Types of Glass

Glass facts Float glass

Float Glass is a term for perfectly flat, clear glass (basic product). The term "float" glass derives from the production method, introduced in the UK by Sir Alastair Pilkington in the late 1950's, by which 90% of today's flat glass is manufactured. Production: The raw materials (silica sand, calcium, oxide, soda and magnesium) are properly weighted and mixed and then introduced into a furnace where they are melted at 1500° C. The molten glass then flows from the glass furnace into a bath of molten tin in a continuous ribbon. The glass, which is highly viscous, and the tin, which is very fluid, do not mix and the contact surface between these two materials is perfectly flat. When it leaves the bath of molten tin the glass has cooled down sufficiently to pass to an annealing chamber called a lehr. Here it is cooled at controlled temperatures, until it is essentially at room temperature.

Basic glass Body-tinted glass

It is a normal float-clear glass into whose melt colorants are added for tinting and solar-radiation absorption properties. This reduces heat penetration in buildings. Coloured glass is an important architectural element for the exterior appearance of façades. It is also used in interior decoration (doors, partitions, staircase panels, mirrors,...). Production is the same as in float glass production. The only variation is the colorants mixed at the beginning with the standard raw materials. Different additives may produce differently coloured glasses. Some of the most-used colorants and colours they produce are listed below:

Basic glass Reflective glass

This is an ordinary float glass with a metallic coating to reduce solar heat. This special metallic coating also produces a mirror effect, preventing the subject from seeing through the glass. It is mainly used in façades. Production Pyrolitic (On-Line): in this process, semi-conducted metal oxides are directly applied to the glass during the float glass production while the glass is still hot in the annealing lehr. These are hard coatings which are relatively harmful to the environment. Vacuum (magnetron) Process (off-line):in this process one or more coats of metal oxide are applied under a vacuum to finished glass. The coatings applied by this technique are soft and must be protected against external influences and are therefore used for the interior side of glass panes. There are some other techniques for the OFF-LINE coating:  Immersion Process  Chemical Process  Foil  Screened Glazing

Basic glass Low-e glass

Low-emission glass (Low-E) is a clear glass, it has a microscopically-thin coating of metal oxide. This allows the sun's heat and light to pass through the glass into the building. At the same time it blocks heat from leaving the room, reducing heat loss considerably. Production ? On-line coated (pyrolitic process): this is a clear glass which has been coated with a metal oxide through pyrolysis when the glass leaves the tin bath (at 650°C). The coating is therefore very resistant to mechanical damage, and this Low-E glass can be cut, tempered or laminated just as normal uncoated glass. ? Off-line coated (magnetron process): is a clear glass which has received, on one of its faces, a silver coating applied by magnetically-enhanced cathodic sputtering. This type of Low-E must be used exclusively in insulating glass, with the coating on an internal face. It can be tempered and laminated.

Basic glass Mirror

Mirrors are commonly made of glass with a smooth, polished surface that forms images by the reflection of rays and light. Mirrors are exceptionally useful and practical devices and are commonly used in every area of daily life. Production The original method of making glass mirrors consists of depositing a coating of metal, mostly silver, on the surface of clear or body-tinted glass. A layer of copper, which is in turn protected by a painted backing, usually protects this deposit. The silver gives the mirror its reflective properties.

Basic glass Insulating glass

Insulating glass is a multi-glass combination consisting of two or more panes enclosing a hermetically-sealed air space. The most important function of insulation glass is to reduce thermal losses, which offers many advantages: lower energy consumption, perfect transparency by reducing the incidence of condensation on the warm air side and the possibility of using larger glazed areas without increasing energy consumption. Production Insulating glass is a glazed unit composed of two or more glass panes separated by spacers filled with dehydrated air or gas. The sheets are connected by a spacer, using sealants to reduce water vapor penetration. The whole unit is hermetically assembled by a secondary edge seal which gives structural robustness to the insulating glass. The spacer contains a desiccant which absorbs humidity from within the air space. The insulating glass unit (IGU) is made manually or with an automatic plant.

Decorative glass Enameled/Screen printed glass

Enamelled glass is tempered or heat-strengthened glass, one face of which is covered, either partially or totally, with mineral pigments. In addition to its decorative function, enamelled glass is also a solar ray controller. Enamelled glass is used for glazing and for cladding in facades and roofs. It can be assembled into laminated glass or glazed insulation. Production Enamelled glass is produced by depositing special mineral pigments on the glass surface which vitrify at the annealing or tempering temperatures. This is a stable, non-biodegradable deposit, and can be made in one or more colours, and in different figures (tips, letters, pads).

Decorative glass Pattern glass

Patterned glass is a not-perfectly-smooth structure with different patterns impressed on it. The depth, size and shape of the patterns largely determine the magnitude and direction of reflection. Patterned glass usually transmits only slightly less light than clear glass. It can be used for a variety of applications: interior design and decorations, furniture, windows, street furniture etc. Production Patterned glass is made with a rolled glass process. The semi-molten glass is squeezed between two metal rollers. The bottom roller is engraved with the negative of the potter. Thickness is controlled by adjustment of the gap between the rollers.

Decorative glass Antique mirror

Is a decorative silvered glass mostly used for interiors. This method of making glass consists of varying the regularity of metallic deposits. In addition to its decorative effect, the antique mirror creates a gentle and softened reflection, which contributes pleasantly to interior light levels.

Special glass Photovoltaic glass

Photovoltaic glass is a special glass with integrated solar cells, to convert solar energy into electricity. This means that the power for an entire building can be produced within the roof and façade areas. Production The solar cells are embedded between two glass panes and a special resin is filled between the panes, securely wrapping the solar cells on all sides. Each individual cell has two electrical connections, which are linked to other cells in the module, to form a system which generates a direct electrical current.

Special glass X-ray protection glass

This is an amber-colored glass containing 70% lead oxide, which significantly reduces ionizing radiation (X and Y). It is available as single sheets, laminated or incorporated into double glazed units. X-ray protection glass is used in medical or industrial radiology rooms.

Special glass Electrically heated glass

Electrically heated glass is a laminated glass, incorporating almost invisible electrically-conductive wires. It comprises two or more sheets of glass interlaid with one or more films of polyvinyl butyral (PVB). This assembly combines comfort with safety, whilst preventing condensation. Electrically heated glass is suitable for any situation where there is high moisture content in the air and where the difference between the internal and external temperature may lead to condensation risk.

Special Glass Electrochromic glass

Electrochromic glass is an energy-saving component for buildings that can change color on command. It works by passing low-voltage electrical charges across a microscopically-thin coating on the glass surface, activating a electrochromic layer which changes color from clear to dark. The electric current can be activated manually or by sensors which react to light intensity. Glass darkening reduces solar transmission into the building. When there is little sunlight, the glass brightens, so that the need for the artificial light is minimized. OFF ON

Special glass Liquid crystal glazing

This is laminated glass, with a minimum of two clear or colored sheets of glass and a liquid crystal film, assembled between at least two plastic interlayers. In the OFF state, the liquid crystals are not aligned, which prevents vision, yet allows light to pass through the glass. When is it switched ON, the liquid crystals align, turning the glass transparent and allowing vision through the glass. The change of transparency takes place within milliseconds. Liquid crystal glazing is designed for internal applications, including partitions, display cases, bank screens.

Special glass Self-Cleaning glass

Self-cleaning glass is an ordinary float glass with a special photocatalytic coating. It is made by chemically bonding and integrating a microscopically-thin surface layer to the exterior surface of clear glass. The integrated coating reacts to the sun?s ultraviolet rays to gradually and continuously break down organic dirt through what is called a photocatalytic effect. In other words photocatalytic means that the active integrated coating on the outside of the glass absorbs the sun?s ultraviolet rays. This causes a reaction on the surface which breaks down dirt and loosens it from the glass. This type of glass also has hydrophilic properties, meaning that rain flows down the pane as a sheet, washing away the dirt instead of, as with normal glasses, leaving the dirt behind. As a result of these two effects, the special self-cleaning coating keeps the glass cleaner for a longer period than with normal glass in applications where it is exposed to the rain.

Decorative glass Sand-blasted glass

This is produced by spraying sand at high velocities over the surface of the glass. This gives the glass a translucent surface, which is usually rougher than that obtained by etching. During sandblasting, only the areas that are to remain transparent are masked for protection. The depth and degree of the translucency of the sand-blasted finishing vary with the force and type of sand used. Sand-blasted glass can be used in numerous interior design applications in both residential and commercial settings: doors, shower screens, partitions and interior screens, furniture, etc.

Decorative glass Acid-etched glass

It is produced by acid etching one side of float glass. Acid-etched glass has a distinctive, uniformly smooth and satin-like appearance. Acid-etched glass admits light while providing softening and vision control. It can be used in both residential and commercial settings (doors, shower screens, furniture, wall paneling, etc.).

Decorative glass Bent glass

Bent glass is a normal glass, which is curved with a special process. It can be used for external sites, such as facades, shop fronts, panoramic lifts etc. and is also commonly used for internal sites in showcases, shower doors, refrigerator cabinets etc. Production Bent glass is produced in a horizontal mould by slowly heating the glass to approximately 600°C, at which the glass softens sufficiently and takes the shape of the mould. The glass is then slowly cooled to avoid any internal stress. The mould itself plays a very important role in bent glass manufacturing because it determines the quality and angle of the curve.

Safety glass Tempered glass

Tempered (toughened) glass is two or more times stronger than annealed glass. When broken, it shatters into many small fragments which prevent major injuries. This type of glass is intended for glass façades, sliding doors, building entrances, bath and shower enclosures and other uses requiring superior strength and safety properties. Production There are two different methods used to produce tempered glass: ? Heat treating: Where the annealed glass is subjected to a special heat-treatment in which it is heated to about 680°C and afterwards cooled. If it is cooled rapidly, the glass is up to four times stronger then annealed glass and its breaks into many small fragments (fully-tempered). If it is cooled slowly, the glass is twice as strong as annealed glass and the fragments of the broken glass are linear and more likely to remain in the frame. ? Chemical Strengthening: The glass is covered by a chemical solution which produces a higher mechanical resistance. Chemically-strengthened glass has similar properties to thermal-treated glass. The product is not generally used for window glass, but more commonly seen in industries where thin, strong glass is needed.

Safety glass Laminated glass

Laminated glass is a combination of two or more glass sheets with one or more interlayers of plastic (PVB) or resin. In case of breakage, the interlayer holds the fragments together and continues to provide resistance to the passage of persons or objects. This glass is particularly suitable where it is important to ensure the resistance of the whole sheet after breakage such as: shop-fronts, balconies, stair-railings, roof glazing. Production There are two types of laminated glass: PVB and resin laminated glass: ? PVB laminated glass is two or more sheets of glass which are bonded together with one or more layers (PVB) under heat and pressure to form a single piece. ? Resins laminated glass is manufactured by pouring liquid resin into the cavity between two sheets of glass which are held together until the resin cures.

Safety glass Fire-resistant glass

Fire-resistant glass can be classified in two categories: Fire-resistant glass - heat transmitting glass: contains flames and inflammable gas for a short period of time, but does not prevent the transmission of heat to the other side of the glazing.(example: wired glass, reinforced laminated glass). Fire-resistant glass - fire-insulating glass: contains flames and inflammable gas for a longer period of time and prevents not only the transmission of flames and smoke but also of heat to the other side of glazing.

Safety glass Wired glass

Wired glass is a product in which a wire mesh has been inserted during production. It has an impact resistance similar to that of normal glass, but in case of breakage, the mesh retains the pieces of glass. This product is traditionally accepted as low-cost fire glass. Production A steel wire mesh is sandwiched between two separate ribbons of semi-molten glass, and then passed through a pair of metal rollers which squeeze the "sandwich of glass and wire" together.

Special glass Alarm glass

Is a special laminated glass designed and manufactured for security purposes. The interlayer is embedded with a very thin wire and then "sandwiched" between two or more sheets of glass. The wire forms an electrical circuit which activates alarm when the glass is forced.

Special glass Anti-reflective glass

Anti-reflective glass is float glass with a specially-designed coating which reflects a very low % of light. It offers maximum transparency and optical clarity, allowing optimum viewing through the glass at all times. The clarity of vision makes anti-reflective glass suitable for all applications where glass should be transparent. Exteriors: shop fronts and commercial frontages, glazing where vision is important, particularly at nighttime(panoramic restaurants, air traffic control towers, petrol station windows) etc. Interiors: high quality picture framing, display cabinets and interior display windows, dividing screens in cinema projection rooms, television studios, machine control rooms etc.

Glass facts

Glass facts

History of glass

Archaeological findings indicate that glass was first made in the Middle East, sometime in the 3000's B.C. In the beginning glass manufacturing was slow and costly. Glass melting furnaces were very small and hardly produced enough heat to melt glass properly. In ancient times, glass was a luxury item and few people could afford it. An unknown person discovered the blowpipe in the 1st century B.C. on the Phoenician coast. Glass manufacturing flourished in the Roman empire and spread from Italy to all countries under Roman jurisdiction. Due to mass production, glass become an everyday object and was removed from the list of luxuries. By the time of the Crusades, glass manufacture had been revived in Venice as a result of good contacts with Byzantium. Equipment was transferred to the Venetian island of Murano, where Soda Lime glass, better known as cristallo was developed. Venetian glass-blowers created some of the most delicate and graceful glass the world has ever seen. Despite their efforts to keep the technology secret, it soon spread around Europe. After 1890, glass uses and manufacturing developments increased so rapidly as to be almost revolutionary. The science and engineering of glass as a material was much better understood, and in the late 1950's Sir Alastair Pilkington introduced a new revolutionary production method (float glass production), by which 90% of flat glass is still manufactured today. HISTORY OF GLASS MANUFACTURE GLASS MANUFACTURE IN THE UNITED KINGDOM - CHRONOLOGY Glass was not produced in significant quantities in this country until :- 1226 BROAD SHEET was first made in Sussex, but of poor quality, and fairly opaque. Manufacture slowly decreased and ceased by the early 16th Century. 1330 French glassmakers produced CROWN GLASS for the first time at Rouen. Some French Crown and Broad Sheet was imported into the UK. 1620 BLOWN PLATE was produced in London by grinding and polishing Broad Sheet, and was used for mirrors and Coach Plates. 1678 CROWN GLASS was first produced in London. Because of its finer quality, this process predominated until the mid nineteenth century. 1688 The French produced POLISHED PLATE in larger sizes by casting and hand polishing. 1773 English POLISHED PLATE by the French process was produced at Ravenshead. By 1800 a steam engine was used to carry out the grinding and polishing of the cast glass. 1834 Robert Lucas Chance introduced IMPROVED CYLINDER SHEET, using a German process to produce finer quality and larger panes. This glass was used to glaze The Crystal Palace. The process was used extensively until early in the 20th Century to make window glass. From this period onwards machines were developed to automate the production of obscured Glass and later, window glass. 1847 James Hartley introduced a ROLLED PLATE glass with obscured ribbed finish, which is often found glazed in the roofs of railway termini. 1888 Chance Bros introduced MACHINE ROLLED patterned glass. 1898 Pilkingtons introduced Hexagonal Rolled WIRED CAST. 1903 MACHINE DRAWN CYLINDER Glass invented in the USA, was manufactured in the UK by Pilkingtons from 1910 to 1933. 1913 Belgium produced the first machine FLAT DRAWN SHEET glass. It was first drawn in the UK in 1919 in Kent . 1923 First UK production of continuous POLISHED PLATE glass, using single grinding system. 1938 Pilkingtons developed the twin ground POLISHED PLATE system. 1959 FLOAT GLASS was launched on the UK Market, invented by Sir Alistair Pilkington. Production of glass FLOAT GLASS PROCESS The term "float" glass derives from the production method, introduced in the UK by Sir Alastair Pilkington in 1959, by which process 90% of today's flat glass is manufactured. The raw materials (soda lime glass, silica sand, calcium, oxide, soda and magnesium) are properly weighted and mixed and then introduced into a furnace where they are melted at 1500° C. The molten glass then flows from the glass furnace onto a bath of molten tin in a continuous ribbon. The glass, which is highly viscous, and the tin, which is very fluid, do not mix so that the contact surface between these two materials is perfectly flat. When leaving the bath of molten tin the glass has cooled down sufficiently to pass to an annealing chamber called a lehr. Here it is cooled under controlled temperatures, until it is essentially at room temperature. ROLLED GLASS PROCESS This describes glass made through a rolling process, whereby the semi-molten glass is squeezed between metal rollers to produce a ribbon with pre-defined thicknesses and patterned surfaces. This process is used for patterned figure and cast glass production. OTHER PROCESSES There are some other processes, such as the Pittsburgh process, or the Libbey-Owens process, nowadays rarely used for the production of flat glass. A list of most common glass types in the flat glass industry. Starting from basic glass types such as float glass, mirrors, trough security types and finishing with special glass types like electrochromic and photovoltaic glass. Selecting a glass type you will find a page with detailed description and topic related external links where you can scan more in depth. Float glass Body-tinted glass Reflective glass Low-e glass Mirror Insulating glass Enameled/Screen printed glass Pattern glass Antique mirror Photovoltaic glass X-ray protection glass Electrically heated glass Electrochromic glass Liquid crystal glazing Self-Cleaning glass Sand-blasted glass Acid-etched glass Bent glass Tempered glass Laminated glass Fire-resistant glass Wired glass Alarm glass Anti-reflective glass The Future of glass Glass as a material in its own right will always exist. But many new applications and manufacturing processes will involve glass in combination with other materials. Optical fibres, for example, are currently manufactured with one or more different coating, which are often plastics. With the increasing sophistication of opto-electronic devices, there is an increasing need to combine optical and electronic devices for many applications such as transmission of audio, video and data information. Glasses and ceramics, either alone or composite with other materials, will find increasing application in biological and medical areas. Materials such as photochromic, electrochromic and thermochrominc glasses, which respond to external stimuli, are being developed with various, sometimes unusual, applications. For More technical specifications and other detail visit : http://en.wikipedia.org/wiki/Glass#Glass_in_buildings Regards Designer Mayur N. Mehta