Glassary - L

Laminate:
another term for laminated glass.

Laminated glass:
laminated glass is produced by combining layers of glass with plastic (PVB) or resin (CIP) interlayers to form sandwiches of material with specific design properties.

Laminated toughened glass:
laminated glass made with all the panes in toughened glass. This is often specified for overhead and structural glazing applications.

Laurel™:
Pilkington Laurel™ is the brand name for one of the Pilkington Oriel™ range of acid etched decorative glass. See consumer leaflet Pilkington Texture Glass™ for further details.

Lead cames:
the lead used in traditional leaded lights to hold the individual small panes of glass in position. The lead cames are relatively flexible, so large leaded lights may need additional support from cross bars attached at intervals to the lead cames.

Leaded glass:
an alternative name for leaded lights.

Leaded light:
glazing which is formed either:

• in the traditional manner by using lead cames to fix small panes of glass, or
• by sticking applied leading on to the surface of a single pane. See Product Data Sheet Pilkington Leaded Decorative Glass.

Lehr:
terminology used in float glass manufacturing. The annealing Lehr is the cooling area on a float line. Glass leaves the float tank and passes for several hundred yards down the Lehr where it is cooled in a carefully controlled way to prevent stresses being set up in the glass. See also annealed glass.

L.E.S.:
Lehr end size. Sheets of glass that are the width of the annealing lehr. Normally 3210mm by another dimension.

Light diffusion:
see diffusing.

Light reflectance:
the proportion of the visible spectrum, which is reflected by the glass, expressed as a fraction. (See optical properties).

Light reflection:
an alternative term for light reflectance, expressed as a percentage.

Light reflection can be described as low (<=15%) or high (>=15%).

Light shelf:
a reflective device (possibly a partial mirror), placed in a position near the upper edge of a window, which redirects light from the sun and sky onto the ceiling or towards the back of the room, in order to improve the natural illumination within the room.

Light transmittance:
the proportion of the visible spectrum, which is transmitted by the glass, expressed as a fraction. (See optical properties).

Light transmission:
an alternative term for light transmittance, expressed as a percentage. Light transmission can be described as low (<=25%), medium (>=25% and <=50%), or high (>=50%).

Lighting conditions:
the level of illumination, specifically the illumination on the public side and the private side in relation to one-way vision effects. See Product Data Sheet Pilkington Mirropane™.

Linkon™:
Pilkington Linkon™ is the brand name for one of the Pilkington Texture Glass™ range (see consumer leaflet Pilkington Texture Glass™) of patterned glass. Pilkington Linkon™ has an obscuration level of 4.

Linseed oil putty:
the traditional glazing compound for single glazed timber windows. Linseed oil putty is NOT suitable for insulating glass units or laminated glass.

Location blocks:
small separators placed between the frame and the edge of the glass to maintain the edge clearance between the glass and the frame. The separators are called location blocks when positioned on the vertical and top edges of the pane. At the bottom edge their equivalents are setting blocks. Location blocks are not required in every instance, but are commonly used in opening windows, where there may be a tendency for the glass to move in the frame.

Long wavelength energy:
an alternative term for long wavelength radiation.

Long wavelength radiation:
that part of the electromagnetic spectrum (i.e. from 5000 to 50000nm wavelength), which is produced by objects at around room temperatures. Glass is opaque to this radiation so short wave radiation from the sun is trapped by the glass, giving the green house effect. It is possible to design coatings which are transparent to visible light, but which are highly reflective, i.e. have a low emissivity, to long wavelength radiation. Glass with such a coating is called Low E Glass, Pilkington K Glass™ and Pilkington Optitherm™ are examples.

Long wave shading coefficient:
see shading coefficients.

Low reflectance:
see Suncool™.

Low E Glass:
see low emissivity glass.

Low emissivity glass:
simply a glass that keeps more heat in the building than ordinary glass. Glass is coated with a special metallic coating. To be a Low emissivity glass it has to have an emissivity less than 0.2 in the long wavelength radiation part of electromagnetic radiation. Uncoated glass has an emissivity of around 0.9. by comparison. The purpose of Low E glass is to reduce the radiation component of heat transfer across the cavity of an insulating glass unit. Since radiation is a significant component of the heat transfer across a cavity, insulating glass units incorporating Low E glass have much improved thermal insulation properties when compared to units without Low E glass (30% better insulation). Building Regulations across Europe are being tightened to make the use of Low E glass mandatory. Further information is available in the Product Data Sheets on Pilkington K Glass™ and Pilkington Optitherm™ and the Technical Bulletin Glass and Energy Management – Thermal Insulation.

Low level glazing:
glazing which is wholly or partly within the critical location up to 800mm from finished floor level.

LR:
Low reflectance see Suncool™.

Luxaclair:
This is the brand name for special blinds fitted inside a Pilkington Insulight™ unit. Contact Pilkington Plyglass for further details.

LWSC:
long wave shading coefficient.