Toughened architectural glass is roughly four times as strong as float glass, since it has been thermally tempered. Toughened glass is also impact resistant, and upon damage shatters into small cubes, thus preventing serious injury of any kind. Similar treatment options as with float glass such as machining and drilling, however, are not an option after the glass has been toughened into architecturally strong glass that can be used as building material. Toughened glass is 4 to 5 times stronger than annealed glass, has enhanced thermal resistance, and breaks into small cuboid fragments rather than irregular shards of glass .Toughened glass is made from annealed glass via a thermal tempering process. The glass is placed onto a roller table, taking it through a furnace that heats it to above its annealing point of 600 °C. It is then rapidly cooled with forced draughts of air while the inner portion of the glass remains free to flow for a short time