Papermaking

ដោយវិគីភីឌា

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The Diamond Sutra of the Chinese Tang Dynasty, the oldest dated printed book in the world, found at Dunhuang, from 868 CE. Papermaking is the process of making paper, a substance which is used universally today for writing and packaging. In papermaking a dilute suspension of fibers in water is drained through a screen, so that a mat of randomly interwoven fibres is laid down. Water is removed from this mat of fibers by pressing and drying to make paper. Since the invention of the Fourdrinier machine in the 19th century, most paper has been made from wood pulp because of cost. But other fibre sources such as cotton and textiles are used for high-quality papers. One common measure of a paper's quality is its non-woodpulp content, e.g., 25% cotton, 50% rag, etc. Previously, paper was made up of rags and kemp as well as other materials.

Contents [hide] 1 History 2 Manual papermaking 3 Industrial papermaking 4 History of paper sheet production 4.1 Folio 4.2 Quarto 4.3 Octavo 4.4 Sixteen-mo 4.5 Octavo bookbinding 4.6 Standardisation ISO sizes 4.7 Vatmen paper 5 See also 6 References 7 Further reading [edit]History

Main article: History of paper


Hemp wrapping paper, China, circa 100 BCE. Papermaking is known to have been traced back to China about 105 CE, when Cai Lun, an official attached to the Imperial court during the Han Dynasty (202 BCE-220 CE), created a sheet of paper using mulberry and other bast fibres along with fishnets, old rags, and hemp waste.[1] However a recent archaeological discovery has been reported from Gansu province of paper with legible Chinese writings on it dating from 8 BCE,[2] while paper had been used in China for wrapping and padding since the 2nd century BCE.[3] Paper used as a writing medium became widespread by the 3rd century,[4] and by the 6th century toilet paper was starting to be used in China as well.[5] During the Tang Dynasty (618-907 CE) paper was folded and sewn into square bags to preserve the flavor of tea,[3] while the later Song Dynasty (960-1279 CE) was the first government on Earth to issue paper-printed money. In the 8th century, paper spread to the Islamic world, where the rudimentary and laborious process of papermaking was refined and machinery was designed for bulk manufacturing of paper. Production began in Baghdad under the supervision of the Grand Vizier Ja'far ibn Yahya, they invented a method to make a thicker sheet of paper. This helped transform papermaking from an art into a major industry.[6] The earliest use of water-powered mills in paper production, specifically the use of pulp mills for preparing the pulp for papermaking, dates back to Samarkand in the 8th century.[7] The earliest references to paper mills also come from the medieval Islamic world, where they were first noted in the 9th century by Arabic geographers in Damascus.[8] Papermaking was diffused across the Islamic world, from where it was diffused further west into Europe.[9] Paper is recorded as being manufactured in Italy by 1220 and Germany by 1400, just about the time when the woodcut printmaking technique was transferred from fabric to paper in the old master print and popular prints.[10] Modern papermaking began in the early 19th century in Europe with the development of the Fourdrinier machine, which produces a continuous roll of paper rather than individual sheets. These machines have become very large, up to 500 feet (~150 m) in length, producing a sheet 400 inches (~10 m) wide, and operating at speeds of over 60 mph (100 km/h).[11] In 1844, both Canadian inventor Charles Fenerty and German inventor F.G. Keller had invented the machine and process for pulping wood for the use in papermaking.[12] This would end the nearly 2000-year use of pulped rags and start a new era for the production of newsprint and eventually almost all paper was made out of pulped wood. [edit]Manual papermaking

Papermaking, regardless of the scale on which it is done, involves making a dilute suspension of fibres in water and allowing this suspension to drain through a screen so that a mat of randomly interwoven fibres is laid down. Water is removed from this mat of fibres by pressing and drying to make paper.


An illustration from 105 AD depicting the papermaking process as designed by Cai Lun. First the fibres are suspended in water to form a slurry in a large vat. The mold is a wire screen in a wooden frame (somewhat similar to an old window screen), which is used to scoop some of the slurry out of the vat. The slurry in the screen mold is sloshed around the mold until it forms a uniform thin coating. The fibres are allowed to settle and the water to drain. When the fibres have stabilized in place but are still damp, they are turned out onto a felt sheet which was generally made of an animal product such as wool or rabbit fur, and the screen mold immediately reused. Layers of paper and felt build up in a pile (called a 'post') then a weight is placed on top to press out excess water and keep the paper fibres flat and tight. The sheets are then removed from the post and hung or laid out to dry. A step-by-step procedure for making paper with readily available materials can be found online.[13] When the paper pages are dry, they are frequently run between rollers (calendered) to produce a harder writing surface. Papers may be sized with gelatin or similar to bind the fibres into the sheet. Papers can be made with different surfaces depending on their intended purpose. Paper intended for printing or writing with ink is fairly hard, while paper to be used for water color, for instance, is heavily sized, and can be fairly soft. The wooden frame is called a "deckle". The deckle leaves the edges of the paper slightly irregular and wavy, called "deckle edges", one of the indications that the paper was made by hand. Deckle-edged paper is occasionally mechanically imitated today to create the impression of old-fashioned luxury. The impressions in paper caused by the wires in the screen that run sideways are called "laid lines" and the impressions made, usually from top to bottom, by the wires holding the sideways wires together are called "chain lines". Watermarks are created by weaving a design into the wires in the mold. This is essentially true of Oriental molds made of other substances, such as bamboo. Handmade paper generally folds and tears more evenly along the laid lines. Handmade paper is also prepared in laboratories to study papermaking and to check in paper mills the quality of the production process. The "handsheets" made according to TAPPI Standard T 205[14] are circular sheets 15.9 cm (6.25 in) in diameter and are tested on paper characteristics as paper brightness, strength, degree of sizing.[15]