LATEST DEVELOPMENT & ARCHITECTURALAPPLICATIONS OF FLOAT GLASS.

Shuaib Kazaure Najib

Glass Technology Section, Department Of IndustrialDesign, Ahmadu Bello University, Zaria

(March 2014)

INTRODUCTIONWhen a piece of floating glass is placed on top of a piece of molten metal, the final product iscalled FLOAT GLASS. This process creates a uniform piece of glass that is entirely solid.Float glass is derived from a mixture of raw materials including sand, limestone, dolomite, and soda ash. These materials are mixed together, and then placed into an extremely hot furnace. Once the glass has reached the desired temperature, it is stabilized, and then placed inside of a molten tin bath. Due to the reactionbetween the glass and the molten tin, the glass eventually makes its way to the surface of the tin bath. The side of the glass that has been incontact with the tin has a very small amount of

the tin embedded in its surface. This quality makes that side of the glass easier to be coatedin order to turn it into a mirror, however that side is also softer and easier to scratch.Glass is produced in standard metric thicknessesof 2, 3, 4, 5, 6, 8, 10, 12, 15, 19 and 22 mm. Molten glass floating on tin in a nitrogen/hydrogen atmosphere will spread out to a thickness of about 6 mm and stop due to surface tension. Thinner glass is made by stretching the glass while it floats on the tin and cools. Similarly, thicker glass is pushed back and not permitted to expand as it cools on the tin.As soon as the glass is cool enough to handle, it is passed through two mechanical rollers. The speed of the rolling machine indicates the width and size of the glass, which is why some pieces of float glass are larger or smaller thanothers. Finally, the glass is placed into a lehrkiln, a temperature controlled kiln that is specially made for the glass process. The resultof this entire procedure is a perfectly smooth piece of uniform glass. As soon as a piece of glass is stable temperature-wise, it is then cut into specific shapes and patterns according to a customer's needs. Within the glass world, the float glass

process is frequently referred to as the Pilkington process, since Alastair Pilkington islargely credited with the invention of float

glass.A finished float glass is clear and it has high transparency which means it provides high light transmission. It is not translucent because it is free from optical distortion and waviness. Like other glasses, it also has the ability to be coloured.Float glass is widely used in various places, however, it is most commonly used in windows andsometimes it is even referred to as window glass.Float glass can be treated, engineered or altered so that its properties can be enhanced based on the area of application desired. These alterations lead to the formation of float glasses with enhanced properties, a few of whichare as follows:-• Reflective Glass

• Safety Glassi. Laminated Glass ii. Toughened Glass

• Security Glass i. Bulletproof Glass

• Insulated Glass • Heat strengthened Glass • Low - E Glass• Ceramic decorated glass • Prism Glass

Float Glass; because of its ability to be manuevered, provides it with new and diverse possibilites of development.Below is a pictoral view of a simple finished unaltered float glass

BRIEF HISTORY OF FLOAT GLASS

Before the dawn of the 17th century, almost all glass panels were cut from crown glass. In orderto manufacture crown glass, glass manufacturers had to create large cylinder shapes that were then cut in half and flattened to form one window pane. In 1848, an English engineer by thename of Henry Bessemer attempted to form a glassmanufacturing process that was less tedious thanthe original crown glass process. Bessemer's manufacturing system included one large ribbon of flat glass that was rolled between two rollers. In addition to the rolling of the glass, each pane of glass had to be polished by hand. This turned out to be a very costly manufacturing process. Numerous inventors attempted to create a more efficient system, though none succeeded. It was not until the early 1950s that Alastair Pilkington and Kenneth Bickerstaff invented a new kind of glass termed float glassThe contribution to business success in the shape of technology comes in many forms. For Pilkington it came with the help of a washing upbowl.Alastair Pilkington, then technical director of the "family" business, conceived the idea of float glass when he was doing the washing up. Hewas fascinated by the sight of a plate floating

on water and wondered whether the principle could be applied to glass making.Seven years later in 1959 it was. Instead of a floating plate he produced a ribbon of glass by floating the raw materials at higher temperatureover a bath of molten tin.The end product was more economical, high class glass for shop windows, cars and mirrors withoutthe distortions. Development costs of £7m (£80m in today's money) almost broke Pilkington.It took four years before float glass became profitable but the production technique revolutionised the industry. Pilkington was provided with a world-lead and profitable platform for growth although the decision to swiftly licence the technology to provide incomeand deter rivals from improving the technique robbed the company of a bigger return.In the early 1960s, Most of the window glass wasproduced by sheet process. Polished glass was mainly utilized for special usage (mirrors).Float glass had to face a pretty strong pushbackfrom fans of polished glass who did not believe that float would replace polished glass.

LATEST DEVELOPMENTS OF FLOAT GLASSINDUSTRY

Over the decades, the float glass industry has greatly expanded, new discoveries and business practices are being implemented the advances in the float glass industry range from electricallyengineered float glass to ultra-thin glass, as well as tinted float glass.Below is a short list of modern tinted float glass,which are as follows :-Clear Glass: Ideal where high visibility and clarity are required. Thicknesses from 1.7 mm to12 mm. It is mainly used in:-

• Windows• Solariums• Shelves• Tabletops• Skylights

• Greenhouses

• Display cases

• Picture frame glass

• Doors• Mirrors

• Handrails• Appliances• Atriums• Safety glazing• Furniture applications

Green: Suitable when high light transmission andreduced solar heat gain are required. Standard thicknesses from 2 mm through 8 mm (5/16"); other thicknesses may be available on request. It is used for :-

• Windows• Solariums• Tabletops

• Skylights• Handrails• Atriums

• Safety glazing• Furniture applications

Bronze and Gray: Suitable when reduced light transmission and reduced solar heat gain are required and when color is desired to enhance aesthetics and increase design flexibility. Standard thicknesses of 3, 5, and 6 mm.UltraWhite : Standard clear glass is actually farfrom clear. To make UltraWhite,a raw material formula that increases light transmission and neutrality while reducing the greenish tint thatis most apparent in clear glass when viewed fromthe edge is used. This green tint becomes more visible as standard glass gets thicker. The result is pure, sparkling, very clear glass. This is available in thicknesses ranging from 3 mm to 12 mm and sizes up to 130” x 204”.High Performance Tinted Float GlassIn recent years a number of float glass manufacturers have developed high performance tinted float products that are engineered to limit the traditional compromise between high light transmission and low solar gain. Other products have been designed for very low light transmission for privacy or to assist computer viewing. These products, which are a further

development on standard tinted products, also give significant benefits when used in conjunction with Low E glass in Insulating GlassUnits. Some of these products may require toughening in applications that create high thermal stress in the glass.Arctic Blue Arctic Blue is a unique blue tinted float engineered for high light transmittance, low solar heat gain combined with a cool blue colour. It also provides a crisp undistorted view from the interior, enhancing sky and ocean colours.

Panasap GreenPanasap Green is a dark natural green tinted float glass, similar to Evergreen in appearance,providing excellent light transmission and low

solar heat gain. Its natural green colour enhances the greenery from the environment.

Azurlite (Azuria) Azurlite tinted float is a unique aqua blue tinted glass with a higher light transmittance than Arctic blue but with the same low solar heat gain. Its aqua blue colour enhances sky andocean colours.

Glass Substrates

Glass substrates are the individual plies of glass used to fabricate glass units. Glass substrate options include clear, tinted and low iron.• Clear is the most commonly specified glass substrate and has a slight green tint. In applications where designers wish to reduce the green, low iron glass is often specified in place of clear glass.

• Low iron is a type of float glass manufactured with less iron than standard clear glass. With this reduction in iron content, the green hue is reduced.

• Tinted glass is available in an assortment ofcolors and light transmission levels. In addition to providing a specific appearance, tinted glass has the added benefit of improving performance.

Glass Substrate ThicknessAll glass substrates are available 1/4” (6mm) thick. Clear and each of the low iron substratesare also available in thicknesses of 3/16” (3mm), 5/16” (8mm) and 3/8” (10mm). For tinted substrates, specialty substrates or other thicknesses of clear or low iron glass substrates.

Glass Substrate LocationIn units with multiple glass plies, it is important to specify the specific glass substrate for each ply. When a tinted glass substrate is selected typically only one ply of the fabricated glass unit is tinted while the other ply remains clear. The tinted ply should be placed to the exterior to reduce solar heat gain. One exception is laminated glass. Since there is no airspace to keep the heat absorbed by the tinted exterior ply from re-radiating into the building, the solar heat gain can be improved by moving the tinted ply to the inboard. This improvement happens when the clearcoated outboard with high solar reflectance is placed in front of the tinted glass.

Specialty Glass SubstratesA few specialty glass substrates have been developed for limited use in specific applications. Due to their unique characteristics, specialty glass substrates cannot be combined with reflective or Low-E coatings. Velour Acid Etched Glass – For a translucent appearance in an application where solar performance requirements are minimal, this acid etched glass substrate is used. This specialty

substrate has a single acid etched surface whichcan be used for interior or exterior applications.

OptiView Anti-Reflective Glass – This specialty glass substrate has 5% exterior reflectance. When compared to clear glass with 8% exterior reflectance, OptiView is a practical choice for retail storefronts or other applications where minimizing exterior reflectance is a necessity. OptiView can also be laminated with the anti-reflective surfaces facing outward to provide a glass unit with 2% exterior and 2% interior reflectance.CrystalGray – CrystalGray is an innovative new float glass substrate with a very light gray tint, ideal for a wide range of architectural glass markets. In addition to an attractive neutral color,CrystalGray offers an improved light to solar gain ratio compared to standard blue and gray tinted float glass. The technologybehind CrystalGray allows higher light transmission while reflecting infrared energy, thereby reducing the heat gain for many architectural applications. This new float glassin combination with high-performance coatings can help buildings achieve LEED (Leadership in Energy and Environmental Design) certification.

Like standard float glass, all Specialty Glass Substrates can be used monolithically, tempered,laminated and fabricated. It can also be used onthe exterior or interior lite of a vision insulated glass unit or in spandrel glass applications. Available in various thicknesses.

Glass Substrates for Solar CellsGlass substrates are also used for solar cells, which can offer more advanced functions and higher added value. mass-production and sales ofglass substrates for chemical compound solar cells has begun in various industries. Chemical compound solar cells are new, and they generate power by efficiently absorbing light through thin films of chemical compounds formed on glasssubstrates. These glass substrates possess superior functions, including high strain point properties, which prevent thermal deformation from taking place during thermal processing. They also offer a high degree of surface precision, which is suitable for forming thin films.

Ultra Thick Float GlassUltra thick clear float glass is made form high quality raw material silica sand powder, soda ash and dolomite etc., melted in high temperatures furnace . with the technologically advanced oat process, which provides high flconsistency in achieving smoothness and atness flon both surfaces of the glass. It is an ideal product for numerous architectural and interior applications. It has High light transmission, it is easily cutdue to optimum tension within the glass, and it is also easily toughened and bent which makes itconvenient for all utilizations.Beacause of its properties above, it is mainly used for Architectural works, Shop fronts and show rooms, Glacade, Interior decoration, Furniture fabrication (table tops), Exhibition display, Of ce partition etc.fi

Ultra Thin Float GlassUltra thin float glass is made from high qualityraw matrial silica sand powder, soda ash , and dolomite etc, melted in hgh temperatures furnaces. Molten glass flows onto the surfae of molten tin in a continuous ribbon bath, after the tin bath, it is cooled and annealed in a lehr becoming flat glass. the products can be tempered , insulated, bent and coated processingfor different applicationsIts main advantages are its excellent flatness, clear and practically colorless appearance, verythin thickness tolerance and low optical distortionBecause of these advantages, ultra- thin float glass can be used in LED and LCD display , whichis found in mobile phones, flat screen tvs etc, It is also used in Electronis instrumentation, Display screen protection etc. On 18th December 2013, 0.55mm ultra-thin electronic float glass was drawn in a one-time success on the ultra-thin float glass productionline of a Chinese industry and good products were rolled off the line at that day. Since the commissioning, 1.3mm, 1.1mm, 0.7mm and 0.55mm glass have been produced on this line successfully just within two months, setting a new record of the speed of good products rolling

off the similar ultra-thin float glass production lines at home and abroad.

Another aspect of development in float glass industry is the numerous float glass manufacturing plants that are continuously beingestablished all around the world. These developments are highly credited to some large Glass Industries Some of which are as follows:- Pilkington UKGuardian Glass LuxembourgEmirates Float Glass U.A.ESejal Architectural Saint-Gobain Glass IndiaBengbu Design & Research Institute for Glass Industry ChinaBelow are a few headlines from news sources about some of their new researches and establishments for development in float glass around the world.THE ASPIRING ECONOMY OF BOSTWANA IS SET TO RECEIVE A BOOST WITH THE ADVENT OF NEW FLOAT GLASS MANUFACTURING PLANT, WHICG COULS ALSO SIGNAL INCREASEDINDUSTRIAL GAS BACKGROUNDEmirates Float Glass Emirates Float Glass plans to develop a float glass factory in Mussafah. The new plant covers an area of 320,000 sq.m. and will have • Designed and built 56 new float

glass furnaces • Designed and re-built 46 float glass furnaces • Designed and built 10 turnkey float glass plantsSEJAL FLOAT GLASS LTD A SUBSIDIARY OF SEJAL ARCHITECTURAL SAINT-GOBAIN GLASS INDIA organized a Bhoomi Puja or ground breaking ceremony for its new float glassplant on 25th August, 2010 at Bhiwadi, Rajasthan, India. This new float plant has a production capacity of 1,000 tonnes of clear float glass per day, the largest in the world, and represents an investment of around € 135

GUARDIAN BEGINS CONSTRUCTION OF A NEW FLOAT GLASS PLANT IN DEWITT, IOWA by "PR Newswire"; Business News, opinion and commentary Flat This award shows the continuous trust that Saint-Gobain has in SetLinings, following the recently successfully built new Egyptian Float Glass plant and also the award of The software ensures that the new factory can compete effectively in United Float Glass Company manufactures 600 tons of high-quality float glass from its plant at.GUARDIAN ANNOUNCES THE CONSTRUCTION OF A NEW FLOAT GLASS PLANT IN SAUDI ARABIA by "PR Newswire". GUARDIAN GLASS IS PLEASED TO ANNOUNCE THE LAUNCH OF ClimaGuard DS, an advanced soft coat Low E glass which has similar durability and performance to alternative hard coat Low E options.

Historically, hard coat Low E glass has been known to have a slight brown colour distortion with an element of haze when viewed from particular angles, as the sun’s light catches the coated surface. Guardian’s new ClimaGuard DSis an offline, magnetron sputter-coated Low E glass, which offers similar attributes to its hard coat Low E rival, without the brown colour distortion or issue relating to haze. Unlike other soft coat Low E glass options, ClimaGuard DS can be treated much more like a hard coat glass. It doesn’t require edge deletion (the process of removing a perimeter ofthe coating from the glass surface before manufacturing into an insulting glass unit) and has a far more robust coating, allowing it to beprocessed and manufactured like hard coat glass.The new ClimaGuard DS uses advanced magnetron glass coating technology to achieve a low 1.3 centre pane U value in a common Argon filled 28mm unit. Combined with a high g value (solar heat gain), ClimaGuard DS offers similar performance in Window Energy Ratings to other hard coat Low E glass options, easily achieving a Window Energy Rating band C for Building Regulation Document L compliance. Unlike hard coat Low E, the lower U values achievable with ClimaGuard DS makes it easier tocomply with Building Regulation Document L

through the whole window U value route of compliance. ClimaGuard DS can easily achieve a 1.6 Uw compared to other hard coat Low E glass options which tend to rely on Window Energy Ratings for Building Regulation Document L compliance.BENGBU CTIEC INFORMATION DISPLAY MATERIALS CO, LTD ROLLED OFF ULTRA-THIN ELECTROANIC FLOAT GLASS This production line adopts up-to-date technology andcomplete set of equipment for ultra-thin float electronic glass independently developed by Bengbu Institute and CTIEC and gets the best of decades of technical reserve. The technology andequipments of each link can reach or close to international advanced level. Since the line wasput into production on 16th October 2013, all members of the company have made technical breakthroughs for ultra-thin float electronic glass production and successfully solved dozens of problems on raw materials, melting, forming, annealing, cutting, unloading and packaging for whole production process of the ultra-thin floatelectronic glass by working hard together. Afterpreliminary inspection, the key indexes of 1.3mm, 1.1mm, 0.7mm and 0.55mm ultra-thin float electronic glass produced during the commissioning can meet the requirements of “Thinfloat glass used for LCD”. Client authenticationtest on some products is under the way.

- Source P.R News

ARCHITECTURAL APPLICATIONS OF FLOAT GLASSBased on the write-up above, it is pretty clear that float glass has so many uses, one of which is architectural.Float Glass is used as transparent glazing material in the building envelope, including windows in the external walls. It is also applied in architecture where it is used for internal partitions and as an architectural feature. When used in buildings, Float glass is often of a safety type, which include reinforced, toughened and laminated glasses.Windows; Windows are important aspects of architecture, the type of window used in a building is important. From the aforementioned, it is said that there are high performance tinted float glass which have the ability of selective re-absorbtion of sunlight rays, these glasses are incorporated into architectural works as windows to satisfy the desired need of the client. Others like clear glass are also used for windows where affordability is in question.

a simple clear float glass, used for windows.Partitions; Float glass is also used in offices or establishments where clear partitions are required. This is where re-inforced clear float glasses are used, here , strength of the float glass is required because of its purpose. The partitions can be tinted for fashion or to satisfy the taste of the client.

float glass used as partitionFurniture; Another aspect of architecture where float glass is used is in furniture, a primary example is in table tops.Walls; There are certain special architectural structures that use float glass for its walls .

a float glass wall Float glass is not just only used for walls , itis also engineered to build an entire house, there are glass houses made of float glass, someof which are used as botanical garden to facilitate the provision of sunlight rays

a building made of float glass , with a glass composite roofing

another glass building made of float glass

a botanical garden.

To Conclude• Float glass is glass that is made by ladling molten glass into a molten tin bath

• Float glass started as an idea by Alastair Pilkington.

• Advancement in float glass has brought about the formation of new float glasses such as tinted float, glass substrates, ultra-thin glass etc.

• Because of its ability to be manuevered, there are so many diverse possibilties of advancement in the float glass industry.

• Ultra-Thin float glasses are one of the latest technological advancement in the flat

glass industry, and they have so much possibilities of improvement especially sincethey are used in technological areas where there is a lot of competition among manufacturers such as mobile phones, Tv screens etc.

• It has so many architectural uses ranging from window glass to advanced strengthened float glass for walls and even complete building.

References"From Flat Glass To Float Glass Industry" ~ Bernard Jean Savaete"Glass for Europe input to the study on recyclable waste glass"June 2012"Present Status and Internationalization Prospect of China Float Glass Technology" ~ Shou PengReport 2013 ~ Nippon Electric Glass Co. Ltd"Review Lecture. The Float Glass Process". Proceedings of the Royal Society of London. Series A, Mathematical and Physical SciencesUllman's Encyclopedia For Industrial ChemistryGlassOnWeb.comWisegeek.netschlolar.google.com