Glass panes of up to 6000 mm x 3210 mm (jumbo size) can be coated, outputting approximately one pane a minute. A large variety of materials can be sputtered, both elemental metal, metal alloys or ceramics (a metal combined typically with either oxygen or nitrogen), provided they are at least somewhat conductive and not magnetic. Metals can also be sputtered in an atmosphere containing oxygen or nitrogen gas alongside the standard argon, resulting in the formation of a metal oxide or nitride on the glass substrate respectively.
Coating ‘stacks’ of multiple materials can be built up in one transit of the glass under sequential cathodes, the exact structure of the overall film determined by the function it is required to fulfil.
A variety of coated glass products are available to meet customer needs. Properties of the coated product, such as light transmission, g value, or colour, can be manipulated by adjusting the thickness of layers in the stack. Sputtered coated class is suitable for many applications, it can be used in insulating glass units or laminated glass. It can be provided as a toughenable, annealed or single stock coating as needed. Active research and development in this area is ongoing, to keep our sputtered coatings at the cutting edge of capability and to maintain our ability to fulfil future customer requirements.
On-line coatings
On-line modifications are made while the glass is hot and still in the annealing lehr. They may still be considered as basic products, and size and tolerance constraints are similar to those for clear float glass.
Surface coatings, either for solar control purposes or for reduced emissivity (a property to improve thermal insulation), are called pyrolitic coatings because they are generally applied to the hot glass during its passage through the annealing lehr. They involve the thermal decomposition of gases, liquids or powders sprayed on to the glass to form a metal oxide layer which fuses to the surface.
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 variety of colour.
Dielectric coatings
The range of performances available from the use of metallic coatings is limited because of the thickness of coating which has to be applied. The use of dielectric coatings, which produce interference effects, allows higher light transmission with increased selectivity; the range of colours is also increased.
The maximum sizes of coated glass are dependent on the various facilities, and manufacturers' literature should be consulted.
It is not possible to toughen or bend most off-line coated glass; such work must be carried out before coating. It is possible to combine coatings in double glazed and laminated products.