Float glass
(update)
Contents |
Material analysis
MasterFormat Number: 08 44 26
What is float glass? Float glass is the name for the basic glass mixture that has been turned into sheets for application to different parts of buildings. When the formula for the mixture of glass was discovered this was one of the first methods developed to give this material a purpose and to be used in Roman buildings. (update)
Traditional uses
- The use of float glass can be traced as far back as 1840 when they were used as fishing floats.
- The Norwegians used a small egg-sized float on which they tied a fishing line and a hook.
- As the use of nets increased, Norway went on to produce other sizes of floats since an economical method of supporting the nets and offered plenty of buoyancy and many European countries soon began using glass floats.
Emerging uses / trends
- About 90% of the world’s flat glass is currently formed via the float method—which produces glass with extremely flat, parallel surfaces.
- This glass can then put through various applications such as Toughening,Staining,Tinting,Bending etc.
Applications
- Commercial
- Glazing
- Atriums
- Skylights
- Residential
- Furniture
- Partitions
- Speciality glass
- Night clubs
- Window Display
- Automotive
- Windscreens
Installation
Float glass lites can be installed onto buildings using glazing methods. One way is to inject liquid glass (silicon) into a frame using a caulking gun. There is also dry glazing which is mostly used in residential applications.(update)
Finish and aesthetic qualities
- High light transmission
- High transperancy
- Free from optical distortion and waviness
Surface forms / shapes
- Float glass is the term for perfectly flat, clear glass.
- This glass can then be treated :[1]
- Reflective Glass
- Laminated Glass
- Security Glass
- Insulated Glass
- Heat treated glass
- Ceramic decorated glass
Material properties
Primary structural use
- Float glass has great tensile strength and is used in Atriums and Skylights.
- Due to its reflective use float glass is used as a Glazing material in high rise construction.
Dimensions
- Float glass can be cut into large standard sheets or cut to size.
There are standards or “Ribbon Sizes” for glass sheets that are followed by all kinds of glass manufacturers. For instance, a glass sheet can be is 600 x 321cm. (update)
- Glass sheet sizes avry from manufacturers. Standard glaas sizes are 3.2m X 7.0m but could go up to 3.2m X 10.0m.
- Glass thickness varies from 2mm to 10mm. Furthermore, float glass' thickness ranges from approximately 1/8 to 1-1/4 in. (3 to 32mm) for architectural purposes. But in commercial construction the most commonly used sizes are ¼ to ½ in. (6 to 12 mm). If a larger size is being used, the glass thickness must increase to provide the necessary support.
Acoustic property
- Glass can transmit sound as well as light into a building's interior. Laminated glass can effectively reduce unwanted sound and noise better than conventional glazing systems.
- The shear dampening characteristics of laminated glass can reduce interference caused by disruptive noise - from traffic and jet aircraft to office machinery and industrial equipment.
- Laminated glass effectively reduces the coincidence dip in the 1,000 to 2,000 Hertz range common to glass products.
Today, there are glass bricks in the manufacturing field that are relatively larger in thickness and they hold a better acoustic property than float glass. Float glass generally is not used in places where acoustics are a key feature of the room. Further more, high pitch sounds can cause the glass to shatter, therefore, float glass is not the best option for places where there will be a lot of noise as it will reflect it or allow it to pass through. (update)
Manufacturing process
It is made by melting raw materials consisting of sand, limestone, soda ash, dolomite, iron oxide and salt cake. These materials are mixed together and fed into a large furnace that is natural gas or fuel oil fired at 1500°C. The molten glass is fed into the float bath (tin bath) through a delivery canal. The amount of glass allowed to pour onto the molten tin is controlled by a refractory gate called a tweel. The tin bath is provided with a protective atmosphere consisting of a mixture of nitrogen and hydrogen to prevent oxidation of the tin. The glass flows out onto the tin surface forming a floating ribbon with perfectly smooth glossy surface on both sides with an even thickness. Thinner glass is made by stretching the glass ribbon to achieve the proper thickness. The process of making float glass using tin bath is also known as the pilkington process. (update)
Machines called attenuators are used in the tin bath to control both the thickness and the width of the glass ribbon. It then passes through the lehr where it is further cooled gradually so that it anneals without strain and does not crack from the change in temperature. The glass travels down the rollers in the lehr and comes out at the "cold end" where it is cut by machines.[2]
Environmental impact
- Advanced laminate systems can help control solar heat gain and reduce cooling loads in commercial buildings.
- The interlayer absorbs energy in the ultraviolet (UV), visible and infrared wavelength spectrums and dissipates most of the absorbed energy to the outside.
- For increased solar or thermal performance, glass can be fabricated into insulating glass units.
Float glass is 100% recyclable. This means that for every sheet that is recycled, lots of CO2 emission has been saved and less material has to be produced and taken away from the environment. In the long run, reusing glass can help save energy. (update)
LEED
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Life Safety & Rating Standards
Flammability rating
- Being incombustible it has an excellent flammability rating.
Coefficient of friction
- Glass is not recommended for floor use but custom glass surfaces can be treated to adhere to slip standards as needed.
References
Notes
Student contributions
- Laura Druan, Fall 2005
- Nicole Dagle, Spring 2007
- Harshita Merchant, Spring 2008
See Also
Similar materials
- Glass
- Glass block
- Lightblocks
- Smart glass
- Structural glass
External links
Additional resources
- Brantley, L. Reed. Building Materials Technology. New York, NY: McGraw-Hill, Inc., 1996.
Leading manufacturers
