Reprographics is a blanket term encompassing multiple methods of reproducing content, such as scanning , photography, xerography and digital printing. The term applies to both physical ( hard copy ) and digital ( soft copy ) reproductions of documents and images.
Letterpress
Letterpress printing is a technique of relief printing using a printing press. A worker composes and locks movable type into the bed of a press, inks it, and presses paper against it to transfer the ink from the type.
In practice, letterpress also includes other forms of relief printing with printing presses, such as wood engravings, photo-etched zinc "cuts" (plates), and linoleum blocks, which can be used alongside metal type in a single operation, as well as stereotypes and electrotypes of type and blocks. With certain letterpress units it is also possible to join movable type with slugs cast using hot metal typesetting.
Letterpress printing was the normal form of printing text from its invention by Johannes Gutenberg in the mid-15th century until the 19th century and remained in wide use for books and other uses until the second half of the 20th century. Letterpress printing remained the primary way to print and distribute information until the twentieth century, when offset printing was developed, which largely supplanted its role in printing books and newspapers. More recently, letterpress printing has seen a revival in an artisanal form.
Woodblock Printing
Woodblock printing is a technique for printing text, images or patterns used widely throughout East Asia and originating in China in antiquity as a method of printing on textiles and later paper. As a method of printing on cloth, the earliest surviving examples from China date to before 220, and woodblock printing remained the most common East Asian method of printing books and other texts, as well as images, until the 19th century. Ukiyo-e is the best known type ofJapanese woodblock art print. Most European uses of the technique for printing images on paper are covered by the art term woodcut, except for the block-books produced mainly in the 15th century.
The wood block is carefully prepared as a relief pattern, which means the areas to show 'white' are cut away with a knife, chisel, or sandpaper leaving the characters or image to show in 'black' at the original surface level. The block was cut along the grain of the wood. It is necessary only to ink the block and bring it into firm and even contact with the paper or cloth to achieve an acceptable print. The content would of course print "in reverse" or mirror-image, a further complication when text was involved. The art of carving the woodcut is technically known as xylography, though the term is rarely used in English.
For colour printing, multiple blocks are used, each for one colour, although overprinting two colours may produce further colours on the print. Multiple colours can be printed by keying the paper to a frame around the woodblocks.
There are three methods of printing to consider:
Stamping
- Used for many fabrics, and most early European woodcuts (1400–40). These items were printed by putting paper or fabric on a table or a flat surface with the block on top, and pressing, or hammering, the back of the block.
- Rubbing
- Apparently the most common for Far Eastern printing. Used for European woodcuts and block-books later in the 15th century, and very widely for cloth. The block is placed face side up on a table, with the paper or fabric on top. The back of the paper or fabric is rubbed with a "hard pad, a flat piece of wood, a burnisher, or a leather frotton".
- Printing in a press
- "Presses" only seem to have been used in Asia in relatively recent times. Simple weighted presses may have been used in Europe, but firm evidence is lacking. Later, printing-presses were used (from about 1480). A deceased Abbess ofMechelen in Flanders in 1465 had "unum instrumentum ad imprintendum scripturas et ymagines ... cum 14 aliis lapideis printis" ("an instrument for printing texts and pictures ... with 14 stones for printing") which is probably too early to be aGutenberg-type printing press in that location.
In addition, jia xie is a method for dyeing textiles (usually silk) using wood blocks invented in the 5th-6th centuries in China. An upper and a lower block is made, with carved out compartments opening to the back, fitted with plugs. The cloth, usually folded a number of times, is inserted and clamped between the two blocks. By unplugging the different compartments and filling them with dyes of different colours, a multi-coloured pattern can be printed over quite a large area of folded cloth. The method is not strictly printing however, as the pattern is not caused by pressure against the block.
Etching
Etching is the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio in the metal (the original process—in modern manufacturing other chemicals may be used on other types of material). As an intaglio method of printmaking, it is, along with engraving, the most important technique for old master prints, and remains in wide use today.
In pure etching, a metal (usually copper, zinc or steel) plate is covered with a waxy ground which is resistant to acid. The artist then scratches off the ground with a pointed etching needle where he or she wants a line to appear in the finished piece, so 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, technically called the mordant (French for "biting") or etchant, or has acid washed over it. The acid "bites" into the metal, where it is exposed, leaving behind lines sunk into the plate. The remaining ground is then cleaned off the plate. The plate is inked all over, and then the ink wiped off the surface, leaving only the ink in the etched 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 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 also be added to by repeating the whole process; this creates an etching which exists in more than one state.
Etching has often been combined with other intaglio techniques such as engraving (e.g. Rembrandt) or aquatint (e.g. Goya).
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