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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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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

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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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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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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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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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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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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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. 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.

Its use 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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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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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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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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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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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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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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flat glass

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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Float glass

The phrase float glass describes the manufacturing process of flat glass. Molten glass is literally floated on a bed of metal, usually tin. Windows and glass doors are made from float glass. 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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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 block, glass brick

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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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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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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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. the description 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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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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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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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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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 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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laminated glass

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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laminated tempered glass

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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LED glass

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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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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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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mirror, 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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mirror, glass, mirrored glass

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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paint, glass, painted glass

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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plate glass

Plate glass

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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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. It is most frequently used for building facades.

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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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

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 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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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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Sidelite, architectural


Architectural glass sidelites

Vertical windows alongside a door are called sidelites. A popular housing design is to have a door with sidelites and sometimes with sidelites and a transom window.

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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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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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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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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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Tempered glass

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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toughened glass, tempered glass

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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transom glass

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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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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Two-way glass

A phrase that is used interchangeably with two-way mirror, “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

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.

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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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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window film

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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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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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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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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