There are many different production techniques and processes for working glass.
Glass has different states of viscosity (= resistance of a fluid to the sliding of one layer relative to another) according to its temperature. At 1500 degrees it has a viscosity close to that of honey, but it is never liquid. When glass has cooled somewhat, it becomes malleable and can be reshaped. The material finally becomes solid and rigid. This property is very useful for glass working.
Techniques of production
Blown glass is a very old technique. Glass blowing produces hollow or flat volumes.
The industry produces drawn glass: the hot mass is stretched continuously, horizontally or vertically. In Romont, the ThermoFisher company produces drawn glass at a height of 7m, with a thickness of 1mm!
The molten mass of glass flows continuously from the furnace on to a bath of molten tin.
Modification of glass
Examples include tempered glass, laminated glass, and engraved glass.
Tempered glass is treated to make it more resistant than ordinary glass.
Laminated glass is an assembly of two or more sheets of glass, joined together by one or more interlayers, usually plastic films (polyvinyl butyral, PVB, known for its strength, adhesion and elasticity). Depending on the number of sheets and their thickness, laminated glass acquires increased resistance against burglary, shooting, explosions, and vandalism.
The windscreens of cars or locomotives are made of laminated glass: in the event of an impact, the interlayer film acts as a reinforcement that prevents the surface from shattering. This type of glass is also used in aeronautics.
The technique consists of engraving the hardened glass with a powerful sandblast that produces an abrasive action: the glass becomes translucent, allowing light to pass through, but is no longer transparent. The more violent the sandblast, the more the glass is frosted: it therefore varies from a light frosting to a deep engraving. This method makes it possible to play with the transparency, opacity, mattness and brilliance, by sandblasting part or all of a piece of glass, at varying intensities.
Neutral or coloured glass can be used; the material takes on a satin-like appearance.
The glassmaker combines the ingredients of glass in a melting furnace. He then reworks the glass in another type of furnace.
The glass arts
Contemporary glass artists use a wide variety of techniques to create their works. They are often enthusiastic in their thirst for experimentation in the technical field, which inspires them to new creations: torch blowing, fusing, casting, gemmail, collage, sandblasting ...