Glass

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MasterFormat Number: 04 00 00

Contents

History and Place of Origin of Glass

There is still no specific date as to when the first sight of glass was seen, or the first creation of glass was discovered. No one really knows where or when glass was made. Different forms of glass exist, including naturally made and man-made glass. Each was first spotted at different times in history and in different places throughout the world. Natural glass, from volcanic eruptions, date back to the Stone Age. Man-made glass has been dated back to the second millennium BC. by the Egyptians. But it was originated in Mesopotamia, the Bronze Age, as pieces of fully made glass, past their crystallized stage, were discovered there. This discovery of glass dates back to the third millennium BC. Glass was seen as something very important and unique. Glass making began and became popular in many places. First originated in Mesopotamia, this art of glass making then made its way to Egypt. In Egypt and Eastern Mesopotamia glass objects began to arise as early as 3500 BC. This included glass beads that were not always transparent, but had colour compounds added to it. Glass making continued to thrive in Egypt, Iraq and Iran. It did not flourish immediately in Europe as it took until the 13th century with the creation of stained glass windows. It mainly flourished due to Venice becoming Europe’s main glass producer. Glass began to thrive in bigger scale areas in Europe such as buildings themselves. It was the Romans who brought forth the concept of using glass for architectural purposes, with the discovery of clear glass around AD 100.

Raw State of glass

There are different raw states of glass since it can be made naturally as well as manufactured. The basic state of glass includes sand and heat striking one another at high temperatures. This is how it is mainly created in nature. But there are many different ways that glass can be made naturally. This includes when lightning strikes sand, when lightning strikes a rock, and when a meteorite collides with Earth.

Glass can also be man-made. The main ingredient in glass is sand (silicon dioxide); this is the most important material in order to produce glass. The other materials needed are soda ash (sodium carbonate) and limestone (calcium carbonate). All these materials come together at high temperature and then become cooled. Household baking soda (sodium bicarbonate) can also work. These materials, of course, all have a purpose and role when glass is being made. Soda ash helps the mixture to melt at a lower temperature than would be required without it. Glass can actually be made from just sand and soda ash put together but the limestone is added in order to control the water content, therefore preventing the mixture from becoming too fluid.

Manufacturing locations

There are many glass manufacturing locations all over the world. Due to the fact that glass is so commonly used and has made its way globally, many glass manufacturers have developed. Some Canadian glass manufacturers include: Pegasus Glass in Cambridge, Ontario; MD Glass Tempering Ltd in Montreal, Quebec; Almark Travers Ltd in Markham, Ontario; and CIF Composites Inc. in Saanichton, British Columbia. Schott is a famous glass manufacturer with locations all over North America. This includes one in Midland, Ontario, Canada, fifteen locations in America, and two locations in Mexico.

Process

Melting is an important part of the production of glass. The individual raw materials are combined together at high temperatures to create molten glass. After the melting process, the glass is removed from the furnace for further processing and then the glass is cooled. There are different melting methods and different furnaces used to melt the materials. There are pot furnaces that are used to manufacture mouth-blown glass products and special glasses. About six to twelve pots with different glass types can be melted at the same time.

The tank melting method is used when large amounts of glass need to be processed, especially machine produced glass. During the day, day tanks are refilled with a batch to make the glass. At night, the material is melted and the next day the glass goes into production. This method allows time for any changes such as having to melt a different type of glass on a short notice. Day tanks are generally used for soft special glasses, coloured glass, and crystal glass. Continuous tanks are used in industrial mass production for flat glasses, container glass, and some mass-produced optical glass. Glass melting tanks are one of the largest industrial furnaces. The daily output of glass from these tanks ranges from 100 to 400 tons per day. The glass making process is continuous, requiring continuous feeding of batch material and continuous processing.

There are several steps in the melting process including primary melting, refining, and conditioning. The main component of glass, sand, begins to melt between 1000 to 1200˚C . First, the sand dissolves and the silica acid from the sand combines with the sodium oxide in the soda ash, and all other batch material. Simultaneously, there are gases escaping through sulfates, nitrates, carbonates, and hydrates. This creates water, nitrogen, oxygen, carbon dioxide, and sulfur dioxide. The glass melt will eventually become transparent and the melting phase would be completed. The refining process eliminates all the bubbles from the melt by mixing and degassing the glass. After that, the conditioning phase lowers the temperature to around 900 or 1200˚C. Different types of glass can be produced through this process. Flat glass refers to all glasses that are produced in a flat form. Rolled glass is glass that is poured and rolled flat but not fully transparent. Molten glass flows from the melting tank onto a machine slab where the glass flow enters two water-cooled rollers. The distance between the rollers depends on how thick the glass needs to be. If the glass needs any texture or pattern, patterned rollers are used. The glass is then slowly cooled until it is lukewarm; it is later cut to standard sizes and packed into shipping crates.

Hollowware is the most common glass product made. It is seen everywhere especially in consumer goods, like bottles, drinking glasses, and glass lamps. To create the shape of hollowware, glassworkers make each piece individually by blowing air into the glass through a pipe. When hollowware is mass-produced, blowing machines are used instead. These machines would put the glass in molds and then blow into it to take the shape of that mold, creating bottles, jars, or any other product.


Cultural Significance

Before, windows were just holes in the wall but with the development of glass it has helped to maintain contact with the exterior without jeopardizing the security of a place. In the past, glass became a great fascination among people because of the material’s unique properties. Its adaptable and resourceful properties help to illuminate interiors and enhance the interaction with nature from the inside. There was a study made by Dr. John Ott, where it showed that students in a classroom with sunlight instead of fluorescent lighting had better academic performance. The students were calmer and more attentive than those who were in another room feeling fatigue, hyperactive, and had difficulty concentrating. Hospitals also use this “light therapy” to treat their patients so they heal faster and healthier.

“Glass was used to enhance the beauty of other elements rather than being a beautiful material itself. A lot of times its not what the glass does to people’s emotion but it is the effect of the light passing through the glass that affects people.

For Christians, the stained glass windows create beauty in a church by providing a constantly changing pattern of colours. The coloured rays of light create a calming atmosphere inside the church, providing a relaxed and peaceful space for meditation and prayer. This light is magnificent as it is like a brilliance of holy light joining heaven and earth. The glass designs were used to tell a biblical story, "They were sermons which reached the heart through the eyes instead of entering at the ears.” This coloured light that came into the churches created an emotional impact on those looking for comfort and gave them inspiration to live a better life and strengthen their faith. However stained glass has also been used for other purposes, such as to create a romantic atmosphere and to increase the imagination in people’s minds. Glazed windows were luxury items but after the Middle Age stained-glass windows became more popular in public buildings, inns, and in homes of the wealthy.

There are also certain beliefs and superstitions involving glass itself. In Turkey, they have the Evil Eye glass beads, which they put just about anywhere. Many people wear them as jewelry, give them away as gifts and hang them in their car mirrors. They believe that the evil eye gives protection and good luck, and that it would see all the evil in the world and would remove all the poverty and ignorance in it. This belief was later spread to Egypt, the Mediterranean, the Middle East and Europe. There has also been the famous superstition that if one breaks a mirror they will have seven years of bad luck. This goes back to the Romans who first created glass mirrors. The people from Rome, Greece, China, Africa and India believed that mirrors could take a part of the person’s soul so if the reflected image of the person ever became distorted, it meant corruption of their soul.

Glass has affected many through emotional, mental, and cultural aspects on people’s lives. But in our present world, since glass is less expensive than ever before, people sometimes take it for granted. Although it is still widely used in many new constructions today, glass isn’t appreciated as much as the past as there are so many more materials that have been discovered since then.

Physical Properties

There are multiple variations when it comes to the physical properties of glass. This includes the different chemical compounds for glass that are predetermined depending on how it will need to be used in the future. Glass is actually a non-crystalline material; due to its atomic structure it lacks the symmetry normally found in a crystalline substance. The atomic arrangement of glass is close to that of a liquid; this is quite obvious when glass is seen at its molten state before it is cooled. During the cooling process the glass reaches a perfect temperature for crystal growth or nucleation but can never fully become a crystal. This is why when the glass is fully cooled it becomes brittle and solid. Glass is usually described as being transparent. Oxide and fluoride compounds of glass are transparent to light in the visible and inferred regions whereas chalcogenide glass is translucent to light in the visible and inferred regions. These are just a couple examples of how the physical properties of glass can be manipulated with different chemical compounds. Strength, temperature, resistance and reactivity of glass all vary on chemical manipulation. Glass in a home for example, can be one of the major sources of heat loss. A low emissive coating can be applied to the glass and can reduce heat transmission up to 30%-50%. Double and triple pane glass has a gas sandwiched in between the panes of glass, providing with more insulation.

Installation and Maintenance

Installations for glass will vary depending on the use. Glass tiles should be installed by using a white, fast-drying polymer-modified thinset. Mastic adhesives are not recommended because there is a tendency for moisture to get trapped between the non-porous tile and the moist mastic adhesive; this can cause mold and bonding issues. Also, any colour thinset besides white will show through the tile. There are three other main ways glass can be installed. Silicon is a common way to install glass; it is most commonly used to install shower glass walls. A bead of silicone is laid where the glass sits and acts similarly to glue holding the glass in. An aluminum or steel channel is also commonly used to install glass. This is common in sliding track glass doors. The glass sits in the channel and can be held by screws and/or silicone. Glass can also be drilled. This installation is popular in cases such as shower doors held by screws and hinges. The drill heads for glass include: the diamond coated drill head and the carbide spear point drill head; these will give the best results.

Once installed, glass can become fairly easy to maintain. In most cases all that glass requires is a little soap and water. Glass cleaners and other products can be used as well. The problem with using glass cleaners is it may damage any grout or silicone around the glass. In the case of glass cracks or scratches, external help may be required to repair or replace the glass. To repair the glass a compound is injected into the crack or scratch, which is cured by the ultraviolet rays of the sun.


Installations (local and largest)

A lot of glass manufacturers do not install glass themselves; instead they supply it to the contractor or the builder. Trulite Industries, a Canadian glass manufacturer, is an example of a company that supplies to the builder. Even though they do not install the glass they do make recommendations on which types of glass a builder should install depending on the type of building (commercial/residential), location of the building and the future function of the glass. Trulite Industries has done some major industrial sized projects such as the glass on the AGO façade, the Tip Top Tailors condominium building in Toronto and the University of Waterloo Pharmacy building.

The manufacturers who supply the glass can also do the installation. One notable company is Adanac Glass Limited (Toronto, Canada) that specializes in interior glass applications such as glass shower walls, mirrors, glass stairs and more. They manufacture their products as well as provide a design and installation service. There are many products that are not fully made of glass, they are made out of other materials but it still contains some glass. Some glasses that are a part of another entity, such as a door or a ready-made window, are usually installed by the manufacturer of that product. For example, Canuck Door Systems provide glass doors to residential and commercial places. The glass is not manufactured by this company but is installed as the ready-made glass door by Canuck Door Systems. The locations of this company spans across the greater Toronto area.

Testing

There are different tests performed on glass depending on its future use. Some tests include:

  • Performance Testing
  • Failure Analysis
  • Temperature Testing
  • Glass Chemistry
  • Residual Stress Evaluation

When a test piece of glass fails, scientists analyze the pattern created when the piece breaks to identify how and why the glass broke. Temperature resistance of glass is very important because different uses require a certain amount of heat resistance, such as in cookware. Scientists can also find the weakest pressure points within a glass structure; this comes in handy when evaluating the resistance during the packaging and transporting process. Once again, there are many tests that different glass pieces go through, but it all depends on what the glass will be used for.

Availability (lead times to install)

Installation times will differ depending on the company and the appointment. However, the temperature outside should not be too hot or too cold, thus to prevent any bending, shrinking or expansion that can occur to the glass. If there is a temperature change applied to one side of the glass it will cause it to expand and contract unevenly across the pane, thus warping the glass causes it to shatter, break and in some cases explode. A film can be placed on the glass to decrease the chances of this happening; this is common for windowpanes.

Various common and innovative interior uses

Glass is used in many ways within an interior space. Some types of glass are used in the structural design of the space whereas some types of glass are found within a space; through furniture, etc.

There are many types of rolled glass that can be found:

  • Raw glass can be used for applications that do not require transparency or specific optical properties.
  • Ornamental glass is textured by patterned or embossing rollers and can be used for decorative purposes or for dispersion and reduction of glare.
  • Greenhouse glass is translucent glass with a special surface to scatter light.
  • Wire-reinforced glass has wire netting embedded to prevent break-ins and the spreading of fire. It is generally found in entrance doors, hall doors, or storage area doors. The wire holds the glass together when it breaks.
  • Wire-reinforced ornamental glass is wire-reinforced glass with texture and is used for practical and decorative uses within an interior space.
  • Profile glass is U-shaped rolled glass for architectural use. It is used for skylights.
  • Coloured cast glass is coloured glass which is usually broken into smaller pieces and arranged to create an artistic design, often seen in churches.
  • Opaque glass let’s no light to pass through and it comes in different colours. It is watertight so it can be used as wall cladding (tiles) for exterior and interior architectural applications. It is also used for furniture, shelves, and countertops.
  • Window glass is the big sheets of glass that are used for windows
  • Antique glass is glass of the highest purity and clarity and is popular for rustic or nostalgic style decoration. It is often glazed with lead or brass strips to furniture and windows.
  • Flashed glass has a layer of coloured or opal glass which is used to evenly disperse light and create glare-free room illumination. It is used in translucent room dividers, bathroom windows, shelves in showcases and X-ray picture viewers.
  • Safety glass includes a special treatment to help prevent the glass from breaking. It is used for glass doors.
  • Fire resisting glass is used to slow down the spread of fires in buildings. There are different methods used to accomplish this including wire meshing and fire resisting glazing.

There are also many types of hollowware glass that can be used in interior spaces:

  • Beverage bottles are glass bottles that hold drinks including wine, liquor, juice, and soda.
  • Bottling jars are used to preserve foods and are made of clear glass for clear vision of the contents within the jar.
  • Glass tableware is also referred to as household glassware, which can include drinking glass, ashtrays, table and floor vases, flower bowls, candleholders, and large glass dishes.
  • Transparent borosilicate glass is thermal toughened glass produced by Duran (Schott) and Pyrex (Corning). They are dishes, baking molds, teapots, glasses/cups, coffee-maker jugs and baby feeding bottles.

Ecological Footprint & VOC’s & Sustainability

Glass is basically made out of sand, which is available, and it does not pollute. But in glass production, the majority of the glass furnaces use air to burn fuels, air which is made up almost 80% nitrogen. The furnaces change some of that nitrogen into nitrogen oxide and if high amounts are realeased, many serious problems may arise. This includes respiratory problems, deterioration of water quality, visibility impairment, global warming and reaction of toxic chemicals. A more sustainable way to fuel the furnaces is by using a mixture that is over 90% oxygen; the only thing is that it is more expensive for companies. Another way to look at glass’ ecological footprint is to look at the VOC emission of the materials used for the joinery and maintenance. There are silicones with very little or no VOC’s, and as for maintenance, there are glass cleaners with no VOC’s. There are products that do release VOC’s, but there are also more eco-friendly options out there.

Typical Unit Size (For Architectural Glass)

  • 2 Basic sizes for mouth blown glass
  • Most German glass comes in sheets approx. 35x25 in.
  • English Antique glass: 22x18 in. Standard Variable thickness, ranging from 1/16” to 3/16”, the average thickness being 1/8 “
  • Rolled Glass: 60x30 in
  • Rolled Glass and Float Glass: machine made products, so they come in predetermined thicknesses
  • Float Glass: standard format known as “ribbon size” is 600x321 cm
  • Float Glass standard/nominal thicknesses are 2,3,4,5,6,8,10,12,15,19mm

FLOAT GLASS 

Thickness	 Tolerance
2,3,4,5,6,mm	+/- 0.2 mm
8,10,12 mm	+/- 0.3 mm
15 mm	        +/- 0.5 mm
19, 25 mm	+/- 1.0 mm

DRAWN SHEET GLASS 

Thickness	Tolerance
2,3,4 mm	+/- 0.2 mm
5,6 mm   	+/- 0.3 mm
8 mm	        +/- 0.4 mm
10 mm	        +/- 0.5 mm
12 mm	        +/- 0.6 mm

Supply Cost

The supply cost varies enormously, depending on the type of glass and the size of it. Antique Glass is relatively expensive. However, flashed glass is more expensive than regular antique. Rolled glass is less expensive than Genuine Antique Glass because it is often less than a quarter of its cost. Furthermore, the cost of different colours also varies enormously. For example, the colour red would be more expensive than other colours.

Life Cycle Costs (for clients)

When looking at the life cycle costs of glass, analyzing its life and performance attributes to fit the requirements defined by the clients is important. The glass should be selected to fit on a “least cost basis” which would include the conditions for safe maintenance. If life of the glass is less than the intended life of the building it is being installed in, than the design should consider the safety and simplicity of the removal and replacement of glass.

Design Life

Replaceable: Understand and be aware of the replacement of glass incase it has a shorter life span than indicated for the building. Maintainable: A proper maintenance and periodic inspection should be carried out every so often. This will help the glass to maintain strength and durability for a longer. Lifelong: When the glass will last as long as the building, with minimal or no maintenance at all. The use of existing parts of a building cannot be fully predicted; therefore, designers have no control over this. Furthermore, it is unlikely to have a history of glass products at the leading edge of technology.

Recycling/Biodegradability Opportunities of Glass

Glass is a great material to recycle. This is because it can be recycled forever; the same glass can be recycled a million times and still have the same durability and properties as a new piece of glass. By crushing glass, it returns it to its natural state. It does not create harm to the environment, as it is non-toxic. Glass is 100% recyclable as it can be brought back to its natural state. The energy needed to form glass is very small compared to other materials, and since it retains a decent amount of energy it makes it that much easier and energy efficient to re-melt and reform. Recycling glass is a very beneficial process since glass can be formed from a mixture that is 80% scraps, called “cullet.” There are many glass tiles and pieces that are made up of cullet combined with cement or polyester resin. Fibreglass can also be made into two different types of fibres: continuous fibres; which are commonly used for glass reinforced plastics or cements and short fibres; which can be produced into a material that is used for insulation. Glass, like mostly all materials, is biodegradable. With this said, unlike most materials, glass takes a million years to biodegrade fully. In this case, it is better to recycle glass as it can always be reused rather than leaving it to fill up landfills.

Students

Ryerson University:

  • Fiona Chan
  • Iris Hsueh
  • Erica Fuda
  • Vicky Kwon
  • Kelly Klemp
  • Laura Marthe

Bibliography

http://www.glassonline.com/infoserv/history.html (accessed Oct. 1, 2010).

http://www.extremehowto.com/xh/article.asp?article_id=60152 (accessed September 28, 2010).


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