text:
255

Year 255 (CCLV) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Valerianus and Gallienus (or, less frequently, year 1008 Ab urbe condita). The denomination 255 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

China

 * Sima Shi quells Guanqiu Jian and Wen Qin's rebellion.
 * March 23 – Sima Shi passes away.
 * Sima Zhao, Sima Shi's younger brother, inherits his brother's authority.

Science

 * Ma Jun, Chinese mechanical engineer from Cao Wei, invents the south-pointing chariot, a path-finding directional compass vehicle that uses a differential gear, not magnetics.

Births

 * January 6 – Marcellus I, bishop of Rome (d. 309)
 * Dorotheus of Tyre, Syrian bishop and martyr (d. 362)
 * Zhang Gui, Chinese governor of the Jin Dynasty (d. 314)
 * Zuo Fen, Chinese poet of the Western Jin Dynasty (d. 300)
 * Saint Helena, Roman empress who was the reputed discoverer of Christ’s cross and mother of Emperor Constantine (d. 318)

Deaths

 * February 23 – Guo Huai (or Boji), Chinese general
 * March 16 – Guanqiu Jian, Chinese general and politician
 * March 23 – Sima Shi, Chinese general and regent (b. 208)
 * Fu Gu (or Lanshi), Chinese official and politician (b. 209)
 * Liu Zan (or Zhengming), Chinese general (b. 183)
 * Sun Luyu (or Xiaohu), Chinese princess

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: 255


text:
Hans Richter (artist)

Hans (Johannes Siegfried) Richter (6 April 1888 – 1 February 1976) was a German Dada painter, graphic artist, avant-garde film producer, and art historian. In 1965 he authored the book Dadaism about the history of the Dada movement. He was born in Berlin into a well-to-do family and died in Minusio, near Locarno, Switzerland.

From Expressionism through Dadaism, Constructivism and Neoplasticism, he was one of the major figures of avant-garde art in the 1910s and 1920s and a catalyst for intellectuals and artists in many disciplines. Richter helped organise exhibitions which revived interest in Dada, both in the United States and Europe. In 1956 he made Dadascope, a film dedicated to Dada poetry.

Germany
In 1908 Richter entered the Academy of Fine Art in Berlin, and the following year the Academy of Fine Art in Weimar. Richter's first contacts with Modern Art were in 1912 through the Blaue Reiter and in 1913 through the Erster Deutscher Herbstsalon gallery Der Sturm, in Berlin. In 1914 he was influenced by Cubism.

At that time he also befriended Franz Pfemfert, who was the editor of Die Aktion. Richter contributed to the periodical Die Aktion in Berlin. His first exhibition was in Munich in 1916, and Die Aktion published a special edition about him. In the same year he was wounded and discharged from the army and went to Zürich and met Tristan Tzara, Marcel Janco, Jean Arp, and Hugo Ball, who together were forming the Dada movement, which he joined.

Richter believed that the artist's duty was to be politically active by opposing war and supporting revolution. His first abstract art works were made in 1917. In 1918, Tristan Tzara introduced Richter to Viking Eggeling and the two experimented together with film. Richter was co-founder, in 1919, of the Association of Revolutionary Artists (Artistes Radicaux) at Zürich. In the same year he created his first Prélude: an orchestration of a theme developed in eleven drawings. In 1920, he became a member of the November Group in Berlin and contributed to the Dutch periodical De Stijl.

Throughout his career, Richter claimed that his 1921 film, Rhythmus 21, was the first abstract film ever created, but in fact it was preceded by the Italian Futurist films by Bruno Corra and Arnaldo Ginna (as they report in the Futurist Manifesto of Cinema), as well as by fellow German artist Walter Ruttmann, who produced Lichtspiel Opus 1 in 1920. Nevertheless, Richter's film Rhythmus 21 is considered an important early abstract film.

In 1933, The Nazis ransacked Richter's studio in Berlin, confiscating or destroying his work. He was stripped of his German citizenship and labelled a "degenerate" artist and "cultural Bolshevik". After attempting, in vain, to make an anti-Nazi film in the Soviet Union in 1931–1932, Richter travelled around Europe. He worked for Philips in Holland and made commissioned films in Switzerland. He also gave numerous lectures about film.

About Richter's woodcuts and drawings Michel Seuphor wrote that Richter's black-and-whites graphic work, together with that of Hans Arp and Marcel Janco, are the most typical works of the Zürich period of Dada. From 1923 to 1926, Richter edited, together with Werner Gräff and Mies van der Rohe, the periodical G. Material zur elementaren Gestaltung. Richter wrote of his own attitude toward film: "I conceive of the film as a modern art form particularly interesting to the sense of sight. Painting has its own peculiar problems and specific sensations, and so has the film. But there are also problems in which the dividing line is obliterated, or where the two infringe upon each other. More especially, the cinema can fulfill certain promises made by the ancient arts, in the realization of which painting and film become close neighbors and work together."

United States
Richter moved from Switzerland to the United States in 1940 and became an American citizen. Beginning in 1941 he taught at the Institute of Film Techniques at the City College of New York before taking over as director. While living in New York City, Richter directed two feature films, Dreams That Money Can Buy (1947) and 8 x 8: A Chess Sonata in 8 Movements (1957) in collaboration with Max Ernst, Jean Cocteau, Paul Bowles, Fernand Léger, Alexander Calder, Marcel Duchamp, and others, which was partially filmed on the lawn of his summer house in Southbury, Connecticut. In 1957, he finished a film entitled Dadascope with original poems and prose spoken by their creators: Hans Arp, Marcel Duchamp, Raoul Hausmann, Richard Huelsenbeck, and Kurt Schwitters. After 1958, Richter spent parts of the year in Ascona and Connecticut and returned to painting. Peggy Guggenheim organized his first solo show in the United States in which his large painted scrolls, inspired by the Second World War, featured prominently. In 1963, he directed the short film From the Circus to the Moon about the American artist Alexander Calder. In 1965, Richter was also the author of a first-hand account of the Dada movement titled Dada: Art and Anti-Art which also included his reflections on the emerging Neo-Dada artworks.

Personal life
Hans Richter was married four times: in 1916 to Elisabeth (Lisa, Lies, Lieska) Steinert († 1923), in 1921 to Maria von Vanselow (divorced 1922), in 1927 to Erna Niemeyer (pseudonyms: Renate Green, Ré Soupault, René Mensch), in 1951 to Frida Ruppel (1910-78), whose two children Hans Ruppel and Ursula Lawder administered the estate.

Filmography

 * Rhythmus 21 (1921)
 * Rhythmus 23 (1923)
 * Rhythmus 25 (1925)
 * Filmstudie (1926) with music by Hans Heinz Stuckenschmidt
 * Inflation (1927)
 * Vormittagsspuk ("Ghosts Before Breakfast", with music by Hindemith) (1928)
 * Zweigroschenzauber (1929)
 * The Storming of La Sarraz (written only, directed by Sergei Eisenstein, lost) (1929)
 * Rennsymphonie (1929)
 * Alles dreht sich, alles bewegt sich (1929)
 * Everyday (1929)
 * Neues Leben (1930)
 * Europa Radio (1931)
 * Hallo Everybody (1933)
 * Keine Zeit für Tränen (1934)
 * Vom Blitz zum Fernsenhbild (1936)
 * Dreams That Money Can Buy (1947)
 * 8 x 8: A Chess Sonata in 8 Movements (1957)
 * Dadascope (1961)
 * From the Circus to the Moon (1963)

title: Hans Richter (artist)


text:
322

Year 322 (CCCXXII) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Probianus and Iulianus (or, less frequently, year 1075 Ab urbe condita). The denomination 322 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

Technology

 * The first dependable representation of a horse rider with paired stirrups is found in China, in a Jin Dynasty tomb.

Births

 * Kang of Jin (or Shitong), Chinese emperor (d. 344)
 * Xun Xian (or Lingze), Chinese general (d. 359)

Deaths

 * Philogonius (or Filogonius), bishop of Antioch
 * Rabbah bar Rav Huna, Jewish Talmudist
 * Xu Kan, Chinese bandit leader and warlord
 * Yang Xianrong, Chinese empress

title: 322


text:
323

Year 323 (CCCXXIII) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Severus and Rufinus (or, less frequently, year 1076 Ab urbe condita). The denomination 323 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

Roman Empire

 * Emperor Constantine the Great defeats the invading Goths and Sarmatians north of the Danube in Dacia, and claims the title of Sarmaticus Maximus.

China

 * Crown Prince Ming of Jin succeeds his father Yuan of Jin as emperor of the Eastern Jin Dynasty.

Religion

 * The poetic work Banquet (Thalia) by the Libyan-born Egyptian Christian priest Arius, age 73, expresses the doctrine that Jesus of Nazareth was not of the same substance as God but rather had a finite nature. As an ascetic, he leads a Christian community near Alexandria, and comes under suspicion of heresy. Arius writes to his former schoolmate Eusebius, bishop of Nicomedia, asking for support. Eusebius writes to other bishops, and when Arius is condemned in September, Eusebius gives him safe haven, and sponsors a synod at Bithynia in October, which nullifies Arius's excommunication (see Council of Nicaea).

Births

 * Constans I, Roman consul and emperor (d. 350)

Deaths

 * January 3 – Yuan of Jin (or Jingwen), Chinese emperor (b. 276)
 * Tiberius Julius Rhadamsades, Roman prince and client king
 * Zhang Bin (or Mengsun), Chinese general and strategist

title: 323


text:
355

Year 355 (CCCLV) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Arbitio and Maesius (or, less frequently, year 1108 Ab urbe condita). The denomination 355 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

Roman Empire

 * January 1 – Arbitio and Lollianus Mavortius begin their term as Roman consuls.
 * August 11 – Claudius Silvanus, accused of treason, proclaims himself Roman Emperor. After 28 days, Ursicinus arrives from Rome and has Silvanus murdered.
 * November 6 – In Mediolanum (Italy), Emperor Constantius II raises his cousin Julian the Apostate to the rank of Caesar. He takes command of the western provinces and marries Constantius' sister, Helena.

Europe

 * The Lentienses, a Germanic tribe, are fined by the Roman commander Arbetio under Constantius II for several incursions against the Roman Empire.
 * The Franks besiege Colonia Agrippinensium for ten months.

Asia

 * The Huns of Central Asia begin their great drive westwards with an advance into Scythia (modern Russia). They overcome and absorb the Alans, a nomadic and warlike horse breeding people from the steppes northeast of the Black Sea.

Religion

 * Pope Liberius refuses to sign a condemnation of Athanasius, Patriarch of Alexandria, imposed at Milan by Constantius II. Liberius is exiled to Beroea (Greece) and replaced by Felix II. He becomes an antipope and bishop of Rome.

Births

 * Fan Tai, Chinese general of the Jin Dynasty (d. 428)
 * Murong Bao, Chinese emperor of Later Yan (d. 398)

Deaths

 * September 7 – Claudius Silvanus, Roman usurper
 * Aedesius, Roman Neoplatonist philosopher and mystic
 * Fu Jian, Chinese emperor of the Former Qin (b. 317)
 * Liang, Chinese empress of the Former Qin Dynasty
 * Zhang Yaoling, Chinese ruler of Former Liang (b. 344)
 * Zhang Zuo (or Taibo), Chinese ruler of Former Liang

title: 355


text:
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 of material. As a method of printmaking, it is, along with engraving, the most important technique for old master prints, and remains in wide use today. In a number of modern variants such as microfabrication etching and photochemical milling, it is a crucial technique in modern technology, including circuit boards.

In traditional pure etching, a metal plate (usually of copper, zinc or steel) is covered with a waxy ground which is resistant to acid. The artist then scratches off the ground with a pointed etching needle where the artist wants a line to appear in the finished piece, exposing the bare metal. The échoppe, a tool with a slanted oval section, is also used for "swelling" lines. The plate is then dipped in a bath of acid, known as the mordant (French for "biting") or etchant, or has acid washed over it. The acid "bites" into the metal (it undergoes a redox reaction) to a depth depending on time and acid strength, leaving behind the drawing (as carved into the wax) on the metal plate. The remaining ground is then cleaned off the plate. For first and renewed uses the plate is inked in any chosen non-corrosive ink all over and the surface ink drained and wiped clean, leaving ink in the etched forms.

The plate is then put through a high-pressure printing press together with a sheet of paper (often moistened to soften it). The paper picks up the ink from the etched lines, making a print. The process can be repeated many times; typically several hundred impressions (copies) could be printed before the plate shows much sign of wear. The work on the plate can be added to or repaired by re-waxing and further etching; such an etching (plate) may have been used in more than one state.

Etching has often been combined with other intaglio techniques such as engraving (e.g., Rembrandt) or aquatint (e.g., Francisco Goya).

Etching in antiquity
Etching was already used in antiquity for decorative purposes. Etched carnelian beads are a type of ancient decorative beads made from carnelian with an etched design in white, which were probably manufactured by the Indus Valley civilization during the 3rd millennium BCE. They were made according to a technique of alkaline etching developed by the Harappans, and vast quantities of these beads were found in the archaeological sites of the Indus Valley civilization. They are considered as an important marker of ancient trade between the Indus Valley, Mesopotamia and even Ancient Egypt, as these precious and unique manufactured items circulated in great numbers between these geographical areas during the 3rd millennium BCE, and have been found in numerous tomb deposits. Sumerian kings, such as Shulgi c. 2000 BCE, also created etched carnelian beads for dedication purposes.

Early etching
Etching by goldsmiths and other metal-workers in order to decorate metal items such as guns, armour, cups and plates has been known in Europe since the Middle Ages at least, and may go back to antiquity. The elaborate decoration of armour, in Germany at least, was an art probably imported from Italy around the end of the 15th century—little earlier than the birth of etching as a printmaking technique. Printmakers from the German-speaking lands and Central Europe perfected the art and transmitted their skills over the Alps and across Europe.

The process as applied to printmaking is believed to have been invented by Daniel Hopfer (c. 1470–1536) of Augsburg, Germany. Hopfer was a craftsman who decorated armour in this way, and applied the method to printmaking, using iron plates (many of which still exist). Apart from his prints, there are two proven examples of his work on armour: a shield from 1536 now in the Real Armeria of Madrid and a sword in the Germanisches Nationalmuseum of Nuremberg. An Augsburg horse armour in the German Historical Museum, Berlin, dating to between 1512 and 1515, is decorated with motifs from Hopfer's etchings and woodcuts, but this is no evidence that Hopfer himself worked on it, as his decorative prints were largely produced as patterns for other craftsmen in various media. The oldest dated etching is by Albrecht Dürer in 1515, although he returned to engraving after six etchings instead of developing the craft.

The switch to copper plates was probably made in Italy, and thereafter etching soon came to challenge engraving as the most popular medium for artists in printmaking. Its great advantage was that, unlike engraving where the difficult technique for using the burin requires special skill in metalworking, the basic technique for creating the image on the plate in etching is relatively easy to learn for an artist trained in drawing. On the other hand, the handling of the ground and acid need skill and experience, and are not without health and safety risks, as well as the risk of a ruined plate.

Callot's innovations: échoppe, hard ground, stopping-out
Jacques Callot (1592–1635) from Nancy in Lorraine (now part of France) made important technical advances in etching technique.

Callot also appears to have been responsible for an improved, harder, recipe for the etching ground, using lute-makers' varnish rather than a wax-based formula. This enabled lines to be more deeply bitten, prolonging the life of the plate in printing, and also greatly reducing the risk of "foul-biting", where acid gets through the ground to the plate where it is not intended to, producing spots or blotches on the image. Previously the risk of foul-biting had always been at the back of an etcher's mind, preventing too much time on a single plate that risked being ruined in the biting process. Now etchers could do the highly detailed work that was previously the monopoly of engravers, and Callot made full use of the new possibilities.

Callot also made more extensive and sophisticated use of multiple "stoppings-out" than previous etchers had done. This is the technique of letting the acid bite lightly over the whole plate, then stopping-out those parts of the work which the artist wishes to keep light in tone by covering them with ground before bathing the plate in acid again. He achieved unprecedented subtlety in effects of distance and light and shade by careful control of this process. Most of his prints were relatively small—up to about six inches or 15 cm on their longest dimension, but packed with detail.

One of his followers, the Parisian Abraham Bosse, spread Callot's innovations all over Europe with the first published manual of etching, which was translated into Italian, Dutch, German and English.

The 17th century was the great age of etching, with Rembrandt, Giovanni Benedetto Castiglione and many other masters. In the 18th century, Piranesi, Tiepolo and Daniel Chodowiecki were the best of a smaller number of fine etchers. In the 19th and early 20th century, the Etching revival produced a host of lesser artists, but no really major figures. Etching is still widely practiced today.

Variants
Aquatint uses acid-resistant resin to achieve tonal effects.

Soft-ground etching uses a special softer ground. The artist places a piece of paper (or cloth etc. in modern uses) over the ground and draws on it. The print resembles a drawing. Soft ground can also be used to capture the texture or pattern of fabrics or furs pressed into the soft surface.

Other materials that are not manufactured specifically for etching can be used as grounds or resists. Examples including printing ink, paint, spray paint, oil pastels, candle or bees wax, tacky vinyl or stickers, and permanent markers.

There are some new non-toxic grounds on the market that work differently than typical hard or soft grounds.

Relief etching was invented by William Blake in about 1788, and he has been almost the only artist to use it in its original form. However, from 1880 to 1950 a photo-mechanical ("line-block") variant was the dominant form of commercial printing for images. A similar process to etching, but printed as a relief print, so it is the "white" background areas which are exposed to the acid, and the areas to print "black" which are covered with ground. Blake's exact technique remains controversial. He used the technique to print texts and images together, writing the text and drawing lines with an acid-resistant medium.

Carborundum etching (sometimes called carbograph printing) was invented in the mid-20th century by American artists who worked for the WPA. In this technique, a metal plate is first covered with silicon carbide grit and run through an etching press; then a design is drawn on the roughened plate using an acid-resistant medium. After immersion in an acid bath, the resulting plate is printed as a relief print. The roughened surface of the relief permits considerable tonal range, and it is possible to attain a high relief that results in strongly embossed prints.

Printmaking technique in detail
A waxy acid-resist, known as a ground, is applied to a metal plate, most often copper or zinc but steel plate is another medium with different qualities. There are two common types of ground: hard ground and soft ground.

Hard ground can be applied in two ways. Solid hard ground comes in a hard waxy block. To apply hard ground of this variety, the plate to be etched is placed upon a hot-plate (set at 70 °C, 158 °F), a kind of metal worktop that is heated up. The plate heats up and the ground is applied by hand, melting onto the plate as it is applied. The ground is spread over the plate as evenly as possible using a roller. Once applied the etching plate is removed from the hot-plate and allowed to cool which hardens the ground.

After the ground has hardened the artist "smokes" the plate, classically with 3 beeswax tapers, applying the flame to the plate to darken the ground and make it easier to see what parts of the plate are exposed. Smoking not only darkens the plate but adds a small amount of wax. Afterwards the artist uses a sharp tool to scratch into the ground, exposing the metal.

The second way to apply hard ground is by liquid hard ground. This comes in a can and is applied with a brush upon the plate to be etched. Exposed to air the hard ground will harden. Some printmakers use oil/tar based asphaltum or bitumen as hard ground, although often bitumen is used to protect steel plates from rust and copper plates from aging.

Soft ground also comes in liquid form and is allowed to dry but it does not dry hard like hard ground and is impressionable. After the soft ground has dried the printmaker may apply materials such as leaves, objects, hand prints and so on which will penetrate the soft ground and expose the plate underneath.

The ground can also be applied in a fine mist, using powdered rosin or spraypaint. This process is called aquatint, and allows for the creation of tones, shadows, and solid areas of color.

The design is then drawn (in reverse) with an etching-needle or échoppe. An "echoppe" point can be made from an ordinary tempered steel etching needle, by grinding the point back on a carborundum stone, at a 45–60 degree angle. The "echoppe" works on the same principle that makes a fountain pen's line more attractive than a ballpoint's: The slight swelling variation caused by the natural movement of the hand "warms up" the line, and although hardly noticeable in any individual line, has a very attractive overall effect on the finished plate. It can be drawn with in the same way as an ordinary needle.

The plate is then completely submerged in a solution that eats away at the exposed metal. ferric chloride may be used for etching copper or zinc plates, whereas nitric acid may be used for etching zinc or steel plates. Typical solutions are 1 part FeCl3 to 1 part water and 1 part nitric to 3 parts water. The strength of the acid determines the speed of the etching process.
 * The etching process is known as biting (see also spit-biting below).
 * The waxy resist prevents the acid from biting the parts of the plate which have been covered.
 * The longer the plate remains in the acid the deeper the "bites" become.

During the etching process the printmaker uses a bird feather or similar item to wave away bubbles and detritus produced by the dissolving process, from the surface of the plate, or the plate may be periodically lifted from the acid bath. If a bubble is allowed to remain on the plate then it will stop the acid biting into the plate where the bubble touches it. Zinc produces more bubbles much more rapidly than copper and steel and some artists use this to produce interesting round bubble-like circles within their prints for a Milky Way effect.

The detritus is powdery dissolved metal that fills the etched grooves and can also block the acid from biting evenly into the exposed plate surfaces. Another way to remove detritus from a plate is to place the plate to be etched face down within the acid upon plasticine balls or marbles, although the drawback of this technique is the exposure to bubbles and the inability to remove them readily.

For aquatinting a printmaker will often use a test strip of metal about a centimetre to three centimetres wide. The strip will be dipped into the acid for a specific number of minutes or seconds. The metal strip will then be removed and the acid washed off with water. Part of the strip will be covered in ground and then the strip is redipped into the acid and the process repeated. The ground will then be removed from the strip and the strip inked up and printed. This will show the printmaker the different degrees or depths of the etch, and therefore the strength of the ink color, based upon how long the plate is left in the acid.

The plate is removed from the acid and washed over with water to remove the acid. The ground is removed with a solvent such as turpentine. Turpentine is often removed from the plate using methylated spirits since turpentine is greasy and can affect the application of ink and the printing of the plate.

Spit-biting is a process whereby the printmaker will apply acid to a plate with a brush in certain areas of the plate. The plate may be aquatinted for this purpose or exposed directly to the acid. The process is known as "spit"-biting due to the use of saliva once used as a medium to dilute the acid, although gum arabic or water are now commonly used.

A piece of matte board, a plastic "card", or a wad of cloth is often used to push the ink into the incised lines. The surface is wiped clean with a piece of stiff fabric known as tarlatan and then wiped with newsprint paper; some printmakers prefer to use the blade part of their hand or palm at the base of their thumb. The wiping leaves ink in the incisions. You may also use a folded piece of organza silk to do the final wipe. If copper or zinc plates are used, then the plate surface is left very clean and therefore white in the print. If steel plate is used, then the plate's natural tooth gives the print a grey background similar to the effects of aquatinting. As a result, steel plates do not need aquatinting as gradual exposure of the plate via successive dips into acid will produce the same result. A damp piece of paper is placed over the plate and it is run through the press.

Nontoxic etching
Growing concerns about the health effects of acids and solvents led to the development of less toxic etching methods in the late 20th century. An early innovation was the use of floor wax as a hard ground for coating the plate. Others, such as printmakers Mark Zaffron and Keith Howard, developed systems using acrylic polymers as a ground and ferric chloride for etching. The polymers are removed with sodium carbonate (washing soda) solution, rather than solvents. When used for etching, ferric chloride does not produce a corrosive gas, as acids do, thus eliminating another danger of traditional etching.

The traditional aquatint, which uses either powdered rosin or enamel spray paint, is replaced with an airbrush application of the acrylic polymer hard ground. Again, no solvents are needed beyond the soda ash solution, though a ventilation hood is needed due to acrylic particulates from the air brush spray.

The traditional soft ground, requiring solvents for removal from the plate, is replaced with water-based relief printing ink. The ink receives impressions like traditional soft ground, resists the ferric chloride etchant, yet can be cleaned up with warm water and either soda ash solution or ammonia.

Anodic etching has been used in industrial processes for over a century. The etching power is a source of direct current. The item to be etched (anode) is connected to its positive pole. A receiver plate (cathode) is connected to its negative pole. Both, spaced slightly apart, are immersed in a suitable aqueous solution of a suitable electrolyte. The current pushes the metal out from the anode into solution and deposits it as metal on the cathode. Shortly before 1990, two groups working independently developed different ways of applying it to creating intaglio printing plates.

In the patented Electroetch system, invented by Marion and Omri Behr, in contrast to certain nontoxic etching methods, an etched plate can be reworked as often as the artist desires    The system uses voltages below 2 volts which exposes the uneven metal crystals in the etched areas resulting in superior ink retention and printed image appearance of quality equivalent to traditional acid methods. With polarity reversed the low voltage provides a simpler method of making mezzotint plates as well as the "steel facing" copper plates.

Some of the earliest printmaking workshops experimenting with, developing and promoting nontoxic techniques include Grafisk Eksperimentarium, in Copenhagen, Denmark, Edinburgh Printmakers, in Scotland, and New Grounds Print Workshop, in Albuquerque, New Mexico.

Photo-etching
Light sensitive polymer plates allow for photorealistic etchings. A photo-sensitive coating is applied to the plate by either the plate supplier or the artist. Light is projected onto the plate as a negative image to expose it. Photopolymer plates are either washed in hot water or under other chemicals according to the plate manufacturers' instructions. Areas of the photo-etch image may be stopped-out before etching to exclude them from the final image on the plate, or removed or lightened by scraping and burnishing once the plate has been etched. Once the photo-etching process is complete, the plate can be worked further as a normal intaglio plate, using drypoint, further etching, engraving, etc. The final result is an intaglio plate which is printed like any other.

Types of metal plates
Copper is a traditional metal, and is still preferred, for etching, as it bites evenly, holds texture well, and does not distort the color of the ink when wiped. Zinc is cheaper than copper, so preferable for beginners, but it does not bite as cleanly as copper does, and it alters some colors of ink. Steel is growing in popularity as an etching substrate. Increases in the prices of copper and zinc have steered steel to an acceptable alternative. The line quality of steel is less fine than copper, but finer than zinc. Steel has a natural and rich aquatint.

The type of metal used for the plate impacts the number of prints the plate will produce. The firm pressure of the printing press slowly rubs out the finer details of the image with every pass-through. With relatively soft copper, for example, the etching details will begin to wear very quickly, some copper plates show extreme wear after only ten prints. Steel, on the other hand, is incredibly durable. This wearing out of the image over time is one of the reasons etched prints created early in a numbered series tend to be valued more highly. An artist thus takes the total number of prints he or she wishes to produce into account whenever choosing the metal.

Industrial uses
Etching is also used in the manufacturing of printed circuit boards and semiconductor devices, and in the preparation of metallic specimens for microscopic observation.

Prior to 1100 AD, the New World Hohokam culture independently utilized the technique of acid etching in marine shell designs. The shells were daubed in pitch and then bathed in acid probably made from fermented cactus juice.

Controlling the acid's effects
There are many ways for the printmaker to control the acid's effects.

Hard grounds
Most typically, the surface of the plate is covered in a hard, waxy 'ground' that resists acid. The printmaker then scratches through the ground with a sharp point, exposing lines of metal which the mordant acid attacks.

Aquatint
Aquatint is a variation giving only tone rather than lines when printed. Particulate resin is evenly distributed on all or parts of the plate, then heated to form a screen ground of uniform, but less than perfect, density. After etching, any exposed surface will result in a roughened (i.e., darkened) surface. Areas that are to be light in the final print are protected by varnishing between acid baths. Successive turns of varnishing and placing the plate in acid create areas of tone difficult or impossible to achieve by drawing through a wax ground.

Sugar lift
Designs in a syrupy solution of sugar or Camp Coffee are painted onto the metal surface prior to it being coated in a liquid etching ground or 'stop out' varnish. When the plate is placed in hot water the sugar dissolves, leaving the image. The plate can then be etched.

Spit bite
A mixture of nitric acid and gum arabic (or, very rarely, saliva) which can be dripped, spattered or painted onto a metal surface giving interesting results. A mixture of nitric acid and rosin may also be used.

Printing
Printing the plate is done by covering the surface with printing ink, then rubbing the ink off the surface with tarlatan cloth or newsprint, leaving ink in the roughened areas and lines. Damp paper is placed on the plate, and both are run through a printing press; the pressure forces the paper into contact with the ink, transferring the image (c.f., chine-collé). Unfortunately, the pressure subtly degrades the image in the plate, smoothing the roughened areas and closing the lines; a copper plate is good for, at most, a few hundred printings of a strongly etched imaged before the degradation is considered too great by the artist. At that point, the artist can manually restore the plate by re-etching it, essentially putting ground back on and retracing their lines; alternatively, plates can be electro-plated before printing with a harder metal to preserve the surface. Zinc is also used, because as a softer metal, etching times are shorter; however, that softness also leads to faster degradation of the image in the press.

Faults

Foul-bite or "over-biting" is common in etching, and is the effect of minuscule amounts of acid leaking through the ground to create minor pitting and burning on the surface. This incidental roughening may be removed by smoothing and polishing the surface, but artists often leave faux-bite, or deliberately court it by handling the plate roughly, because it is viewed as a desirable mark of the process.

"Etchings" euphemism
The phrase "Want to come up and see my etchings?" is a romantic euphemism by which a person entices someone to come back to their place with an offer to look at something artistic, but with ulterior motives. The phrase is a corruption of some phrases in a novel by Horatio Alger Jr. called The Erie Train Boy, which was first published in 1891. Alger was an immensely popular author in the 19th century—especially with young people—and his books were widely quoted. In chapter XXII of the book, a woman writes to her boyfriend, "I have a new collection of etchings that I want to show you. Won't you name an evening when you will call, as I want to be certain to be at home when you really do come." The boyfriend then writes back "I shall no doubt find pleasure in examining the etchings which you hold out as an inducement to call."

This was referenced in a 1929 James Thurber cartoon in which a man tells a woman in a building lobby: "You wait here and I'll bring the etchings down". It was also referenced in Dashiell Hammett's 1934 novel The Thin Man, in which the narrator answers his wife asking him about a lady he had wandered off with by saying: "She just wanted to show me some French etchings."

The phrase was given new popularity in 1937: in a well publicized case, violinist David Rubinoff was accused of inviting a young woman to his hotel room to view some French etchings, but instead seducing her.

As early as 1895, Hjalmar Söderberg used the reference in his "decadent" début novel Delusions (swe: Förvillelser), when he lets the dandy Johannes Hall lure the main character's younger sister Greta into his room under the pretence that they browse through his etchings and engravings (e.g., Die Sünde by Franz Stuck).

title: Etching


text:
421

Year 421 (CDXXI) was a common year starting on Saturday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Agricola and Eustathius (or, less frequently, year 1174 Ab urbe condita). The denomination 421 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

Roman Empire

 * February 8 – Constantius III is appointed co-emperor (Augustus) with his ineffectual brother-in-law, Honorius, and becomes the real ruler of the Western Roman Empire.
 * March 25 – Venice is founded at twelve o'clock noon (according to legend) with the dedication of the first church, San Giacomo, at the islet of Rialto (Italy).
 * June 7 – Emperor Theodosius II marries Aelia Eudocia, a woman of Greek origin. The wedding is celebrated at Constantinople with chariot racing in the Hippodrome.
 * September 2 – Constantius III dies suddenly of an illness; his wife Galla Placidia becomes, for the second time, a widow. She departs with her children Grata Honoria and Valentinian to the court of Constantinople.

Europe

 * Rugila, chieftain of the Huns, attacks the dioceses of Dacia and Thrace (Balkans). Theodosius II allows Pannonian Ostrogoths to settle in Thrace, to defend the Danube frontier.
 * The Franks conquer new territories in their kingdom and sack the old Roman capital Augusta Treverorum (modern Trier).

Persia

 * Roman–Sassanid War: Theodosius II starts a war against the Sassanids, sending an expeditionary force under command of Ardaburius, and invades Mesopotamia.
 * Autumn – Ardaburius devastates Arzanene (Armenia) and forces the Persians to retreat to Nisibis (Syria). King Bahram V allies himself with the Lakhmid Arabs of Hirah.

Deaths

 * September 2 – Constantius III, emperor of the Western Roman Empire
 * Jin Gongdi, last emperor of the Jin Dynasty (b. 386)
 * Li Xun, ruler of the Chinese state Western Liang
 * Mary of Egypt, patron saint (approximate date)
 * Ravina I, rabbi (teacher) and Jewish Talmudist

title: 421


text:
Screen printing

Screen printing is a printing technique where a mesh is used to transfer ink (or dye) onto a substrate, except in areas made impermeable to the ink by a blocking stencil. A blade or squeegee is moved across the screen to fill the open mesh apertures with ink, and a reverse stroke then causes the screen to touch the substrate momentarily along a line of contact. This causes the ink to wet the substrate and be pulled out of the mesh apertures as the screen springs back after the blade has passed. One colour is printed at a time, so several screens can be used to produce a multi-coloured image or design.

Traditionally, silk was used in the process. Currently, synthetic threads are commonly used. The most popular mesh in general use is made of polyester. There are special-use mesh materials of nylon and stainless steel available to the screen-printer. There are also different types of mesh size which will determine the outcome and look of the finished design on the material.

The technique is used not only for garment printing but for printing on many other substances, including decals, clock and watch faces, balloons, and many other products. Advanced uses include laying down conductors and resistors in multi-layer circuits using thin ceramic layers as the substrate.

Origins
Screen printing first appeared in a recognizable form in China during the Song dynasty (960–1279 AD). It was then adapted by other Asian countries like Japan, and was further created using newer methods.

Adoption in the West
Screen printing was largely introduced to Western Europe from Asia sometime in the late 18th century, but did not gain large acceptance or use in Europe until silk mesh was more available for trade from the east and a profitable outlet for the medium discovered.

Early in the 1910s, several printers experimenting with photo-reactive chemicals used the well-known actinic light–activated cross linking or hardening traits of potassium, sodium or ammonium chromate and dichromate chemicals with glues and gelatin compounds. Roy Beck, Charles Peter and Edward Owens studied and experimented with chromic acid salt sensitized emulsions for photo-reactive stencils. This trio of developers would prove to revolutionize the commercial screen printing industry by introducing photo-imaged stencils to the industry, though the acceptance of this method would take many years. Commercial screen printing now uses sensitizers far safer and less toxic than bichromates. Currently, there are large selections of pre-sensitized and "user mixed" sensitized emulsion chemicals for creating photo-reactive stencils.

A group of artists who later formed the National Serigraph Society, including WPA artists Max Arthur Cohn, Anthony Velonis and Hyman Warsager, coined the word "serigraphy" in the 1930s to differentiate the artistic application of screen printing from the industrial use of the process. "Serigraphy" is a compound word formed from Latin "sēricum" (silk) and Greek "graphein" (to write or draw).

Historians of the New York WPA poster shop give sole credit to Anthony Velonis for establishing Silkscreen methods used there, a reputation bolstered by the publication of his 1937 booklet Technical Problems of the Artist: Technique of the Silkscreen Process. Guido Lengweiler has corrected this misunderstanding in his book, A History of Screen Printing, published in English in 2016. Outgrowths of these WPA poster shops, at least two New York City studios in wartime started decorating ceramic tiles with fire-on underglaze applied by silkscreen starting as early as 1939: Esteban Soriano and Harold Ambellan's workshop called Designed Tiles.

The Printers' National Environmental Assistance Center says, "Screenprinting is arguably the most versatile of all printing processes. Since rudimentary screenprinting materials are so affordable and readily available, it has been used frequently in underground settings and subcultures, and the non-professional look of such DIY culture screenprints have become a significant cultural aesthetic seen on movie posters, record album covers, flyers, shirts, commercial fonts in advertising, in artwork and elsewhere.

1960s to present
Credit is given to the artist Andy Warhol for popularising screen printing as an artistic technique. Warhol's silk screens include his 1962 Marilyn Diptych, which is a portrait of the actress Marilyn Monroe printed in bold colours. Warhol was supported in his production by master screen printer Michel Caza, a founding member of Fespa.

Sister Mary Corita Kent gained international fame for her vibrant serigraphs during the 1960s and 1970s. Her works were rainbow coloured, contained words that were both political, and fostered peace and love and caring.

American entrepreneur, artist and inventor Michael Vasilantone started to use, develop, and sell a rotatable multicolour garment screen printing machine in 1960. Vasilantone later filed for a patent on his invention in 1967 granted number 3,427,964 on 18 February 1969. The original machine was manufactured to print logos and team information on bowling garments, but was soon directed to the new fad of printing on T-shirts. The Vasilantone patent was licensed by multiple manufacturers and the resulting production and boom in printed T-shirts made this garment screen printing machine popular. Screen printing on garments currently accounts for over half of the screen printing activity in the United States.

Graphic screen-printing is widely used today to create mass- or large-batch produced graphics, such as posters or display stands. Full colour prints can be created by printing in CMYK (cyan, magenta, yellow and black).

Screen printing lends itself well to printing on canvas. Andy Warhol, Arthur Okamura, Robert Rauschenberg, Roy Lichtenstein, Harry Gottlieb and many other artists have used screen printing as an expression of creativity and artistic vision.

Another variation, digital hybrid screen printing, is a union between analog screen printing and traditional digital direct-to-garment printing, two of the most common textile embellishment technologies in use today. Essentially, digital hybrid screen printing is an automatic screen-printing press with a CMYK digital enhancement located on one of the screen print stations. Digital hybrid screen printing is capable of variable data options, creating endless customizations, with the added ability of screen print specific techniques.

Method

A screen is made of a piece of mesh stretched over a frame. The mesh could be made of a synthetic polymer, such as nylon, and a finer and smaller aperture for the mesh would be utilized for a design that requires a higher and more delicate degree of detail. For the mesh to be effective, it must be mounted on a frame and it must be under tension. The frame which holds the mesh could be made of diverse materials, such as wood or aluminum, depending on the sophistication of the machine or the artisan procedure. The tension of the mesh may be checked by using a tensiometer; a common unit for the measurement of the tension of the mesh is Newton per centimeter (N/cm).

A stencil is formed by blocking off parts of the screen in the negative image of the design to be printed; that is, the open spaces are where the ink will appear on the substrate.

Before printing occurs, the frame and screen must undergo the pre-press process, in which an emulsion is 'scooped' across the mesh. Once this emulsion has dried, it is selectively exposed to ultra-violet light, through a film printed with the required design. This hardens the emulsion in the exposed areas but leaves the unexposed parts soft. They are then washed away using a water spray, leaving behind a clean area in the mesh with the identical shape as the desired image, which will allow passage of ink. It is a positive process.

In fabric printing, the surface supporting the fabric to be printed (commonly referred to as a pallet) is coated with a wide 'pallet tape'. This serves to protect the 'pallet' from any unwanted ink leaking through the screen and potentially staining the 'pallet' or transferring unwanted ink onto the next substrate.

Next, the screen and frame are lined with a tape to prevent ink from reaching the edge of the screen and the frame. The type of tape used in for this purpose often depends upon the ink that is to be printed onto the substrate. More aggressive tapes are generally used for UV and water-based inks due to the inks' lower viscosities and greater tendency to creep underneath tape.

The last process in the 'pre-press' is blocking out any unwanted 'pin-holes' in the emulsion. If these holes are left in the emulsion, the ink will continue through and leave unwanted marks. To block out these holes, materials such as tapes, speciality emulsions and 'block-out pens' may be used effectively.

The screen is placed atop a substrate. Ink is placed on top of the screen, and a floodbar is used to push the ink through the holes in the mesh. The operator begins with the fill bar at the rear of the screen and behind a reservoir of ink. The operator lifts the screen to prevent contact with the substrate and then using a slight amount of downward force pulls the fill bar to the front of the screen. This effectively fills the mesh openings with ink and moves the ink reservoir to the front of the screen. The operator then uses a squeegee (rubber blade) to move the mesh down to the substrate and pushes the squeegee to the rear of the screen. The ink that is in the mesh opening is pumped or squeezed by capillary action to the substrate in a controlled and prescribed amount, i.e. the wet ink deposit is proportional to the thickness of the mesh and or stencil. As the squeegee moves toward the rear of the screen the tension of the mesh pulls the mesh up away from the substrate (called snap-off) leaving the ink upon the substrate surface.

There are three common types of screen printing presses: flat-bed, cylinder, and rotary. A development of screen printing with flat screens from 1963 was to wrap the screen around to form a tube, with the ink supply and squeegee inside the tube. The resulting roller rotates at the same speed as the web in a roll-to-roll machine. The benefits are high output rates and long rolls of product. This is the only way to make high-build fully patterned printing/coating as a continuous process, and has been widely used for manufacturing textured wallpapers.

Textile items printed with multi-coloured designs often use a wet on wet technique, or colours dried while on the press, while graphic items are allowed to dry between colours that are then printed with another screen and often in a different colour after the product is re-aligned on the press.

Most screens are ready for re-coating at this stage, but sometimes screens will have to undergo a further step in the reclaiming process called de-hazing. This additional step removes haze or "ghost images" left behind in the screen once the emulsion has been removed. Ghost images tend to faintly outline the open areas of previous stencils, hence the name. They are the result of ink residue trapped in the mesh, often in the knuckles of the mesh (the points where threads cross). A properly cleaned screen will not have any residual traces of the previous image apparent on its surface.

Stencils

A method of stenciling that has increased in popularity over the past years is the photo emulsion technique:

 * 1) The original image is created on a transparent overlay, and the image may be drawn or painted directly on the overlay, photocopied, or printed with a computer printer, but making so that the areas to be inked are not transparent. Any material that blocks ultra violet light can be used as the film, even card stock. A black-and-white positive may also be used (projected onto the screen).  However, unlike traditional plate-making, these screens are normally exposed by using film positives.
 * 2) A screen must then be selected. There are several different mesh counts that can be used depending on the detail of the design being printed. Once a screen is selected, the screen must be coated with a photosensitive emulsion and dried.  Once dry, it is then possible to burn/expose the print.
 * 3) The overlay is placed over the screen, and then exposed with a light source containing ultraviolet light in the 350–420 nanometer spectrum.
 * 4) The screen is washed off thoroughly. The areas of emulsion that were not exposed to light dissolve and wash away, leaving a negative stencil of the image on the mesh.

Garment printing inks

 * Caviar beads: A caviar bead is a glue that is printed in the shape of the design, to which small plastic beads are then applied – works well with solid block areas creating an interesting tactile surface.
 * Cracking ink: Ink may be so applied as to produce a cracked surface after drying. Similar cracking may occur unintentionally if the ink does not cure fully.
 * Discharge inks: Discharge inks use zinc formaldehyde sulfoxylate (the zinc analogue of Rongalite) to remove, or discharge, the dye back off the fabric. Cons of using discharge inks are that the process only works properly on dark fabrics that have a content of 100% cotton. Fabrics with under-dyes and fabric blends will discharge their dye to different degrees. The fumes resulting from the application and curing are pungent and strong ventilation and a face mask are commonly needed to relieve exposure. Pros to this process is that discharge is especially effective for distressed prints and under-basing on dark garments that are to be printed with additional layers of plastisol. It adds variety to the design and gives it that natural soft feel.
 * Expanding ink (puff): Expanding ink, or puff, is an additive to plastisol inks which raises the print off the garment, creating a 3D feel and look to the design. Mostly used when printing on apparel.
 * Flocking: Flocking consists of a glue printed onto the fabric and then flock material is applied for a velvet touch.
 * Foil: Foil is much like flock, starting with an adhesive glue or plastisol ink base layer. Foil is finished by applying a thin sheet of reflective/mirror like material on top of the screened base, then heat pressed to set. The foil substrate does not adhere to non-screened areas of the design, and the balance of the foil sheet is discarded.
 * Four-colour process or the CMYK colour model: Four-colour process is when the artwork is created and then separated into four colours (CMYK) which combine to create the full spectrum of colours needed for photographic prints. This means a large number of colours can be simulated using only 4 screens, reducing costs, time, and set-up. This processes utilises halftones. The inks are required to blend and are more translucent, meaning a compromise with vibrancy of colour.
 * Glitter/shimmer: Glitter or shimmer ink is when metallic flakes become an additive in the ink base to create this sparkle effect. Usually available in gold or silver but can be mixed to make most colours.
 * Gloss: Gloss ink is when a clear base laid over previously printed inks to create a shiny finish.
 * Metallic: Metallic ink is similar to glitter, but smaller particles suspended in the ink. A glue is printed onto the fabric, then nano-scale fibers applied on it. This is often purchased already made.
 * Mirrored Ink: Mirrored silver and gold are highly reflective, solvent-based inks. Mirrored inks can be prone to tarnishing over time.
 * Nylobond: Nylobond is a special ink additive for printing onto technical or waterproof fabrics.
 * Plastisol: Plastisol is the most common ink used in commercial garment decoration. Good colour opacity onto dark garments and clear graphic detail with, as the name suggests, a more plasticized texture. This print can be made softer with special additives or heavier by adding extra layers of ink. Plastisol inks require heat (approx. 150 °C (300 °F) for many inks) to cure the print, except in the case of low cure inks.
 * PVC and phthalate free: PVC and phthalate free is relatively new breed of ink and printing with the benefits of plastisol but without the two main toxic components. It also has a soft texture and is being produced by most major suppliers.
 * Suede ink: Suede ink is a milky coloured additive that is added to plastisol. With suede additive you can make any colour of plastisol have a suede feel. It is actually a puff blowing agent that does not bubble as much as regular puff ink. The directions vary from manufacturer to manufacturer, but generally up to 50% suede can be added to normal plastisol.
 * Water-based inks: These penetrate the fabric more than the plastisol inks and create a much softer feel. Ideal for printing darker inks onto lighter coloured garments. Also useful for larger area prints where texture is important. Some inks require heat or an added catalyst to make the print permanent.
 * Water-based dye (ink): As opposed to a thicker plastisol ink, this dye arrives as a concentrate which is mixed into a printing paste (thickener) to allow screen printing, this process is best used on light garments and as the dye is in the fibers themselves is often used for dish cloths, napkins and the like. This is similar to traditional textile printing.
 * High density: High density is a process which uses a type of varnish against a lower mesh count with many coats of emulsion or a thicker grade of emulsion (e.g., Capillex). After the varnish passes through to the substrate, an embossed-appearing, 'raised' area of varnish is created. When cured at the end of the process, the varnish yields a Braille effect, hence the term 'high density'.

Non-garment uses

Screen printing is more versatile than traditional printing techniques. The surface does not have to be printed under pressure, unlike etching or lithography, and it does not have to be planar. Different inks can be used to work with a variety of materials, such as textiles, ceramics, wood, paper, glass, metal, and plastic. As a result, screen printing is used in many different industries, including:
 * Balloons
 * Clothing
 * Decals
 * Medical devices
 * Printed electronics, including circuit board printing
 * Product labels
 * Snowboard graphics
 * Textile fabric
 * Thick film technology
 * Pinball machines
 * Drinkware

In screen printing on wafer-based solar photovoltaic (PV) cells, the mesh and buses of silver are printed on the front; furthermore, the buses of silver are printed on the back. Subsequently, aluminum paste is dispensed over the whole surface of the back for passivation and surface reflection. One of the parameters that can vary and can be controlled in screen printing is the thickness of the print. This makes it useful for some of the techniques of printing solar cells, electronics etc.

Solar wafers are becoming thinner and larger, so careful printing is required to maintain a lower breakage rate, though high throughput at the printing stage improves the throughput of the whole cell production line.

Automation
To print multiple copies of the screen design on garments in an efficient manner, amateur and professional printers usually use a screen printing press, which is a colloquial term as most screen printing machines are vastly different from offset printing presses. Many companies offer simple to sophisticated printing presses. These presses come in one of three types, manual (also referred to as handbench), semi-automatic, and fully automatic. Most printing companies will use one or more semi-automatic or fully automatic machines with manual machines for small runs and sampling.

Whilst manual screen printing can be done with carousels, handbenches (both of which are often referred to colloquially as presses) or even on to tables. Semi- and fully-automatic machines are broken into two main categories; flatbed printers (poster, art printing or other flat substrates) and carousels and oval machines (garments and other apparel, amongst other textiles). Both which are fundamentally similar in terms of automation but differ in areas such as physical footprint and upgrade paths.

These machines are much faster and use either pneumatic pressure generated by air compressors or use electric motors to draw the squeegees, rotate and raise or lower pallets removing much of the manual labour from the task and use UV for instant image curing - resulting in significant reductions in operator fatigue as well as more consistent results.

Printed circuit boards (PCB)
In electronic design automation, the silk screen is part of the layer stack of the printed circuit board (PCB), and the top and bottom sides are described in individual Gerber files like any other layers (such as the copper and solder-stop layers). Typical names for these service print overlays include /  aka  /  or  /  (EAGLE),  /  (KiCad),  /  (TARGET),  /  (Fritzing),  /  (OrCAD),  /  (PADS),  /  (WEdirekt) or  /  (Gerber and many others ).

title: Screen printing


text:
Ben K. Green

Ben K. Green (1912–1974) was an author who wrote about horses and the post-World War I American West. His books consist of anecdotes drawn from his own experiences in the Southwestern United States.

He was born in Cumby, Texas and raised in Weatherford, Texas. Before he was twenty years old he had successfully earned a living trading horses and mules and raising cattle and sheep. The common trading practice – "cheat or be cheated" – is reflected in his stories, told using the language and humor of the area and not excluding himself from either outcome.

He was persuaded to settle in Fort Stockton, Texas and practiced in the entire Trans-Pecos Region. A large part of his work involved identifying plants which grew in that alkali soil and contained substances poisonous to horses, cattle, sheep, and hogs (lechuguilla, yellow-weed, pinguey, locoweed).

List of books

 * Horse Tradin', New York: Alfred A. Knopf, 1967
 * Some More Horse Tradin', Amazon, 2000
 * The Village Horse Doctor West of the Pecos, New York: Alfred A. Knopf, 1971
 * Wild Cow Tales
 * A Thousand Miles of Mustangin', Northland Press
 * Horse Tales
 * The Color of Horses: A Scientific and Authoritative Identification of the Color of the Horse, Northland Press, 1974
 * The Shield Mares, Encino Press, 1967
 * " Horse Conformation as to soundness and performance ", Northland Press, 1969, revised 1988, ISBN 0-87358--135-0

title: Ben K. Green


text:
922

Year 922 (CMXXII) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar.

Byzantine Empire

 * Summer – Battle of Constantinople: Emperor Romanos I sends Byzantine troops to repel another Bulgarian raid at the outskirts of Constantinople. The Byzantines storm the Bulgarian camp, but are defeated when they are confronted by the main Bulgarian forces. Having won the battle, the Bulgarians lack the maritime power to conduct a successful siege of Constantinople.

Europe

 * Summer – The West Frankish nobles revolt and depose King Charles III (the Simple) after a 24-year reign. He seeks refuge in Lotharingia and is replaced by Robert I, a brother of the late King Odo, who is crowned king of the West Frankish Kingdom in the cathedral at Rheims.
 * Adalbert I, margrave of Ivrea, leads a rebellion with the support of the Italian nobles against King Berengar I. He crosses the Alps into Burgundy and invites Rudolph II of Upper Burgundy to invade Italy. Berengar flees again to Verona and Rudolph is crowned King of Italy at Pavia.

Religion

 * March 26 – Mansur al-Hallaj, a Persian mystic writer, is sentenced to death for heresy after a long trial at Baghdad. Having supported reform in the Abbasid Caliphate, he has been seen as a rabble-rouser, and is flogged, mutilated and executed (by beheading).

Births

 * Hedwig of Nordgau, countess of Luxemburg (approximate date)
 * Ibn Abi Zayd, Muslim imam and scholar (d. 996)
 * Ki no Tokibumi, Japanese nobleman and waka poet (d. 996)
 * Sigfried, founder of Luxemburg (approximate date)
 * Wang Pu, Chinese chancellor and writer (d. 982)

Deaths

 * February 20 – Theodora, Byzantine empress
 * March 26 – Mansur al-Hallaj, Persian mystic writer
 * May 23 – Li Sizhao, Chinese general and governor
 * Æthelweard, son of Alfred the Great of England (or 920)
 * Al-Nayrizi, Persian mathematician and astronomer (b. 865)
 * Fortún Garcés ("the Monk"), king of Pamplona
 * Galindo II Aznárez, count of Aragon (Spain)
 * Li Cunjin, general of the Tang dynasty (b. 857)
 * Li Cunzhang, general of the Tang dynasty
 * Lucídio Vimaranes, count of Portugal
 * Ma Chuo, general and official of Wuyue (or 923)
 * Wang Chuzhi, Chinese warlord (b. 862)
 * Zhang Chengye, Chinese eunuch official (b. 846)
 * Zhang Chujin, Chinese governor (jiedushi)

title: 922


text:
Printmaking

Printmaking is the process of creating artworks by printing, normally on paper, but also on fabric, wood, metal, and other surfaces. "Traditional printmaking" normally covers only the process of creating prints using a hand processed technique, rather than a photographic reproduction of a visual artwork which would be printed using an electronic machine (a printer); however, there is some cross-over between traditional and digital printmaking, including risograph.

Prints are created by transferring ink from a matrix to a sheet of paper or other material, by a variety of techniques. Common types of matrices include: metal plates for engraving, etching and related intaglio printing techniques; stone, aluminum, or polymer for lithography; blocks of wood for woodcuts and wood engravings; and linoleum for linocuts. Screens made of silk or synthetic fabrics are used for the screen printing process. Other types of matrix substrates and related processes are discussed below.

Except in the case of monotyping, all printmaking processes have the capacity to produce identical multiples of the same artwork, which is called a print. Each print produced is considered an "original" work of art, and is correctly referred to as an "impression", not a "copy" (that means a different print copying the first, common in early printmaking). However, impressions can vary considerably, whether intentionally or not. Master printmakers are technicians who are capable of printing identical "impressions" by hand. A print that copies another work of art, especially a painting, is known as a "reproductive print".

Multiple impressions printed from the same matrix form an edition. Since the late 19th century, artists have generally signed individual impressions from an edition and often number the impressions to form a limited edition; the matrix is then destroyed so that no more prints can be produced. Prints may also be printed in book form, such as illustrated books or artist's books.

Overview
Printmaking techniques are generally divided into the following basic categories:
 * Relief, where ink is applied to the original surface of the matrix, while carved or displaced grooves are absent of ink. Relief techniques include woodcut or woodblock, wood engraving, linocut and metalcut.
 * Intaglio, where ink is forced into grooves or cavities in the surface of the matrix. Intaglio techniques include collagraphy, engraving, etching, mezzotint, aquatint.
 * Planographic, where the matrix retains its original surface, but is specially prepared and/or inked to allow for the transfer of the image. Planographic techniques include lithography, monotyping, and digital techniques.
 * Stencil, where ink or paint is pressed through a prepared screen or material with cutout elements, including screen printing, risograph, and pochoir.

A type of printmaking outside of this group is viscosity printing. Contemporary printmaking may include digital printing, photographic mediums, or a combination of digital, photographic, and traditional processes.

Many of these techniques can also be combined, especially within the same family. For example, Rembrandt's prints are usually referred to as "etchings" for convenience, but very often include work in engraving and drypoint as well, and sometimes have no etching at all.

Woodcut
Artists using this technique include Albrecht Dürer, Hans Burgkmair, Ugo da Carpi, Hiroshige, Hokusai, Frans Masereel, Gustave Baumann, Ernst Ludwig Kirchner, Eric Slater Antonio Frasconi

Woodcut, a type of relief print, is the earliest printmaking technique. It was probably first developed as a means of printing patterns on cloth, and by the 5th century was used in China for printing text and images on paper. Woodcuts of images on paper developed around 1400 in Japan, and slightly later in Europe. These are the two areas where woodcut has been most extensively used purely as a process for making images without text. The artist either draws a design directly on a plank of wood, or transfers a drawing done on paper to a plank of wood. Traditionally, the artist then handed the work to a technician, who then uses sharp carving tools to carve away the parts of the block that will not receive ink. In the Western tradition, the surface of the block is then inked with the use of a brayer; however in the Japanese tradition, woodblocks were inked with a brush. Then a sheet of paper, perhaps slightly damp, is placed over the block. The block is then rubbed with a baren or spoon, or is run through a printing press. If the print is in color, separate blocks can be used for each color, or a technique called reduction printing can be used.

Reduction printing is a name used to describe the process of using one block to print several layers of color on one print. Both woodcuts and linocuts can employ reduction printing. This usually involves cutting a small amount of the block away, and then printing the block many times over on different sheets before washing the block, cutting more away and printing the next color on top. This allows the previous color to show through. This process can be repeated many times over. The advantages of this process is that only one block is needed, and that different components of an intricate design will line up perfectly. The disadvantage is that once the artist moves on to the next layer, no more prints can be made.

Another variation of woodcut printmaking is the cukil technique, made famous by the Taring Padi underground community in Java, Indonesia. Taring Padi Posters usually resemble intricately printed cartoon posters embedded with political messages. Images—usually resembling a visually complex scenario—are carved unto a wooden surface called cukilan, then smothered with printer's ink before pressing it unto media such as paper or canvas.

Engraving
The process was developed in Germany in the 1430s from the engraving used by goldsmiths to decorate metalwork. Engravers use a hardened steel tool called a burin to cut the design into the surface of a metal plate, traditionally made of copper. Engraving using a burin is generally a difficult skill to learn.

Gravers come in a variety of shapes and sizes that yield different line types. The burin produces a unique and recognizable quality of line that is characterized by its steady, deliberate appearance and clean edges. Other tools such as mezzotint rockers, roulettes (a tool with a fine-toothed wheel) and burnishers (a tool used for making an object smooth or shiny by rubbing) are used for texturing effects.

To make a print, the engraved plate is inked all over, then the ink is wiped off the surface, leaving ink only in the engraved lines. The plate is then put through a high-pressure printing press together with a sheet of paper (often moistened to soften it). The paper picks up the ink from the engraved lines, making a print. The process can be repeated many times; typically several hundred impressions (copies) could be printed before the printing plate shows much sign of wear, except when drypoint, which gives much shallower lines, is used.

In the 20th century, true engraving was revived as a serious art form by artists including Stanley William Hayter whose Atelier 17 in Paris and New York City became the magnet for such artists as Pablo Picasso, Alberto Giacometti, Mauricio Lasansky and Joan Miró.

Etching
Artists using this technique include Albrecht Dürer, Rembrandt, Francisco Goya, Wenceslaus Hollar, Whistler, Otto Dix, James Ensor, Edward Hopper, Käthe Kollwitz, Pablo Picasso, Cy Twombly, Lucas van Leyden Etching is part of the intaglio family. In pure etching, a metal plate (usually copper, zinc, or steel) is covered with a waxy or acrylic ground. The artist then draws through the ground with a pointed etching needle, exposing the metal. The plate is then etched by dipping it in a bath of etchant (e.g. nitric acid or ferric chloride). The etchant "bites" into the exposed metal, leaving behind lines in the plate. The remaining ground is then cleaned off the plate, and the printing process is then just the same as for engraving.

Although the first dated etching is by Albrecht Dürer in 1515, the process is believed to have been invented by Daniel Hopfer (c. 1470–1536) of Augsburg, Germany, who decorated armor in this way, and applied the method to printmaking. Etching soon came to challenge engraving as the most popular printmaking medium. Its great advantage was that, unlike engraving which requires special skill in metalworking, etching is relatively easy to learn for an artist trained in drawing.

Etching prints are generally linear and often contain fine detail and contours. Lines can vary from smooth to sketchy. An etching is opposite of a woodcut in that the raised portions of an etching remain blank while the crevices hold ink.

A non-toxic form of etching that does not involve an acid is Electroetching.

Mezzotint
Artists using this technique include John Martin, Ludwig von Siegen, John Smith, Wallerant Vaillant, Carol Wax

An intaglio variant of engraving in which the image is formed from subtle gradations of light and shade. Mezzotint—from the Italian mezzo ("half") and tinta ("tone")—is a "dark manner" form of printmaking, which requires artists to work from dark to light. To create a mezzotint, the surface of a copper printing plate is roughened evenly all over with the aid of a tool known as a rocker; the image is then formed by smoothing the surface with a tool known as a burnisher. When inked, the roughened areas of the plate will hold more ink and print more darkly, while smoother areas of the plate hold less or no ink, and will print more lightly or not at all. It is, however, possible to create the image by only roughening the plate selectively, so working from light to dark.

Mezzotint is known for the luxurious quality of its tones: first, because an evenly, finely roughened surface holds a lot of ink, allowing deep solid colors to be printed; secondly because the process of smoothing the texture with burin, burnisher and scraper allows fine gradations in tone to be developed.

The mezzotint printmaking method was invented by Ludwig von Siegen (1609–1680). The process was used widely in England from the mid-eighteenth century, to reproduce oil paintings and in particular portraits.

Aquatint
Artists using this technique include Norman Ackroyd, Jean-Baptiste Le Prince, William Daniell, Francisco Goya, Thomas Rowlandson

A technique used in Intaglio etchings. Like etching, aquatint technique involves the application of acid to make marks in a metal plate. Where the etching technique uses a needle to make lines that retain ink, traditional aquatint relies on powdered rosin which is acid resistant in the ground to create a tonal effect. The rosin is applied in a light dusting by a fan booth, the rosin is then cooked until set on the plate. At this time the rosin can be burnished or scratched out to affect its tonal qualities. The tonal variation is controlled by the level of acid exposure over large areas, and thus the image is shaped by large sections at a time.

Contemporary printmakers also sometimes using airbrushed asphaltum or spray paint, as well as other non toxic techniques, to achieve aquatint due to rosin boxes posing a fire hazard.

Goya used aquatint for most of his prints.

Drypoint
Artists using this technique include Mary Cassatt, Francis Seymour Haden, Master of the Housebook, Richard Spare, William Lionel Wyllie

A variant of engraving, done with a sharp point, rather than a v-shaped burin. While engraved lines are very smooth and hard-edged, drypoint scratching leaves a rough burr at the edges of each line. This burr gives drypoint prints a characteristically soft, and sometimes blurry, line quality. Because the pressure of printing quickly destroys the burr, drypoint is useful only for very small editions; as few as ten or twenty impressions. To counter this, and allow for longer print runs, electro-plating (here called steelfacing) has been used since the nineteenth century to harden the surface of a plate.

The technique appears to have been invented by the Housebook Master, a south German fifteenth-century artist, all of whose prints are in drypoint only. Among the most famous artists of the old master print, Albrecht Dürer produced three drypoints before abandoning the technique; Rembrandt used it frequently, but usually in conjunction with etching and engraving.

Lithography
Artists using this technique include Honoré Daumier, Vincent van Gogh, George Bellows, Pierre Bonnard, Edvard Munch, Emil Nolde, Pablo Picasso, Odilon Redon, Henri de Toulouse-Lautrec, Salvador Dalí, M. C. Escher, Willem de Kooning, Joan Miró, Stow Wengenroth, Elaine de Kooning, Louise Nevelson

Lithography is a technique invented in 1798 by Alois Senefelder and based on the chemical repulsion of oil and water. A porous surface, normally limestone, is used; the image is drawn on the limestone with a greasy medium. Acid is applied, transferring the grease-protected design to the limestone, leaving the image 'burned' into the surface. Gum arabic, a water-soluble substance, is then applied, sealing the surface of the stone not covered with the drawing medium. The stone is wetted, with water staying only on the surface not covered in grease-based residue of the drawing; the stone is then 'rolled up', meaning oil ink is applied with a roller covering the entire surface; since water repels the oil in the ink, the ink adheres only to the greasy parts, perfectly inking the image. A sheet of dry paper is placed on the surface, and the image is transferred to the paper by the pressure of the printing press. Lithography is known for its ability to capture fine gradations in shading and very small detail.

Variations of Lithography
Photo-lithography captures an image by photographic processes on metal plates; printing is more or less carried out in the same way as stone lithography.

Halftone lithography produces an image that illustrates a gradient-like quality.

Mokulito is a form of lithography on wood instead of limestone. It was invented by Seishi Ozaku in the 1970s in Japan and was originally called Mokurito.

Screenprinting
Artists using this technique include Josef Albers, Ralston Crawford, Gene Davis. Robert Indiana, Roy Lichtenstein, Julian Opie, Bridget Riley, Edward Ruscha, Andy Warhol.

Screen printing (occasionally known as "silkscreen", or "serigraphy") creates prints by using a fabric stencil technique; ink is simply pushed through the stencil against the surface of the paper, most often with the aid of a squeegee. Generally, the technique uses a natural or synthetic 'mesh' fabric stretched tightly across a rectangular 'frame,' much like a stretched canvas. The fabric can be silk, nylon monofilament, multifilament polyester, or even stainless steel. While commercial screen printing often requires high-tech, mechanical apparatuses and calibrated materials, printmakers value it for the "Do It Yourself" approach, and the low technical requirements, high quality results. The essential tools required are a squeegee, a mesh fabric, a frame, and a stencil. Unlike many other printmaking processes, a printing press is not required, as screen printing is essentially stencil printing.

Screen printing may be adapted to printing on a variety of materials, from paper, cloth, and canvas to rubber, glass, and metal. Artists have used the technique to print on bottles, on slabs of granite, directly onto walls, and to reproduce images on textiles which would distort under pressure from printing presses.

Monotype
Monotyping is a type of printmaking made by drawing or painting on a smooth, non-absorbent surface. The surface, or matrix, was historically a copper etching plate, but in contemporary work it can vary from zinc or glass to acrylic glass. The image is then transferred onto a sheet of paper by pressing the two together, usually using a printing-press. Monotypes can also be created by inking an entire surface and then, using brushes or rags, removing ink to create a subtractive image, e.g. creating lights from a field of opaque color. The inks used may be oil based or water based. With oil based inks, the paper may be dry, in which case the image has more contrast, or the paper may be damp, in which case the image has a 10 percent greater range of tones.

Unlike monoprinting, monotyping produces a unique print, or monotype, because most of the ink is removed during the initial pressing. Although subsequent reprintings are sometimes possible, they differ greatly from the first print and are generally considered inferior. A second print from the original plate is called a "ghost print" or "cognate". Stencils, watercolor, solvents, brushes, and other tools are often used to embellish a monotype print. Monotypes are often spontaneously executed and with no preliminary sketch.

Monotypes are the most painterly method among the printmaking techniques, a unique print that is essentially a printed painting. The principal characteristic of this medium is found in its spontaneity and its combination of printmaking, painting, and drawing media.

Monoprint
Monoprinting is a form of printmaking that uses a matrix such as a woodblock, litho stone, or copper plate, but produces impressions that are unique. Multiple unique impressions printed from a single matrix are sometimes known as a variable edition. There are many techniques used in monoprinting, including collagraph, collage, hand-painted additions, and a form of tracing by which thick ink is laid down on a table, paper is placed on the ink, and the back of the paper is drawn on, transferring the ink to the paper. Monoprints can also be made by altering the type, color, and viscosity of the ink used to create different prints. Traditional printmaking techniques, such as lithography, woodcut, and intaglio, can be used to make monoprints.

Mixed-media prints
Mixed-media prints may use multiple traditional printmaking processes such as etching, woodcut, letterpress, silkscreen, or even monoprinting in the creation of the print. They may also incorporate elements of chine colle, collage, or painted areas, and may be unique, i.e. one-off, non-editioned, prints. Mixed-media prints are often experimental prints and may be printed on unusual, non-traditional surfaces.

Digital prints
Artists using this technique include Istvan Horkay, Ralph Goings, Enrique Chagoya

Digital prints refers to images printed using digital printers such as inkjet printers instead of a traditional printing press. Images can be printed to a variety of substrates including paper, cloth, or plastic canvas.

Dye-based inks
Dye-based inks are organic (not mineral) dissolved and mixed into a liquid. Although most are synthetic, derived from petroleum, they can be made from vegetable or animal sources. Dyes are well suited for textiles where the liquid dye penetrates and chemically bonds to the fiber. Because of the deep penetration, more layers of material must lose their color before the fading is apparent. Dyes, however, are not suitable for the relatively thin layers of ink laid out on the surface of a print.

Pigment-based inks
Pigment is a finely ground, particulate substance which, when mixed or ground into a liquid to make ink or paint, does not dissolve, but remains dispersed or suspended in the liquid. Pigments are categorized as either inorganic (mineral) or organic (synthetic). Pigment-based inks have a much longer permanence than dye-based inks.

Giclée
Giclée (pron.: /ʒiːˈkleɪ/ zhee-KLAY or /dʒiːˈkleɪ/), is a neologism coined in 1991 by printmaker Jack Duganne for digital prints made on inkjet printers. Originally associated with early dye-based printers it is now more often refers to pigment-based prints. The word is based on the French word gicleur, which means "nozzle". Today fine art prints produced on large format ink-jet machines using the CcMmYK color model are generally called "Giclée".

Foil imaging
In art, foil imaging is a printmaking technique made using the Iowa Foil Printer, developed by Virginia A. Myers from the commercial foil stamping process. This uses gold leaf and acrylic foil in the printmaking process.

Direct-to-garment printing (DTG printing)
Direct-to-garment printing (DTG) is a process of printing on textiles using specialized aqueous ink jet technology. DTG printers typically have a platen designed to hold the garment in a fixed position, and the printer inks are jetted or sprayed onto the textile by the print head.

Color
Printmakers apply color to their prints in many different ways. Some coloring techniques include positive surface roll, negative surface roll, and A la poupée. Often color in printmaking that involves etching, screen printing, woodcut, or linocut is applied by either using separate plates, blocks or screens or by using a reductionist approach. In multiple plate color techniques, a number of plates, screens or blocks are produced, each providing a different color. Each separate plate, screen, or block will be inked up in a different color and applied in a particular sequence to produce the entire picture. On average about three to four plates are produced, but there are occasions where a printmaker may use up to seven plates. Every application of another plate of color will interact with the color already applied to the paper, and this must be kept in mind when producing the separation of colors. The lightest colors are often applied first, and then darker colors successively until the darkest.

The reductionist approach to producing color is to start with a lino or wood block that is either blank or with a simple etching. Upon each printing of color the printmaker will then further cut into the lino or woodblock removing more material and then apply another color and reprint. Each successive removal of lino or wood from the block will expose the already printed color to the viewer of the print. Picasso is often cited as the inventor of reduction printmaking, although there is evidence of this method in use 25 years before Picasso's linocuts.

The subtractive color concept is also used in offset or digital print and is present in bitmap or vectorial software in CMYK or other color spaces.

Registration
In printmaking processes requiring more than one application of ink or other medium, the problem exists as to how to line up properly areas of an image to receive ink in each application. The most obvious example of this would be a multi-color image in which each color is applied in a separate step.

The lining up of the results of each step in a multistep printmaking process is called "registration." Proper registration results in the various components of an image being in their proper place. But, for artistic reasons, improper registration is not necessarily the ruination of an image. Andy Warhol was known to intentionally employ improper registration.

This can vary significantly from process to process. This involves the matrices of different colors (generally three or four) being printed successively on the paper in a correct alignment to provide the print in color.

Protective printmaking equipment
Protective clothing is very important for printmakers who engage in etching and lithography (closed toed shoes and long pants). Whereas in the past printmakers put their plates in and out of acid baths with their bare hands, today printmakers use rubber gloves. They also wear industrial respirators for protection from caustic vapors. Most acid baths are built with ventilation hoods above them.

Protective respirators and masks should have particle filters, particularly for aquatinting. As a part of the aquatinting process, a printmaker is often exposed to rosin powder. Rosin is a serious health hazard, especially to printmakers who, in the past, simply used to hold their breath using an aquatinting booth.

Print preservation
Modern prints onto paper protected from the sun and moisture will last an incredibly long time. Prints made using newer alkaline and acid-free paper have a life expectancy of over 1,000 years for the best paper and 500 years for average grades. When it comes to older prints, the condition of a print largely depends on the technique used to make the paper. Prints that are several hundred years old may be in better condition than prints that are less than 50 years old. Many older prints will yellow or brown over time owing to acids in the paper and any matting or backing papers. To preserve/restore older prints, washing, deacidification and treatment with stain reducing agents may be in order. Further, if the print is framed, archival or conservation grade picture mats are essential since acids within older or inexpensive matting will attack a print even if the print was produced using acid-free paper. Color prints can be susceptible to fading depending on the type of inks used. Lighting of sensitive prints should be limited to 50 lux (5 foot-candles) or less and artificial lights can be equipped with UV-filtering sleeves or tubes.

Prints onto animal skins (vellum) should also be maintained at a humidity level between 25% and 40%. Prints onto silk are particularly sensitive to any light including camera flashes.

Printmakers by nationality

 * Engravers by nationality
 * Etchers by nationality
 * Printmakers by nationality

title: Printmaking


text:
Curl (programming language)

Curl is a reflective object-oriented programming language for interactive web applications, whose goal is to provide a smoother transition between content formatting and computer programming. It makes it possible to embed complex objects in simple documents without needing to switch between programming languages or development platforms. The Curl implementation initially consisted of an interpreter only; a compiler was added later.

Curl combines text markup (as in HyperText Markup Language (HTML)), scripting (as in JavaScript), and heavy-duty computing (as in Java, C#, or C++) within one unified framework. It is used in a range of internal enterprise, business-to-business (B2B), and business-to-consumer (B2C) applications.

Curl programs may be compiled into Curl applets, that are viewed using the Curl RTE, a runtime environment with a plugin for web browsers. Currently, it is supported on Microsoft Windows. Linux, and macOS was dropped on March 25, 2019 (starting with version 8.0.10). Curl supports "detached applets", which is a web deployed applet which runs on the user's desktop independent of a browser window much as in Microsoft Silverlight 3 and Adobe AIR.

Architecture
The Curl language attempts to address a long-standing problem: the different building blocks that make up any modern web document most often require wildly different methods of implementation: different languages, different tools, different frameworks, often completely different teams. The final, and often most difficult, hurdle has been getting all of these blocks to communicate with each other in a consistent manner. Curl attempts to side-step these problems by providing a consistent syntactic and semantic interface at all levels of web content creation: from simple HTML to complex object-oriented programming.

Curl is a markup language like HTML—that is, plain text is shown as text; at the same time, Curl includes an object-oriented programming language that supports multiple inheritance. Curl applications are not required to observe the separation of information, style, and behavior that HTML, Cascading Style Sheets (CSS), and JavaScript have imposed, although that style of programming can be used in Curl if desired.

While the Curl language can be used as an HTML replacement for presenting formatted text, its abilities range all the way to those of a compiled, strongly typed, object-oriented system programming language. Both the authoring (HTML-level) and programming constructs of Curl can be extended in user code. The language is designed so Curl applications can be compiled to native code of the client machine by a just-in-time compiler and run at high speed. Curl applets can also be written so that they can run off-line when disconnected from a network (occasionally connected computing). The Curl IDE is an application written in Curl.

Syntax
A simple Curl applet for a "Hello, World!" program might be:

This code will run if the user has at least one of the Curl versions 7.0 or 8.0 installed.

Curl provides both macros and text-procedures in addition to anonymous procedures and named methods. An alternative using the text-procedure paragraph would be:

Recently this style of layout has been adopted by "builders" in the Groovy language for the Java virtual machine (JVM), but is also familiar to users of CSS or Tcl/Tk. Most features for web applications now implemented through combinations of JavaScript libraries + HTML + CSS are already found within the Curl language, including features usually associated with Prototype + script.aculo.us such as accordion panes.

Curl sets callbacks in the manner also adopted by Groovy:

Curl comments use the vertical bar in several variations. The simplest is as follows:

As lightweight markup
Because Curl provides for both user-defined text procedures and style sheets, it can be used readily as domain-specific lightweight markup. A major advantage over plain text HTML markup is that the text encoding can be set to UTF-8, and text entered in a Unicode-enabled text editor with no escaping of characters (like JavaScript, Curl is Unicode friendly). A poetry example is:

which can initially be implemented by defining the poem and stanza markup as paragraph text formats. Stanza could be further refined to include a hidden navigation anchor for page navigation using the Curl {destination} which is itself a text procedure.

The same markup can be used for different results, as one can style text to be visible in one context and invisible in another. Curl also permits top-level file inclusion so that a source text in markup can be included in different parent files. In education, for example, one could create a source file of test questions, and include it in both a student and a teacher version of the text.

title: Curl (programming language)


text:
User:Cable Hills

Cable Hills

is the user name for Mike Pearson, who was born in the hills near Cable, Illinois. I have lived in:
 * Illinois
 * Colorado
 * Texas
 * Louisiana
 * Vietnam
 * Thailand
 * Oklahoma
 * New Jersey
 * New York
 * Texas again
 * Iowa, where I will stay.

New Articles

 * Ben K. Green, a favorite author of mine
 * Nikita Khrushchev, a most wanted subject
 * Helsinki Final Act, just found a link

Major Revisions

 * Rockwell

title: User:Cable Hills