Georgian Wired Glass

Georgian wired glass (BS EN 572-3: 2004) is produced by rolling a sandwich of a 13 mm electrically welded steel wire mesh between two ribbons of molten glass. This produces the standard cast 7 mm sheet, suitable when obscuration is required. For visual clarity the cast product is subsequently ground with sand and water then polished with jeweller's rouge to 6 mm sheet (Fig. 7.9). Both the cast and polished grades have a light transmission of 80%. Wired glass is not stronger than the equivalent thickness of annealed glass; however, when cracked, the pieces remain held together.

On exposure to fire, the wire mesh dissipates some heat, but ultimately Georgian glass will crack, particularly if sprayed with water when hot. However, the wire mesh holds the glass in position, thus retaining its integrity and preventing the passage of smoke and flame. Accidental damage may cause the breakage of the glass, but again it is retained in position by the mesh, at least until the wires are affected by corrosion.

Georgian wired glass is available in sheet sizes up to 1985 X 3500 mm (cast) and 1985 X 3300 mm (polished). It is easily cut and can be laminated to other glasses but cannot be toughened. Standard

Fig. 7.9 Georgian wired glass

Georgian glass is not considered to be a safety glass to BS 6206: 1981, which defines three classes with decreasing impact resistance down from Class A to Class C. However, certain laminates or products with increased wire thickness do achieve the impact resistance standards for safety glass to BS 6206: 1981 and should be marked accordingly. They may therefore be used in locations requiring safety glass according to Part N of the Building Regulations and BS 6262-4: 2005.

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