Glass
From CollabLandWiki
New Zealand
Manufacturing / extraction processes
Glass and glass making
History: Glass occurs naturally in the form of black obsidian (Obsius is the mythological discoverer of this stone), produced by volcanism, and as fulgurites (L: fulgur= lightning), produced by lightning strikes. As early as 3000BC, glass was used to coat pottery, but it took until 1500BC before glass was used for containers in Egypt and Mesopotamia. After declining, the glass industry bloomed in Roman times around 50AD, when transparent glass of various colours could be made and blown. Glass was made by mixing sand with soda and lime, and heating it. Miraculously, a clear liquid formed, which went very hard when cooled. In the early Middle Ages (1300-1500), Venice developed an advanced glass industry, making cristallo, finely ornamented glasswork. Glass making spread further over Europe to Bohemia, England, and other places. By the end of the 19th century, glass making was sufficiently understood to make almost any quality required. Over 1000 recipes exist. Today, glass is recycled in many countries in order to save materials and energy.
Chemistry: When pure silica sand (SiO2) is heated above 1700ºC, it melts. When left to cool very, very slowly, it crystallises into quartz, a hard, very clear, resilient crystal with excellent optical qualities. Glass and quartz derive their stability and hardness from the formation of SiO4 tetrahedra (pyramid bonds), with connecting O-Si-O and Si-O-Si bonds. When cooled rather quickly, crystals can't form and fused silica glass is formed, remaining a 'super-cooled' liquid instead. Unlike solids, glass does not suddenly become liquid when heated, but becomes gradually more fluid. This is called an amorphous (L: a=not; morphe= form; shapeless) solid. Glasses can be made from various substances, but those made from silica sand are the most widely used. Like other silica compounds in the Earth's mantle, various oxides can be substituted for silicon oxide, resulting in glasses with varying properties:
• Fused silica glass, vitreous silica glass: = silica (SiO2) 99% + water 1%. Has very low thermal expansion, is very hard and resists high temperatures (1000-1500ºC). It is also the most resistant against weathering (alkali ions leaching out of the glass, while staining it). It is used for high temperature applications such as furnace tubes, melting crucibles, etc.
• Soda-lime-silica glass, window glass: Silica 72% + sodium oxide (Na2O) 14.2% + magnesia (MgO) 2.5% + lime (CaO) 10.0% + alumina (Al2O3) 0.6%. Is transparent, easily formed and most suitable for window glass. It has a high thermal expansion and can't stand heat well (500-600ºC). Used for windows, containers, light bulbs, tableware.
• Sodium borosilicate glass, Pyrex: = silica 81% + boric oxide (B2O3) 12% + soda (Na2O) 4.5% + alumina (Al2O3) 2.0%. Stands heat expansion three times better than window glass. Used for chemical glassware, cooking glass, car head lamps, etc.
• Lead-oxide glass, crystal glass: = silica 59%+ soda (Na2O) 2.0% + lead oxide (PbO) 25% + potassium oxide (K2O) 12% + alumina 0.4% + zinc oxide (ZnO) 1.5%. Has a high refractive index, making the look of glassware more brilliant (crystal glass). It also has a high elasticity, making glassware 'ring'. It is also more workable in the factory, but cannot stand heating very well.
• Alumino-silicate glass: = silica 57% + alumina 16% + boric oxide (B2O3) 4.0% + barium oxide (BaO) 6.0% + magnesia 7.0% + lime 10%. Extensively used for fibreglass, used for making glass-reinforced plastics (boats, fishing rods, etc.). Also for halogen bulb glass.
• Oxide glass: = alumina 90% + germanium oxide (GeO2) 10%. Extremely clear glass, used for fibre-optic wave guides in communication networks. Light loses only 5% of its intensity through 1km of glass fibre!
• Over 1000 specialty glasses exist, a nightmare for recycling it. Glass can be stained with various oxides to produce vivid colours. All glasses are excellent insulators of electricity and heat. Glass can be etched by fluoric acid (HFl).
Check out this pretty basic video detailing the steps of Glass Extraction: http://www.webcastgroup.com/client/start.asp?wid=0870801051775#
Material properties
No other material is more adaptable than this blend of sand and other minerals; you can mix it with almost all elements of the periodic table and obtain a large variety of glass with different chemical and physical properties
Ability to stand up to constant use, does not affect contents
Thermal stability over a wide temperature range, retaining transparency
High chemical durability and low thermal expansion
Some are easy to cut ,polish and/or engrave
Some are resistant to thermal shock, easy to clean , microwavable
Wide range of refractive indices and dispersion coefficients
High strength to weight ratio, resistant to corrosive substances
Format & finish of materials
Glass can possess a lot of identity with the application of different methods. The most common form of glass today is float glass, due to mass-production and being relatively inexpensive. The principal properties of float glass are it's flatness, transparency and flawlessness. Alterations can be made to the transparency of the material through various techniques such as bevelling, etching and sandblasting. These manipulations of the surface distort the passage of light through glass, creating numerous effects which are applicable to the intended use of the material.
• Sandblasting involves eroding the surface of the glass with grit, projected at high speed, to create translucent white areas. This allows light to pass but causes enough dispersal to prevent a clear perception of images on the other side of the glass. By using various gades of grit, from coarse to fine, the tones of white on the surface can be adjusted. "Frosting" describes the obscured, matt surface. Imagery and text can be stenciled onto the glass contrasted by the areas left transparent. This type of finishing is useful in providing private spaces. The semi-opaque glass makes it difficult to see through without blocking light into the space. Strengthened glass that has been sand-blasted can be used as a non-slip flooring surface.
• Acid-etching uses the corrosive property of hydrofluoric acid to etch the surface of the glass, creating more subtle and delicate effects than sand-blasting. A variety of textual effects can be created by using different acid mixtures and by controlling the depth of the glass corroded by acid. A technique using white acid (mixture of neutralising sodas and hydrofluoric acid) produces an effect similar to the "frosting" by sandblasting but with a smooth rather than grazed surface.
• Bevelling is the process of grinding and polishing glass with abrasive stone wheels. Bevels are angles cut into the edges of glass which act as prisms under light, providing an interesting spectrum of colours through diffraction. the process can be carried out under computer-controlled machines. The beveled finishing on sparkles in direct sunlight, granting glass sculptures a shimmering, kinetic quality.
With the incorporation of other elements teamed with placement within a space - the use of glass as a design material can create emotive atmospheres. Arrangement of glass screens and sculptures play on visual effects to evoke interest and expression; Changes in sunlight, the seasons and day & night change the apperance of the hard material through the level of light and the morphing surroundings. The mirriored property of glass promotes an interplay between the observer's senses and the constantly changing light. When used at intervals with other materials, for example panels of glass set into dry-stone walls, a visual contrast can be achieved against the heavy stone of the structure.
Textural surfaces for decorative purposes are also popular in assisting with the intented 'theme' of a designed space. Links to : http://www.fusionglass.co.uk/kiln.html to see different decorative texture available.
Common fixing methods
Presently, glass roof structures are common in the urban landscape as they protect and shelter pedestrians from the weather. Heat-strengthened glass is used in these cases as it improves durability and allows access onto the glass canopy for cleaning. Frameless panes of glass are suspended from a steel structure through holes drilled close to the edge and bolted to a cable truss system.
Durability and maintenance requirements
Glass is a very durable product. It can be harder than concrete nevertheless wearable.But easy to clean.
Some of them are even self cleaning:glass from Pilkington Activ™ has a special transparent exterior coating that lasts the lifetime of the window. Its unique dual action uses the forces of nature - natural ultraviolet light and rain - to help keep the glass free from organic dirt.
Life-cycle / recycling possibilities
When it comes to recycling, glass has the ability to be recycled endlessly without compromising its unique qualities. The process of recycling glass is a simple and greatly benificial process due to the nature of it's structure - it does not detoriorate when reprocessed.
Benefits of recycling include:
• Reducing the demand for raw materials. The material used in recycling glass can be quarried from the landscape. This is a great environmental advantage - using recycled glass means raw materials, such as limestone, dolomite and clay are preserved.
• Although glass does not readily react with other chemicals and is not directly hazardous to the environment, when disposed of in the earth, it will remain there indefinitely. Recycling reduces the amount of glass which needs to be landfilled.
• Everyone can contribute to the recycling of glass. Correctly disposing of household objects such as bottles and jars, makes us think about the positive effect we are having on the environment. Communities, as a whole can work towards a greater level of sustainability.
Through stages of the recycling process, the appearance and properties of glass are manipulated. This aspect can be of great potential to designers;
Designer Andy Cao, intercepted the recycling process at the point where the glass had been crushed, but not yet melted. The pieces if glass at this stage possess a frosty appearance and have no sharp edges, making them soft to hold. Using this new material, he created the Echo Park Garden. Glass is present throughout the garden landscape in the form of coloured, crushed glass pieces. The material provides frim surfaces to walk on as well as forming a satisfactory mulch between planting areas. Despite the crisp texture of the material, the overall impression of the garden is of a soft and sensual landscape.
Images of Echo Park Garden can be viewed at http://www.4culture.org/publicart/registry/sites/sites_artist.asp?ArtistID=13
Another example of the application of recycled glass to the landscape, is displayed in a creative event in Mid-Canterbury, held by Wastebusters Trust.
Recycling a Beach, a complete cycle
“We used crushed recycled glass that looks exactly like sand,” says WasteBusters spokesperson Sandie McKenzie. “It has huge potential as a product. You can’t tell the difference between it and real sand unless you use a microscope.” The Recycled Materials Foundation in Christchurch has the ability to process the glass.
By reusing the material in this context, a conclusive step may have been discovered towards saving beaches around the world that are suffering from sand erosion and decline.
See also for recycle glass http://www.landscape2go.com/1.htm
List of manufacturers / contractors / suppliers
• Pacific Glass International Limited
Address: 18 Constable Rd Waiuku Auckland
Phone number: 0-9-536 5020
• The Glass Company Ltd
16 a Tennyson St Upper Hutt Wellington
Phone number: 0800 777 007
• Birchfield's Glass & Glazing
Unit 6 954 Ferry Rd Christchurch
Phone number: 0-3-384 2488
Product information / specifications
Glass, in its most common form, is a transparent, strong, hard wearing, inactive material, that can be moulded to varying shapes and finishes. Some people believe that glass is actually a liquid of practically infinite viscosity. This means that it flows, much the same as liquid, only very slowly. This theory however, has never been proved and lacks solid evidence to justify this claim.
Fibreglass is a material made of extremely fine granules of glass. It is useful because of its high surface area to weight ratioo, yet more vulnerable to chemical attack.
Pitch is a name given to many seemingly solid materials that are actually highly viscious liquids. Pitch flows at room temparature, although very slowly. It has a viscosity 100 billion times that of water.
Precedent 1
A local example of Glass being used on an everyday basis in Landscape Architecture is this octagonal seat box next to, and above, the Old Bank Arcade, at the end of Lambton Quay. At street level, this feature adheres to what Jan Gehl described as optional activities, that is "those pursuits that are participated in if there is a wish to do so and if time and weather make it possible". It provides a place to sit and chat, stop for a break, or even "sitting around anjoying life". Gehl talks in his book "Life between Buildings - Using Public Space" about humans need for contact. Simple features such as this provide oppourtunities for these contacts to take place. Underground, the transparancy of the glass allows for natural lighting to occur in the passage under Willis St and Customhouse Quay. This simple, rather plain peice of Landscape Architecture harnesses the properties and benefits of Glass to allow for the basic needs of everyday people, as well as providing a unique link between the street and the sub-terrainian.
Precedent 2
.....3 cups of sand a bit of soda lime and wee bit of high heat ......and Voilà .see more at http://http://www.chihuly.com/Video/gardensandglass.html
Precedent 3
See also
References
• Glass
Structure and technology in Architecture, Sophia and Stefan Behling, Prestel 1999
• Architectural Glass Art
Form and technique in contemporary glass, Andrew Moor, Rizzoli International Publications, inc. 1997
• The New Tech Garden
Paul Cooper, Octopus Publishing Group Ltd 2001
• [1]
External links
Landscape Architecture design with glass :
Christopher Bradley-Hole Chelsea Flower Show 2000 http://www.christopherbradley-hole.co.uk/projects/watergarden/watergarden.htm Topher Dealney The Kuhling Garden http://www.tdelaney.com National Association of Manufacturers http://www.nam.org Glass Encyclopedia http://www.glassencyclopedia.com
USA
Manufacturing / extraction processes
Glass and glass making
Naturally occurring glass is formed when unstable tectonics allow volcanic opportunity. Felsic lava rich in silica or SiO2 (silicon dioxide), then cools rapidly which intern stunts the development of crystalline minerals. The lack of crystalline growth enables obsidian the ability fracture conchoidally producing razor sharp extremely thin shards. These razor sharp shards of obsidian were valuable tools durring the Stone Age. Common uses were predominately, mirrrors, blades for arrows and knives, and decorative art.
Man made glass, per ancient-Roman historian Pliny (AD 23-79), states that Phoenecian merchants became aware of glass in 5000 BC while cooking on an open fire. When the heat from the fire melted an adjacent rock, it incorporated with the sand below forming an opaque liquid.
Man made glass as a craft, dates around 3500 BC in Egypt and Eastern Mesopotamia. What may have been a coincidental finding due to the accidental pairing of calciferous sand, soda and an overheated kiln produced the first glass craft in the form of glazes for pottery. However, the earliest glass artifacts are from the 16th century BC found in Mesopotamia and durring which other regimes such as China, Mycenae (Greece) and Tirol were busy developing similar independent productions.
Hollow glass production soon followed when Egyptian craftsmen used compacted sand in combination with molten glass to form glassware which was rolled smoothed and decorated (1500 BC).
Further evolution in glass craft didnt occur until 27 BC when Syrian craftsmen used long tubes to roll and blow glass to shape. When the Romans discovered this glass blowing from the Syrians they added a mold to the above process increasing the variety of shapes attainable through glass craft. However, the great leap forward in glass craft is largely attributed to the Romans due to the long reach of the their empire and thus the spread of glass craft innovation. Architecturaly, the romans are once again attributed with the addition of Mangabese Oxide to molten glass forming a much improved clear glass better suited for windows.
The early Middle Ages (1000 AD) witnessed a split in glass making technology. Due to trading difficulties, glass north of the alps replaced soda glass with that of potash. Areas south of the Alps continued to use soda glass. Soon after, north of the Alps, sheet glass was developed, however, it was greatly refined by the Venetian craftsmen (13th c.).
“By blowing a hollow glass sphere and swinging it vertically, gravity would pull the glass into a cylindrical "pod" measuring as much as 3 metres long, with a width of up to 45 cm. While still hot, the ends of the pod were cut off and the resulting cylinder cut lengthways and laid flat. Other types of sheet glass included crown glass (also known as "bullions"), relatively common across western Europe. With this technique, a glass ball was blown and then opened outwards on the opposite side to the pipe. Spinning the semi-molten ball then caused it to flatten and increase in size, but only up to a limited diameter. The panes thus created would then be joined with lead strips and pieced together to create windows.” [2]
Venetian Glass Empire
Because the Venetian merchants and navy ruled the mediterranean, Venetian glass craft was well suited to expand its glass craft knowledge and capabilities. The free flow of information enabled through becoming the dominating port city state in Europe and nearest to other glass
Industrial Revolution
The mass production of glass didn't come until the Industrial Revolution that brought mechanical technologies to the trade. Scientific research looking into the composition of glass and its physical qualities happened along with this and greatly improved practices. The effects of numerous chemical elements on the optical and thermal properties of glass was looked at by a couple prominent scientists of the time. Towards the end of the 19th century process' such as the automatic bottle blowing machine were invented. By the year 1920, in the United States, there were around 200 automatic bottle blowing machines. The automation of glass was furthered with such additions as the gob feeder and IS (individual section) machines. A combination of these two machines is still used in glass production today.
In 1905 came the first real innovation in flat glass technology in a while. There were improvements in production whereas they could draw a continuous sheet of glass of a consistent width from the tank. Commercialization of this method didn't finally get underway till 1914. Around the end of the first world war a Belgian engineer developed a process where molten glass was poured from a pot directly through two rollers. These two methods gained and ever increasingly even thickness of glass, and made grinding and polishing easier and more economical. Other improvements and innovations with glass around this time were laminated glass, another method of drawing sheet glass, and the float process. The float process, which was developed shortly after the second world war, combined the brilliant finish of sheet glass with the optical qualities of plate glass.
Chemistry
The main constituent of flat glass is SiO2 (silica sand). It has a high melting point which starts around 1700 degrees C and its state at this temperature is like a very thick syrup on a very cold day. Solids that continue to slowly become more liquid with increased temperatures are called amorphous solids. The high melting point and viscosity of silica is reduced by adding sodium oxide in the form of a carbonate. This is done for both practical and economic reasons.
Precedent Donohue
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As a construction element in the landscape, glass, serves many purposes and is fairly diverse in its application. the first application i used identifies with the Fargo landscape in particular. Aand B Glassblock on Roberts Street is used to create a blend of sidewalk and glazed area.D Glass in the landscape also occurs naturally.EGlass taken out of the landscape.FRoman Glass from Archeological dig.GLitter.
Precedent 1
user:chidozie
See also
- Obsidian use in Mesoamerica
- Hyaloclastite, tachylite - volcanic glasses with basaltic composition
- Flintknapper|Flint knapping
Recycling
Using recycled glass not only saves landfill space, it also prevents depletion of natural resources. Glass can be recycled as part of a simple but hugely benefical process, as its structure does not deteriorate when reprocessed.
Benefits of glass recycling:
-Recycling glass creates only half the greenhouse gas compared to new glass using for greenhouse.
-Its also creates more landfill space for other waste resources.
-Could save up to 32% of energy to make new glass from raw materials.
The glass recycling process is a closed-loop system, creating no additional waste. One of the most exciting aspects of recycling glass waste is the limitless potential end uses for designers. The design of Recycled Garden Glass for Landscaping; the glass had been crushed but not yet melted. Glass is present throughout the garden landscape in the form of coloured. The proprietary production process produces glass that has virtually no sharp edges. This garden had several mulch mixed that combine different colors of glass with white marble gravel. These mulch mixes was using for garden pathways.
Image of Recycled Garden Glass for Landscaping: http://www.homestead.com/prosites-closetheloop/recycled_glass.html
Precedent Hammrich
Contemporary Uses for Glass
Doors/Entryways Shower Enclosures Windows Partitions Staircases Countertops Gates Lighting Mirrors Sculpture Flooring
Types of Contemporary Glass
Fused Glass
Laminated Glass
Etched Glass
Leaded Glass
Laminated Glass
Sand-Carved Glass
Precedent 3
Glass uses in Landscape
