![Fassade Wilhelmstrasse 65, Berlin-Mitte, 160417, ako](https://upload.wikimedia.org/wikipedia/commons/4/43/Fassade_Wilhelmstrasse_65%2C_Berlin-Mitte%2C_160417%2C_ako.jpg)
Glass is a non-
crystalline
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...
, often
transparent
Transparency, transparence or transparent most often refer to:
* Transparency (optics), the physical property of allowing the transmission of light through a material
They may also refer to:
Literal uses
* Transparency (photography), a still, ...
,
amorphous solid
In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal.
Etymology
The term comes from the Greek ''a'' ("wi ...
that has widespread practical, technological, and decorative use in, for example,
window
A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent mat ...
panes,
tableware
Tableware is any dish or dishware used for setting a table, serving food, and dining. It includes cutlery, glassware, serving dishes, and other items for practical as well as decorative purposes. The quality, nature, variety and number of o ...
, and
optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultrav ...
. Glass is most often formed by rapid cooling (
quenching
In materials science, quenching is the rapid cooling of a workpiece in water, oil, polymer, air, or other fluids to obtain certain material properties. A type of heat treating, quenching prevents undesired low-temperature processes, such as pha ...
) of the
molten
Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which inc ...
form; some glasses such as
volcanic glass
Volcanic glass is the amorphous solid, amorphous (uncrystallized) product of rapidly cooling magma. Like all types of glass, it is a state of matter intermediate between the closely packed, highly ordered array of a crystal and the highly disorde ...
are naturally occurring. The most familiar, and historically the oldest, types of manufactured glass are "silicate glasses" based on the chemical compound
silica
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...
(silicon dioxide, or
quartz
Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...
), the primary constituent of
sand
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class o ...
.
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) for beverages, food, and some commodity items. Some glass bakeware is made of soda-lime ...
, containing around 70% silica, accounts for around 90% of manufactured glass. The term ''glass'', in popular usage, is often used to refer only to this type of material, although silica-free glasses often have desirable properties for applications in modern communications technology. Some objects, such as drinking glasses and
eyeglasses
Glasses, also known as eyeglasses or spectacles, are vision eyewear, with lenses (clear or tinted) mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms (known as temples or ...
, are so commonly made of silicate-based glass that they are simply called by the name of the material.
Despite being brittle, buried silicate glass will survive for very long periods if not disturbed, and many examples of glass fragments exist from early glass-making cultures. Archaeological evidence suggests glass-making dates back to at least 3,600 BC in
Mesopotamia
Mesopotamia ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن or ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in the northern part of the ...
,
Egypt
Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Medit ...
, or
Syria. The earliest known glass objects were
beads
A bead is a small, decorative object that is formed in a variety of shapes and sizes of a material such as stone, bone, shell, glass, plastic, wood, or pearl and with a small hole for threading or stringing. Beads range in size from under ...
, perhaps created accidentally during
metalworking
Metalworking is the process of shaping and reshaping metals to create useful objects, parts, assemblies, and large scale structures. As a term it covers a wide and diverse range of processes, skills, and tools for producing objects on every scal ...
or the production of
faience
Faience or faïence (; ) is the general English language term for fine tin-glazed pottery. The invention of a white pottery glaze suitable for painted decoration, by the addition of an oxide of tin to the slip of a lead glaze, was a major a ...
. Due to its ease of
formability Formability is the ability of a given metal workpiece to undergo plastic deformation without being damaged. The plastic deformation capacity of metallic materials, however, is limited to a certain extent, at which point, the material could experienc ...
into any shape, glass has been traditionally used for vessels, such as
bowls,
vase
A vase ( or ) is an open container. It can be made from a number of materials, such as ceramics, glass, non-rusting metals, such as aluminium, brass, bronze, or stainless steel. Even wood has been used to make vases, either by using tree species ...
s,
bottle
A bottle is a narrow-necked container made of an impermeable material (such as glass, plastic or aluminium) in various shapes and sizes that stores and transports liquids. Its mouth, at the bottling line, can be sealed with an internal stop ...
s, jars and drinking glasses. In its most solid forms, it has also been used for
paperweights
A paperweight is a small solid object heavy enough, when placed on top of papers, to keep them from blowing away in a breeze or from moving under the strokes of a painting brush (as with Chinese calligraphy). While any object, such as a stone, ...
and
marbles
A marble is a small spherical object often made from glass, clay, steel, plastic, or agate. They vary in size, and most commonly are about in diameter. These toys can be used for a variety of games called ''marbles'', as well being placed in mar ...
. Glass can be coloured by adding metal salts or painted and printed as
enamelled glass
Enamelled glass or painted glass is glass which has been decorated with vitreous enamel (powdered glass, usually mixed with a binder) and then fired to fuse the glasses. It can produce brilliant and long-lasting colours, and be translucent or o ...
. The
refractive
In physics, refraction is the redirection of a wave as it passes from one medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commonly observed phenomeno ...
,
reflective
Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves. The ' ...
and
transmission properties of glass make glass suitable for manufacturing
optical lenses,
prism
Prism usually refers to:
* Prism (optics), a transparent optical component with flat surfaces that refract light
* Prism (geometry), a kind of polyhedron
Prism may also refer to:
Science and mathematics
* Prism (geology), a type of sedimentary ...
s, and
optoelectronics
Optoelectronics (or optronics) is the study and application of electronic devices and systems that find, detect and control light, usually considered a sub-field of photonics. In this context, ''light'' often includes invisible forms of radiat ...
materials. Extruded
glass fibres have application as
optical fibres
An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means t ...
in communications networks, thermal insulating material when matted as
glass wool so as to trap air, or in
glass-fibre
Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clot ...
reinforced plastic (
fibreglass
Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clo ...
).
Microscopic structure
![Silica](https://upload.wikimedia.org/wikipedia/commons/4/4b/Silica.svg)
The standard definition of a ''glass'' (or vitreous solid) is a solid formed by rapid melt
quenching
In materials science, quenching is the rapid cooling of a workpiece in water, oil, polymer, air, or other fluids to obtain certain material properties. A type of heat treating, quenching prevents undesired low-temperature processes, such as pha ...
.
However, the term "glass" is often defined in a broader sense, to describe any non-crystalline (
amorphous) solid that exhibits a
glass transition when heated towards the liquid state.
Glass is an
amorphous solid
In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal.
Etymology
The term comes from the Greek ''a'' ("wi ...
. Although the atomic-scale structure of glass shares characteristics of the structure of a
supercooled liquid
Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid or a gas below its melting point without it becoming a solid. It achieves this in the absence of a seed crystal or nucleus around which a crystal ...
, glass exhibits all the mechanical properties of a solid.
As in other
amorphous solid
In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal.
Etymology
The term comes from the Greek ''a'' ("wi ...
s, the atomic structure of a glass lacks the long-range periodicity observed in
crystalline solids. Due to
chemical bonding
A chemical bond is a lasting attraction between atoms or ions that enables the formation of molecules and crystals. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds, or through the sharing o ...
constraints, glasses do possess a high degree of short-range order with respect to local atomic
polyhedra
In geometry, a polyhedron (plural polyhedra or polyhedrons; ) is a three-dimensional shape with flat polygonal faces, straight edges and sharp corners or vertices.
A convex polyhedron is the convex hull of finitely many points, not all on ...
. 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 in solids). Though a material viscosity on the order of 10
17–10
18 Pa s can be measured in glass, such a high value reinforces the fact that glass would not change shape appreciably over even large periods of time.
Formation from a supercooled liquid
For melt quenching, if the cooling is sufficiently rapid (relative to the characteristic
crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the
supercooled liquid is frozen into the solid state at T
g. The tendency for a material to form a glass while quenched is called glass-forming ability. This ability can be predicted by the
rigidity theory.
Generally, a glass exists in a structurally
metastable
In chemistry and physics, metastability denotes an intermediate energetic state within a dynamical system other than the system's state of least energy.
A ball resting in a hollow on a slope is a simple example of metastability. If the ball i ...
state with respect to its
crystalline
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...
form, although in certain circumstances, for example in
atactic
Tacticity (from el, τακτικός, taktikos, "relating to arrangement or order") is the relative stereochemistry of adjacent chiral centers within a macromolecule. The practical significance of tacticity rests on the effects on the physical p ...
polymers, there is no crystalline analogue of the amorphous phase.
Glass is sometimes considered to be a liquid due to its lack of a first-order
phase transition
In chemistry, thermodynamics, and other related fields, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic states o ...
where certain
thermodynamic
Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of the ...
variables such as
volume
Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). Th ...
,
entropy
Entropy is a scientific concept, as well as a measurable physical property, that is most commonly associated with a state of disorder, randomness, or uncertainty. The term and the concept are used in diverse fields, from classical thermodynam ...
and
enthalpy
Enthalpy , a property of a thermodynamic system, is the sum of the system's internal energy and the product of its pressure and volume. It is a state function used in many measurements in chemical, biological, and physical systems at a constant ...
are discontinuous through the glass transition range. The
glass transition may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the
thermal expansivity
Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature, usually not including phase transitions.
Temperature is a monotonic function of the average molecular kinetic ...
and
heat capacity
Heat capacity or thermal capacity is a physical property of matter, defined as the amount of heat to be supplied to an object to produce a unit change in its temperature. The SI unit of heat capacity is joule per kelvin (J/K).
Heat capacity ...
are discontinuous, however this is incorrect.
The equilibrium theory of phase transformations do not hold for glass, and hence the glass transition cannot be classed as one of the classical equilibrium phase transformations in solids.
Furthermore, it does not describe the temperature dependence of Tg upon heating rate, as found in differential scanning calorimetry.
Occurrence in nature
Glass can form naturally from volcanic magma.
Obsidian is a common volcanic glass with high silica (SiO
2) content formed when felsic lava extruded from a volcano cools rapidly.
Impactite
Impactite is rock created or modified by one or more impacts of a meteorite. Impactites are considered metamorphic rock, because their source materials were modified by the heat and pressure of the impact. On Earth, impactites consist primarily o ...
is a form of glass formed by the impact of a
meteorite, where
Moldavite
Moldavite ( cs, vltavín) is a forest green, olive green or blue greenish vitreous silica projectile glass formed by a meteorite impact in southern Germany (Nördlinger Ries Crater) that occurred about 15 million years ago. It is a type of tekti ...
(found in central and eastern Europe), and
Libyan desert glass
Libyan Desert glass or Great Sand Sea glass is an impactite, made mostly of lechatelierite, found in areas in the eastern Sahara, in the deserts of eastern Libya and western Egypt. Fragments of desert glass can be found over areas of tens of s ...
(found in areas in the eastern
Sahara, the
deserts of eastern Libya and
western Egypt) are notable examples.
Vitrification
Vitrification (from Latin ''vitreum'', "glass" via French ''vitrifier'') is the full or partial transformation of a substance into a glass, that is to say, a non- crystalline amorphous solid. Glasses differ from liquids structurally and glasses po ...
of
quartz
Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...
can also occur when
lightning
Lightning is a naturally occurring electrostatic discharge during which two electrically charged regions, both in the atmosphere or with one on the ground, temporarily neutralize themselves, causing the instantaneous release of an avera ...
strikes
sand
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class o ...
, forming hollow,
branching rootlike structures called
fulgurite
Fulgurites (), commonly known as "fossilized lightning", are natural tubes, clumps, or masses of sintered, vitrified, and/or fused soil, sand, rock, organic debris and other sediments that sometimes form when lightning discharges into ground. ...
s.
Trinitite
Trinitite, also known as atomsite or Alamogordo glass, is the glassy residue left on the desert floor after the plutonium-based Trinity nuclear bomb test on July 16, 1945, near Alamogordo, New Mexico. The glass is primarily composed of arkosic sa ...
is a glassy residue formed from the desert floor sand at the
Trinity
The Christian doctrine of the Trinity (, from 'threefold') is the central dogma concerning the nature of God in most Christian churches, which defines one God existing in three coequal, coeternal, consubstantial divine persons: God th ...
nuclear bomb test site.
Edeowie glass
Edeowie glass is a natural glass, or lechatelierite, found in the Australian state of South Australia. It is slag-like, opaque material found as vesicular free forms or sheet-like/ropy masses. It is located throughout a semi-continuous swath in ...
, found in
South Australia
South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...
, is proposed to originate from
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...
grassland fires,
lightning
Lightning is a naturally occurring electrostatic discharge during which two electrically charged regions, both in the atmosphere or with one on the ground, temporarily neutralize themselves, causing the instantaneous release of an avera ...
strikes, or
hypervelocity impact by one or several
asteroids or
comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ...
s.
File:Lipari-Obsidienne (5).jpg, A piece of volcanic obsidian glass
File:Moldavite Besednice.jpg, Moldavite
Moldavite ( cs, vltavín) is a forest green, olive green or blue greenish vitreous silica projectile glass formed by a meteorite impact in southern Germany (Nördlinger Ries Crater) that occurred about 15 million years ago. It is a type of tekti ...
, a natural glass formed by meteorite impact, from Besednice, Bohemia
File:Fulgurites-algeria.jpg, Tube fulgurites
File:Trinitite from Trinity Site.jpg, Trinitite
Trinitite, also known as atomsite or Alamogordo glass, is the glassy residue left on the desert floor after the plutonium-based Trinity nuclear bomb test on July 16, 1945, near Alamogordo, New Mexico. The glass is primarily composed of arkosic sa ...
, a glass made by the Trinity nuclear-weapon test
File:Libyan Desert Glass.jpg, Libyan desert glass
Libyan Desert glass or Great Sand Sea glass is an impactite, made mostly of lechatelierite, found in areas in the eastern Sahara, in the deserts of eastern Libya and western Egypt. Fragments of desert glass can be found over areas of tens of s ...
History
![Roman diatretglas](https://upload.wikimedia.org/wikipedia/commons/c/c5/Roman_diatretglas.jpg)
Naturally occurring
obsidian glass was used by
Stone Age societies as it fractures along very sharp edges, making it ideal for cutting tools and weapons.
Glassmaking dates back at least 6000 years, long before humans had discovered how to
smelt
Smelt may refer to:
* Smelting, chemical process
* The common name of various fish:
** Smelt (fish), a family of small fish, Osmeridae
** Australian smelt in the family Retropinnidae and species ''Retropinna semoni''
** Big-scale sand smelt ''Ath ...
iron.
Archaeological evidence suggests that the first true synthetic glass was made in
Lebanon
Lebanon ( , ar, لُبْنَان, translit=lubnān, ), officially the Republic of Lebanon () or the Lebanese Republic, is a country in Western Asia. It is located between Syria to Lebanon–Syria border, the north and east and Israel to Blue ...
and the coastal north
Syria,
Mesopotamia
Mesopotamia ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن or ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in the northern part of the ...
or
ancient Egypt.
The earliest known glass objects, of the mid-third millennium BC, were
beads
A bead is a small, decorative object that is formed in a variety of shapes and sizes of a material such as stone, bone, shell, glass, plastic, wood, or pearl and with a small hole for threading or stringing. Beads range in size from under ...
, perhaps initially created as accidental by-products of
metalworking
Metalworking is the process of shaping and reshaping metals to create useful objects, parts, assemblies, and large scale structures. As a term it covers a wide and diverse range of processes, skills, and tools for producing objects on every scal ...
(
slags) or during the production of
faience
Faience or faïence (; ) is the general English language term for fine tin-glazed pottery. The invention of a white pottery glaze suitable for painted decoration, by the addition of an oxide of tin to the slip of a lead glaze, was a major a ...
, a pre-glass
vitreous material made by a process similar to
glazing.
Early glass was rarely transparent and often contained impurities and imperfections,
and is technically faience rather than true glass, which did not appear until the 15th century BC. However, red-orange glass beads excavated from the
Indus Valley Civilization dated before 1700 BC (possibly as early as 1900 BC) predate sustained glass production, which appeared around 1600 BC in Mesopotamia and 1500 BC in Egypt. During the
Late Bronze Age
The Bronze Age is a historic period, lasting approximately from 3300 BC to 1200 BC, characterized by the use of bronze, the presence of writing in some areas, and other early features of urban civilization. The Bronze Age is the second prin ...
there was a rapid growth in
glassmaking
Glass production involves two main methods – the float glass process that produces sheet glass, and glassblowing that produces bottles and other containers. It has been done in a variety of ways during the history of glass.
Glass container ...
technology in
Egypt
Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Medit ...
and
Western Asia
Western Asia, West Asia, or Southwest Asia, is the westernmost subregion of the larger geographical region of Asia, as defined by some academics, UN bodies and other institutions. It is almost entirely a part of the Middle East, and includes Ana ...
.
Archaeological finds from this period include coloured glass
ingots, vessels, and beads.
Much early glass production relied on grinding techniques borrowed from
stoneworking
Stonemasonry or stonecraft is the creation of buildings, structures, and sculpture using stone as the primary material. It is one of the oldest activities and professions in human history. Many of the long-lasting, ancient shelters, temples, m ...
, such as grinding and carving glass in a cold state.
The term ''glass'' developed in the late
Roman Empire
The Roman Empire ( la, Imperium Romanum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post- Republican period of ancient Rome. As a polity, it included large territorial holdings around the Mediter ...
. It was in the
Roman glass
Roman glass objects have been recovered across the Roman Empire in domestic, industrial and funerary contexts. Glass was used primarily for the production of vessels, although mosaic tiles and window glass were also produced. Roman glass productio ...
making centre at
Trier
Trier ( , ; lb, Tréier ), formerly known in English as Trèves ( ;) and Triers (see also names in other languages), is a city on the banks of the Moselle in Germany. It lies in a valley between low vine-covered hills of red sandstone in the ...
(located in current-day Germany) that the
late-Latin term ''glesum'' originated, probably from a
Germanic word for a
transparent
Transparency, transparence or transparent most often refer to:
* Transparency (optics), the physical property of allowing the transmission of light through a material
They may also refer to:
Literal uses
* Transparency (photography), a still, ...
,
lustrous
Lustre (British English) or luster (American English; see spelling differences) is the way light interacts with the surface of a crystal, rock, or mineral. The word traces its origins back to the Latin ''lux'', meaning "light", and generally ...
substance.
Glass objects have been recovered across the Roman Empire in domestic,
funerary
A funeral is a ceremony connected with the final disposition of a corpse, such as a burial or cremation, with the attendant observances. Funerary customs comprise the complex of beliefs and practices used by a culture to remember and respect ...
, and industrial contexts, as well as trade items in marketplaces in distant provinces. Examples of
Roman glass
Roman glass objects have been recovered across the Roman Empire in domestic, industrial and funerary contexts. Glass was used primarily for the production of vessels, although mosaic tiles and window glass were also produced. Roman glass productio ...
have been found outside of the former
Roman Empire
The Roman Empire ( la, Imperium Romanum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post- Republican period of ancient Rome. As a polity, it included large territorial holdings around the Mediter ...
in
China, the
Baltics
The Baltic states, et, Balti riigid or the Baltic countries is a geopolitical term, which currently is used to group three countries: Estonia, Latvia, and Lithuania. All three countries are members of NATO, the European Union, the Eurozone, ...
, the
Middle East
The Middle East ( ar, الشرق الأوسط, ISO 233: ) is a geopolitical region commonly encompassing Arabia (including the Arabian Peninsula and Bahrain), Asia Minor (Asian part of Turkey except Hatay Province), East Thrace (Europ ...
, and
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
. The Romans perfected
cameo glass
Cameo glass is a luxury form of glass art produced by cameo glass engraving or etching and carving through fused layers of differently colored glass to produce designs, usually with white opaque glass figures and motifs on a dark-colored backgroun ...
, produced by
etching
Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio (incised) in the metal. In modern manufacturing, other chemicals may be used on other types ...
and carving through fused layers of different colours to produce a design in relief on the glass object.
![Vitrail-Passion](https://upload.wikimedia.org/wikipedia/commons/6/64/Vitrail-Passion.jpg)
In
post-classical
In world history, post-classical history refers to the period from about 500 AD to 1500, roughly corresponding to the European Middle Ages. The period is characterized by the expansion of civilizations geographically and development of trade ...
West Africa,
Benin
Benin ( , ; french: Bénin , ff, Benen), officially the Republic of Benin (french: République du Bénin), and formerly Dahomey, is a country in West Africa. It is bordered by Togo to the west, Nigeria to the east, Burkina Faso to the nort ...
was a manufacturer of glass and glass beads.
Glass was used extensively in Europe during the
Middle Ages
In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...
.
Anglo-Saxon glass
Anglo-Saxon glass has been found across England during archaeological excavations of both settlement and cemetery sites. Glass in the Anglo-Saxon period was used in the manufacture of a range of objects including vessels, beads, windows and was ev ...
has been found across England during archaeological excavations of both settlement and cemetery sites. From the 10th century onwards, glass was employed in
stained glass windows of churches and
cathedral
A cathedral is a church that contains the '' cathedra'' () of a bishop, thus serving as the central church of a diocese, conference, or episcopate. Churches with the function of "cathedral" are usually specific to those Christian denominatio ...
s, with famous examples at
Chartres Cathedral
Chartres Cathedral, also known as the Cathedral of Our Lady of Chartres (french: Cathédrale Notre-Dame de Chartres), is a Roman Catholic church in Chartres, France, about southwest of Paris, and is the seat of the Bishop of Chartres. Mostly con ...
and the
Basilica of Saint-Denis
The Basilica of Saint-Denis (french: Basilique royale de Saint-Denis, links=no, now formally known as the ) is a large former medieval abbey church and present cathedral in the commune of Saint-Denis, a northern suburb of Paris. The building ...
. By the 14th century, architects were designing buildings with walls of
stained glass such as
Sainte-Chapelle
The Sainte-Chapelle (; en, Holy Chapel) is a royal chapel in the Gothic style, within the medieval Palais de la Cité, the residence of the Kings of France until the 14th century, on the Île de la Cité in the River Seine in Paris, France.
...
, Paris, (1203–1248) and the East end of
Gloucester Cathedral. With the change in architectural style during the
Renaissance
The Renaissance ( , ) , from , with the same meanings. is a period in European history
The history of Europe is traditionally divided into four time periods: prehistoric Europe (prior to about 800 BC), classical antiquity (800 BC to AD ...
period in Europe, the use of large stained glass windows became much less prevalent, although stained glass had a major revival with
Gothic Revival architecture
Gothic Revival (also referred to as Victorian Gothic, neo-Gothic, or Gothick) is an Architectural style, architectural movement that began in the late 1740s in England. The movement gained momentum and expanded in the first half of the 19th cent ...
in the 19th century.
During the 13th century, the island of
Murano,
Venice
Venice ( ; it, Venezia ; vec, Venesia or ) is a city in northeastern Italy and the capital of the Veneto region. It is built on a group of 118 small islands that are separated by canals and linked by over 400 bridges. The isla ...
, became a centre for glass making, building on medieval techniques to produce colourful ornamental pieces in large quantities.
Murano glass
Venetian glass () is glassware made in Venice, typically on the island of Murano near the city. Traditionally it is made with a soda–lime "metal" and is typically elaborately decorated, with various "hot" glass-forming techniques, as well as ...
makers developed the exceptionally clear colourless glass
cristallo
Cristallo is a glass which is totally clear (like rock crystal), without the slight yellow or greenish color originating from iron oxide impurities. This effect is achieved through small additions of manganese oxide.R. W. Douglas: ''A history of ...
, so called for its resemblance to natural crystal, which was extensively used for windows, mirrors, ships' lanterns, and lenses.
In the 13th, 14th, and 15th centuries, enamelling and
gilding on glass vessels was perfected in Egypt and Syria.
Towards the end of the 17th century,
Bohemia became an important region for glass production, remaining so until the start of the 20th century. By the 17th century, glass in the Venetian tradition was also being produced in
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
. In about 1675,
George Ravenscroft
George Ravenscroft (1632 – 7 June 1683) was an English businessman in the import/export and glass making trades. He is primarily known for his work in developing clear lead crystal glass (also known as flint glass) in England.
Personal life
L ...
invented
lead crystal
Lead glass, commonly called crystal, is a variety of glass in which lead replaces the calcium content of a typical potash glass. Lead glass contains typically 18–40% (by weight) lead(II) oxide (PbO), while modern lead crystal, historically als ...
glass, with
cut glass
Cut glass or cut-glass is a technique and a style of decorating glass. For some time the style has often been produced by other techniques such as the use of moulding, but the original technique of cutting glass on an abrasive wheel is still u ...
becoming fashionable in the 18th century.
Ornamental glass objects became an important art medium during the
Art Nouveau period in the late 19th century.
Throughout the 20th century, new
mass production techniques led to widespread availability of glass in much larger amounts, making it practical as a building material and enabling new applications of glass. In the 1920s a
mould-etch process was developed, 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 coloured glass, led to cheap glassware in the 1930s, which later became known as
Depression glass
Depression glass is glassware made in the period 1929–1939, often clear or colored translucent machine-made glassware that was distributed free, or at low cost, in the United States and Canada around the time of the Great Depression. Depres ...
. In the 1950s,
Pilkington Bros.,
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
, developed the
float glass process, producing high-quality distortion-free flat sheets of glass by floating on molten
tin
Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal.
Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...
.
Modern multi-story buildings are frequently constructed with
curtain walls made almost entirely of glass.
Laminated glass
Laminated glass (LG) is a type of safety glass that holds together when shattered. In the event of breaking, it is held in place by a thin polymer interlayer, typically of polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), lonoplast polyme ...
has been widely applied to vehicles for windscreens. Optical glass for spectacles has been used since the Middle Ages. The production of lenses has become increasingly proficient, aiding
astronomer
An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...
s as well as having other application in medicine and science.
Glass is also employed as the aperture cover in many
solar energy collectors.
In the 21st century, glass manufacturers have developed different brands of
chemically strengthened glass
Chemically strengthened glass is a type of glass that has increased strength as a result of a post-production chemical process. When broken, it still shatters in long pointed splinters similar to float glass. For this reason, it is not considered ...
for widespread application in
touchscreen
A touchscreen or touch screen is the assembly of both an input ('touch panel') and output ('display') device. The touch panel is normally layered on the top of an electronic visual display of an information processing system. The display is ofte ...
s for
smartphone
A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, whic ...
s,
tablet computer
A tablet computer, commonly shortened to tablet, is a mobile device, typically with a mobile operating system and touchscreen display processing circuitry, and a rechargeable battery in a single, thin and flat package. Tablets, being com ...
s, and many other types of
information appliance
An information appliance (IA) is an appliance that is designed to easily perform a specific electronic function such as playing music, photography, or editing text.
Typical examples are smartphones and personal digital assistants (PDAs). Inf ...
s. These include
Gorilla Glass
Gorilla Glass is a brand of chemically strengthened glass developed and manufactured by Corning, now in its seventh generation. Designed to be thin, light and damage-resistant, the glass gains its surface strength, ability to contain flaws, and ...
, developed and manufactured by
Corning,
AGC Inc.'s
Dragontrail
Dragontrail, manufactured by AGC Inc., is an alkali- aluminosilicate sheet glass engineered for a combination of thinness, lightness and damage-resistance, similar to Corning's proprietary Gorilla Glass. The material's primary properties are its ...
and
Schott AG
Schott AG is a German multinational glass company specializing in the manufacture of glass and glass-ceramics. Headquartered in Mainz, Germany, it is owned by the Carl Zeiss Foundation. The company's founder and namesake, Otto Schott, is cre ...
's Xensation.
Physical properties
Optical
Glass is in widespread use in optical systems due to its ability to refract, reflect, and transmit light following
geometrical optics
Geometrical optics, or ray optics, is a model of optics that describes light propagation in terms of '' rays''. The ray in geometrical optics is an abstraction useful for approximating the paths along which light propagates under certain circumstan ...
. The most common and oldest applications of glass in optics are as
lenses
A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...
,
window
A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent mat ...
s, mirrors, and
prism
Prism usually refers to:
* Prism (optics), a transparent optical component with flat surfaces that refract light
* Prism (geometry), a kind of polyhedron
Prism may also refer to:
Science and mathematics
* Prism (geology), a type of sedimentary ...
s.
The key optical properties refractive index, Dispersion (optics), dispersion, and Transparency and translucency, transmission, of glass are strongly dependent on chemical composition and, to a lesser degree, its thermal history.
Optical glass typically has a refractive index of 1.4 to 2.4, and an Abbe number (which characterises dispersion) of 15 to 100.
Refractive index may be modified by high-density (refractive index increases) or low-density (refractive index decreases) additives.
Glass transparency results from the absence of grain boundary, grain boundaries which diffuse reflection, diffusely scatter light in polycrystalline materials.
Semi-opacity due to crystallization may be induced in many glasses by maintaining them for a long period at a temperature just insufficient to cause fusion. In this way, the crystalline, devitrified material, known as Réaumur's glass porcelain is produced.
Although generally transparent to visible light, glasses may be Opacity (optics), opaque to other Electromagnetic spectrum, wavelengths of light. While silicate glasses are generally opaque to infrared wavelengths with a transmission cut-off at 4 μm, heavy-metal Fluoride glass, fluoride and Chalcogenide glass, chalcogenide glasses are transparent to infrared wavelengths of up to 7 and up to 18 μm, respectively.
The addition of metallic oxides results in different coloured glasses as the metallic ions will absorb wavelengths of light corresponding to specific colours.
Other
In the manufacturing process, glasses can be poured, formed, extruded and molded into forms ranging from flat sheets to highly intricate shapes. The finished product is brittle and will fracture, unless laminated glass, laminated or Tempered glass, tempered to enhance durability. Glass is typically inert, resistant to chemical attack, and can mostly withstand the action of water, making it an ideal material for the manufacture of containers for foodstuffs and most chemicals.
Nevertheless, although usually highly resistant to chemical attack, glass will corrode or dissolve under some conditions.
The materials that make up a particular glass composition have an effect on how quickly the glass corrodes. Glasses containing a high proportion of alkali metal, alkali or Alkaline earth element, alkaline earth elements are more susceptible to corrosion than other glass compositions.
The density of glass varies with chemical composition with values ranging from for Fused quartz, fused silica to for dense flint glass. Glass is stronger than most metals, with a theoretical tensile strength for pure, flawless glass estimated at to due to its ability to undergo reversible compression without fracture. However, the presence of scratches, bubbles, and other microscopic flaws lead to a typical range of to in most commercial glasses.
Several processes such as Toughened glass, toughening can increase the strength of glass. Carefully drawn flawless glass fibres can be produced with strength of up to .
Reputed flow
The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption is incorrect, as once solidified, glass stops flowing. The sags and ripples observed in old glass were already there the day it was made; manufacturing processes used in the past produced sheets with imperfect surfaces and non-uniform thickness.
(The near-perfect
float glass used today only became widespread in the 1960s.)
The rate of glass flow in mediaeval windows was calculated in 2017. It was found that the glass was 16 orders of magnitude (10
16 times) less viscous (hence freer-flowing) than expected at room temperature—16 orders of magnitude less than previous estimates based on soda–lime–silicate glass. It was estimated that the rate of flow would not exceed 1Nanometre, nm per billion years.
Types
Silicate
![Quartz sand](https://upload.wikimedia.org/wikipedia/commons/c/cc/Quartz_sand.jpg)
Silicon dioxide (SiO
2) is a common fundamental constituent of glass. Fused quartz is a glass made from chemically-pure silica.
It has very low thermal expansion and excellent resistance to thermal shock, being able to survive immersion in water while red hot, resists high temperatures (1000–1500 °C) and chemical weathering, and is very hard. It is also transparent to a wider spectral range than ordinary glass, extending from the visible further into both the UV and Infrared, IR ranges, and is sometimes used where transparency to these wavelengths is necessary. Fused quartz is used for high-temperature applications such as furnace tubes, lighting tubes, melting crucibles, etc.
However, its high melting temperature (1723 °C) and viscosity make it difficult to work with. Therefore, normally, other substances (fluxes) are added to lower the melting temperature and simplify glass processing.
Soda–lime
Sodium carbonate (Na
2CO
3, "soda") is a common additive and acts to lower the glass-transition temperature. However, sodium silicate is water solubility, water-soluble, so lime (mineral), lime (CaO, calcium oxide, generally obtained from limestone), along with magnesium oxide (MgO), and aluminium oxide (Al
2O
3), are commonly added to improve chemical durability. Soda–lime glasses (Na
2O) + lime (CaO) + magnesia (MgO) + alumina (Al
2O
3) account for over 75% of manufactured glass, containing about 70 to 74% silica by weight.
[B.H.W.S. de Jong, "Glass"; in "Ullmann's Encyclopedia of Industrial Chemistry"; 5th edition, vol. A12, VCH Publishers, Weinheim, Germany, 1989, , pp. 365–432.] Soda–lime–silicate glass is transparent, easily formed, and most suitable for window glass and tableware.
However, it has a high thermal expansion and poor resistance to heat.
Soda–lime glass is typically used for
window
A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent mat ...
s,
bottle
A bottle is a narrow-necked container made of an impermeable material (such as glass, plastic or aluminium) in various shapes and sizes that stores and transports liquids. Its mouth, at the bottling line, can be sealed with an internal stop ...
s, light bulbs, and jars.
Borosilicate
![Measuring cup](https://upload.wikimedia.org/wikipedia/commons/c/ce/Measuring_cup.jpg)
Borosilicate glasses (e.g. Pyrex, Duran (glass), Duran) typically contain 5–13% boron trioxide (B
2O
3).
Borosilicate glasses have fairly low Coefficient of thermal expansion, coefficients of thermal expansion (7740 Pyrex CTE is 3.25/°C as compared to about 9/°C for a typical soda–lime glass). They are, therefore, less subject to Stress (mechanics), stress caused by thermal expansion and thus less vulnerable to Crack propagation, cracking from thermal shock. They are commonly used for e.g. labware, cookware, household cookware, and sealed beam car head lamps.
Lead
The addition of lead(II) oxide into silicate glass lowers melting point and viscosity of the melt. The high density of lead glass (silica + lead oxide (PbO) + potassium oxide (K
2O) + soda (Na
2O) + zinc oxide (ZnO) + alumina) results in a high electron density, and hence high refractive index, making the look of glassware more brilliant and causing noticeably more specular reflection and increased Dispersion (optics), optical dispersion.
Lead glass has a high elasticity, making the glassware more workable and giving rise to a clear "ring" sound when struck. However, lead glass cannot withstand high temperatures well.
Lead oxide also facilitates solubility of other metal oxides and is used in colored glass. The viscosity decrease of lead glass melt is very significant (roughly 100 times in comparison with soda glass); this allows easier removal of bubbles and working at lower temperatures, hence its frequent use as an additive in vitreous enamels and glass solders. The high ionic radius of the Pb
2+ ion renders it highly immobile and hinders the movement of other ions; lead glasses therefore have high electrical resistance, about two orders of magnitude higher than soda–lime glass (10
8.5 vs 10
6.5 Ω⋅cm, direct current, DC at 250 °C).
Aluminosilicate
Aluminosilicate glass typically contains 5–10% alumina (Al
2O
3). Aluminosilicate glass tends to be more difficult to melt and shape compared to borosilicate compositions, but has excellent thermal resistance and durability.
Aluminosilicate glass is extensively used for fiberglass,
used for making glass-reinforced plastics (boats, fishing rods, etc.), top-of-stove cookware, and halogen bulb glass.
Other oxide additives
The addition of barium also increases the refractive index. 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 eyeglasses. Iron can be incorporated into glass to absorb infrared radiation, for example in heat-absorbing filters for movie projectors, while cerium(IV) oxide can be used for glass that absorbs ultraviolet wavelengths. Fluorine lowers the dielectric constant of glass. Fluorine is highly electronegative and lowers the polarizability of the material. Fluoride silicate glasses are used in manufacture of integrated circuits as an insulator.
Glass-ceramics
![Ceranfeld](https://upload.wikimedia.org/wikipedia/commons/3/36/Ceranfeld.jpg)
Glass-ceramic materials contain both non-crystalline glass and
crystalline
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...
ceramic phases. They are formed by controlled nucleation and partial crystallisation of a base glass by heat treatment.
Crystalline grains are often embedded within a non-crystalline intergranular phase of grain boundary, grain boundaries. Glass-ceramics exhibit advantageous thermal, chemical, biological, and dielectric properties as compared to metals or organic polymers.
The most commercially important property of glass-ceramics is their imperviousness to thermal shock. Thus, glass-ceramics have become extremely useful for countertop cooking and industrial processes. The negative thermal expansion coefficient (CTE) of the crystalline ceramic phase can be balanced with the positive CTE of the glassy phase. At a certain point (~70% crystalline) the glass-ceramic has a net CTE near zero. This type of glass-ceramic exhibits excellent mechanical properties and can sustain repeated and quick temperature changes up to 1000 °C.
Fibreglass
Fibreglass (also called glass fibre reinforced plastic, GRP) is a composite material made by reinforcing a plastic resin with glass fibres. It is made by melting glass and stretching the glass into fibres. These fibres are woven together into a cloth and left to set in a plastic resin.
Fibreglass has the properties of being lightweight and corrosion resistant, and is a good Insulator (electricity), insulator enabling its use as building insulation materials, building insulation material and for electronic housing for consumer products. Fibreglass was originally used in the United Kingdom and United States during World War II to manufacture radomes. Uses of fibreglass include building and construction materials, boat hulls, car body parts, and aerospace composite materials.
Glass wool, Glass-fibre wool is an excellent thermal insulation, thermal and sound insulation, sound insulation material, commonly used in buildings (e.g. attic and cavity wall insulation), and plumbing (e.g. pipe insulation), and soundproofing.
It is produced by forcing molten glass through a fine mesh by centripetal force, and breaking the extruded glass fibres into short lengths using a stream of high-velocity air. The fibres are bonded with an adhesive spray and the resulting wool mat is cut and packed in rolls or panels.
Non-silicate
![CD-RW bottom](https://upload.wikimedia.org/wikipedia/commons/c/cf/CD-RW_bottom.jpg)
Besides common silica-based glasses many other inorganic and Organic chemistry, organic materials may also form glasses, including Metallic glass, metals, aluminates, phosphates, borates, chalcogenide glass, chalcogenides, fluorides, germanates (glasses based on Germanium oxide, GeO
2), tellurites (glasses based on TeO
2), antimonates (glasses based on Sb
2O
3), arsenates (glasses based on As
2O
3), titanates (glasses based on TiO
2), tantalates (glasses based on Ta
2O
5), nitrates, carbonates, plastics, acrylic glass, acrylic, and many other substances.
Some of these glasses (e.g. Germanium dioxide (GeO
2, Germania), in many respects a structural analogue of silica, fluoride glass, fluoride, aluminate, phosphate glass, phosphate, borate glass, borate, and chalcogenide glass, chalcogenide glasses) have physico-chemical properties useful for their application in Optical fiber, fibre-optic waveguides in communication networks and other specialized technological applications.
Silica-free glasses may often have poor glass forming tendencies. Novel techniques, including containerless processing by aerodynamic levitation (cooling the melt whilst it floats on a gas stream) or splat quenching (pressing the melt between two metal anvils or rollers), may be used increase cooling rate, or reduce crystal nucleation triggers.
Amorphous metals
![Bulk Metallic Glass Sample](https://upload.wikimedia.org/wikipedia/commons/e/e6/Bulk_Metallic_Glass_Sample.jpg)
In the past, small batches of amorphous metals with high surface area configurations (ribbons, wires, films, etc.) have been produced through the implementation of extremely rapid rates of cooling. Amorphous metal wires have been produced by sputtering molten metal onto a spinning metal disk.
A number of alloys have been produced in layers with thickness exceeding 1 millimeter. These are known as bulk metallic glasses (BMG). Liquidmetal, Liquidmetal Technologies sell a number of zirconium-based BMGs.
Batches of amorphous steel have also been produced that demonstrate mechanical properties far exceeding those found in conventional steel alloys.
Experimental evidence indicates that the system Al-Fe-Si may undergo a ''first-order transition'' to an amorphous form (dubbed "q-glass") on rapid cooling from the melt. Transmission electron microscopy (TEM) images indicate that q-glass nucleates from the melt as discrete particles with a uniform spherical growth in all directions. While x-ray diffraction reveals the isotropic nature of q-glass, a nucleation barrier exists implying an interfacial discontinuity (or internal surface) between the glass and melt phases.
Polymers
Important polymer glasses include amorphous and glassy pharmaceutical compounds. These are useful because the solubility of the compound is greatly increased when it is amorphous compared to the same crystalline composition. Many emerging pharmaceuticals are practically insoluble in their crystalline forms. Many polymer thermoplastics familiar from everyday use are glasses. For many applications, like glass bottles or eyewear, polymer glasses (acrylic glass, polycarbonate or polyethylene terephthalate) are a lighter alternative to traditional glass.
Molecular liquids and molten salts
Molecular liquids, electrolytes, molten salts, and aqueous solutions are mixtures of different molecules or ions that do not form a covalent network but interact only through weak van der Waals forces or through transient hydrogen bonds. In a mixture of three or more ionic species of dissimilar size and shape, crystallization can be so difficult that the liquid can easily be supercooled into a glass. Examples include LiCl:''R''H
2O (a solution of lithium chloride salt and water molecules) in the composition range 4<''R''<8. sugar glass, or Ca
0.4K
0.6(NO
3)
1.4. Glass electrolytes in the form of Ba-doped Li-glass and Ba-doped Na-glass have been proposed as solutions to problems identified with organic liquid electrolytes used in modern lithium-ion battery cells.
Production
![Float Glass Unloading](https://upload.wikimedia.org/wikipedia/commons/9/9f/Float_Glass_Unloading.jpg)
Following the glass batch preparation and mixing, the raw materials are transported to the furnace.
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) for beverages, food, and some commodity items. Some glass bakeware is made of soda-lime ...
for
mass production is melted in Glass melting furnace, glass melting furnaces. Smaller scale furnaces for specialty glasses include electric melters, pot furnaces, and day tanks.
After melting, homogenization and refining (glass), refining (removal of bubbles), the glass is Template:Glass forming, 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, who created a continuous ribbon of glass using a molten tin bath on which the molten glass flows unhindered under the influence of gravity. The top surface of the glass is subjected to nitrogen under pressure to obtain a polished finish. Container glass for common bottles and jars is formed by Glass container production#Forming process, blowing and pressing methods. This glass is often slightly modified chemically (with more alumina and calcium oxide) for greater water resistance.
![Skansen, Stockholm, Sweden (Unsplash)](https://upload.wikimedia.org/wikipedia/commons/9/9f/Skansen%2C_Stockholm%2C_Sweden_%28Unsplash%29.jpg)
Once the desired form is obtained, glass is usually annealing (glass), annealed for the removal of stresses and to increase the glass's hardness and durability.
Surface treatments, coatings or lamination may follow to improve the chemical durability (Glass production#Coatings, glass container coatings, Glass production#Internal treatment, glass container internal treatment), strength (toughened glass, bulletproof glass, windshields), or optical properties (insulated glazing, anti-reflective coating).
New chemical glass compositions or new treatment techniques can be initially investigated in small-scale laboratory experiments. 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. Care must be taken that the raw materials have not reacted with moisture or other chemicals in the environment (such as alkali metal, alkali or alkaline earth metal oxides and hydroxides, or boron trioxide, boron oxide), or that the impurities are quantified (loss on ignition).
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 selenium dioxide (SeO
2). Also, more readily reacting raw materials may be preferred over relatively Chemically inert, inert ones, such as Aluminium hydroxide, aluminum hydroxide (Al(OH)
3) over Aluminium oxide, alumina (Al
2O
3). Usually, the melts are carried out in platinum crucibles to reduce contamination from the crucible material. Glass homogeneous (chemistry), homogeneity is achieved by homogenizing the raw materials mixture (glass batch), by stirring the melt, and by crushing and re-melting the first melt. The obtained glass is usually annealing (glass), annealed to prevent breakage during processing.
Colour
Colour in glass may be obtained by addition of homogenously distributed electrically charged ions (or Transparent materials#Absorption of light in solids, colour centres). While ordinary soda–lime glass appears colourless in thin section, iron(II) oxide (FeO) impurities produce a green tint in thick sections.
Manganese dioxide (MnO
2), which gives glass a purple colour, may be added to remove the green tint given by FeO. FeO and chromium(III) oxide (Cr
2O
3) additives are used in the production of green bottles.
Iron (III) oxide, on the other-hand, produces yellow or yellow-brown glass.
Low concentrations (0.025 to 0.1%) of cobalt oxide (CoO) produces rich, deep blue cobalt glass. Chromium is a very powerful colourising agent, yielding dark green.
Sulphur combined with carbon and iron salts produces amber glass ranging from yellowish to almost black. A glass melt can also acquire an amber colour from a reducing combustion atmosphere. Cadmium sulfide produces imperial red, and combined with selenium can produce shades of yellow, orange, and red.
The additive Copper(II) oxide (CuO) produces a turquoise (color), turquoise colour in glass, in contrast to Copper(I) oxide (Cu
2O) which gives a dull brown-red colour.
File:Bottle, wine (AM 1997.80.28-1).jpg, alt=A green glass bottle, Iron(II) oxide and chromium(III) oxide additives are often used in the production of green bottles.
File:Bristol.blue.glass.arp.750pix.jpg, alt=Several examples of deep blue glass, Cobalt oxide produces rich, cobalt glass, deep blue glass, such as Bristol blue glass.
File:Colour Eclipse, Danny Lane.jpg, alt=Three glass disks, with one colored turquoise, another purple, and a third colored red, Different oxide additives produce the different colours in glass: turquoise (color), turquoise (Copper(II) oxide), purple (Manganese dioxide), and red (Cadmium sulfide).
File:Chinese snuff bottle, Qing dynasty, glass bottle with amber stopper, Honolulu Museum of Art.JPG, Red glass bottle with yellow glass overlay
File:Glass ornaments.JPG, Amber-coloured glass
File:Glass garland bowl MET DP122006.jpg, Four-colour Roman glass bowl, manufactured circa 1st century B.C.
Uses
Architecture and windows
Soda–lime Plate glass, sheet glass is typically used as transparent glazing in architecture, glazing material, typically as
window
A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent mat ...
s in external walls of buildings. Float or rolled sheet glass products is cut to size either by Scoring (industrial process), scoring and snapping the material, laser cutting, Water jet cutter, water jets, or diamond bladed saw. The glass may be thermally or chemically Tempered glass, tempered (strengthened) for safety glass, safety and bent or curved during heating. Surface coatings may be added for specific functions such as scratch resistance, blocking specific wavelengths of light (e.g. infrared or ultraviolet), dirt-repellence (e.g. self-cleaning glass), or switchable Electrochromism, electrochromic coatings.
Structural glazing systems represent one of the most significant architectural innovations of modern times, where glass buildings now often dominate skylines of many modern cities.
These systems use stainless steel fittings countersunk into recesses in the corners of the glass panels allowing strengthened panes to appear unsupported creating a flush exterior.
Structural glazing systems have their roots in iron and Conservatory (greenhouse), glass conservatories of the nineteenth century
Tableware
Glass is an essential component of tableware and is typically used for water, Beer glassware, beer and wine glass, wine drinking glasses.
Wine glasses are typically stemware, i.e. goblets formed from a bowl, stem, and foot. Crystal or Lead glass, Lead crystal glass may be cut and polished to produce decorative drinking glasses with gleaming facets. Other uses of glass in tableware include decanters, jugs, Plate (dishware), plates, and bowls.
File:Jubilee Campus MMB «62 Melton Hall Christmas Dinner.jpg, Wine glasses and other glass tableware
File:British dimpled glass pint jug with ale.jpg, Dimpled glass beer pint jug
File:Crystal glass.jpg, Cut Lead glass, lead crystal glass
File:Decanter and Stopper LACMA 56.35.29a-b.jpg, A glass decanter and Bung, stopper
Packaging
The inert and impermeable nature of glass makes it a stable and widely used material for food and drink packaging as glass bottles and jars. Most container glass is soda–lime glass, produced by Glass production#Forming process, blowing and pressing techniques. Container glass has a lower magnesium oxide and sodium oxide content than flat glass, and a higher silica, calcium oxide, and aluminum oxide content.
["High temperature glass melt property database for process modeling"; Eds.: Thomas P. Seward III and Terese Vascott; The American Ceramic Society, Westerville, Ohio, 2005, ] Its higher content of water-insoluble oxides imparts slightly higher chemical durability against water, which is advantageous for storing beverages and food. Glass packaging is sustainable, readily recycled, reusable and refillable.
For electronics applications, glass can be used as a substrate in the manufacture of integrated passive devices, thin-film bulk acoustic resonators, and as a hermetic sealing material in device packaging, including very thin solely glass based encapsulation of integrated circuits and other semiconductors in high manufacturing volumes.
Laboratories
Glass is an important material in scientific laboratories for the manufacture of experimental apparatus because it is relatively cheap, readily formed into required shapes for experiment, easy to keep clean, can withstand heat and cold treatment, is generally non-reactive with many reagents, and its transparency allows for the observation of chemical reactions and processes.
Laboratory glassware applications include Laboratory flask, flasks, petri dishes, test tubes, pipettes, graduated cylinders, glass lined metallic containers for chemical processing, fractionation columns, glass pipes, Schlenk lines, Gauge (instrument), gauges, and thermometers.
Although most standard laboratory glassware has been mass-produced since the 1920s, scientists still employ skilled glassblowers to manufacture bespoke glass apparatus for their experimental requirements.
File:Vigreux column lab.jpg, A Vigreux Fractionating column, column in a laboratory setup
File:Double vac line front view.jpg, A Schlenk line with four ports
File:Different types of graduated cylinder- 10ml, 25ml, 50ml and 100 ml graduated cylinder.jpg, Graduated cylinders
File:250 mL Erlenmeyer flask.jpg, Erlenmeyer Laboratory flask, flask
Optics
Glass is a ubiquitous material in
optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultrav ...
by virtue of its ability to Refraction, refract, Reflection (physics), reflect, and Transmittance, transmit light. These and other optical properties can be controlled by varying chemical compositions, thermal treatment, and manufacturing techniques. The many applications of glass in optics includes glasses for eyesight correction, imaging optics (e.g. lenses and mirrors in telescopes, microscopes, and cameras), fibre optics in telecommunications technology, and Photonic integrated circuit, integrated optics. Microlenses and gradient-index optics (where the refractive index is non-uniform) find application in e.g. reading optical discs, laser printers, photocopiers, and laser diodes.
Art
![Stained Glass Panel with the Visitation MET MED700](https://upload.wikimedia.org/wikipedia/commons/9/9a/Stained_Glass_Panel_with_the_Visitation_MET_MED700.jpg)
Glass as art dates to least 1300 BC shown as an example of natural glass found in Tutankhamun's pectoral,
[Tut's gem hints at space impact](_blank)
BBC News, July 19, 2006. which also contained vitreous enamel, that is to say, melted coloured glass used on a metal backing. Enamelled glass, the decoration of glass vessels with coloured glass paints, has existed since 1300 BC, and was prominent in the early 20th century with Art Nouveau glass and that of the House of Fabergé in St. Petersburg, Russia. Both techniques were used in
stained glass, which reached its height roughly from 1000 to 1550, before a revival in the 19th century.
The 19th century saw a revival in ancient glass-making techniques including
cameo glass
Cameo glass is a luxury form of glass art produced by cameo glass engraving or etching and carving through fused layers of differently colored glass to produce designs, usually with white opaque glass figures and motifs on a dark-colored backgroun ...
, achieved for the first time since the Roman Empire, initially mostly for pieces in a neoclassicism, neo-classical style. The
Art Nouveau movement made great use of glass, with René Lalique, Émile Gallé, and Daum (studio), Daum of Nancy in the first French wave of the movement, producing coloured vases and similar pieces, often in cameo glass or in lustre glass techniques.
Louis Comfort Tiffany in America specialized in
stained glass, both secular and religious, in panels and his famous lamps. The early 20th-century saw the large-scale factory production of glass art by firms such as Waterford Crystal, Waterford and Lalique. Small studios may hand-produce glass artworks. Techniques for producing glass art include glassblowing, blowing, kiln-casting, fusing, slumping, pâte de verre, flame-working, hot-sculpting and cold-working. Cold work includes traditional stained glass work and other methods of shaping glass at room temperature. Objects made out of glass include vessels,
paperweights
A paperweight is a small solid object heavy enough, when placed on top of papers, to keep them from blowing away in a breeze or from moving under the strokes of a painting brush (as with Chinese calligraphy). While any object, such as a stone, ...
, marbles, beads, sculptures and installation art.
Image:Portland Vase BM Gem4036 n5.jpg, The Portland Vase, Roman cameo glass
Cameo glass is a luxury form of glass art produced by cameo glass engraving or etching and carving through fused layers of differently colored glass to produce designs, usually with white opaque glass figures and motifs on a dark-colored backgroun ...
, about 5–25 AD
File:Medallion St Demetrios Louvre OA6457.jpg, Byzantine cloisonné enamel plaque of St Demetrios, c. 1100, using the ''senkschmelz'' or "sunk" technique
File:British Museum Royal Gold Cup.jpg, The Royal Gold Cup with ''basse-taille'' enamels on gold; weight 1.935 kg, late 14th-century. Saint Agnes appears to her friends in a vision.
Image:Reichsadlerhumpen.jpg, The ''Reichsadlerhumpen'', enamelled glass
Enamelled glass or painted glass is glass which has been decorated with vitreous enamel (powdered glass, usually mixed with a binder) and then fired to fuse the glasses. It can produce brilliant and long-lasting colours, and be translucent or o ...
with the double-headed eagle of the Holy Roman Empire, and the arms of the various territories on its wings, was a popular showpiece of enamelled glass in the German lands from the 16th century on.
File:Venetian Jar CMOG.jpg, alt=white jar with fine stripes, Filigree style Venetian glass jar
File:Gallé, nancy, vaso clematis, 1890-1900.JPG, Émile Gallé, Marquetry glass vase with clematis flowers (1890-1900)
File:Vase (Perruches) by René Jules Lalique, 1922, blown four mold glass - Cincinnati Art Museum - DSC04355.JPG, Glass vase by art nouveau artist René Lalique
File:Clara driscoll per tiffany studios, lampada laburnum, 1910 ca. 02.jpg, Clara Driscoll (glass designer), Clara Driscoll Tiffany lamp, laburnum pattern, c. 1910
File:Glass.sculpture.kewgardens.london.arp.jpg, A glass sculpture by Dale Chihuly, "The Sun" at the "Gardens of Glass" exhibition in Kew Gardens, London
File:Modern stained glass - geograph.org.uk - 921350.jpg, Modern stained glass window
See also
* Fire glass
* Flexible glass
* Kimberley points
* Prince Rupert's drop
* Smart glass
References
External links
*
The Story of Glass Making in Canadafrom The Canadian Museum of Civilization.
"How Your Glass Ware Is Made"by George W. Waltz, February 1951, ''Popular Science''.
All About Glassfrom the Corning Museum of Glass: a collection of articles, multimedia, and virtual books all about glass, including th
Glass Dictionary
National Glass AssociationThe largest trade association representing the flat (architectural), auto glass, and window & door industries
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