Tempered Glass Vanities
Tougher than ordinary annealed glass, tempered glass is processed by heating glass in a furnace close to its softening point of 650 to 700 degrees Centigrade and then quenching it by a uniform blast of high pressure compressed air.
Tempered glass has bending and impact strengths which are three to five times higher than those of annealed glass of the same thickness.
Tempered glass possesses the basic optical qualities of annealed glass. The induced stress condition sometimes produces a slight bow in tempered glass lights. Tempered glass that has been manufactured in a vertical tempering oven contains small surface depressions resembling dimples along one edge.
These marks are caused by the pointed metal tongs which support the glass during its passage through the oven. Glass which is passed horizontally through an oven may contain a very slight surface wave caused by contact with the rollers.
The waviness can sometimes be detected when viewing reflected images from a large distance. Finally, the air quench nozzles discharge air in a fixed, reciprocating or rotating motion. The area of air quench can be seen through polarized glass as arrays of iridescent spots or lines. Under some lighting conditions these patterns can be seen in ordinary light
Tempered (toughened) glass is two or more times stronger than annealed glass. When broken, it shatters into many small fragments which prevent major injuries. This type of glass is intended for glass faï¿½ades, sliding doors, building entrances, bath and shower enclosures and other uses requiring superior strength and safety properties.
Production There are two different methods used to produce tempered glass
Heat treating: Where the annealed glass is subjected to a special heat-treatment in which it is heated to about 680½C and afterwards cooled. If it is cooled rapidly, the glass is up to four times stronger then annealed glass and its breaks into many small fragments (fully-tempered). If it is cooled slowly, the glass is twice as strong as annealed glass and the fragments of the broken glass are linear and more likely to remain in the frame.
Chemical Strengthening: The glass is covered by a chemical solution which produces a higher mechanical resistance. Chemically-strengthened glass has similar properties to thermal-treated glass. The product is not generally used for window glass, but more commonly seen in industries where thin, strong glass is needed