GlassCatalogue_LowRes

Glossary Of Terms / O-P
On-line coatings
On-line coatings are made while the glass is still in the float bath. They may still be
considered as basic products, and the size and tolerance constraints are similar to
those for clear float glass.
These coatings, either for solar control purposes or for reduced emissivity (a property
to improve thermal insulation), are called pyrolytic coatings. On-line coatings have
advantages of hardness and durability over off-line coatings and are suitable for
bending and toughening. They tend to be limited in colour/variety.
Opacifier
Applied polyester film or coating to the surface of glass rendering it opaque.
Opacity
The relative capacity of a coating material to obstruct the transmission of light.
Opalescent
Showing varying colours as an opal does.
Opaque
A glass which can not be seen through.
Optical properties
The light transmittance and light reflectance of glass.
Orange peel effect
A rough surface texture on paint or ceramic ink coating having the appearance of orange
peel and regarded as undesirable when viewed against light.
Overall U value
The U value of a window. This means the combination of glass and frame.
Overhead glass
Generally regarded as glass or glazing installed at above 2 metres and sloped more than
15° from the vertical. It relates to glass that people can walk under. Vertical glazing to upper
levels is not generally regarded as overhead glass.
Painted glass
A term used for painted glass such as ColourBak or ceramic enamel glass.
Pascal (Pa)
The unit of pressure or stress that arises when a force of one Newton is applied uniformly
over an area of one square metre.
Patterned glass
Glass having a pattern impressed on one side. Used extensively for diffusing light, privacy,
bathrooms and decorative glazing. Sometimes called rolled, figured or obscure glass.
Pinholes
Tiny, transparent openings in a coating film. Any small hole that permits passage of light.
240 Product Catalogue For Glass Processors & IG Manufacturers