Glass in our Lives
Glass is omnipresent in our lives. We find it in many objects; sometimes its presence is so discreet that we don't even notice it. Glass is the only solid mineral material that retains its transparent properties regardless of its size and shape. Transparent, hard (only diamond can scratch it), resistant, rot-proof, waterproof, non-flammable and non-combustible: glass is an ideal material for many uses, and we're certainly not done discovering more!
The word “glass” refers to the material, of course – but also to the ubiquitous container made from it and used for drinking. Despite this widespread double meaning in many languages, it is only since the 19th century that the use of glass containers has become widespread, both at the table or for the conservation of foodstuffs.
A tumbler is a glass without a stem. The story goes that stemmed glasses were created to prevent the server from pouring a poison into it, since it is customary to hold it by the stem: you can thus clearly see the content, and the serving hand never goes near it. Gourmets, however, assure us that stemmed glasses exists in order to appreciate a wine at the ideal temperature.
Shape, capacity and adaptation according to content: drinking glasses are highly diverse objects.
Obviously, a pair of glasses consists of a frame that attaches corrective lenses (convergent lenses for the aging or long-sighted, or divergent lenses for the short-sighted).
The monks of the Middle Ages used a “reading stone”, a magnifying glass made of rock crystal. It was Alhazen, a physicist born in Basra in present-day Iraq, who laid the foundations of optics around the year 1000. In 13th century Venice, people wore so called “rivet spectacles” (glasses riveted together so they could grip the nose). The need for glasses grew with the invention of printing and the first framed glasses appeared in Paris in the 18th century.
Until the 19th century, round lenses were worn; oval lenses, smaller and of better quality appear during this time, and glasses with double-focus were invented in England.
Fashion did not take hold in this field until the mid-1950s. Today's optical market is flourishing, with hardened, thinned, anti-reflective, anti-smear or anti-condensation treated lenses … Our current spectacle lenses consist of organic materials and are no longer made with a silica base. Today, glasses are created that offer augmented reality vision, or include an integrated camera.
In order for a mirror to reflect the most faithful image – by reflecting incident light in the right direction – it must have a perfectly polished surface: a glass plate therefore protects the thin metal layer of the mirror from oxidation.
The first mirrors were pieces of polished stone, then metal. To prevent oxidation of the metal, glass was added as a protective layer. The metal was then replaced by an alloy of tin and mercury.
In the Brothers Grimm tale Snow White, the Queen's mirror is incapable of lying: it is a symbol of truth. It is the mirror that tells the Queen that Snow White is still alive and that her beauty surpasses all else.
Lewis Carroll wrote a sequel to the Alice’s Adventures in Wonderland entitled Through the Looking Glass, in which the mirror is associated with a door leading to another world. Alice passes through to the other side of the mirror in her living room; the world is as if reversed: you have to run very fast to stay in place, to move away to reach an object, and time, too, is turned upside down.
Electric light bulbs
The outer surface of a light bulb – the casing for the whole system of producing light from energy, filament, wires … - is made of glass. Without the glass shell, the heated filament would come in contact with oxygen and burn instantly: the glass insulates the device.
Prolific engineer, ingenious inventor and industrialist Thomas Edison (1847-1931) discovered how to enclose a filament in a hermetic glass bulb emptied of air: it produces electric light! He patented his invention in 1879. Thomas Edison is also the inventor of the electric chair!
Contemporary glazing is made of “float glass”: the liquid raw material is poured from the furnace onto a bath of molten tin, on the surface of which it floats. The resulting glass is extremely smooth and perfectly flat.
Before the use of glass, windows were closed with parchment, oiled cloth, or Muscovite mica (a mineral) to keep them translucent. Wooden shutters or hay bales were also used to block the openings of homes.
When creating an aquarium, a very precise volume calculation must be made to determine the thickness of the glass making up the tank walls. The water exerts continuous stress on the glass, which increases with depth; the outer face must also resist any lesion so as not to cause the whole plate to break. The glass must therefore be sufficiently thick and rigid.
A mirror attached to a vehicle, the rear-view mirror allows drivers to see what's going on behind them. Ray Harroun is considered to be the first driver who benefited from a rear-view mirror in the 1911 Indianapolis 500-mile race; he won the competition. The system was then patented in the United States.
Glass marbles and beads
Playing marbles are small solid glass spheres. Their centre is decorated with one or more coloured stripes seen through the glass. There are also opaque glass beads. They can be manufactured industrially: at the exit of the furnace a shear cuts the flow of molten mass of several mixed colours; these small segments fall into moving cylinders which shape them and prevent them from sticking until they cool down. The more complex balls are made by hand.
Marbles have different names depending on their decoration and especially their size, which can vary from 1.5 to 7 cm in diameter. These names vary from country to country. The largest marble, sometimes known as a “Tom Bowler” (or the “boulard” in France) is indispensable in a collection, even if it is rarely used for playing.
The game of marbles has been listed in the inventory of the intangible cultural heritage of France since 2012. Each country, or even each region, has its own rules. The pichenette, the pincer or the pot are, however, widely used.
In Fribourg, people play poletz, not marbles. This is an expression in Bolze, the dialect spoken in the Lower Town, a picturesque mixture of Swiss German and French.
A kaleidoscope is a device consisting of a tube containing several mirrors whose arrangement allows coloured glass fragments placed in the tube to produce various patterns when set in motion. The patterns change with each movement of an element of the system. In this way, the instrument infinitely reflects, in multiple colours, light from the outside that enters facing the observer. The kaleidoscope can take the form of a hand-held toy or a large-format installation.
It was the Scottish physicist David Brewster who, in 1816, invented the kaleidoscope by conducting experiments on the polarization of light. He called it a “scientific toy”.
From a limited number of elements placed in an enclosed space, the kaleidoscope opens up an infinite or indefinite number of combinations: it symbolizes the act of creation, and has inspired writers and philosophers.
In Greek, kalos means beautiful, eidos aspect, and skopein to look. The kaleidoscope, therefore, creates beautiful images to look at! It is sometimes claimed that geometric shapes have a soothing effect on the viewer.
Figuratively speaking, a “kaleidoscope” refers to a rapid succession of various sensations or impressions. The term is therefore widely used – be it to name creative companies, lists or as a song
The telescope is an optical instrument for astronomical observation. The image is formed by refraction (reflection) through a lens cut into the glass (or a combination of lenses). The telescope allows you to observe distant objects moving slowly. In addition to the objective lens, the telescope includes an eyepiece, a kind of sophisticated magnifying glass. The first telescope was designed in Holland in 1608. Early telescope lenses are thought to have been in use as early as 1590.
An instrument for observing objects invisible to the naked eye, the optical microscope consists of a tube fitted with a system of lenses producing the image of a sample illuminated for transparency. The lens and eyepiece of a microscope are high quality optical glasses.
In the 16th century, a Dutch eyeglass manufacturer created the first microscope by superimposing two eyeglass lenses of the time in sliding tubes. It was through the microscope that Pasteur observed the microbes responsible for contagious diseases, and Flemming discovered the first antibiotic.
Anyone who has ever dropped their mobile phone violently has experienced this: the screen is made of glass, slightly blue in colour. Glass constitutes the surface plate of all touchscreens, regardless of the technology used.
Fusing, flame-spun glass, Murano glass, thermoformed glass, enamelled, sandblasted, cast glass, blown glass: glass is processes in all sorts of ways to become pearls, necklaces, bracelets, rings, pendants, earrings or pendants.
Photovoltaic solar panels absorb sunlight as a source of energy to generate direct current electricity.
Solar panels integrate photovoltaic cells into a glass covering, usually tempered glass. The glass protects the system from aggressive atmospheric conditions and ensures optimum light transmission. A photovoltaic cell is an electronic component that, when exposed to light, produces electricity through the photovoltaic effect (Source: Wikipedia).
An apparatus for measuring and displaying the value of temperature, the thermometer operates by means of the expansion – or contraction – of a substance contained in a glass tube. It is used in the fields of medicine, meteorology, cooking, and industry among others.
The thermometer was developed in the 16th and 17th centuries. It was Galileo who first noted that the air expanded or contracted depending on the temperature. A few years later, thermometers with liquids such as water, alcohol and then mercury expansion appeared. The latter being a toxic element, it is now usually replaced by organic liquids.
Illness, trauma (such as a stab wound), chemical burn or chronic inflammation may require the complete or partial removal of an eye. An ocular prosthesis – a "glass eye" – fills the empty eye socket and ensures aesthetics and comfort.
An ocularist, a glass-blower with a thorough knowledge of anatomy, carries out this precision work by hand and to measure: he reproduces the shape and colour of the white of the eye, the blood vessels and the colour of the iris. The prosthesis is adapted to the eye socket muscle. Tears and dust corrode it.
Eyes made of precious stones are known to have been placed on the dead of ancient Egypt. With Amboise Paré in the 16th century appear the first prostheses, expensive and heavy. Around 1600, Shakespeare had his King Lear say “Find yourself glass eyes”. Today, polymer prostheses are also manufactured.
Chemists and biologists use a multiplicity of glass vessels, instruments and equipment in their laboratories for experiments. This is known as “laboratory glassware”. Containers must resist heat, shocks, the aggressive nature of the products, radiation ... Glass is one of the materials that best meets these criteria. Ordinary (soda-lime) glass is used for many instruments; borosilicate glass withstands higher temperatures and is more resistant to thermal and mechanical shocks. Laboratory glassware can even be made of polymers or plastics, and is still called glassware. Large experimental laboratories have their own glassblower, who designs and creates the objects that scientists need.
Dropper, pipette, beaker, cup, capsule, crystallizer, funnel, Erlenmeyer flask, pill bottle, test tube, balloon, ampoule, burette, stopper, petri dish, retort, desiccator, sleeve: the uses of glass in chemical laboratories are infinite.
Glass fibre is a glass filament produced by drawing molten glass. It is lightweight, impact resistant, insulating, chemically stable, and has the ability to transmit light. It is mainly used to reinforce concrete or polymers (fiberglass), but it has many other applications in everyday life: insulation (glass wool), optics (endoscopy, telecommunications), transport (airplanes, high-speed trains, bumpers), electricity and electronics, sports (skis, athletic poles).
Glass wool is obtained by agglomeration of glass fibres. It has exceptional insulating characteristics – it is thermal and soundproof as well is fire resistant, and is therefore used for fire protection. The Isover de Lucens company (part of the Saint-Gobain group) produces more than 30,000 tonnes of glass wool every year, making it the leader in this material.
It is possible to manufacture real fabrics from glass fibre. The first were presented at the Exhibition of Products of French Industry in 1844!
An optical fibre is a flexible wire whose central conductor (the “core” of the fibre) is made of glass or plastic; it is used to transmit light. The glass core is often surrounded by a transparent cladding material with a lower index of refraction. The light signal is coded by the variation in intensity. Optical fibre is mainly used for the transmission of digital data. Its information flow is very fast. It can therefore transmit an enormous amount of information over very long distances. The use of optical fibre in telecommunications enables a very fast data transmission rate; it is insensitive to electromagnetic interference and extremely stable.
The principle of fibre optics dates back to the beginning of the 20th century. In 1950, the fibre optic microscope was used to transport images along glass fibres. In 1970 the American company Corning Glass Works used it for telecommunications, revolutionizing the field. By 1977, the centre of Chicago was equipped with an optical telephone communication system.
Optical fibre is also used for medical imaging, lighting and thermal sensors.
Glass in space
Glass is one of the main materials used in aerospace. Cockpit windows for airplanes and helicopters are designed to protect the pilot and passengers, while being as aerodynamic as possible and allowing an unobstructed view. The glass company Saint-Gobain is the supplier of the Airbus A380 and A350.
Glass is also used for certain fire-resistant parts of space crafts (fibres) and for the casing of measuring instruments.
Bulletproof glass is made from layers of glass, bonded together by an interlayer of plastic sheeting. It is also called laminated glass. Bulletproof glass is designed to resist vandalism, break-ins, the impact of gunfire and explosions. Generally, glass is not resistant to direct proximity to an explosion; however, laminated glass reacts to such a blast without shattering, thus avoiding injuries.
PanzerGlass is the registered trademark of a protective coating for screens made from specially hardened, ultra-clear, scratch-resistant, very thin, oleophobic (oil- and grease-repellent, to prevent fingerprints) glass.
Acrylic glass (methyl methacrylate), often known by the brand name Plexiglas, is a polymeric, hard, transparent and unbreakable plastic. It can be moulded into many colours and shapes.
It was discovered by a German chemist in 1902; the name Plexiglas was registered in 1933.
It is sometimes used as a substitute for safety glass because of its low weight, low cost, its qualities as a good conductor of light, and its high scratch-resistance. Even at great thickness, it keeps its transparency, and it does not yellow.
Its many uses include: the aeronautics industry (noses of American bombers, portholes), lenses of submarine periscopes, helmets of Apollo astronauts, medical prostheses, computer industry, telecommunications (fibre optics), showcases, various objects.
In the field of art, it has often been used as part of installations since the emergence of Pop Art in the 1960s, as well as for designer furniture.
Placed outside, it tends to harden and crack.
Current research indicates that Polycarbonate (polyester of carbonic acid, derived from the organic compound bisphenol A) has even more interesting characteristics than Plexiglas: in addition to its hardness and resistance, it is very malleable.
Radioactive waste and glass
Glass is a so-called amorphous material (a solid whose molecules or atoms are distributed randomly, not according to a crystalline structure).
Some glasses (the borosilicates: silicon, boron and aluminium) can remain intact for several thousands of years. In addition, they have the ability to absorb radiation. Because of these qualities, they can be used to store sensitive materials, such as the waste products of nuclear fission. This is called “vitrification” of radioactive waste: the containers of radioactive material are reduced to small pieces and mixed with molten glass. This is called containment glass. As the radioactive material disintegrates, the atoms in the glass become disordered, but since the glass is not orderly in the first place, there is virtually no difference: it remains disordered!
In Würenlingen (Canton of Aargau), low-level waste is already stored in a mass of glass, which is incinerated, melted down and then solidified.
Glass and high-tech
Some examples of glass use include:
In optics: anti-reflection treatment of spectacle lenses, hardening layers for lenses.
Housing: scratch-resistant treatment (worktops, credenzas, kitchen or bathroom surfaces), lighting, doors, railings, stairs, columns, shower and sauna walls, pergolas, roofs, conservatories, greenhouses, screens, furniture, floors, facades, and partitions.
Photonics: branch of physics that studies the components that enable the generation, transmission, processing or conversion of optical signals (study of photons).
The list of applications quoted here is far from exhaustive: it is rightly said that “everything is possible with glass”.