer and sometimes noble gases, to help insulate a building. Triple glazing is insulating glass that uses three panes of glass with two spacers, the general idea being that it offers more noise reduction and better energy efficiency.

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A child sitting in front of two-way glass.

Two-way glass

A phrase that is used interchangeably with two-way mirror and two-sided glass, two-way glass refers to glass that is reflective on one side and clear on the other, allowing persons on one side to see through, while people on the other see a reflection of themselves. Most people are familiar with the concept of a two-way mirror/two-way glass from Hollywood’s depiction of police dramas and the questioning room with two-way glass for observation of interrogations.

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two-way mirror, two way glass

Two-way mirror

Also known as two-way glass, a two-way mirror is glass that is reflective on one side and clear on the other, giving the appearance of a mirror to those who see the reflection but allowing people on the clear side to see through, as if at a window. Most people are familiar with the concept of a two-way mirror/two-way glass from Hollywood’s depiction of police dramas and the questioning room with two-way glass for observation of interrogations, but this isn’t their only use. Many ballet studios use them so that parents can watch their children practice during lessons.

Two-way mirrored glass is made the same way traditional mirrors are made, with a thin coating of metal behind the glass; however, two-way mirrored glass only has half the amount of metal backing that traditional mirrors do. One coat of metal causes most of the light to reflect back toward the source but does prevent some of it from passing through, which allows occupants on the other side to see through. The metal coating does, however, darken what can be seen from the non-reflective side, giving the impression of looking through a tinted window.

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A diagram of U-factor graph and a clipart home.


A rating factor that measures how much heat is lost through a given window. The lower the U-value, the less heat is lost and the more insulating properties the window offers. The U-value is directly opposite the numbers of an R-value. A low U-factor equates to a high R-value, and both mean the window offers good insulating properties. (A high U-factor would mean a low R-value, and both indicate the window allows a lot of heat to escape the building.)

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A red arrow with a sun and a blue arrow with a snowflake


The U-Value of glass is the same as the U-Factor. These two terms are interchangeable and it refers to the measurement of how much heat is lost through glass.

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variable transmittance glass, suspended particle devices, electrochromic glass

Variable transmittance glass

Commonly called smart glass or switchable glass, variable transmittance glass can change from light to dark or from opaque to transparent and back again when exposed to voltage, light or heat. The catalyst triggers ions within the glass to align and reduce the amount of light the glass will transmit – the light transmittance of the glass is variable, depending on the situation, thus the name variable transmittance glass.

The most widely recognized use of this kind of glass is transition lenses on eye wear, but the technology has been successfully applied to architectural glass for many years. When used on surfaces facing the outside of a building, glass that automatically tints when facing sunlight will become clear as the sun shifts in the sky and away from that part of the building. This use of variable transmittance glass provides energy efficiency without the use of window film or window dressings, the latter of which require upkeep from the inside.

Another, somewhat more recent, kind of variable transmittance glazing are glazings the light transmittance of which can be controlled by electricity. These fall into two categories: suspended particle devices (SPDs) and electrochromic glass.

SPDs and electrochromic glasses provide adjustable privacy without the use of drapery or window dressings, which require upkeep and can collect dust and germs, which is a key selling point for using the technology in hospitals or other locations where people with compromised immune systems might live, work or seek treatment.

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Verre Eglomise

French for “gilded glass,” verre eglomise is a technique for making decorative glass by painting a design on the backside of glass with gold leaf to make an image or design that can be viewed as a mirror from the front.

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Visible Transmittance

Visible transmittance, also referred to as light transmittance or solar transmittance, is the measurement of visible light passing through a piece of glass. Visible transmittance can be altered by the addition of glass coatings, etchings, solar films, and more. It is measured as a percentage where 100% would be completely clear and transmit all the light, while 50% would only let half the light through.

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A scratched piece of glass with water spots.

Water Spots

When water, particularly hard water, dries on a glass surface, it can leave behind the impurities in the water, such as dirt and any chemicals or minerals. These show up as light colored or white spots on the surface of the glass. Water spots, at best, can disrupt the look of the glass and at worst impede clear vision through the glass. They can permanently mar the glass if the chemicals left behind are corrosive enough to etch the glass. Cleaning water spots from the glass as soon as they form, in conjunction with removing water and drying glass surfaces thoroughly after exposure to water, are the best ways to prevent water spots from forming.

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window film shaped like cactus'

Window film

Very thin polymer plastic can be added to glass, either during the manufacturing of a unit or as an aftermarket add-on, to change the properties provided by the glass. The film, generally referred to as window film, as it is most frequently applied to windows, can be either functional or decorative in nature.

After-market window film can be used as part of safety or security glazing anchoring systems, providing an extra layer of protection to catch broken glass and slow the entrance of debris into a space that has been breached.

Film also provides options for less expensive and less permanent decorative options for glass, ranging from different colors to a frosted or etched look, nearly all of which can be cut and layered to create images, patterns or depth. The most commonly known window film application, though, is for solar control, such as the tint on car windows. However, solar control window film is available in different degrees of tint, spanning from nearly transparent to the darkest tint, what most people know as “limo tint.”

After a rigorous cleaning of the glass, window film is applied with a solution of soapy water, which creates the surface tension needed to hold the film in place. Most window films have an adhesive that bonds with the glass once the water solution dries, though there are some that are adhesive free.

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A white window frame.

Window Frames

The architectural elements that hold and support the glass in a window make up the window frame. Window frames can be made of wood, aluminum, fiberglass, or vinyl, and there are pros and cons for each material.

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Window Sash

A window sash is the part of a window that encases the window’s glass, or the window’s insulated glass unit. The sash acts as a frame to the glass and sits between the window’s glass and the window frame. It may be movable or stationary depending on the type of window and can slide either vertically or horizontally.

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glass windscreen windshield


The window glass at the front of a vehicle, through which the driver and front seat passenger of a car view the road and the world is known in some countries as the windscreen. In most of North America and specifically in the United States, this glass is called the windshield.

Most modern windshields are made of laminated safety glass and bonded in place by a urethane sealant. Windscreens were initially designed to protect vehicle occupants from the wind created by traveling, but over time the role of the windshield has expanded. Today, windscreens also are a safety component in most passenger vehicles, as they help contain front airbags when deployed.

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A women's hand on a steering wheel


The window glass at the front of a vehicle, through which the driver and front seat passenger of a car view the road and the world is known in the United States and most of North America as the windshield. In many other countries, the same glass is referred to as the windscreen. Most modern windshields are made of laminated safety glass and bonded in place by a urethane sealant.

Windshield were initially designed to protect vehicle occupants from the wind created by traveling, but over time the role of the windshield has expanded. Today, windshields also are a safety component in most passenger vehicles, as they help contain front airbags when deployed.

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A man sits in the driver seat of a car with his windshield wipers on.

Windshield Wipers

Windshield or windscreen wipers consist of a rubber wedge, known as the blade, attached to an arm that pivots on the end of a metal arm. When activated, the metal arm drags the windshield wipers across the windshield and the wiper blade sweeps material such as rain or snow off the windshield.

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wired glass

Wired glass

The glass lites in some doors of older buildings, especially in public facilities built in the 1970s, have what appears to be chicken wire within the glass. Wired glass was an early form of safety glazing, as the wire would catch much of the glass and prevent it from falling. The glass was also frequently treated with a fire retardant to prevent the glass from breakage if exposed to high temperatures and the wire to hold it together in case it did break. This combination was an early type of fire-rated glass and protected inhabitants from fire and possibly smoke on the opposite side of the door. While it can successfully help protect occupants from a fire or certain other situations, wired glass itself can present other hazards. When the glass surrounding the wires does break, the exposed wires can cause injury if a person physically comes in contact with them. As glass safety has evolved, the need and desire for traditional wired glass has declined and other solutions have become available.

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