Glass etching comprises the techniques of creating art on the surface of glass by applying acidic, caustic, or abrasive substances. Traditionally this is done after the glass is blown or cast, although mold-etching has replaced some forms of surface etching; the removal of minute amounts of glass causes the characteristic rough surface and translucent quality of frosted glass. Various techniques are used to achieve an etched surface in glass, whether for artistic effect, or to create a translucent surface. Acid etching is done using hexafluorosilicic acid; the acid is prepared by dissolving silica in a mixture of hydroelectric acid, quartz powder, calcium fluoride, concentrated sulfuric acid derived after heating. Glass etching cream is used by hobbyists as it is easier to use than acid. Available from art supply stores, it consists of fluoride compounds, such as hydrogen fluoride and sodium fluoride; as the types of acids used in this process are hazardous, abrasive methods have gained popularity.
Abrasive blasting is another common technique for creating patterns in glassware, creating a "frosted" look to the glass. It is used commercially. High pressure air mixed with an abrasive material cuts away at the glass surface to create the desired effect; the longer the stream of air and abrasive material are focused in one spot, the deeper the cut. Leptat glass is glass, etched using a patented acid process. Leptat takes its name from the Czech word meaning "to etch", because the technique was inspired by a Bohemian, Czech Republic glass exhibit viewed at a past World's Fair in Osaka and patented in the United States by Bernard E. Gruenke, Jr. of the Conrad Schmitt Studios. Abstract, figural and traditional designs have been executed in Leptat glass. A secondary design or pattern is sometimes etched more into the negative areas, for further interest. Gold leaf or colored enamels can be inlaid to highlight the designs; the Leptat technique allows the glass to reflect light like a jewel-cut gem.
Mold etching In the 1920s a mold-etch process was invented, in which art was etched directly into the mold, so that each cast piece emerged from the mold with the texture on the surface of the glass. This reduced manufacturing costs and, combined with a wider use of colored glass, led to cheap glassware in the 1930s, which became known as Depression glass. Frost etching is the process in which vinyl window material is cut to produce a pattern and applied to a window to give a frosted patterned effect. Glass engraving Satin glass Sea glass Sandcarver Intro to Sandblasting Glass etching in Dubai
In glassblowing, cane refers to rods of glass with color. Caneworking refers to the process of making cane, to the use of pieces of cane, lengthwise, in the blowing process to add intricate spiral and stripes to vessels or other blown glass objects. Cane is used to make murrine, thin discs cut from the cane in cross-section that are added to blown or hot-worked objects. A particular form of murrine glasswork is millefiori, in which many murrine with a flower-like or star-shaped cross-section are included in a blown glass piece. Caneworking is an ancient technique, first invented in southern Italy in the second half of the third century BC, elaborately developed centuries on the Italian island of Murano. There are several different methods of making cane. In each, the fundamental technique is the same: a lump of glass containing some pattern of colored and clear glass, is heated in a furnace and pulled, by means of a long metal rod attached at each end; as the glass is stretched out, it retains whatever cross-sectional pattern was in the original lump, but narrows quite uniformly along its length.
Cane is pulled until it reaches the diameter of a pencil, depending on the size of the original lump, it may be anywhere from one to fifty feet in length. After cooling, it is broken into sections from four to six inches long, which can be used in making more complex canes or in other glassblowing techniques; the simplest cane, called vetro a fili is clear glass with one or more threads of colored glass running its length. It is made by heating and shaping a chunk of clear, white, or colored glass on the end of a punty, ‘’gathering’’ molten clear glass over the color by dipping the punty in a furnace containing the clear glass. After the desired amount of clear glass is surrounding the color, this cylinder of hot glass is shaped and heated until uniform in shape and temperature. An assistant prepares a'post', another punty with a small platform of clear glass on the end; the post is pressed against the end of the hot cylinder of glass to connect them, the glassblower and assistant walk away from each other with the punties, until the cane is stretched to the desired length and diameter.
The cane is cut into small sections. A simple single-thread cane can be used to make more complex canes. A small bundle of single-thread canes can be heated until they fuse, or heated canes, laid parallel, can be picked up on the circumference of a hot cylinder of clear or colored glass; this bundle, treated just as the chunk of color in the description above, is cased in clear glass and pulled out, forming a vetro a fili cane with multiple threads and a clear or solid color core. If the cane is twisted as it is pulled, the threads take a spiral shape called vetro a retorti or zanfirico. Ballotini is a cane technique in which several vetro a fili canes are picked up while laid side-by-side rather than a bundle, with a clear glass gather over them; this gather is shaped into a cylinder with the canes directed along the axis, so that the canes form a sort of “fence” across the diameter of the cylinder. When this is twisted and pulled, the resulting cane has a helix of threads across its thickness.
Another technique for forming cane is to use optic molds to make more complex cross sections. An optic mold is an open-ended cone-shaped mold with some sort of lobed or star shape around its inside circumference; when a gather or blown bubble is forced into the mold, its outside takes the shape of the mold. Canes with complicated, multi-colored patterns are formed by placing layers of different or alternating colors over a solid-color core, using various optic molds on the layers as they are built; because the outer layers are hotter than those inside when the molds are used, the mold shape is impressed into the outer color without deforming the inner shapes. Canes made in this way are used in making millefiori. Discs from eight different canes have been used to make the pendant in the photo. Flameworkers sometimes make cane by building up the cross-section using ordinary flameworking or bead making techniques; this permits subtle gradations of color and shading, is the way murrine portraits are made.
The generic term for blown glass made using canes in the lengthwise direction is filigrano, as contrasted with murrine when the canes are sliced and used in cross-section.. One way glassblowers incorporate cane into their work is to line up canes on a steel or ceramic plate and heat them to avoid cracking; when the surfaces of the canes just begin to melt, the canes adhere to each other. The tip of a glassblowing pipe is covered with a'collar' of clear molten glass, touched to one corner of the aligned canes; the tip of the blowpipe is rolled along the bottom of the canes, which stick to the collar, aligned cylindrically around the edge of the blowpipe. They are heated further until soft enough to shape; the cylinder of canes is sealed at the bottom with jacks and tweezers, to form the beginning of a bubble. The bubble is blown using traditional glassblowing techniques
An optical fiber is a flexible, transparent fiber made by drawing glass or plastic to a diameter thicker than that of a human hair. Optical fibers are used most as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths than electrical cables. Fibers are used instead of metal wires. Fibers are used for illumination and imaging, are wrapped in bundles so they may be used to carry light into, or images out of confined spaces, as in the case of a fiberscope. Specially designed fibers are used for a variety of other applications, some of them being fiber optic sensors and fiber lasers. Optical fibers include a core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by the phenomenon of total internal reflection which causes the fiber to act as a waveguide. Fibers that support many propagation paths or transverse modes are called multi-mode fibers, while those that support a single mode are called single-mode fibers.
Multi-mode fibers have a wider core diameter and are used for short-distance communication links and for applications where high power must be transmitted. Single-mode fibers are used for most communication links longer than 1,000 meters. Being able to join optical fibers with low loss is important in fiber optic communication; this is more complex than joining electrical wire or cable and involves careful cleaving of the fibers, precise alignment of the fiber cores, the coupling of these aligned cores. For applications that demand a permanent connection a fusion splice is common. In this technique, an electric arc is used to melt the ends of the fibers together. Another common technique is a mechanical splice, where the ends of the fibers are held in contact by mechanical force. Temporary or semi-permanent connections are made by means of specialized optical fiber connectors; the field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics.
The term was coined by Indian physicist Narinder Singh Kapany, acknowledged as the father of fiber optics. Guiding of light by refraction, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840s. John Tyndall included a demonstration of it in his public lectures in London, 12 years later. Tyndall wrote about the property of total internal reflection in an introductory book about the nature of light in 1870:When the light passes from air into water, the refracted ray is bent towards the perpendicular... When the ray passes from water to air it is bent from the perpendicular... If the angle which the ray in water encloses with the perpendicular to the surface be greater than 48 degrees, the ray will not quit the water at all: it will be reflected at the surface.... The angle which marks the limit where total reflection begins is called the limiting angle of the medium. For water this angle is 48°27′, for flint glass it is 38°41′, while for diamond it is 23°42′.
In the late 19th and early 20th centuries, light was guided through bent glass rods to illuminate body cavities. Practical applications such as close internal illumination during dentistry appeared early in the twentieth century. Image transmission through tubes was demonstrated independently by the radio experimenter Clarence Hansell and the television pioneer John Logie Baird in the 1920s. In the 1930s, Heinrich Lamm showed that one could transmit images through a bundle of unclad optical fibers and used it for internal medical examinations, but his work was forgotten. In 1953, Dutch scientist Bram van Heel first demonstrated image transmission through bundles of optical fibers with a transparent cladding; that same year, Harold Hopkins and Narinder Singh Kapany at Imperial College in London succeeded in making image-transmitting bundles with over 10,000 fibers, subsequently achieved image transmission through a 75 cm long bundle which combined several thousand fibers. Their article titled "A flexible fibrescope, using static scanning" was published in the journal Nature in 1954.
The first practical fiber optic semi-flexible gastroscope was patented by Basil Hirschowitz, C. Wilbur Peters, Lawrence E. Curtiss, researchers at the University of Michigan, in 1956. In the process of developing the gastroscope, Curtiss produced the first glass-clad fibers. A variety of other image transmission applications soon followed. Kapany coined the term fiber optics, wrote a 1960 article in Scientific American that introduced the topic to a wide audience, wrote the first book about the new field; the first working fiber-optical data transmission system was demonstrated by German physicist Manfred Börner at Telefunken Research Labs in Ulm in 1965, followed by the first patent application for this technology in 1966. NASA used fiber optics in the television cameras. At the time, the use in the cameras was classified confidential, employees handling the cameras had to be supervised by someone with an appropriate security clearance. Charles K. Kao and George A. Hockham of the British company Standard Telephones and Cables were the first, in 1965, to promote the idea that the attenuation in optical fibers could be reduced below 20 decibels per kilometer, making fibers a practical communication medium.
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A mirror is an object that reflects light in such a way that, for incident light in some range of wavelengths, the reflected light preserves many or most of the detailed physical characteristics of the original light, called specular reflection. This is different from other light-reflecting objects that do not preserve much of the original wave signal other than color and diffuse reflected light, such as flat-white paint; the most familiar type of mirror is the plane mirror. Curved mirrors are used, to produce magnified or diminished images or focus light or distort the reflected image. Mirrors are used for personal grooming or admiring oneself, for viewing the area behind and on the sides on motor vehicles while driving, for decoration, architecture. Mirrors are used in scientific apparatus such as telescopes and lasers and industrial machinery. Most mirrors are designed for visible light. There are many types of glass mirrors, each representing a different manufacturing process and reflection type.
An aluminium glass mirror is made of a float glass manufactured using vacuum coating, i.e. aluminium powder is evaporated onto the exposed surface of the glass in a vacuum chamber and coated with two or more layers of waterproof protective paint. A low aluminium glass mirror is manufactured by coating silver and two layers of protective paint on the back surface of glass. A low aluminium glass mirror is clear, light transmissive and reflects accurate natural colors; this type of glass is used for framing presentations and exhibitions in which a precise color representation of the artwork is essential or when the background color of the frame is predominantly white. A safety glass mirror is made by adhering a special protective film to the back surface of a silver glass mirror, which prevents injuries in case the mirror is broken; this kind of mirror is used for furniture, glass walls, commercial shelves, or public areas. A silkscreen printed glass mirror is produced using inorganic color ink that prints patterns through a special screen onto glass.
Various colors and glass shapes are available. Such a glass mirror is durable and more moisture resistant than ordinary printed glass and can serve for over 20 years; this type of glass is used for decorative purposes. A silver glass mirror is an ordinary mirror, coated on its back surface with silver, which produces images by reflection; this kind of glass mirror is produced by coating a silver, copper film and two or more layers of waterproof paint on the back surface of float glass, which resists acid and moisture. A silver glass mirror provides clear and actual images, is quite durable, is used for furniture and other decorative purposes. Decorative glass mirrors are handcrafted. A variety of shades and glass thickness are available. A beam of light reflects off a mirror at an angle of reflection equal to its angle of incidence; that is, if the beam of light is shining on a mirror's surface, at a θ ° angle vertically it reflects from the point of incidence at a θ ° angle, vertically in the opposite direction.
This law mathematically follows from the interference of a plane wave on a flat boundary. In a plane mirror, a parallel beam of light changes its direction as a whole, while still remaining parallel. In a concave mirror, parallel beams of light become a convergent beam, whose rays intersect in the focus of the mirror. Known as converging mirror In a convex mirror, parallel beams become divergent, with the rays appearing to diverge from a common point of intersection "behind" the mirror. Spherical concave and convex mirrors do not focus parallel rays to a single point due to spherical aberration. However, the ideal of focusing to a point is a used approximation. Parabolic reflectors resolve this. Parabolic reflectors are not suitable for imaging nearby objects because the light rays are not parallel. Objects viewed in a mirror will appear not vertically inverted. However, a mirror does not "swap" left and right any more than it swaps top and bottom. A mirror reverses the forward/backward axis. To be precise, it reverses the object in the direction perpendicular to the mirror surface.
Because left and right are defined relative to front-back and top-bottom, the "flipping" of front and back results in the perception of a left-right reversal in the image. Looking at an image of oneself with the front-back axis flipped results in the perception of an image with its left-right axis flipped; when reflected in the mirror, your right hand remains directly opposite your real right hand, but it is perceived as the left hand of your image. When a person looks into a mirror, the image is front-back reversed, an effect similar to the holl
Impactite is rock created or modified by the impact of a meteorite. Impactite includes shock-metamorphosed target rocks and mixtures of the two, as well as sedimentary rocks with significant impact-derived components. In June 2015, NASA reported; such material may contain preserved signs of ancient life --. When a meteor strikes a planet's surface, the energy release from the impact can melt rock and soil into a liquid. If the liquid cools and hardens into a solid, impact glass forms before the atoms have time to arrange into a crystal lattice. Impact glass is dark brown black, transparent. Alamo bolide impact of Nevada Alga crater on Arizona. Charlevoix crater of Québec Darwin Crater from Tasmania Lake Lappajärvi, Finland Manicouagan crater of Québec Neugrund crater of Estonia Nördlinger Ries crater, Germany Rochechouart crater, France Wabar craters, Saudi Arabia Glossary of meteoritics Meteorite shock stage Meteorite crater glossary
Millefiori is a glasswork technique which produces distinctive decorative patterns on glassware. The term millefiori is a combination of the Italian words "mille" and "fiori". Apsley Pellatt in his book Curiosities of Glass Making was the first to use the term "millefiori", which appeared in the Oxford English Dictionary in 1849. While the use of this technique long precedes the term "millefiori", it is now most associated with Venetian glassware. Since the late 1980s, the millefiori technique has been applied to other materials; as the polymer clay is quite pliable and does not need to be heated and reheated to fuse it, it is a much easier medium in which to produce millefiori patterns than glass. The manufacture of mosaic beads can be traced to Ancient Roman and Alexandrian times. Canes made in Italy, have been found as far away as 8th century archaeological sites in Ireland. Millefiori beads have been uncovered from digs at Sandby borg, Öland, dating from the late 5th or early 6th century. A piece of millefiori was found, along with unworked garnets, in a purse at the early 7th century Anglo-Saxon burial site at Sutton Hoo.
The technical knowledge for creating millefiori was lost by the eighteenth century, the technique was not revived until the nineteenth century. Within several years of the technique's rediscovery, factories in Italy and England were manufacturing millefiori canes, they were incorporated into fine glass art paperweights. Until the 15th century, Murano glass makers were only producing drawn Rosetta beads made from molded Rosetta canes. Rosetta beads are made by the layering of a variable number of layers of glass of various colors in a mold, by pulling the soft glass from both ends until the cane has reached the desired thickness, it is cut into short segments for further processing. The millefiori technique involves the production of glass canes or rods, known as murrine, with multicolored patterns which are viewable only from the cut ends of the cane. A murrine rod is heated in a furnace and pulled until thin while still maintaining the cross section's design, it is cut into beads or discs when cooled.
Mille-fleur, a French term used to refer to a background composed of small flowers Glass museums and galleries Venetian beads
London is the capital and largest city of both England and the United Kingdom. Standing on the River Thames in the south-east of England, at the head of its 50-mile estuary leading to the North Sea, London has been a major settlement for two millennia. Londinium was founded by the Romans; the City of London, London's ancient core − an area of just 1.12 square miles and colloquially known as the Square Mile − retains boundaries that follow its medieval limits. The City of Westminster is an Inner London borough holding city status. Greater London is governed by the Mayor of the London Assembly. London is considered to be one of the world's most important global cities and has been termed the world's most powerful, most desirable, most influential, most visited, most expensive, sustainable, most investment friendly, most popular for work, the most vegetarian friendly city in the world. London exerts a considerable impact upon the arts, education, fashion, healthcare, professional services and development, tourism and transportation.
London ranks 26 out of 300 major cities for economic performance. It is one of the largest financial centres and has either the fifth or sixth largest metropolitan area GDP, it is the most-visited city as measured by international arrivals and has the busiest city airport system as measured by passenger traffic. It is the leading investment destination, hosting more international retailers and ultra high-net-worth individuals than any other city. London's universities form the largest concentration of higher education institutes in Europe. In 2012, London became the first city to have hosted three modern Summer Olympic Games. London has a diverse range of people and cultures, more than 300 languages are spoken in the region, its estimated mid-2016 municipal population was 8,787,892, the most populous of any city in the European Union and accounting for 13.4% of the UK population. London's urban area is the second most populous in the EU, after Paris, with 9,787,426 inhabitants at the 2011 census.
The population within the London commuter belt is the most populous in the EU with 14,040,163 inhabitants in 2016. London was the world's most populous city from c. 1831 to 1925. London contains four World Heritage Sites: the Tower of London. Other landmarks include Buckingham Palace, the London Eye, Piccadilly Circus, St Paul's Cathedral, Tower Bridge, Trafalgar Square and The Shard. London has numerous museums, galleries and sporting events; these include the British Museum, National Gallery, Natural History Museum, Tate Modern, British Library and West End theatres. The London Underground is the oldest underground railway network in the world. "London" is an ancient name, attested in the first century AD in the Latinised form Londinium. Over the years, the name has attracted many mythicising explanations; the earliest attested appears in Geoffrey of Monmouth's Historia Regum Britanniae, written around 1136. This had it that the name originated from a supposed King Lud, who had taken over the city and named it Kaerlud.
Modern scientific analyses of the name must account for the origins of the different forms found in early sources Latin, Old English, Welsh, with reference to the known developments over time of sounds in those different languages. It is agreed; this was adapted into Latin as Londinium and borrowed into Old English, the ancestor-language of English. The toponymy of the Common Brythonic form is much debated. A prominent explanation was Richard Coates's 1998 argument that the name derived from pre-Celtic Old European *lowonida, meaning "river too wide to ford". Coates suggested that this was a name given to the part of the River Thames which flows through London. However, most work has accepted a Celtic origin for the name, recent studies have favoured an explanation along the lines of a Celtic derivative of a proto-Indo-European root *lendh-, combined with the Celtic suffix *-injo- or *-onjo-. Peter Schrijver has suggested, on these grounds, that the name meant'place that floods'; until 1889, the name "London" applied to the City of London, but since it has referred to the County of London and Greater London.
"London" is sometimes written informally as "LDN". In 1993, the remains of a Bronze Age bridge were found on the south foreshore, upstream of Vauxhall Bridge; this bridge either reached a now lost island in it. Two of those timbers were radiocarbon dated to between 1750 BC and 1285 BC. In 2010 the foundations of a large timber structure, dated to between 4800 BC and 4500 BC, were found on the Thames's south foreshore, downstream of Vauxhall Bridge; the function of the mesolithic structure is not known. Both structures are on the south bank. Although there is evidence of scattered Brythonic settlements in the area, the first major settlement was founded by the Romans about four years after the invasion