Glassary - O

Obscuration:
in addition to its obvious meaning, it is also a classification for Pilkington Texture Glass™ see also patterned glass. See Pilkington Texture Glass™ consumer literature for obscuration levels for each pattern.

Obscuration level:
the measure of how much you can see through Pilkington Texture Glass™. A level 1 pattern is least obscuring, Level 5 is most obscuring.

Observed side:
see public side.

Observing side:
see private side.

Octaveband:
the range of sound frequencies over which the frequency is doubled, e.g. 200 to 400Hz.

Off-line coating:
see coated glass.

On-line coating:
see coated glass.

One-way vision:
an optical effect resulting from the relative luminance of transmitted and reflected light, which allows vision through a window from only one side. Typically a 7:
1 lighting ratio is required for this effect to work properly. See also Product Data Sheet Pilkington Mirropane™. This phenomenon is often used for discrete observation in security situations.

Opacified:
made opaque by the application of a backing paint or other backing material, a term related closely to spandrel panels.

Optical properties:
the light transmittance and light reflectance of glass products.

Optical quality:
the presence or absence of visual distortion or small blemishes in the glass.

Optimirror ™ Plus:
Pilkington Optimirror ™ Plus (see Product Data Sheet) the brand name for our silvered glass. This product is more environmentally friendly than traditional silvered glass. That is because there is no copper backing used and no lead in the upper backing paint coat.

Optiwhite™:
Pilkington Optiwhite™ is our brand name for float glass with a reduced Iron Oxide content. This results in a glass that is less green in appearance than Pilkington Optifloat™ of a similar thickness. This product is used in thicker versions of Pilkington Pyrostop™.

Oriel™:
Pilkington Oriel™ is the brand name for our collection of acid etched decorative glasses. See Product Data Sheet Pilkington Oriel™ Collection Decorative Glass.

Outer glass:
see outer pane.

Outer leaf:
see outer pane.

Outer pane:
the pane on the external side of an insulating unit or double window.

Overall U value:
the U value of a window, i.e. the combination of glass and frame.

Overhead glazing:
sloping glazing or horizontal glazing, usually in roofs.