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glassy Glossary

Acoustic Interlayer

If you have noticed less noise in your vehicle cabin than with previous vehicles then you may have an acoustic interlayer. There may also be an A on your windshield as another way to make this designation. 


Active Panel

Primary operating door panel.


Aluminum Surround

The aluminum frame around a screen or energy panel.


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.


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.



A piece of casing or decorative trim installed against the wall immediately beneath the stool of a window.


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.


Argon Gas

A colorless and odorless gas used to fill the airspace between insulating Low E glass. The addition of argon greatly increases the insulating performance of the Low E glass.



A moulding applied to one stile of a French Door, Sliding French Door or French Casement window unit which the other door panel or window sash strikes. Usually head and footbolt devices will be found on the astragal side.


Authentic Divided Lights (ADL)

Also known as True Divided Lights. Permanent stationary muntins and bars separate the glass in a window or door sash to give the sash two or more lights of glass.


Awning Window Unit

A combination of frame and sash, hinged at the top of the vertical jambs which allows the unit to pivot from the top with the sash opening to the exterior of the building.


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.



A block and tackle system used in the jamb liner of double hung or single hung units.



A narrow rabbeted, horizontal or vertical sash or door member in an authentic divided light unit, extending from rail to rail or stile to stile along the total length or width of the glass opening.


Bay Windows

A series of windows installed in a bay which is two flanker units and a center sash; a bay may be an arc or a polygon; when a bay is or closely approaches an arc, the window is termed a bow. See Bow Windows.


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.



The frame member on a double hung window located between the jambs and the casing. The blindstop forms a rabbet that supports either a storm sash or screen.


Bow Windows

A series of adjoining window units, installed on a radius.


Brick Mould Casing BMC

An exterior moulding of window and door frames that abuts the exterior facing material of the structure. The casing serves as the boundary moulding for brick or other siding material and also helps to form a rabbet for screens and/or storm sash or a combination door.


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.


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.


Cam Lock

A lever operated lock which is used to prevent intrusion through the sash. Cam locks and keepers were installed on the jambs and stiles of older Casemasters and awnings.


Cam Pivot

A zinc pivot pin attached to the top and bottom sash stiles of double hung units (bottom sash on single hung units). Cam pivots rest on the clutch system of the balance tube assembly which allow opening and closing of the sash.


Capillary Tubes

A tube inserted into the insulating glass spacer that allows the inside and outside air pressure to equalize in higher elevations.


Casement Window

A combination of frame, sash, weather-strip, concealed hinges and operating device assembled as a complete and properly operating unit. Casements have a flat sill and a sub-sill; screens and/or energy panels are optional. Operating casements have a crank handle for smooth operation.


Ceramic Glass/Glass-Ceramic

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.



Clad products refer to wood window and door parts which are covered with an extruded permanent colored aluminum jacket on the exterior side of the frame and sash.



The plastic and metal assembly on which the cam pivots of a double hung or single hung sash rest. The clutch is attached to the block and tackle system of the balance tubes which allow opening and closing of the sash. The clutches are color coded for easy identification of balance strength.


Combination Door

A wood framed assembly containing an interchangeable storm panel and screen. The unit is installed on the exterior of the door, and is available for wood Inswing and Ultimate Inswing French doors.


Combination Storm

A wood or aluminum storm sash with self-storing screen and operating glass panels. Available for double hungs, gliders and wood swinging doors, these panels are removable.


Combination Window

A wood or clad wood frame storm sash with self-storing screen. Bottom glass panels such as those installed on a double hung unit operate by moving the plungers in and sliding the glass panel up to the desired position. Side glass panels such as those installed on gliders slide to the left or right to the desired position. All inserts are removable from the inside.


Cottage Window

A window with unequal sash, top and bottom.


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.


Daylight Opening (DLO)

The width and the height of the visible 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.


Depth of the Jamb

The point where the exterior casing ends to the point where the interior casing begins. On clad units, the point from the backside of the nailing fin to the interior of the frame.


Direct Glaze

Refers to a window with no sash. The glass is glazed directly into the frame and is stationary.


Divided Lights

Division of light by the use of muntin bars.

Muntins: The actual bars that create a pattern in the window.
Authentic Divided Lights (ADLs): Single or insulating glass, individually glazed between the muntin bars.
Simulated Divided Lights (SDLs): Muntins permanently adhered to the interior and exterior of the glass.
Grilles: Wood muntins fastened to the interior of the sash to create the effect of divided lights, removable for easy glass cleaning.
Spacer Bar: Tiny aluminum bars inserted between SDL muntins to emulate ADL.
Grilles Between Glass (GBG's): Aluminum flat or contour bars divide the glass visually. Because the grille is between the glass, grilles do not become misplaced or damaged. Cleaning is easy without small panes of individual lights.


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.


Double Hung

Double hung windows have two movable sash which operate vertically. Double hung sash are held in an open position with the use of coil spring block and tackle balancing devices.


Double Hung Tilt 

A specially designed, made-to-order, package which includes everything needed to replace double hung sash and hardware in an existing frame without changing the frame. 


Drip Cap

A formed aluminum or vinyl piece which is installed at the top of windows and doors that allows water to run off the casing of the unit instead of seeping around the casing and into the unit.


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.


Electrochromatic 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.


Electric Operator

An electrically operated device which will open casements or awnings units by using a switch. This is used in lieu of a roto gear crank or pole crank.


Energy Panel (EP)

Removable double glazing, is a piece of glass annealed or tempered, and finished on the edges by a surround. EPs are applied to windows or doors and rest on the glazing stop. EPs offer the homeowner added energy efficiency.



A decorative door handle plate attached to the stile directly behind the handle(s). Generally square or rectangular shaped.



Tilt-Turn hardware which houses the gear mechanism for the Tilt-Turn, inswinging casement and hopper handles.


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.



An article or product of vinyl or metal-made by the process of extruding. Extrusions include vinyl sill and head jamb tracks, vinyl jamb liners and aluminum cladding used on the exterior of clad units.



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.



A series of fingers machined into the ends of two pieces of lumber to be joined together. They are then held firmly in position by adhesive. Finger jointed wood is very strong and has a lesser chance of warping than does a clear piece of wood the same length.


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.



A former term used to describe a side or lateral part. Also previously used to describe a 3-wide picture unit or bay. (see two-wide entry)


Flat Casing

Flat, surfaced on four sides, pieces of pine of various widths and thicknesses for trimming door and window openings. The casing serves as the boundary moulding for siding material and also helps to form a rabbet for screens and/or storm sash or combination doors.


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


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.



A locking rod device installed vertically in the stile or astragal of a door or screen which when activated secures the panel or screen in a stationary position.



The stationary portion of a window that encloses either the glass (direct glaze) or the sash (operating or stationary) and consists of the head jamb (top), sill (bottom), sub-sill, side jambs, jamb extension, brick mould or flat casing, and blindstop.


Frame Expander

A flat aluminum extrusion used in conjunction with the 90 degree frame expander to provide a flat casing appearance for clad units.


French Casement

A casement styled unit with two sash in one frame providing a sense of openness unrestricted by a vertical mullion or stiles when both sash are open.


French Door

French Doors are available in either inswinging or outswinging rectangular or arch top style choices.



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.


Glass Block/Glass Brick

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.


Glass Size (GS)

The measurement of the actual glass, not the visible glass.



Installing glass into windows and doors.

SINGLE GLASS: Glazing with a single piece of glass.
INSULATING GLASS: two panes of glass separated by a spacer and hermetically sealed together with dead air space between the panes.


Glazing Bead

Strips of profiled wood or vinyl used to hold the glass in position in the sash. Wood glazing bead is attached to the rails and stiles of the sash using staples, small nails or vinyl barbs. A vinyl bead is held in place by extruded barbs positioned in the kerf. Aluminum caps may be used over the vinyl bead in some cases.


Glazing Tape

A two sided adhesive tape placed between the glass rabbet and the glass and/or the glazing bead and glass of some unit types.



Horizontal operating units which have one sash fixed while the other glides open and shut horizontally.


Gorilla Glass®
Dow Corning 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.



Removable wood dividers made to simulate authentic divided lights. Grilles are often rectangular or diamond shaped and are easily removed for cleaning purposes. 



A term used to describe the right or left hand operation of a window or door.


Head Jamb

The top member of a frame.



A locking rod device installed vertically in the stile or astragal of a door or screen which when activated secures the door in a stationary position.


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.


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.



A term used to define a window or door product meeting the requirements of historical renovation standards.


Hurricane Proof Glass

Like the phrase bullet-proof glass, hurricane-proof glass does not exist. It is a phrase incorrectly used to refer to hurricane resistant glass.


Hurricane Resistance 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.


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.


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®.


Inactive Panel

Secondary operating door panel.


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.


Inswing French Door

A French door with panels that swing to the inside. One, two, three and four panel units available as stationary or operating.


Interior Casing

The casing trim used on the interior perimeter of the window or door. Generally supplied by others except in the case of round top casing which is factory supplied.


Jamb Extension

A jamb-like member, usually surfaced on four sides, which increases or extends the depth of the exterior or interior window or door frame; jamb extensions imply a larger depth than "wood jamb liners."


Jamb Liner

Thin strips of wood attached to the head jamb, side jambs and sill to accommodate various wall thicknesses. Common jamb depths are: 4 9/16", 4 13/16", 5 1/16" and 5 3/16".


Keyed Cylinder Lock

A lock providing an exterior entry and locking convenience.


Krypton Gas

Inert gas known for its ability to provide insulating properties in a small air space.

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.



A method of gluing strips of thin clear wood to the lengthwise surfaces of finger jointed material to provide the appearance of clear stock.


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.


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.


Lever Lock

A lever handle and lever arm operator available as an option on awning units.



A complete door lock system comprised of the lock mechanism together with knobs, keys, plates, strikes and other accessories.


Low E Glass

Low E stands for low emissivity. The lower the emissivity the higher the percentage of long-wave radiation blocked thereby improving thermal performance. Low E glass is coated with a thin microscopic, virtually invisible, metal or metallic oxide layer. The primary function is to reduce the U-value by suppressing radiative heat flow. A secondary feature is the blocking of short wave radiation to impede heat gain. There are two basic types of Low E glass. The first, vacuum or sputter coated Low E, is referred to as soft-coat (See Low E II definition). The second is pyrolytic Low E, commonly referred to as hard-coat. (see pyrolytic definition)


Low E II Glass

A high performance Low E glass, providing the best winter U-value and warmest center glass. It offers significant improvement in reducing solar heat gain coefficient values, providing customers one of the coolest summer glass temperatures of all Low E products. Additionally, ultraviolet light transmission is greatly reduced. The Low E II coated glass products are specifically designed for insulating glass units normally as a second surface coating. See Low E and pyrolitic definitions.


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.


Masonry Opening

A brick, stone or block opening into which a window or door unit is installed including the outside casing.



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.


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.


Mortise and Tenoning

The system by which a projecting tenon on either the muntins or bars fit snugly into a mortise in either a bar, stile or rail.



The act of attaching two or more window or door units together. The joint is then finished with a mullion center cap or mull trim.



The vertical member of a sash, window or door frame between openings in a multiple opening frame.

SPACE MULL: Two or more units mulled together with a space left between the units. The jamb extension surrounds the entire unit.
STUD POCKET: Two or more units mulled together with a space between the units. The jamb extension surrounds each unit separately, providing space for a support member between the units.

Mullion Cover

A clad cover for space mull usage on the a double hung system. It covers a range from 3' minimum to 10' maximum.


Mullion Expander

An aluminum extrusion designed specifically to allow the existing panning to be expanded to a wider width to accommodate a larger rough opening.


Mullion Reinforcement

The 3/8" mullion reinforcement is designed to be used on wood or clad multiple casement, awning and direct glaze assemblies to improve structural performance.


Multi-Lock Hardware

An adjustable lock system used on the French Casement to ensure a tight seal of the sash frame components. It also provides a secure locking system.


Multi-Point Locking System

A line of standard or optional multiple point locking mechanisms installed on the operative panel(s)/ sash of various products to enhance security and performance.


Muntins (or "munt")

A short "bar," horizontal or vertical, extending from a bar to a stile or rail or another bar.


Nailing Fin

A factory installed vinyl strip that is inserted into a kerf in the frame of clad units. Nailing fin installation is the standard method used for installing clad units.


Non-Keyed Cylinder

A handle without a keyed cylinder. The door cannot be locked from the exterior.


Obscure Glass

Glass formed by running molten glass through special rollers. These rollers have a pattern on them causing the glass to become patterned and thus obscure.


One-Wide (1W)

The current term used to describe one frame with single or multiple sash or panels.



Our drawings always illustrate the window sash or door panels as if you are looking at it from the exterior. X means operating, O means stationary.



An operating sash, panel or unit.



Outside Measurement.


Outswing French Door

A French door with panels that swing to the outside. One, two, three, or four panel units available as stationary or operating.



The letters OX or XO identify the operation of window or door units as viewed from the exterior. The letter O stands for stationary while the letter X stands for operating.


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.



A term used to describe the aluminum covering extrusion components (i.e. jambs, sill and head jamb).


Part Stop

A strip of wood with weather-stripping attached which prevents air and water infiltration. Part stops are commonly found at the head jamb of a double hung unit.



A term used to describe the angle of a roof. For example: A 4-12 pitch indicates that the roof rises 4" vertically for each 12" horizontally.


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.


Plinth Block

A decorative wood block placed between the vertical casing and the top casing of a unit to provide an elegant interior casing profile.


Pole Crank

An aluminum extension pole used to open or close roof windows or awnings which would be inaccessible because of their height.



A high level term used to describe triangles, trapezoids, pentagons, hexagons and octagons.



The first coat of paint in an application that consists of two or more coats; also refers to the paint used for such an initial coat - primer.



Lineal profiles of constant cross section manufactured by combining plastic resin and continuous glass fiber reinforcement. These thermally insulating and structural components are ideally suited for applications where strength, thermal stability and weather resistance are required, such as in patio door frames and commercial windows.


Pyrolytic Low E Glass (Hardcoat)

Pyrolytic Low-E is designed to be used either in non-insulating applications such as energy panels that have exposed surfaces or for insulating glass applications. In some northern climatic situations where an application or customer requires increased solar heat gain, over Low E II performance, this is a desirable option. This increased solar heat gain which is desirable in winter may increase summer energy costs if the home is air conditioned. The pyrolytic coating is typically applied to the second surface, but can be applied to the third surface to provide increased solar heat gain.



The resistance a material has to heat flow. Higher numbers indicate greater insulating capabilities.



A groove along or near the edge of a piece of wood.



The length of an imaginary line from the center point of a circle to the arc or circumference of a circle.



The cross or horizontal members of the framework of a sash, door or other panel assembly.


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.


Relief Kerf

Kerfs machined into the frame parts of a unit. Relief kerfs inhibit warping.



Refers to units which are sized for replacement purposes.


Rolled Aluminum

A term used to describe aluminum profiles for screen and energy panel surrounds which are fabricated by the use of a roller or series of rollers to produce a desired profile.


Roller Cams

The adjustable roller hardware devices installed on the sash of the French Casement unit. When adjusted properly with an Allen wrench, they ensure a tight seal between the sash and frame members.



A circular cover plate attached to the stile directly behind a knob or door handle. May be plain or have a decorative design embossed into the cover.



A term used to describe the steel drive worm, gears and crank device used for opening awnings and casements.


Rough Opening

The opening in the wall where a window or door unit is to be installed. Openings are larger than the size of the unit to allow room for insulation and to shim the unit square.


Round Top

Generally a semicircle window which is mulled to the top of another window or door, thus forming the round top appearance. There are full round tops, separated round tops, ellipticals, transoms, inverted corners, ovals and Gothic heads, etc. Round tops can be used separately or combined with other units to create a seemingly endless selection.


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.


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.



The operating and/or stationary portion of the window unit that is separate from the frame. The sash consists of the following parts:

STILES: Vertical sash members.
RAILS: Horizontal sash members.
CHECK RAILS: Horizontal sash members that meet, as in double hung units. These could also be vertical check stiles, as in the glider or patio door.
BARS: Divisional members extending from rail to rail or from stile to stile in an authentic divided light unit.
MUNTINS: Divisional members extending from a bar to a rail or stile or another bar.


Sash Limiter

An optional metal device which attaches to a casement sill and bottom rail which limits the sash to a specified opening -5, 10, 15 or 20 degrees.


Sash Lock

A locking device which holds a window shut, such as a lock at the check rails of a double hung unit. Larger units utilize two locks.


Sash Opening (SO)

The opening between wood frame members for both height and width (disregarding any jamb hardware tracks). 


Sash Retainer Plate

A nylon retainer plate used on a double hung window sash to secure the bottom sash.


Sash Width

Horizontal measurement across the face of a sash.


Screen OM (outside measurement)

The width and the height of a screen including wood or metal surrounds.



A close-mesh woven screen material of metal or fiberglass attached to an aluminum or wood surround. Screens inhibit entry of insects, yet permit light, air and vision. 


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.


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.


Side Jamb

The side (vertical) member of a frame.



When talking about glass, the word sidelight can have two meanings depending on which kind of installation is being discussed.

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.

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.



The horizontal member forming the bottom of a window or exterior door frame; the lowest member of the frame of a structure, resting on the foundation and supporting the frame.



The extension of the lip of a window sill to the outside edge of the casing.


Single Hung

A window very similar to a double hung window, except that the top sash is stationary or non-operable.


Sliding French Door

A sliding door utilizing French door style panels.



The measure of the tilt of a line; rise over run.



An interlocking metal bracket attached at the center of the hinge side of a casement sash and frame with a call number height of 40" or more and both sides of an Awning sash and frame with a call number height of 48" or more. It pulls the sash tightly against the frame weather-strip to maximize performance.



Used to separate the two pieces of glass in an insulating glass panel.


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.


Square Foot

For measuring the area of a unit. RO width (in inches) x RO height (in inches) divided by 144 equals the area in square feet of a unit.


Stabilizer Arm

An optional piece of hardware which is attached to the header and top rail corner drive on the handle side to limit the travel of the sash when operated in the tilt mode. It is automatically disengaged when the sash is swung in the turn mode.


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.



A semi-elliptical area, the lower center is the point where the dividing spokes meet and radiate outward. May be constructed of glazed sash, removable grilles, ADL or SDL.



A non-operating sash, panel or unit.


Stationary Sash Bracket

A 90 degree L bracket used to secure stationary casement and awning sash to the frame. The sash can be removed for replacement by removing the wood stops and bracket screws.



The upright or vertical perimeter pieces of a sash, panel or screen.



A horizontal trim member that laps the window sill above the apron and extends beyond the interior casing. See apron entry.


Storm Sash

A wood framed assembly containing non-removable glass. The storm sash is removed during the summer and replaced with a wood framed screen.


Structural Masonry Brackets

An installation bracket used with multiple high/wide window units or large doors for added structural support. The brackets are also used to attach the unit in the rough opening in lieu of nailing through the casing, thus eliminating unsightly nail holes.



The supplemental member of a frame used under most awning and casement units as an additional sill with the primary purpose being to hold multiple units together at the sill.



A semi-elliptical area, the lower center of which contains a sun-like figure with sun rays radiating therefrom. May be constructed of glazed sash, removable grilles, ADL or SDL.



An attractive, protective trim which is secured to an energy panel by an adhesive or vinyl barb to give the glass panel a safe finished edge. Also the aluminum framework for most standard screens.


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.


Tempered Glass

Float glass panels heated and then cooled rapidly in a controlled environment. This process makes the glass several times stronger than regular glass. It also makes it safer because when broken it yields small pebble-like fragments. Tempered glass is the opposite of annealed glass.



A pattern of a window unit from which dimensions and measurements can be determined. Round Tops require templates for replacement units.


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.


Three-Wide (3W)

Current term referring to any product or unit when three frames (i.e. separate jambs) are mulled together as a multiple unit.


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.



A window above a window or door. Transoms can be either stationary or operating.



A wood or clad patio door having two or three glass panels; one panel operates. Formerly known as a Wood Retro (WR) or Clad Retro (CR) door. The door features a multi-point locking system.


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.


Turn Button

A vinyl or aluminum button and screw. Buttons are used to secure wood combinations, storm sash and wood screens to the exterior casing or energy panels to the sash or door panel.


Two-Way Glass/Two-Way Mirror

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.

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.


Two-Wide (2W)

Current term referring to any product or unit when two frames (i.e. separate jambs) are mulled together as a multiple unit.



A measure of total heat flow through a window or door barrier from room air to outside air. Lower numbers indicate greater insulating capabilities.



A pultruded composite material made of polyester resin and glass fibers which are made by drawing resin-coated glass fibers through a heated die.



One single product.


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 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.


Vinyl Glazing Bead

A vinyl extrusion used on clad units which serves the same purpose as a wood glazing bead for wood units.



A strip of resilient material designed to seal the sash and frame members in order to reduce air and water infiltration.


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.



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.


Wire Glass

Glass with wire embedded into the glass when the glass is still in a molten state. This prevents the glass from falling out of the sash if it should break.

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