Float Glass – Clear & Tinted
History: Until the 16th century, window glass or flat glass was generally cut from large discs (or rondels) of crown glass. Larger sheets of glass were made by blowing large cylinders which were cut open and flattened, then cut into panes. Most window glass in the early 19th century was made using the cylinder method. The 'cylinders' were 6 to 8 feet (1.8 to 2.4 m) long and 10 to 14 inches (250 to 360 mm) in diameter, limiting the width that panes of glass could be cut, and resulting in windows divided by transoms into rectangular panels.
Float glass uses common glass-making raw materials, typically consisting of sand, soda ash (sodium carbonate), dolomite, limestone, and salt cake (sodium sulfate) etc. Other materials may be used as colourants, refining agents or to adjust the physical and chemical properties of the glass. The raw materials are mixed in a batch mixing process, then fed together with suitable cullet (waste glass), in a controlled ratio, into a furnace where it is heated to approximately 1500°C. Common flat glass furnaces are 9 m wide, 45 m long, and contain more than 1200 tons of glass. Once molten, the temperature of the glass is stabilised to approximately 1200°C to ensure a homogeneous specific gravity.
The molten glass is fed into a "tin bath", a bath of molten tin (about 3–4 m wide, 50 m long, 6 cm deep), from a delivery canal and is poured into the tin bath by a ceramic lip known as the spout lip. The amount of glass allowed to pour onto the molten tin is controlled by a gate called a Tweel.
Tin is suitable for the float glass process because it has a high specific gravity, is cohesive, and immiscible into the molten glass. Tin, however, oxidises in a natural atmosphere to form Tin dioxide (SnO2). Known in the production process as dross, the tin dioxide adheres to the glass. To prevent oxidation, the tin bath is provided with a positive pressure protective atmosphere consisting of a mixture of nitrogen and hydrogen.
The glass flows onto the tin surface forming a floating ribbon with perfectly smooth surfaces on both sides and an even thickness. As the glass flows along the tin bath, the temperature is gradually reduced from 1100°C until the sheet can be lifted from the tin onto rollers at approximately 600°C. The glass ribbon is pulled off the bath by rollers at a controlled speed. Variation in the flow speed and roller speed enables glass sheets of varying thickness to be formed. Top rollers positioned above the molten tin may be used to control both the thickness and the width of the glass ribbon.
Once off the bath, the glass sheet passes through a lehr kiln for approximately 100 m, where it is further cooled gradually so that it anneals without strain and does not crack from the change in temperature. On exiting the "cold end" of the kiln, the glass is cut by machines.
Laminated glass: is a type of safety glass that holds together when shattered. In the event of breaking, it is held in place by an interlayer, typically of polyvinyl butyral (PVB), between its two or more layers of glass. The interlayer keeps the layers of glass bonded even when broken, and its high strength prevents the glass from breaking up into large sharp pieces. This produces a characteristic "spider web" cracking pattern when the impact is not enough to completely pierce the glass.
Laminated glass is normally used when there is a possibility of human impact or where the glass could fall if shattered. Skylight glazing and automobile windshields typically use laminated glass. In geographical areas requiring hurricane-resistant construction, laminated glass is often used in exterior storefronts, curtain walls and windows. The PVB interlayer also gives the glass a much higher sound insulation rating, due to the damping effect, and also blocks 99% of incoming UV radiation.
- Clear and Tinted Float Glass
- PVB Clear and Tinted Laminated Safety Glass
- Colourvue PVB
- Coolvue PVB
- Solarshield PVB
- Solarvue PVB
- E Range PVB
- Sound Reducing Glass
- Georgian Wire Glass
- DecorVue Patterned Glass
- Decorlam Patterned Laminated Glass
- Bullet Resistant Glass
- Double Glazed Units
- Processing and Edgework
- Glass Repairs
Clear and Tinted Float Glass
We supply every thickness of clear float glass as well as Grey and Bronze tinted product in all forms. We specialize in processing to specification Cut-to-Size, Bevelling, Polishing, Hole Drilling, Finger Slots and Glass Toughening requirements.
- Glazing for windows
- Interior design and decorative products
- Table tops and shelving
- Picture framing
STOCK SHEETS: We supply every thickness of clear and tinted float glass available on the South African market and are also able to source specialist glass from a worldwide network of manufacturers.
CUT-TO-SIZE, POLISHED AND BEVELLED GLASS: Processed to specification.
TOUGHENED GLASS: Processed to specification.