Great glass begins with high quality float glass that is valued for its high light transmission, optical clarity and adaptability. Manufactured using the float glass manufacturing process, float glass is a clear, distortion-free glass that can be produced in a wide range of sizes and thicknesses to suit many different types of architectural and interior applications. Float glass can be tempered, laminated, painted or coated to enhance its performance and aesthetics.

What are the benefits and properties of float glass?

What is float glass and how is it made?

Float glass is a type of flat glass produced through a process where molten glass is floated on a bath of molten metal (typically tin) to produce a uniform and consistent thickness, flatness and surface quality. This process results in high optical clarity, making it suitable for a wide range of applications, including windows, mirrors, picture frames, tabletops, and shower enclosures. Its versatility and durability make it a popular choice for many industries and applications.

The Float Glass Process

The principal ingredients in soda-lime-silica float glass include sand, soda ash, dolomite, and limestone. The quality of the produced glass depends on the purity and grain size of the input material. The float glass production process begins with the raw materials being melted in a furnace at approximately 2,900°F or 1,600°C. The continuous strip of glass exiting the furnace is known as the “ribbon”.

Forming takes place on a tin bath. The liquid glass floats upon the tin bath at approximately 2,000°F or 1,100°C, to achieve a flat, smooth surface without polishing. On exiting the tin bath, the glass is progressively cooled in the annealing lehr, which releases stress from the glass ribbon. A uniform stress profile supports the reliability of subsequent glass cutting operations. Laser sensors or high-resolution cameras installed along the line capture production data which is evaluated by yield-optimization software to direct a robotic cutting system. The ribbon is cut into stock sheets which are then prepared for storage. The sheets are sprayed with a separation material which helps to prevent scratches and sticking as the lites are arranged into packs.

Size and thickness

Standard float production dimensions can vary slightly depending on the region. In North America for example, the ribbon thickness can range from approximately 3/32” to 19/32”. The typical width of the float glass ribbon is 102 inches, and the maximum length is 240 inches. In Europe, the ribbon thickness can range from approximately 2 mm up to 19 mm. The typical width is 3,21 m and the typical length 6 m. 

Color options

Standard float glass, normally called clear float glass, has a slightly greenish appearance that is particularly visible when looking at the edges of the glass. This slightly greenish tint is due to the presence of iron in the raw materials used to produce float glass. The iron content can be reduced to produce a more neutral glass, known as “low-iron glass”, which can be a good choice for interior design, but also for architects who wish to create very crisp and clean glazed façades.

If a tint to the glass is desired, metal oxides can also be added to the raw materials to provide a grey or green tint. It will not only affect the appearance of the glass but also its visible light and solar heat transmission.

Tinted glass can be combined with low-E coatings to allow more aesthetic options of substrate/coating combinations, to further improve the solar performance of the glass, as well as selecting the right level of light transmission and transparency to help mitigate glare and maintain some privacy.