Moldavite, a natural glass formed by meteorite impact, from Besednice, Bohemia

A modern greenhouse in Wisley Garden, England, made from float glass

Clear glass light bulb

Glass in the common sense refers to a hard, brittle, transparent solid, such as that used for windows, many bottles, or eyewear, including soda-lime glass, acrylic glass, sugar glass, isinglass (Muscovy-glass), or aluminium oxynitride. Moldavite is an olive-green or dull greenish Vitreous substance formed by a Meteorite impact A meteorite is a natural object originating in Outer space that survives an impact with the Earth 's surface Český Krumlov District (Okres Český Krumlov is a district ( Okres) within South Bohemian Region of the Czech Republic. Bohemia (Čechy; Bohemia Czechy is a historical region in central Europe, occupying the western two-thirds of the traditional Czech Lands, currently the A greenhouse (also called a glasshouse or hothouse) is a building where plants are cultivated The Royal Horticultural Society 's garden at Wisley in the English County of Surrey south of London is one of the three most visited England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland Float glass is a sheet of Glass made by floating molten glass on a bed of molten Tin. A lamp is a replaceable component such as an Incandescent light bulb, which is designed to produce Light from Electricity. Hard or "hardness" may refer to Hardness, resistance of physical materials to change under force In Optics, transparency (also called pellucidity) is the Material property of allowing A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. GlassWindowjpg|thumb|right|190px|A stained glass panel depicting Biblical scenes at a historic church in Scotland]] A window is an opening Glass bottles are Bottles created from Glass. They can vary in size considerably but are most commonly found in sizes ranging between about 10ml and 5 Litres Glasses, also called eyeglasses or spectacles, are frames bearing lenses worn in front of the Eyes normally for vision correction, Soda-lime glass, also called soda-lime-silica glass, is the most prevalent type of Glass, used for windowpanes and glass containers (bottles and jars Poly(methyl methacrylate ( PMMA) or poly(methyl 2-methylpropenoate is a Thermoplastic and transparent Plastic. Sugar glass (also called candy glass and breakaway glass is an edible mixture of Sugar, Corn syrup and Water, which has the appearance of Glass Muscovite (also known as Common Mica, Isinglass, or Potash mica) is a phyllosilicate Mineral of Aluminium

In the technical sense, glass is an inorganic product of fusion which has been cooled to a rigid condition without crystallizing. ^{[1][2][3][4][5]} Many glasses contain silica as their main component and glass former. The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide ^[6]

In the scientific sense the term glass is often extended to all amorphous solids (and melts that easily form amorphous solids), including plastics, resins, or other silica-free amorphous solids. An amorphous solid is a Solid in which there is no Long-range order of the positions of the Atoms (Solids in which there is long-range atomic order are Plastic is the general common term for a wide range of synthetic or semisynthetic organic solid materials suitable for the manufacture of industrial products Resin, not to be confused with Rosin, is a Hydrocarbon Secretion of many Plants particularly coniferous trees. In addition, besides traditional melting techniques, any other means of preparation are considered, such as ion implantation, and the sol-gel method. Glass is common in everyday Life, from glass Windows to Glass containers The manufacture of Glass for everyday purposes may involve Ion implantation is a Materials engineering process by which ions of a material can be implanted into another solid thereby changing the physical properties of the The sol-gel process is a wet-chemical technique ( Chemical Solution Deposition) for the fabrication of materials (typically a Metal oxide) starting either from a chemical ^[6] However, glass science commonly includes only inorganic amorphous solids, while plastics and similar organics are covered by polymer science, biology and further scientific disciplines. Traditionally inorganic compounds are considered to be of mineral not biological origin Polymer science or macromolecular science is the subfield of Materials science concerned with Polymers primarily synthetic polymers such as Plastics Foundations of modern biology There are five unifying principles

The optical and physical properties of glass make it suitable for applications such as flat glass, container glass, optics and optoelectronics material, laboratory equipment, thermal insulator (glass wool), reinforcement fiber (glass-reinforced plastic, glass fiber reinforced concrete), and art. Flat glass, sheet glass, or plate glass is a type of Glass, initially produced in plane form commonly used for Windows glass doors transparent Optoelectronics is the study and application of electronic devices that source detect and control Light, usually considered a sub-field of Photonics. Laboratory equipment refers to the various Tools and Equipment used by Scientists working in a Laboratory. Glass wool is a form of Fibreglass where very thin strands of Glass are arranged into a spongy texture similar to Steel wool. Glass-reinforced plastic ( GRP) is a Composite material or Fiber-reinforced plastic made of a Plastic reinforced by fine fibers Glass Fiber Reinforced Concrete ( GFRC) is a type of Fiber reinforced concrete. Glass art and Glass sculpture is the use of Glass as an artistic medium to produce Sculptures or two-dimensional Artworks Specific approaches

General properties, uses, occurrence

Laboratory glassware made from borosilicate glass (Erlenmeyer flask)

Flat panel display, using thin sheets of special alkali-free^[7] glass

Ordinary glass is prevalent due to its transparency to visible light. Laboratory glassware refers to a variety of equipment traditionally made of Glass, used for Scientific experiments and other work in Science, especially Borosilicate glass is a type of Glass with the main glass-forming constituents Silica and Boron oxide. An Erlenmeyer flask, commonly known as a conical flask or E-flask, is a widely used type of Laboratory flask which features a conical base and a cylindrical Flat panel displays encompass a growing number of technologies enabling video displays that are lighter and much thinner than traditional television and video displays that use Cathode In Chemistry, an alkali (from Arabic: Al-Qaly القلي القالي) is a basic, ionic salt of an Alkali metal This transparency is due to an absence of electronic transition states in the range of visible light. The transition state of a Chemical reaction is a particular configuration along the Reaction coordinate. The homogeneity of the glass on length scales greater than the wavelength of visible light also contributes to its transparency as heterogeneities would cause light to be scattered, breaking up any coherent image transmission. In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. Scattering is a general physical process whereby some forms of Radiation, such as Light, Sound or moving particles for example are forced to deviate from Many household objects are made of glass. Drinking glasses, bowls and bottles are often made of glass, as are light bulbs, mirrors, aquaria, cathode ray tubes, computer flat panel displays, and windows. Drinkware or beverageware is a general term for the class of vessels from which people drink A bowl is a common open-top container used in many cultures to serve Food, and is also used for Drinking and storing other items Glass bottles are Bottles created from Glass. They can vary in size considerably but are most commonly found in sizes ranging between about 10ml and 5 Litres The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric Light that works by Incandescence, (a general A mirror is an object with a surface that has good Specular reflection; that is it is smooth enough to form an Image. An aquarium (plural aquariums or aquaria) is a Vivarium consisting of at least one transparent side in which Water -dwelling Plants The cathode ray tube (CRT is a Vacuum tube containing an Electron gun (a source of electrons and a Fluorescent screen with internal or Flat panel displays encompass a growing number of technologies enabling video displays that are lighter and much thinner than traditional television and video displays that use Cathode GlassWindowjpg|thumb|right|190px|A stained glass panel depicting Biblical scenes at a historic church in Scotland]] A window is an opening

In research laboratories, flasks, test tubes, and other laboratory equipment are often made of borosilicate glass for its low coefficient of thermal expansion, giving greater resistance to thermal shock and greater accuracy in measurements. A laboratory (informally lab) is a facility that provides controlled conditions in which scientific Research, Experiments and Laboratory flasks are vessels (containers which fall into the category of Laboratory equipment known as glassware. A test tube, also known as a culture tube, sample tube, test flute or flaccid flute, is a piece of Laboratory glassware composed of Laboratory glassware refers to a variety of equipment traditionally made of Glass, used for Scientific experiments and other work in Science, especially Borosilicate glass is a type of Glass with the main glass-forming constituents Silica and Boron oxide. When the Temperature of a substance changes the energy that is stored in the Intermolecular bonds between atoms changes Thermal shock is the name given to cracking as a result of rapid temperature change For high-temperature applications, quartz glass is used, although it is very difficult to work. Fused quartz and fused silica are types of Glass containing primarily Silica in amorphous (non- Crystalline form Most laboratory glassware is mass-produced, but large laboratories also keep a glassblower on staff for preparing custom made glass equipment. Laboratory glassware refers to a variety of equipment traditionally made of Glass, used for Scientific experiments and other work in Science, especially Mass production (also called flow production, repetitive flow production, series production, or serial production) is the production of Glassblowing is a glassforming technique that involves inflating the molten glass into a bubble or parison with the aid of the blowpipe or blow tube

Sometimes, glass is created naturally from volcanic lava, lightning strikes, or meteorite impacts (e. Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures Lightning is an atmospheric discharge of Electricity, which typically occurs during Thunderstorms and sometimes during volcanic eruptions or A meteorite is a natural object originating in Outer space that survives an impact with the Earth 's surface g. , Lechatelierite, Fulgurite, Darwin Glass, Volcanic Glass, Tektites). Lechatelierite is Silica glass Amorphous SiO2 One common way in which lechatelierite forms naturally is by very high temperature melting of Quartz Fulgurites (from the Latin fulgur meaning thunderbolt are natural hollow Carrot -shaped Glass tubes formed in quartzose Sand or soil Darwin glass is a natural Glass found south of Queenstown in West Coast Tasmania. Volcanic glass can refer to any of several types of Vitreous Igneous rocks Most commonly it refers to Obsidian, a Rhyolitic Tektites (from Greek tektos, molten are natural Glass objects up to a few centimeters in size which most scientists argue were formed by the impact of If the lava is felsic this glass is called obsidian, and is usually black with impurities. Felsic is a term used in Geology to refer to Silicate minerals, Magma, and rocks which are enriched in the lighter elements such as Silicon Obsidian is a naturally occurring Glass formed as an extrusive Igneous rock. Obsidian is a raw material for flintknappers, who have used it to make extremely sharp glass knives since the stone age. A knapper is a person who shapes Flint, Chert, Obsidian or other stone through the process of knapping or Lithic reduction to manufacture A glass knife is a Knife with a blade composed of Glass. The cutting edge of a glass knife is formed from a fracture line and is extremely sharp The Stone Age is a broad prehistoric time period during which Humans widely used stone for toolmaking

Glass sometimes occurs in nature resulting from human activity, for example trinitite (from nuclear testing) and beach glass. Trinitite, also known as Atomite or Alamogordo Glass, is the name given to the Glassy residue left on the desert floor after the Plutonium -based Sea Glass is a 2002 Romance novel by Anita Shreve. It is chronologically the second novel in Shreve's informal trilogy to be set in a large beach

Glass in buildings

Main articles: Architectural Glass, Glazing in architecture, and Window

Extensive use of float glass sheets in apartments in Bristol, England. Architectural glass is glass that is used as a Building material. Glazing is a transparent part of a Wall, usually made of Glass or Plastic ( acrylic and Polycarbonate) GlassWindowjpg|thumb|right|190px|A stained glass panel depicting Biblical scenes at a historic church in Scotland]] A window is an opening Float glass is a sheet of Glass made by floating molten glass on a bed of molten Tin. Bristol ( ˈbrɪstəl is a city, Unitary authority and ceremonial county in South West England, west of London England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland

Glass is commonly used in buildings as transparent windows, internal glazed partitions, and as architectural features. It is also possible to use glass as a structural material, for example, in beams and columns, as well as in the form of "fins" for wind reinforcement, which are visible in many glass frontages like large shop windows. Safe load capacity is, however, limited; although glass has a high theoretical yield stress, it is very susceptible to brittle (sudden) failure, and has a tendency to shatter upon localized impact. This particularly limits its use in columns, as there is a risk of vehicles or other heavy objects colliding with and shattering the structural element. One well-known example of a structure made entirely from glass is the northern entrance to Buchanan Street subway station in Glasgow. Buchanan Street subway station is a station on the Glasgow Subway in Glasgow, Scotland. Glasgow (ˈglæzgoʊ is the largest city in Scotland and third most populous in the United Kingdom

Glass in buildings can be of a safety type, including wired, heat strengthened (tempered) and laminated glass. Glass fibre insulation is common in roofs and walls. Foamed glass, made from waste glass, can be used as lightweight, closed-cell insulation. As insulation, glass (e. g. , fiberglass) is also used. Fiberglass (also called fibreglass and glass fibre see Spelling differences) is material made from extremely fine Fibers of Glass. In the form of long, fluffy-looking sheets, it is commonly found in homes. Fiberglass insulation is used particularly in attics, and is given an R-rating, denoting the insulating ability.

Technological applications

Uses of glass for scientific purposes range from applications such as DNA microarrays to large sized neodymium doped glass lasers and glass fibres

The Hubble Space Telescope orbiting above earth, containing optical instruments

Pure SiO₂ glass (the same chemical compound as quartz, or, in its polycrystalline form, sand) does not absorb UV light and is used for applications that require transparency in this region. For terminology see glossary below A DNA microarray is a High-throughput technology used in Molecular biology and in Neodymium (ˌniːoʊˈdɪmiəm is a Chemical element with the symbol Nd and Atomic number 60 A laser is a device that emits Light ( Electromagnetic radiation) through a process called Stimulated emission. The Hubble Space Telescope ( HST; also known colloquially as "the Hubble" or just "Hubble" is a space telescope that was carried into An optical instrument either processes Light waves to enhance an image for viewing or analyzes light waves (or Photons to determine one of a number of characteristic Fused quartz and fused silica are types of Glass containing primarily Silica in amorphous (non- Crystalline form Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in Polycrystalline materials are solids that are composed of many Crystallites of varying size and orientation Sand is a naturally occurring Granular material composed of finely divided rock and Mineral particles Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 Large natural single crystals of quartz are pure silicon dioxide, and upon crushing are used for high quality specialty glasses. Synthetic amorphous silica, an almost 100 % pure form of quartz, is the raw material for the most expensive specialty glasses, such as optical fiber core. An optical fiber (or fibre) is a Glass or Plastic fiber that carries Light along its length Undersea cables have sections doped with erbium, which amplify transmitted signals by laser emission from within the glass itself. A submarine communications cable is a cable laid beneath the sea to carry Telecommunications between countries Erbium (ˈɝbiəm is a Chemical element with the symbol Er and Atomic number 68 An optical amplifier is a device that amplifies an Optical signal directly without the need to first convert it to an electrical signal A laser is a device that emits Light ( Electromagnetic radiation) through a process called Stimulated emission. Amorphous SiO₂ is also used as a dielectric material in integrated circuits due to the smooth and electrically neutral interface it forms with silicon. A dielectric is a nonconducting substance ie an insulator. The term was coined by William Whewell in response to a request from Michael Faraday. Microchipsjpg|right|thumb|200px|Microchips ( EPROM memory with a transparent window showing the integrated circuit inside Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14

Optical instruments such as glasses, cameras, microscopes, telescopes, and planetaria are based on glass lenses, mirrors, and prisms. An optical instrument either processes Light waves to enhance an image for viewing or analyzes light waves (or Photons to determine one of a number of characteristic Glasses, also called eyeglasses or spectacles, are frames bearing lenses worn in front of the Eyes normally for vision correction, A camera is a device used to capture images either as still Photographs or as sequences of moving images ( Movies or Videos. The optical microscope, often referred to as the "light microscope" is a type of Microscope which uses Visible light and a system of lenses to An optical telescope is a Telescope which is used to gather and focus light mainly from the visible part of the Electromagnetic spectrum A planetarium is a Theatre built primarily for presenting educational and entertaining shows about Astronomy and the night sky or for training in Celestial navigation A lens is an optical device with perfect or approximate Axial symmetry which transmits and refracts Light, converging or diverging A mirror is an object with a surface that has good Specular reflection; that is it is smooth enough to form an Image. In Optics, a prism is a transparent optical element with flat polished surfaces that refract Light. The glasses used for making these instruments are categorized using a six-digit glass code, or alternatively a letter-number code from the Schott Glass catalogue. A glass code is a method of classifying Glasses for optical use such as the manufacture of lenses and prisms. SCHOTT AG is a manufacturer of high-quality industrial Glass products such as fiber-optics and components used in Flat panel displays Schott For example, BK7 is a low-dispersion borosilicate crown glass, and SF10 is a high-dispersion dense flint glass. In Optics, dispersion is the phenomenon in which the Phase velocity of a wave depends on its frequency Borosilicate glass is a type of Glass with the main glass-forming constituents Silica and Boron oxide. Crown glass is type of optical glass used in lenses and other optical components Flint Glass is an experimental electronic project by French electronic musician Gwenn Trémorin The glasses are arranged by composition, refractive index, and Abbe number. In Physics and Optics, the Abbe number, also known as the V-number or constringence of a transparent material is a measure

Glass polymerization is a technique that can be used to incorporate additives that modify the properties of glass that would otherwise be destroyed during high temperature preparation. In Polymer chemistry, polymerization is a process of reacting Monomer Molecules together in a Chemical reaction to form three-dimensional networks Sol gel is an example of glass polymerization and enables embedding of organic and bioactive molecules, to add a new level of functionality to glass. The sol-gel process is a wet-chemical technique ( Chemical Solution Deposition) for the fabrication of materials (typically a Metal oxide) starting either from a chemical ^[8]

Glass production

Main articles: Glass production and Float glass

Oldest mouth-blown window-glass from 1742 from Kosta Glasbruk, Småland, Sweden. Glass is common in everyday Life, from glass Windows to Glass containers The manufacture of Glass for everyday purposes may involve Float glass is a sheet of Glass made by floating molten glass on a bed of molten Tin. Year 1742 ( MDCCXLII) was a Common year starting on Monday (link will display the full calendar of the Gregorian calendar (or a Kosta Glasbruk (later known as Kosta Boda is a Swedish glassworks founded by two foreign officers in Charles XII's army Anders Koskull and Georg Bogislaus Stael von Holstein is a historical province ( landskap) in southern Sweden. Småland borders Blekinge, Scania or Skåne Halland, In the middle the mark from the glass blowers pipe

Glass production history

Glass melting technology has passed through several stages:^[9]

• Glass was manufactured in open pits, ca. Glassblowing is a glassforming technique that involves inflating the molten glass into a bubble or parison with the aid of the blowpipe or blow tube 3000 B. C. until the invention of the blowpipe in ca. 250 B. C.

• The mobile wood-fired melting pot furnace was used until around the 17th century by traveling glass manufacturers.

• Around 1688, a process for casting glass was developed, which led to glass becoming a much more commonly used material. Casting is a manufacturing process by which a liquid material is (usually poured into a mold which

• The local pot furnace, fired by wood and coal was used between 1600 and 1850.

• The cylinder method of creating flat glass was used in the United States of America for the first time in the 1820s. Cylinder blown sheet is a type of hand- blown window Glass. It is created with a similar process to Broad sheet, but larger cylinders are produced by swinging Flat glass, sheet glass, or plate glass is a type of Glass, initially produced in plane form commonly used for Windows glass doors transparent The United States of America —commonly referred to as the It was used to commercially produce windows.

• The invention of the glass pressing machine in 1827 allowed the mass production of inexpensive glass products^[10].

• The gas-heated melting pot and tank furnaces dating from 1860, followed by the electric furnace of 1910.

• Hand-blown sheet glass was replaced in the 20th century by rolled plate glass. Flat glass, sheet glass, or plate glass is a type of Glass, initially produced in plane form commonly used for Windows glass doors transparent

• The float glass process was invented in the 1950s. Float glass is a sheet of Glass made by floating molten glass on a bed of molten Tin.

Glass ingredients

Quartz sand (silica) as main raw material for commercial glass production

Pure silica (SiO₂) has a "glass melting point"— at a viscosity of 10 Pa·s (100 P)— of over 2300 °C (4200 °F). Sand is a naturally occurring Granular material composed of finely divided rock and Mineral particles The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. The poise (symbol P pwɑːz is the unit of dynamic Viscosity in the Centimetre gram second system of units. The Celsius Temperature scale was previously known as the centigrade scale. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 While pure silica can be made into glass for special applications (see fused quartz), other substances are added to common glass to simplify processing. Fused quartz and fused silica are types of Glass containing primarily Silica in amorphous (non- Crystalline form One is sodium carbonate (Na₂CO₃), which lowers the melting point to about 1500 °C (2700 °F) in soda-lime glass; "soda" refers to the original source of sodium carbonate in the soda ash obtained from certain plants. Sodium carbonate (also known as washing soda or soda ash), is a Sodium Salt of Carbonic acid. Soda-lime glass, also called soda-lime-silica glass, is the most prevalent type of Glass, used for windowpanes and glass containers (bottles and jars Sodium carbonate (also known as washing soda or soda ash), is a Sodium Salt of Carbonic acid. However, the soda makes the glass water soluble, which is usually undesirable, so lime (calcium oxide (CaO), generally obtained from limestone), some magnesium oxide (MgO) and aluminium oxide are added to provide for a better chemical durability. Lime is a general term for various naturally occurring Minerals and materials derived from them in which Carbonates Oxides and Hydroxides of Calcium oxide ( CaO) commonly known as burnt lime, lime or quicklime, is a widely used Chemical compound. Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3 The resulting glass contains about 70 to 74 percent silica by weight and is called a soda-lime glass. Soda-lime glass, also called soda-lime-silica glass, is the most prevalent type of Glass, used for windowpanes and glass containers (bottles and jars ^[9] Soda-lime glasses account for about 90 percent of manufactured glass.

As well as soda and lime, most common glass has other ingredients added to change its properties. Lead glass, such as lead crystal or flint glass, is more 'brilliant' because the increased refractive index causes noticeably more "sparkles", while boron may be added to change the thermal and electrical properties, as in Pyrex. Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Lead crystal (also called crystal) is Lead glass that has been hand- or machine-cut with facets Flint Glass is an experimental electronic project by French electronic musician Gwenn Trémorin The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium Boron (ˈbɔərɒn is a Chemical element with Atomic number 5 and the chemical symbol B. Pyrex is a brand name for glassware introduced by Corning Incorporated in 1915 Adding barium also increases the refractive index. Barium (ˈbɛəriəm is a Chemical element. It has the symbol Ba, and Atomic number 56 Thorium oxide gives glass a high refractive index and low dispersion, and was formerly used in producing high-quality lenses, but due to its radioactivity has been replaced by lanthanum oxide in modern glasses. Thorium dioxide (ThO2 also called thorium(IV oxide (IUPAC is a white crystalline powder Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. Lanthanum(III oxide is La2O3 a chemical compound containing the Rare earth element Lanthanum and Oxygen. Large amounts of iron are used in glass that absorbs infrared energy, such as heat absorbing filters for movie projectors, while cerium(IV) oxide can be used for glass that absorbs UV wavelengths (biologically damaging ionizing radiation). Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Infrared ( IR) radiation is Electromagnetic radiation whose Wavelength is longer than that of Visible light, but shorter than that of Cerium(IV oxide, ceric oxide, ceria, or sometimes simply cerium oxide or cerium dioxide, is a pale yellow-white powder CeO2 Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays

Besides the chemicals mentioned, in some furnaces recycled glass ("cullet") is added, originating from the same factory or other sources. Cullet leads to savings not only in the raw materials, but also in the energy consumption of the glass furnace. However, impurities in the cullet may lead to product and equipment failure. Fining agents such as sodium sulfate, sodium chloride, or antimony oxide are added to reduce the bubble content in the glass. Sodium sulfate is the Sodium salt of Sulfuric acid For sodium chloride in the diet see Salt. Sodium chloride, also known as common salt, table salt, or Halite, is a Antimony trioxide is the Chemical compound with the formula Sb2O3 ^[9]

A further raw material used in the production of soda-lime and fiber glass is calumite, which is a glassy granular by-product of the iron making industry, containing mainly silica, calcium oxide, alumina, magnesium oxide (and traces of iron oxide). ^[11]

For obtaining the desired glass composition, the correct raw material mixture (batch) must be determined by glass batch calculation. Glass batch calculation or glass batching is used to determine the correct mix of raw materials (batch for a Glass melt

Contemporary glass production

Following the glass batch preparation and mixing the raw materials are transported to the furnace. Glass batch calculation or glass batching is used to determine the correct mix of raw materials (batch for a Glass melt Soda-lime glass for mass production is melted in gas fired units. Soda-lime glass, also called soda-lime-silica glass, is the most prevalent type of Glass, used for windowpanes and glass containers (bottles and jars Glass is common in everyday Life, from glass Windows to Glass containers The manufacture of Glass for everyday purposes may involve Smaller scale furnaces for specialty glasses include electric melters, pot furnaces and day tanks. ^[9]

After melting, homogenization and refining (removal of bubbles) the glass is formed. Flat glass for windows and similar applications is formed by the float glass process, developed between 1953 and 1957 by Sir Alastair Pilkington and Kenneth Bickerstaff of the UK's Pilkington Brothers, which created a continuous ribbon of glass using a molten tin bath on which the molten glass flows unhindered under the influence of gravity. Float glass is a sheet of Glass made by floating molten glass on a bed of molten Tin. Lionel Alexander Bethune Pilkington, ( 7 January, 1920 – 5 May, 1995) ( Sir Alastair Pilkington) and his associate Kenneth Bickerstaff Container glass for common bottles and jars is formed by blowing and pressing methods. Glass is common in everyday Life, from glass Windows to Glass containers The manufacture of Glass for everyday purposes may involve Further glass forming techniques are summarized in the table Glass forming techniques.

Once the desired form is obtained, glass is usually annealed for the removal of stresses. Annealing is a process of slowly cooling Glass to relieve internal stresses after it was formed

Various surface treatment techniques, coatings, or lamination may follow to improve the chemical durability (glass container coatings, glass container internal treatment), strength (toughened glass, bulletproof glass, windshields), or optical properties (insulated glazing, anti-reflective coating). A laminate is a material constructed by uniting two or more layers of material together Glass is common in everyday Life, from glass Windows to Glass containers The manufacture of Glass for everyday purposes may involve Glass is common in everyday Life, from glass Windows to Glass containers The manufacture of Glass for everyday purposes may involve Toughened or tempered glass is Glass that has been processed by controlled thermal or chemical treatments to increase its strength compared with normal glass Bulletproof glass is a colloquial term for Glass that is particularly resistant to being penetrated when struck by Bullets Since manufacturing glass of usable The windshield or windscreen of an Aircraft, Automobile, Bus, Motorcycle, or Tram is the front Window Insulated Glazing Unit or Insulating Glass Unit (commonly referred to as IGU) is a set of two or more sheets of glass spaced apart and Hermetically sealed Anti-reflective or antireflection (AR coatings are a type of Optical coating applied to the surface of lenses and other optical devices to reduce

Glassmaking in the laboratory

A vitrification experiment for the study of nuclear waste disposal at Pacific Northwest National Laboratory. Radioactive wastes are Waste types containing radioactive Chemical elements that do not have a practical purpose The Pacific Northwest National Laboratory (PNNL is one of nine United States Department of Energy (DOE multiprogram national laboratories.

Failed laboratory glass melting test. The striations must be avoided through good homogenization. Homogenization (or homogenisation) is a term used in many fields such as Chemistry, Agricultural science, Food technology, Sociology

New chemical glass compositions or new treatment techniques can be initially investigated in small-scale laboratory experiments. A laboratory (informally lab) is a facility that provides controlled conditions in which scientific Research, Experiments and The raw materials for laboratory-scale glass melts are often different from those used in mass production because the cost factor has a low priority. In the laboratory mostly pure chemicals are used. A chemical substance is a Material with a definite chemical composition. Care must be taken that the raw materials have not reacted with moisture or other chemicals in the environment (such as alkali oxides and hydroxides, alkaline earth oxides and hydroxides, or boron oxide), or that the impurities are quantified (loss on ignition). Trends The alkali metals show a number of trends when moving down the group - for instance decreasing electronegativity increasing reactivity and decreasing melting and boiling Biological occurrences Beryllium's low aqueous solubility means it is rarely available to biological systems it has no known role in living organisms and when encountered Boron oxide is one of the oxides of Boron. It is white glassy and solid also known as diboron trioxide, formula B2O3 ^[12] Evaporation losses during glass melting should be considered during the selection of the raw materials, e. g. , sodium selenite may be preferred over easily evaporating SeO₂. Selenium dioxide is the Chemical compound with the formula SeO2 Also, more readily reacting raw materials may be preferred over relatively inert ones, such as Al(OH)₃ over Al₂O₃. In English to be inert is to be in a state of doing little or nothing Aluminium hydroxide, Al(OH3 is the most stable form of Aluminium in normal conditions Usually, the melts are carried out in platinum crucibles to reduce contamination from the crucible material. Glass homogeneity is achieved by homogenizing the raw materials mixture (glass batch), by stirring the melt, and by crushing and re-melting the first melt. Homogenization (or homogenisation) is a term used in many fields such as Chemistry, Agricultural science, Food technology, Sociology Glass batch calculation or glass batching is used to determine the correct mix of raw materials (batch for a Glass melt The obtained glass is usually annealed to prevent breakage during processing. Annealing is a process of slowly cooling Glass to relieve internal stresses after it was formed ^[12][13]

See also: Optical lens design, Fabrication and testing of optical components

Silica-free glasses

Besides common silica-based glasses, many other inorganic and organic materials may also form glasses, including plastics (e. Optical lens design is the science/art of calculating the various lens construction parameters (variables that will meet or at least approach desired performance requirements Optical fabrication and testing spans an enormous range of manufacturing procedures and The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide Traditionally inorganic compounds are considered to be of mineral not biological origin Organic chemistry is a discipline within Chemistry which involves the scientific study of the structure properties composition reactions, and preparation Plastic is the general common term for a wide range of synthetic or semisynthetic organic solid materials suitable for the manufacture of industrial products g. , acrylic glass), carbon, metals, carbon dioxide (see below), phosphates, borates, chalcogenides, fluorides, germanates (glasses based on GeO₂), tellurites (glasses based on TeO₂), antimonates (glasses based on Sb₂O₃), arsenates (glasses based on As₂O₃), titanates (glasses based on TiO₂), tantalates (glasses based on Ta₂O₅), nitrates, carbonates and many other substances. Poly(methyl methacrylate ( PMMA) or poly(methyl 2-methylpropenoate is a Thermoplastic and transparent Plastic. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 An amorphous metal is a Metallic material with a disordered atomic-scale structure A phosphate, an Inorganic chemical, is a salt of Phosphoric acid. Borates in Chemistry are Chemical compounds containing Boron bonded to three Oxygen atoms written as B(OR3 A chalcogenide glass (hard "ch" as in "chemistry" is a Glass containing one or more Chalcogenide element (Group VI in the Periodic Fluoride is the reduced form of Fluorine. Both organic and Inorganic compounds containing the element fluorine are considered fluorides Germanium dioxide, also called germanium oxide and germania, is an Inorganic compound, an Oxide of Germanium. In Inorganic chemistry, a nitrate is a salt of Nitric acid with an Ion composed of one Nitrogen and three Oxygen atoms In Chemistry, a carbonate is a salt or Ester of Carbonic acid. ^[6]

Some glasses that do not include silica as a major constituent may have physico-chemical properties useful for their application in fibre optics and other specialized technical applications. An optical fiber (or fibre) is a Glass or Plastic fiber that carries Light along its length These include fluorozirconate, fluoroaluminate, aluminosilicate, phosphate and chalcogenide glasses. Aluminosilicate Minerals are minerals composed of Aluminium, Silicon, and oxygen A phosphate, an Inorganic chemical, is a salt of Phosphoric acid. A chalcogenide glass (hard "ch" as in "chemistry" is a Glass containing one or more Chalcogenide element (Group VI in the Periodic

Under extremes of pressure and temperature solids may exhibit large structural and physical changes which can lead to polyamorphic phase transitions. In Materials science polyamorphism is the ability of a substance to exist in several different Amorphous modifications ^[14] In 2006 Italian scientists created an amorphous phase of carbon dioxide using extreme pressure. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single The substance was named amorphous carbonia(a-CO₂) and exhibits an atomic structure resembling that of Silica. Amorphous carbonia, also called a-carbonia or a-CO2, is an exotic amorphous solid form of Carbon dioxide that is analogous to amorphous ^[15]

The physics of glass

The amorphous structure of glassy Silica (SiO₂). No long range order is present, however there is local ordering with respect to the tetrahedral arrangement of Oxygen (O) atoms around the Silicon (Si) atoms. A tetrahedron (plural tetrahedra) is a Polyhedron composed of four triangular faces three of which meet at each vertex.

The standard definition of a glass (or vitreous solid) requires the solid phase to be formed by rapid melt quenching. Vitreous refers to a material in an Amorphous, Glassy state (in contrast to a Crystalline state ^[2][3][4] Glass is therefore formed via a supercooled liquid and cooled sufficiently rapidly (relative to the characteristic crystallisation time) from its molten state through its glass transition temperature, T_g, that the supercooled disordered atomic configuration at T_g, is frozen into the solid state. Crystallization is the (natural or artificial process of formation of solid Crystals precipitating from a homogeneous --> identical Solution The glass transition temperature, T g is the temperature at which an Amorphous solid, such as Glass or a Polymer, becomes brittle Generally, the structure of a glass exists in a metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic polymers, there is no crystalline analogue of the amorphous phase ^[16]. Metastability is a general scientific concept which describes states of delicate equilibrium In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating Tacticity (from Greek 'taktikos' of or relating to arrangement or order is the relative Stereochemistry of adjacent chiral centers within a Macromolecule By definition as an amorphous solid, the atomic structure of a glass lacks any long range translational periodicity. An amorphous solid is a Solid in which there is no Long-range order of the positions of the Atoms (Solids in which there is long-range atomic order are In Geometry, a translation "slides" an object by a vector a: T a (p = p + a However, by virtue of the local chemical bonding constraints glasses do possess a high degree of short-range order with respect to local atomic polyhedra^[17]. A chemical bond is the physical process responsible for the attractive interactions between Atoms and Molecules and which confers stability to diatomic and polyatomic It is deemed that the bonding structure of glasses, although disordered, has the same symmetry signature (Hausdorff-Besicovitch dimensionality) as for crystalline materials^[18]. In Mathematics, the Hausdorff dimension (also known as the Hausdorff–Besicovitch dimension) is an extended non-negative Real number associated

Glass versus a supercooled liquid

Glass is generally treated as an amorphous solid rather than a liquid, though both views can be justified. An amorphous solid is a Solid in which there is no Long-range order of the positions of the Atoms (Solids in which there is long-range atomic order are ^[19] However, the notion that glass flows to an appreciable extent over extended periods of time is not supported by empirical research or theoretical analysis (see viscosity of amorphous materials). Viscous flow in amorphous materials (eg in Glasses and melts is a thermally activated process \eta = A \cdot e^{Q/RT} where Q is activation From a more commonsense point of view, glass should be considered a solid since it is rigid according to everyday experience. ^[20]

Some people consider glass to be a liquid due to its lack of a first-order phase transition ^[19][21] where certain thermodynamic variables such as volume, entropy and enthalpy are continuous through the glass transition temperature. In Thermodynamics, phase transition or phase change is the transformation of a thermodynamic system from one phase to another In Physics, thermodynamics (from the Greek θερμη therme meaning " Heat " and δυναμις dynamis meaning " In Thermodynamics, state variables, state parameters or thermodynamic variables describe the momentary condition of a system. The volume of any solid plasma vacuum or theoretical object is how much three- Dimensional space it occupies often quantified numerically In Thermodynamics (a branch of Physics) entropy, symbolized by S, is a measure of the unavailability of a system ’s Energy In Thermodynamics and molecular chemistry, the enthalpy (denoted as H, h, or rarely as χ) is a quotient or description of However, the glass transition temperature may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the thermal expansivity and heat capacity are discontinuous. Thermal Expansion is the tendency of matter to change in Volume in response to a change in temperature Specific heat capacity, also known simply as specific heat, is the measure of the heat energy required to increase the Temperature of a unit quantity Despite this, thermodynamic phase transition theory does not entirely hold for glass, and hence the glass transition cannot be classed as a genuine thermodynamic phase transition. ^[4]

Although the atomic structure of glass shares characteristics of the structure in a supercooled liquid, glass is generally classed as solid below its glass transition temperature. History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny ^[22] There is also the problem that a supercooled liquid is still a liquid and not a solid but it is below the freezing point of the material and will crystallize almost instantly if a crystal is added as a core. The change in heat capacity at a glass transition and a melting transition of comparable materials are typically of the same order of magnitude indicating that the change in active degrees of freedom is comparable as well. Specific heat capacity, also known simply as specific heat, is the measure of the heat energy required to increase the Temperature of a unit quantity The glass transition temperature, T g is the temperature at which an Amorphous solid, such as Glass or a Polymer, becomes brittle The melting point of a solid is the temperature range at which it changes state from solid to Liquid. Both in a glass and in a crystal it is mostly only the vibrational degrees of freedom that remain active, whereas rotational and translational motion becomes impossible explaining why glasses and crystalline materials are hard. Vibration refers to mechanical Oscillations about an equilibrium point. A rotation is a movement of an object in a circular motion A two- Dimensional object rotates around a center (or point) of rotation In Physics, translation is movement that changes the position of an object as opposed to Rotation.

Behavior of antique glass

The observation that old windows are often thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a matter of centuries. It is then assumed that the glass was once uniform, but has flowed to its new shape, which is a property of liquid. The likely source of this unfounded belief is that when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the Crown glass process, described above). Glassblowing is a glassforming technique that involves inflating the molten glass into a bubble or parison with the aid of the blowpipe or blow tube Crown glass was an early type of window glass In this process glass was blown into a "crown" or hollow globe This plate was then cut to fit a window. The pieces were not, however, absolutely flat; the edges of the disk would be thicker because of centripetal force relaxation. The centripetal force is the external force required to make a body follow a curved path When actually installed in a window frame, the glass would be placed thicker side down for the sake of stability and visual sparkle. ^[23] Occasionally such glass has been found thinner side down or on either side of the window's edge, as would be caused by carelessness at the time of installation.

Mass production of glass window panes in the early twentieth century caused a similar effect. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. The resulting glass is thicker at the location of the pour, located at the center of the large sheet. These sheets were cut into smaller window panes with nonuniform thickness. Modern glass intended for windows is produced as float glass and is very uniform in thickness. Float glass is a sheet of Glass made by floating molten glass on a bed of molten Tin.

Several other points exemplify the misconception of the 'cathedral glass' theory:

• Writing in the American Journal of Physics,^[24] physicist Edgar D. Zanotto states ". The American Journal of Physics is a Peer-reviewed Scientific journal published by the American Association of Physics Teachers devoted to the educational Dr Edgar Dutra Zanotto, PhD, is a Brazilian Materials engineer from UFSCar or the Universidade Federal de São Carlos ("Federal University . . the predicted relaxation time for GeO₂ at room temperature is 10³² years. Relaxation time is a general concept in Physics for the Characteristic time in which a system changes to an Equilibrium condition from a non-equilibrium Hence, the relaxation period (characteristic flow time) of cathedral glasses would be even longer".
• If medieval glass has flowed perceptibly, then ancient Roman and Egyptian objects should have flowed proportionately more — but this is not observed. Similarly, prehistoric obsidian blades should have lost their edge; this is not observed either (although obsidian may have a different viscosity from window glass). Obsidian is a naturally occurring Glass formed as an extrusive Igneous rock. ^[19]
• If glass flows at a rate that allows changes to be seen with the naked eye after centuries, then the effect should be noticeable in antique telescopes. Any slight deformation in the antique telescopic lenses would lead to a dramatic decrease in optical performance, a phenomenon that is not observed. ^[19]
• There are many examples of centuries-old glass shelving which has not bent, even though it is under much higher stress from gravitational loads than vertical window glass.

Some glasses have a glass transition temperature close to or below room temperature. The behaviour of a material that has a glass transition close to room temperature depends upon the timescale during which the material is manipulated. If the material is hit it may break like a solid glass, however if the material is left on a table for a week it may flow like a liquid. This simply means that for the fast timescale its transition temperature is above room temperature, but for the slow one it is below. The shift in temperature with timescale is not very large however as indicated by the transition of polypropylene glycol of -72 °C and -71 °C over different timescales. ^[16] To observe window glass flowing as liquid at room temperature we would have to wait a much longer time than the universe exists. Therefore it is safe to consider a glass a solid far enough below its transition temperature: Cathedral glass does not flow because its glass transition temperature is many hundreds of degrees above room temperature. Close to this temperature there are interesting time-dependent properties. One of these is known as aging. Many polymers that we use in daily life such as rubber, polystyrene and polypropylene are in a glassy state but they are not too far below their glass transition temperature. Polystyrene ˌpɒliˈstaɪriːn ( IUPAC Polyphenylethene is an aromatic Polymer made from the aromatic Monomer Styrene Polypropylene or polypropene ( PP) is a Thermoplastic Polymer, made by the Chemical industry and used in a wide variety of applications Their mechanical properties may well change over time and this is serious concern when applying these materials in construction.

Physical properties

The following table lists some physical properties of common glasses. Unless otherwise stated, the technical glass compositions and many experimentally determined properties are taken from one large study. ^[25] Unless stated otherwise, the properties of fused silica (quartz glass) and germania glass are derived from the SciGlass glass database by forming the arithmetic mean of all the experimental values from different authors (in general more than 10 independent sources for quartz glass and Tg of germanium oxide glass). Fused quartz and fused silica are types of Glass containing primarily Silica in amorphous (non- Crystalline form Germanium dioxide, also called germanium oxide and germania, is an Inorganic compound, an Oxide of Germanium. Glass databases are a collection of Glass compositions glass properties Glass models associated Trademark names Patents etc In Mathematics and Statistics, the arithmetic Mean (or simply the mean) of a list of numbers is the sum of all the members of the list divided Those values marked in italic font have been interpolated from sililar glass compositions (see Calculation of glass properties) due to the lack of experimental data. The calculation of glass properties ( glass modeling) is used to predict Glass properties of interest or glass behavior under certain conditions (e

Color

Common soda-lime float glass appears green in thick sections because of Fe²⁺ impurities. The liquidus temperature, TL or Tliq is mostly used for Glasses and Alloys It specifies the maximum temperature at which Crystals The liquidus temperature, TL or Tliq is mostly used for Glasses and Alloys It specifies the maximum temperature at which Crystals Specific heat capacity, also known simply as specific heat, is the measure of the heat energy required to increase the Temperature of a unit quantity Specific heat capacity, also known simply as specific heat, is the measure of the heat energy required to increase the Temperature of a unit quantity For the work of fiction see Surface Tension (short story. Surface tension is a property of the surface of a Liquid that causes it to Corrosion means the breaking down of essential properties in a material due to Chemical reactions with its surroundings Corrosion means the breaking down of essential properties in a material due to Chemical reactions with its surroundings Float glass is a sheet of Glass made by floating molten glass on a bed of molten Tin.

Main article: Glass_production#Colors

Colors in glass may be obtained by addition of coloring ions that are homogeneously distributed and by precipitation of finely dispersed particles (such as in photochromic glasses). Glass is common in everyday Life, from glass Windows to Glass containers The manufacture of Glass for everyday purposes may involve Photochromic lenses are lenses that darken on exposure to UV radiation ^[6] Ordinary soda-lime glass appears colorless to the naked eye when it is thin, although iron(II) oxide (FeO) impurities of up to 0. Soda-lime glass, also called soda-lime-silica glass, is the most prevalent type of Glass, used for windowpanes and glass containers (bottles and jars Iron(II oxide, also known as ferrous oxide, iron oxide/oxidized iron or more commonly rusted 1 wt%^[25] produce a green tint which can be viewed in thick pieces or with the aid of scientific instruments. Green is a Color, the perception of which is evoked by light having a spectrum dominated by energy with a Wavelength of roughly 520–570- nm. Further FeO and Cr₂O₃ additions may be used for the production of green bottles. Chromium(III oxide is the Inorganic compound of the formula Cr2O3 Sulfur, together with carbon and iron salts, is used to form iron polysulfides and produce amber glass ranging from yellowish to almost black. Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 ^[36] Manganese dioxide can be added in small amounts to remove the green tint given by iron(II) oxide. Manganese(IV oxide is the Chemical compound MnO2 commonly called manganese dioxide.

History

Roman Cage Cup from the 4th century A. A Cage Cup, Greek diatreton, also vas diatretum, is a Roman luxury glass vessel D.

Roman glass

see also category Glass history

Naturally occurring glass, especially obsidian, has been used by many Stone Age societies across the globe for the production of sharp cutting tools and, due to its limited source areas, was extensively traded. Obsidian is a naturally occurring Glass formed as an extrusive Igneous rock. According to Pliny the Elder, Phoenician traders were the first to stumble upon glass manufacturing techniques at the site of the Belus River. Gaius or Caius Plinius Secundus, ( AD 23 – August 25, AD 79 better known as Pliny the Elder, was an ancient Author Belus or Belos is a small river in north-western Israel, where according to legend glass-making was invented Agricola, De re metallica, reported a traditional serendipitous "discovery" tale of familiar type:

"The tradition is that a merchant ship laden with nitrum being moored at this place, the merchants were preparing their meal on the beach, and not having stones to prop up their pots, they used lumps of nitrum from the ship, which fused and mixed with the sands of the shore, and there flowed streams of a new translucent liquid, and thus was the origin of glass. De re metallica ( Latin for On the Nature of Metals (Minerals) is a book cataloging the state of the art of Mining, refining and Smelting Niter (US or nitre (UK is the mineral form of Potassium nitrate, KNO3 also known as saltpeter (US or saltpetre (UK "^[37]

This account is more a reflection of Roman experience of glass production, however, as white silica sand from this area was used in the production of Roman glass due to its low impurity levels. But in general archaeological evidence suggests that the first true glass was made in coastal north Syria, Mesopotamia or Old Kingdom Egypt. Mesopotamia (from the Greek meaning "land between the rivers" is an area geographically located between the Tigris and Euphrates rivers largely corresponding The Old Kingdom is the name commonly given to that period in the 3rd millennium BCE when Egypt attained its first continuous peak of civilization in complexity and achievement ^[38] Due to Egypt's favourable environment for preservation, the majority of well-studied early glass is found in Egypt, although some of this is likely to have been imported. The earliest known glass objects, of the mid third millennium BC, were beads, perhaps initially created as accidental by-products of metal-working slags or during the production of faience, a pre-glass vitreous material made by a process similar to glazing. Slag is the By-product of Smelting Ore to purify Metals They can be considered to be a mixture of metal Oxides however For the architectural material see Glazed architectural terra-cotta. Vitreous refers to a material in an Amorphous, Glassy state (in contrast to a Crystalline state ^[39]

During the Late Bronze Age in Egypt and Western Asia there was an explosion in glass-making technology. The term Bronze Age refers to a period in human cultural development when the most advanced Metalworking (at least in systematic and widespread use included techniques for This article is about the country of Egypt For a topic outline on this subject see List of basic Egypt topics. Southwest Asia or Southwestern Asia (largely overlapping with the Middle East) is the southwestern portion of Asia. Archaeological finds from this period include coloured glass ingots, vessels (often coloured and shaped in imitation of highly prized wares of semi-precious stones) and the ubiquitous beads. An ingot is a material usually metal that is cast into a shape suitable for further processing The alkali of Syrian and Egyptian glass was soda ash, sodium carbonate, which can be extracted from the ashes of many plants, notably halophile seashore plants: (see saltwort). Sodium carbonate (also known as washing soda or soda ash), is a Sodium Salt of Carbonic acid. Halophiles are Extremophiles that thrive in environments with very high concentrations of Salt. The earliest vessels were 'core-wound', produced by winding a ductile rope of metal round a shaped core of sand and clay over a metal rod, then fusing it with repeated reheatings. Threads of thin glass of different colours made with admixtures of oxides were subsequently wound around these to create patterns, which could be drawn into festoons with a metal raking tools. The vessel would then be rolled flat ('marvered') on a slab in order to press the decorative threads into its body. Handles and feet were applied separately. The rod was subsequently allowed to cool as the glass slowly annealed and was eventually removed from the centre of the vessel, after which the core material was scraped out. Glass shapes for inlays were also often created in moulds. Inlay is a decorative technique of inserting pieces of coloured materials into depressions in a base object to form patterns or pictures Much early glass production, however, relied on grinding techniques borrowed from stone working. This meant that the glass was ground and carved in a cold state.

By the 15th century BC extensive glass production was occurring in Western Asia and Egypt. Southwest Asia or Southwestern Asia (largely overlapping with the Middle East) is the southwestern portion of Asia. This article is about the country of Egypt For a topic outline on this subject see List of basic Egypt topics. It is thought the techniques and recipes required for the initial fusing of glass from raw materials was a closely guarded technological secret reserved for the large palace industries of powerful states. Glass workers in other areas therefore relied on imports of pre-formed glass, often in the form of cast ingots such as those found on the Ulu Burun shipwreck off the coast of Turkey. The Uluburun Shipwreck is a well-documented late 14th century BC Shipwreck of the Late Bronze Age period discovered off the south coast of Turkey in the

Glass remained a luxury material, and the disasters that overtook Late Bronze Age civilisations seem to have brought glass-making to a halt. It picked up again in its former sites, in Syria and Cyprus, in the ninth century BC, when the techniques for making colourless glass were discovered. In Egypt glass-making did not revive until it was reintroduced in Ptolemaic Alexandria. Ptolemaic Egypt began when Ptolemy I Soter declared himself Pharaoh of Egypt in 305 BC and ended with the death of queen Cleopatra Core-formed vessels and beads were still widely produced, but other techniques came to the fore with experimentation and technological advancements. During the Hellenistic period many new techniques of glass production were introduced and glass began to be used to make larger pieces, notably table wares. This article focuses on the cultural aspects of the Hellenistic age for the historical aspects see Hellenistic period. Techniques developed during this period include 'slumping' viscous (but not fully molten) glass over a mould in order to form a dish and 'millefiori' (meaning 'thousand flowers') technique, where canes of multi-coloured glass were sliced and the slices arranged together and fused in a mould to create a mosaic-like effect. Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. Millefiori is a glasswork technique which produces distinctive decorative patterns on glassware It was also during this period that colourless or decoloured glass began to be prized and methods for achieving this effect were investigated more fully.

During the first century BC glass blowing was discovered on the Syro-Palestinian coast, revolutionising the industry and laying the way for the explosion of glass production that occurred throughout the Roman world. Glassblowing is a glassforming technique that involves inflating the molten glass into a bubble or parison with the aid of the blowpipe or blow tube Over the next 1000 years glass making and working continued and spread through southern Europe and beyond.

South Asia

Indigenous development of glass technology in South Asia may have begun in 1730 BCE. ^[40] Evidence of this culture includes a red-brown glass bead along with a hoard of beads dating to 1730 BCE, making it the earliest attested glass from the Indus Valley locations. The Indus Valley Civilization (Mature period 2600&ndash1900 BCE abbreviated IVC, was an ancient Civilization that flourished in the Indus River basin ^[40] Glass discovered from later sites dating from 600-300 BCE displays common color. ^[40]

Chalcolithic evidence of glass has been found in Hastinapur, India. The Chalcolithic (Greek khalkos + lithos ' Copper stone' period or Copper Age period known as the '''Eneolithic''' ('''Æneolithic''' is a WikipediaWikiProject Indian cities for details --> Hastinapur (हस्‍तिनापुर (Hastinapura in Sanskrit) is a town and a Nagar panchayat India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country ^[41] Some of the texts which mention glass in India are the Shatapatha Brahmana and Vinaya Pitaka. The Shatapatha Brahmana (sa शतपथ ब्राह्मण śatapatha brāhmaṇa, " Brahmana of one-hundred paths" abbreviated ŚB The Vinaya Piṭaka is a Buddhist Scripture, one of the three parts that make up the Tripitaka. ^[41] However, the first unmistakable evidence in large quantities, dating from the 3rd century BCE, has been uncovered from the archaeological site in Taxila, Pakistan. For the Genus of metalmark butterflies, see Taxila (butterfly. Pakistan () officially the Islamic Republic of Pakistan, is a country located in South Asia, Southwest Asia, Middle East and ^[41]

By the beginning of the Common Era, glass was being used for ornaments and casing in South Asia. ^[41] Contact with the Greco-Roman world added newer techniques, and Indians artisans mastered several techniques of glass molding, decorating and coloring by the early centuries of the Common Era. The Greco-Roman or Graeco-Roman World, as understood by medieval and modern scholars geographers and miscellaneous writers refers to those geographical regions and countries ^[41] Satavahana period of India further reveals short cylinders of composite glass, including those displaying a lemon yellow matrix covered with green glass. The Sātavāhanas ( Marathi: सातवाहन Telugu:శాతవాహనులు were a Dynasty which ruled from Junnar ( ^[42]

Romans

A full discussion of Roman glass making and working can be found on the Roman glass page. Roman glass objects have been recovered across the Roman Empire in domestic industrial and Funerary contexts

Anglo-Saxon world

Evidence for glass making, working and use in the 5th to 8th centuries in England is discussed in the Anglo-Saxon glass page. Anglo-Saxon glass has been found across England during archaeological excavations of both settlement and cemetery sites

Islamic world

In the medieval Islamic world, the first clear, colourless, high-purity glasses were produced by Muslim chemists, architects and engineers in the 9th century. Islamic architecture has encompassed a wide range of both secular and religious styles from the foundation of Islam to the present day influencing the design and construction Examples include Silica glass and colourless high-purity glass invented by Abbas Ibn Firnas (810-887), who was the first to produce glass from sand and stones. Fused quartz and fused silica are types of Glass containing primarily Silica in amorphous (non- Crystalline form Abbas Ibn Firnas (810 &ndash 887 AD) was also known as Abbas Qasim Ibn Firnas and العباس بن فرناس ( Arabic language) Sand is a naturally occurring Granular material composed of finely divided rock and Mineral particles In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere ^[43] The Arab poet al-Buhturi (820-897) described the clarity of such glass, "Its colour hides the glass as if it is standing in it without a container. Arabic poetry ( Arabic, الِشعر العربي ash-shi`ru 'l-`arabiy) is the earliest form of Arabic literature. Buhturi, Arabic, أبو الوليد بن عبيدالله البحتري التنوخي ( al-Walīd ibn `Ubayd Allāh al-Buhturī) (820 - 897 was an "^[44]

Stained glass was also first produced by Muslim architects in Southwest Asia using coloured glass rather than stone. For the Blackford Oakes novel see Stained Glass (novel The term stained glass refers either to the material of coloured Glass or to the art Islamic architecture has encompassed a wide range of both secular and religious styles from the foundation of Islam to the present day influencing the design and construction Southwest Asia or Southwestern Asia (largely overlapping with the Middle East) is the southwestern portion of Asia. In the 8th century, the Arab chemist Jabir ibn Hayyan (Geber) scientifically described 46 original recipes for producing coloured glass in Kitab al-Durra al-Maknuna (The Book of the Hidden Pearl), in addition to 12 recipes inserted by al-Marrakishi in a later edition of the book. The araB gene Promoter is a bacterial promoter activated by e L-arabinose binding For the 12th century astronomer see Jabir ibn Aflah. For the anonymous 14th century Spanish alchemist see Pseudo-Geber. ^[45]

The parabolic mirror was first described by Ibn Sahl in his On the Burning Instruments in the 10th century, and later described again in Ibn al-Haytham's On Burning Mirrors and Book of Optics (1021). A parabolic reflector (or dish or mirror) is a Parabola -shaped reflective device used to collect or distribute Energy such as This article is about the physicist For the physician see Ali ibn Sahl Rabban al-Tabari. TemplateInfobox Muslim scholars --> ( Arabic: ابو علی، حسن بن حسن بن هيثم Latinized The Book of Optics ( Arabic: Kitab al-Manazir, Latin: De Aspectibus or Opticae Thesaurus Alhazeni ^[46] By the 11th century, clear glass mirrors were being produced in Islamic Spain. A mirror is an object with a surface that has good Specular reflection; that is it is smooth enough to form an Image. Al-Andalus (الأندلس was the Arabic name given to those parts of the Iberian Peninsula governed by Muslims or The first glass factories were also built by Muslim craftsmen in the Islamic world. A factory (previously manufactory) or manufacturing plant is an industrial Building where workers manufacture goods The first glass factories in Christian Europe were later built in the 11th century by Muslim Egyptian craftsmen in Corinth, Greece. A Christian is a person who adheres to Christianity, a monotheistic Religion centered on the life and teachings of Jesus of Nazareth This article is about the country of Egypt For a topic outline on this subject see List of basic Egypt topics. Corinth, or Korinth ( Greek Κόρινθος ( is a city in Greece. Greece (Ελλάδα transliterated: Elláda, historically, Ellás,) officially the Hellenic Republic (Ελληνική Δημοκρατία ^[47]

Medieval Europe

A 16th-century stained glass window

Glass objects from the 7th and 8th centuries have been found on the island of Torcello near Venice. For the Blackford Oakes novel see Stained Glass (novel The term stained glass refers either to the material of coloured Glass or to the art Torcello is a quiet and sparsely populated Island at the northern end of the Venetian Lagoon. Venice ( Italian: Venezia, Venetian: Venesia or Venexia) is a city in Northern Italy, the capital of the These form an important link between Roman times and the later importance of that city in the production of the material. Around 1000 AD, an important technical breakthrough was made in Northern Europe when soda glass, produced from white pebbles and burnt vegetation was replaced by glass made from a much more readily available material: potash obtained from wood ashes. Potash (or carbonate of potash) is an impure form of Potassium carbonate ( K 2 CO3) From this point on, northern glass differed significantly from that made in the Mediterranean area, where soda remained in common use. ^[48]

Until the 12th century, stained glass -- glass to which metallic or other impurities had been added for coloring -- was not widely used. For the Blackford Oakes novel see Stained Glass (novel The term stained glass refers either to the material of coloured Glass or to the art

The 11th century saw the emergence in Germany of new ways of making sheet glass by blowing spheres. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. The spheres were swung out to form cylinders and then cut while still hot, after which the sheets were flattened. This technique was perfected in 13th century Venice. Venice ( Italian: Venezia, Venetian: Venesia or Venexia) is a city in Northern Italy, the capital of the

The Crown glass process was used up to the mid-19th century. Crown glass was an early type of window glass In this process glass was blown into a "crown" or hollow globe In this process, the glassblower would spin approximately 9 pounds (4 kg) of molten glass at the end of a rod until it flattened into a disk approximately 5 feet (1. Glassblowing is a glassforming technique that involves inflating the molten glass into a bubble or parison with the aid of the blowpipe or blow tube The avoirdupois (ˌævərdəˈpɔɪz French avwaʀdypwɑ system is a system of weights (or properly Mass) based on a pound of sixteen Ounces A foot (plural feet or foot; symbol or abbreviation ft or sometimes &prime – the prime symbol) is a non-SI unit 5 m) in diameter. The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International The disk would then be cut into panes.

Late medieval Northern Europe

Glass making in late medieval Northern Europe is discussed in the article on Forest glass. The term Forest glass or the German name Waldglas is given to late Medieval Glass produced in North-Western Europe from about 1000-1700AD using wood ash

Murano glassmaking

Main articles: Murano glass and Venetian glass

The center for glassmaking from the 14th century was the island of Murano, which developed many new techniques and became the center of a lucrative export trade in dinnerware, mirrors, and other luxury items. Murano glass has been a famous product of the Venetian island of Murano for centuries Venetian glass is a type of Glass object made in Venice, Italy, primarily on the island of Murano. Murano is usually described as an Island in the Venetian Lagoon, although like Venice itself it is actually an Archipelago of islands linked A mirror is an object with a surface that has good Specular reflection; that is it is smooth enough to form an Image. What made Venetian Murano glass significantly different was that the local quartz pebbles were almost pure silica, and were ground into a fine clear sand that was combined with soda ash obtained from the Levant, for which the Venetians held the sole monopoly. Murano glass has been a famous product of the Venetian island of Murano for centuries The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide Sodium carbonate (also known as washing soda or soda ash), is a Sodium Salt of Carbonic acid. See also Names of the Levant The Levant (lə'vænt is a geographical term that denotes a large area in Western Asia, roughly bounded on the north by the In Economics, a monopoly (from Greek monos, alone or single + polein, to sell exists when a specific individual or enterprise has sufficient The clearest and finest glass is tinted in two ways: firstly, a small or large amount of a natural coloring agent is ground and melted with the glass. Many of these coloring agents still exist today; for a list of coloring agents, see below. Black glass was called obsidianus after obsidian stone. Obsidian is a naturally occurring Glass formed as an extrusive Igneous rock. A second method is apparently to produce a black glass which, when held to the light, will show the true color that this glass will give to another glass when used as a dye. ^[49]

The Venetian ability to produce this superior form of glass resulted in a trade advantage over other glass producing lands. Murano’s reputation as a center for glassmaking was born when the Venetian Republic, fearing fire might burn down the city’s mostly wood buildings, ordered glassmakers to move their foundries to Murano in 1291. Murano is usually described as an Island in the Venetian Lagoon, although like Venice itself it is actually an Archipelago of islands linked Murano's glassmakers were soon the island’s most prominent citizens. Glassmakers were not allowed to leave the Republic. Many took a risk and set up glass furnaces in surrounding cities and as far afield as England and the Netherlands.

Glass art

Main article: Glass art

A vase being created at the Reijmyre glassworks, Sweden

Paperweight with items inside the glass, Corning Museum of Glass

Beginning in the late 20th century, glass started to become highly collectible as art. Glass art and Glass sculpture is the use of Glass as an artistic medium to produce Sculptures or two-dimensional Artworks Specific approaches The vase (ˈveɪs /ˈveɪz/ or/ˈvɑːz/ is an open container often used to hold cut Flowers It can be made from a number of materials including Ceramics and Kosta Glasbruk (later known as Kosta Boda is a Swedish glassworks founded by two foreign officers in Charles XII's army Anders Koskull and Georg Bogislaus Stael von Holstein "Sverige" redirects here For other uses see Sweden (disambiguation and Sverige (disambiguation. Paperweights are heavy and often decorative objects designed to hold sheets of paper on a surface to prevent wind from blowing the paper away The Corning Museum of Glass grants permission to Wikipedia to include text from its website in the article below Works of art in glass can be seen in a variety of museums, including the Chrysler Museum, the Museum of Glass in Tacoma, the Metropolitan Museum of Art, the Toledo Museum of Art, and Corning Museum of Glass, in Corning, NY, which houses the world's largest collection of glass art and history, with more than 45,000 objects in its collection. The Corning Museum of Glass grants permission to Wikipedia to include text from its website in the article below Corning New York is the name of two places in Steuben County New York, although it most frequently means the City of Corning ^[50]

Several of the most common techniques for producing glass art include: blowing, kiln-casting, fusing, slumping, pate-de-verre, flame-working, hot-sculpting and cold-working. Glassblowing is a glassforming technique that involves inflating the molten glass into a bubble or parison with the aid of the blowpipe or blow tube Cold work includes traditional stained glass work as well as other methods of shaping glass at room temperature. For the Blackford Oakes novel see Stained Glass (novel The term stained glass refers either to the material of coloured Glass or to the art Glass can also be cut with a diamond saw, or copper wheels embedded with abrasives, and polished to give gleaming facets; the technique used in creating waterford crystal ^[51]. Waterford Crystal is a Trademark brand of crystal Glassware produced in Waterford, Ireland, and in recent years (largely as sub-brands Art is sometimes etched into glass via the use of acid, caustic, or abrasive substances. Traditionally this was done after the glass was blown or cast. In the 1920s a new mould-etch process was invented, in which art was etched directly into the mould, so that each cast piece emerged from the mould with the image already on the surface of the glass. This reduced manufacturing costs and, combined with a wider use of colored glass, led to cheap glassware in the 1930s, which later became known as Depression glass^[52]. As the types of acids used in this process are extremely hazardous, abrasive methods have gained popularity.

Objects made out of glass include not only traditional objects such as vessels (bowls, vases, bottles, and other containers), paperweights, marbles, beads, but an endless range of sculpture and installation art as well. The vase (ˈveɪs /ˈveɪz/ or/ˈvɑːz/ is an open container often used to hold cut Flowers It can be made from a number of materials including Ceramics and A bottle is a container with a neck that is narrower than the body and a "mouth Paperweights are heavy and often decorative objects designed to hold sheets of paper on a surface to prevent wind from blowing the paper away A marble is a small spherical toy usually made from Glass, Clay, or Agate. A bead is a small decorative object that is pierced for threading or stringing Colored glass is often used, though sometimes the glass is painted, innumerable examples exist of the use of stained glass. For the Blackford Oakes novel see Stained Glass (novel The term stained glass refers either to the material of coloured Glass or to the art

The Harvard Museum of Natural History has a collection of extremely detailed models of flowers made of painted glass. The Harvard Museum of Natural History is a Natural history Museum on the grounds of Harvard University in Cambridge Massachusetts. These were lampworked by Leopold Blaschka and his son Rudolph, who never revealed the method he used to make them. Lampworking is a type of glasswork that uses a gas fueled torch to melt rods and tubes of clear and colored glass The Glass Flowers, formally The Ware Collection of Blaschka Glass Models of Plants is a famous collection of highly-realistic Glass botanical models at The Blaschka Glass Flowers are still an inspiration to glassblowers today. The Glass Flowers, formally The Ware Collection of Blaschka Glass Models of Plants is a famous collection of highly-realistic Glass botanical models at ^[53]

See also

• Aluminium oxynitride
• Favrile iridescent glass
• Glass makers and brands
• Glass recycling
• Glass fibre
• Magnifying glass
• Opaline glass

References

Bibliography

• Noel C. Stokes; The Glass and Glazing Handbook; Standards Australia; SAA HB125–1998
• Brugmann, Birte. Standards Australia was established in 1922 and is recognised through a Memorandum of Understanding with the Commonwealth Government as the peak non-government standards development body in Australia Glass Beads from Anglo-Saxon Graves: A Study on the Provenance and Chronology of Glass Beads from Anglo-Saxon Graves, Based on Visual Examination. Oxbow Books, 2004. ISBN 1-84217-104-6
• Gowlett, J. A. J. (1997). High Definition Archaeology: Threads Through the Past. Routledge. ISBN 0415184290.  
• Ghosh, Amalananda (1990). An Encyclopaedia of Indian Archaeology. BRILL. ISBN 9004092625.  

External links

• Glass Encyclopedia - A comprehensive guide to all types of antique and collectable glass, with information, pictures and references
• Free information and articles about Designer Glassware, Vintage Art Glass, Depression Glass & Collectible Glass | JustGlass-Online.com
• The Canadian Museum of Civilization - The Story of Glass Making in Canada
• Corning Museum of Glass
• A comprehensive guide to art glass and crystal around the world
• Working Description Furnace & Moleria - Murano Glass
• Informative website about the glass industry
• Substances used in the Making of Colored Glass
• Glass property measurement and calculation
• Almost 400 articles and images about glass (mostly art glass)