Glossary: K-O

L Squares: An "L" shaped instrument that can be made of wood, plastic, aluminum, or phenolic resin, and has two edges perpendicular to each other, used as a guide for the glass cutter when making 90° angle cuts to the edge of a sheet of glass.

Lacing Tool: Tool whose eyelet threads the locking strip while its heel presses the locking strip into the channel.

Laminate: Vinyl inner layer of laminated glass.

Laminated Glass: A type of safety glass that two or more sheets of glass with an inner layer of transparent plastic to which the glass adheres if broken. Used for enhanced safety and security, as well as sound reduction. Laminated glass is used mainly for windshields, but can now be found in door glass parts as well.

Lap Joint: A joint in which the component parts overlap so that the sealant or adhesive is placed into shear action.

Lap Shear Strength: The strength demonstrated by the diagonal pull of two substrates until adhesive failure. The name comes from the lap joint created by the test samples and the shear action used to pull the samples apart.

LEED: Leadership in Energy and Environmental Design.

LEED Rating System: A "green building" rating system established by the U.S. Green Building Council. Currently applicable to new commercial construction and major renovations, the program is being expanded to include residential construction as well.

Legs: Short cracks that emanate from a break.

Lehr: A long, tunnel-like oven used to control the rate at which glass cools from its molten state.

Liable: Being legally obligated or responsible.

Light Transmittance: The percentage of visible light able to pass through.

Linkage: A mechanism used to operate door latches and door locks.

Lintel: A structural component or beam above a window or door opening that supports the wall above. Also referred to as a header.

Lite: A term for a pane or finished piece of glass. In windows and doors, refers to separately framed panes of glass (as well as designs simulating the look of separately framed pieces of glass).

Load Distribution: The specific placement of a supported weight or mass in a given area.

Locator Tapes: Tapes used to align the glass to the vehicle body during a dry set of the glass. See Dry Set.

Locking Beads: A term for filler strips. See Splines.

Long Crack: A crack on the windshield of more than 6 inches (15.24 cm). See Crack.

Low-emissivity (Low-E) glass: Low emissivity glass; a type of reflective glass that is popular in residential and office applications. A coated glass product that reflects heat.

Masonry opening: Area in a masonry wall left open for windows or a door.

Mastic (broad interpretation): Any field molded sealant or adhesive. Includes materials which are gunned, poured or troweled into place.

Material Substitution Request: An official request in writing provided by a subcontractor or contractor, for the purpose of official notice or approval that an alternated material is requested.

Medium-Density Fiberboard (MDF): A wood-fiber composite used in a variety of window, door and millwork applications.

Model Energy Code (MEC): Established by Energy Policy Act of 1992 to serve as a baseline for state energy codes. Although referenced in some state codes, it has been succeeded by the International Energy Conservation Code (IECC).

Mechanical Window: A term for a product, usually vinyl, in which the corners are assembled using screws or other fastening mechanisms, as opposed to a welded corner construction. Also referred to as a mechanically fastened window.

Mirrors: Deposited layer of silver on one surface of glass.

Misco: Wire glass where the wire is a diamond pattern.

Mobile Unit: A vehicle, usually a van or light truck, properly equipped with repair and safety equipment and tools, driven to an auto glass repair customer's home or place of business. Glass repairs are made from the vehicle.

Model Building Code: A resource of codes that have been written and adopted as the law or standard in a geographical area.

Modulus: The ratio of stress to strain.

Molding or Chrome Release Tool: Tool used to remove molding clips from a windshield or back lite.

Monomer: A material composed of single molecules. A building block in the manufacture of polymers.

Mortise Lock: A lock fitting a rectangular-shaped cavity in the edge of a door.

Material Safety Data Sheets (MSDS): Required for all toxic or hazardous materials used by a company.

Mullion: A component used to structurally join two window or door units.

Multipoint Lock: A locking system operated with one handle; secures a window or door at two or more locking points.

Muntin: Profile or moulding, either vertical or horizontal, used to separate glass in a sash into multiple lites. Generally refers to components used to construct divided lite grids or grilles simulating a divided lite look.

Nailing Fin: An accessory component or integral extension of a window or patio door frame that generally overlaps the conventional stud construction and through which nails are driven to secure the frame in place.

Negligent: Habitually guilty of neglect, extremely careless or casual.

Neoprene: A synthetic rubber having physical properties closely resembling those of natural rubber but not requiring sulfur for vulcanization.  Extremely good weather resistance (both heat and cold) with ultraviolet stability.

Obscure Glass

Obsidian: Glass made by natural forces, often found in volcanic areas where heat has acted upon sand, and sodium and calcium compounds, to produce glass.

OEM: Abbreviation for original equipment manufacturer.

Off-Set Pliers: Pliers used to trim glass in hard to reach places. The jaws contact the glass at right angles to its edge.

One-Part Sealants: Sealants that require no premixing.

One-Part Urethane: An adhesive used in auto glass replacement that has only one component.

One-Step Distributor: An industry term for a wholesale company which buys building products from a manufacturer and sells them to builders, contractors and homeowners is referred to as a one-step distributor. A wholesaler that buys building products from the manufacturer and sells them to lumberyards and home centers, which in turn sell to builders, contractors and homeowners, is referred to as a two-step distributor.

Opacifier: A material, either film or liquid, that is applied to the back of a piece of glass to act as a light shield.

Opalescent: Name of the texture of a type of art glass.

Opaque: Impenetrable by light.

Open Time: The time interval between the application of an adhesive and when it becomes no longer workable.

Open-Celled: As in "Open-celled foam." Foam extrusions can have the body contain connecting open cells. This allows air to pass through the foam to promote adhesive cure.

Oriel: Type of bay window which protrudes from building, but does not touch the ground.

Oval Cutter: Cutters that allow glaziers to cut ovals of specific dimensions. Oval cutters can also cut circles.

Oxidation: Formation of an oxide; the deterioration of rubbery materials due to the action of oxygen or ozone.

Ozone: A reactive form of oxygen. A powerful oxidizing agent, it occurs naturally in the atmosphere.