Paper is a thin sheet material which is produced by the compression of a mat of fibres.
The fibres used are usually naturally occuring cellulose, the most common being obtained from wood pulp, usually from coniferous softwoods. Other vegetable fibres such as cotton, linen and hemp may be used, particularly where a more durable paper is required such as for the production of banknotes.
Most paper is mass-produced as a continuous roll by machine which is cut to standard sizes
before despatch from the factory. Some specialist papers are still made by hand, primarily for niche markets. Whether machine or hand made, the manufacturing process is fundementally the same.
Fibre Preparation: The raw material to be used for the manufacture of the paper is first converted into a concentrated suspension of fibres in water known as "pulp". As the fibres are obtained from natural sources, the preparation of the pulp frequently requires many stages of processing, separation and washing. The fibres in the pulp may be bleached and/or dyed to produce a suitable appearance for the final product.
Forming into Sheets: The processed pulp is formed into the desired shape by the use of a mould with a base of fine mesh or, in the continuous rolling process used in mass production, onto a mesh conveyor belt, where pressure is applied to remove the excess water through the mesh. A watermark may be impressed into the paper at this stage.
Mass produced paper is made by a continuous rolling process to form a reel known as the "web" which passes through successive sets of rollers which apply increasing amounts of pressure to remove the water from the pulp and may be patterned to produce a textured paper.
Finishing: Raw paper made from the compressed and dried pulp is very absorbent (like blotting paper or kitchen towels) and the surface is quite rough and unsuitable for either printing or writing. Large quantities of a wide variety of additives are used in the paper manufacturing industry to produce a paper of the desired quality.
A coating known as a "size" is applied to paper to seal the spaces between the fibres and bind them together to produce a smoother surface. Starches are frequently used, as are polymers such as PVA (polyvinyl acetate). Clay is also frequently used as a sizing agent to improve the smoothness of the paper surface (this produces the smooth, matte finish of papers used in magazines).
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The glossy surface of, for example, the covers of fashion magazines,
is produced by applying a varnish-like layer after the printing has been finished and is not a property of the paper itself.
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Other additives are also employed to enhance various properties of the finished paper. The most common of these are optical brighteners.
Drying: The paper is finally dried to an acceptable moisture content before cutting (or trimming in the case of hand-made paper). Becuase dry paper is much stronger than wet, it may be dried several times during the manufacturing process to ease handling and preventing breakages in the web from halting the production line.
The word "paper" is derived from "papyrus", a writing material used by the Ancient Egyptians which was woven from the stems of the wetland sedge Cyperus papyrus, once abundant in the Nile delta, which to a height of 5 meters (15 ft). It was produced in Egypt as early as 3000 BC and exported throughout the surrounding region, becomming adopted by the Ancient Greeks and the Romans.
Paper manufactured from cotton fibres was invented in China in AD 105 by Ts'ai Lun, a court official. Documents had been written on bamboo making them heavy cumbersome to transport. Silk was sometimes used for writing but was prohibitively expensive.
While paper was exported and spread through East Asia, the Chinese were reluctant to share the secrets of its manufacture which were eventually exported to Japan in 610 where "bast" fibres from the mulberry tree were used.
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The Chinese were the first to "mass produce" maps; the maps would be carved into flat slabs of stone, paper would then be placed over the slabs and the map produced by rubbing colour over the paper (as in modern-day brass rubbing).
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Paper manufacture using hemp and linen rags spread throughout the Middle East after the defeat of the Chinese at the Battle of Talas (751) and it was adopted in India, reaching Italy by the 13th century.
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Before paper became available, most books were made of parchment or velum, a prepared sheep or calfskin.
The word "beech" comes from the Scandinavian word "bok" meaning "book" because the prepared bark of the tree (Fagus sylvatica) was used for writing before the advent of paper (the beech was also used for the making of book covers).
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Some historians consider paper as the key element in global cultural advancement. They claim that Chinese culture was less developed than that in the West in ancient times because bamboo was a clumsier writing material than papyrus and that Chinese culture advanced during the Tang Dynasty and the preceding centuries due to the invention of paper - also that Europe advanced during the Renaissance due to the introduction of paper and the printing press.
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Hand made paper was a luxury item the advent of steam-driven paper making machines in the 19th century allowed paper to be mass produced cheaply. Before the industrial revolution allowed the production of cheap paper and printing using the rotary press books and newspapers were luxuries and illiteracy was the norm for the vast majority of the population.
The availability of cheap, mass-produced paper led to the evolution of the office or white-collar worker during the industrial revolution.
Although a number of machines predated it, the Fourdrinier paper making machine has become the basis for modern paper making.
The original wood pulp based paper was highly acidic and very prone to disintegrate over time. Documents written on more expensive rag paper were far more stable. The majority of modern book publishers now use acid-free paper.
Where durability is required, such as in the production of banknotes which would rapidly disintegrate if made of wood pulp, papers made of rag are used.
Deforestation
The pulp and paper making industry has been accused of being instrumental in the destruction of forests on a large scale. Several major Asian producers, for example, have strong connections to their respective Governments and bureaucracy, have been allowed to systematically strip the rainforest over long periods of time. The logs are transhipped via other countries to disguise the damage wrought on the evironment.
The forests of the Amazon Basin, Cambodia, Indonesia and Malaysia are currently being subject to some of the worst excesses of this irreversible environmental destruction.
Water Pollution
Paper producation, by its nature, requires the availability of large amounts of water and the
processes by which paper is "bleached", rendered white,
are the ones which are most damaging to water quality and the aquatic environment
of rivers on which the paper-making plants are situated.
Many rivers have been badly damaged by the discharges from mills processing the wood pulp.
Rice "paper" is manufactured by drying a paste of rice starch and water between rollers and is edible.
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