Paper

Sheet of paper

Paper is a thin, flat material produced by the compression of fibers. The fibers are usually obtained from natural sources and are composed of cellulose. The most common source of these fibers is wood pulp from pulpwood trees, (largely softwoods) such as spruce. However, other vegetable fiber materials including cotton, hemp, linen, and rice may be used.

• Paper has been and continues to be one of the most important and consequential artifacts of human civilization.

Paper has been central in the rise of literacy and development of human civilization. As a means of communicating and storing ideas, knowledge, and culture, paper has contributed to the rise in power and influence of various societies. The paper industry today is also a large source of revenue and employment for many people.

• Paper is extremely important as a medium for storing and disseminating information relatively cheaply and widely. People who have learned the basic skills of reading and writing can readily access paper-based records.

Paper has been so important for the dissemination of information that, prior to the advent of the Internet and electronic publishing, it was not uncommon for totalitarian or repressive regimes to control access to paper in order to control the spread of information. If it could cut off the supply of newsprint to newspaper publishers, a regime did not need to worry about what they were publishing. Cut off the supply of office paper, and the regime didn’t need to worry that dissidents were using office copiers or mimeograph machines to copy and disseminate information about the regime’s misdeeds.

Some historians have expressed the view that paper was the key element in global cultural advancement. According to this theory, Chinese culture was less developed than the West in ancient times because bamboo, while abundant, was a clumsier writing material than papyrus. Chinese culture advanced during the Han Dynasty and subsequent centuries as a result of the invention of paper, and Europe advanced during the Renaissance based on the introduction of paper and the printing press.

Paper remained mostly a luxury item through the centuries until the advent of steam-driven paper-making machines in the nineteenth century; these machines could make paper with fibers from wood pulp. Together with the invention of the practical fountain pen and the mass-produced pencil of the same period, and in conjunction with the coming of the steam-driven rotary printing press, wood-based paper brought about a major transformation of the nineteenth-century economy, society, and cultue in industrialized countries.

Before this era, a book or newspaper was a rare luxury object, and illiteracy was the norm. With the gradual introduction of cheap paper, schoolbooks, fiction and non-fiction books and other publications, and newspapers became increasingly more available to nearly all members of an industrial society. Cheap, wood-based paper also meant that keeping personal diaries or writing letters ceased to be reserved to a privileged few. The office worker or white-collar worker was slowly born of this transformation — a change that can be considered to be a part of the industrial revolution.

• Most currently available paper is made of wood pulp, but it is also possible to get paper with varying percentages of cotton or rag content, usually between 25 and 100%. Paper containing cotton or rag is used mainly for paper money and documents that are deemed valuable for long-term preservation. Paper documents can be made to last hundreds of years.

Different kinds and uses of paper

At present, many different kinds of paper are manufactured, catering to a wide variety of needs. People use paper to write notes, letters, memos, and diaries; to print pictures; to perform office work; and to publish newspapers, magazines, books, and journals. For these purposes, paper is available in such forms as note paper, office paper, newsprint, and photographic paper. Most magazines use coated paper, which has a smooth, shiny surface suitable for printing pictures without dispersion of the ink.

Paper is used extensively in the fine arts, as the substrate for paintings and drawings and to make reproductions and prints. In addition, various crafts—such as the making of origami shapes and papier-mâché objects—involve the use of paper.

A number of paper products serve a variety of cleaning needs. Examples include paper towels, paper napkins, facial tissue, and toilet tissue. Paper is also used as a packaging and carrying material, such as for envelopes, paper bags, gift wrap, cardboard boxes, and some types of food wrap. Special packaging is used to protect items such as china, clothing, and perishable foods. Some paper products, such as paper cups and plates, are used mainly because of the convenience of portability and disposal.

Legal rights and responsibilities of individuals, groups, businesses, and agencies are linked to documents on paper, and people are held liable for anything they agree to by their signature on paper. For this reason, private and public contracts, titles, deeds, wills, passports, and visas are signed and stored on paper. The Fourth Amendment to the U.S. Constitution guarantees a person's rights to the security of his papers.

Local, state, and national governments record and preserve their laws, bills, and statutes by printing them on paper. Court documents are similarly recorded and preserved.

Paper plays an essential role in education. It is used for textbooks, notebooks, teacher's notes, student submissions, examinations, transcripts, diplomas, and so on. Libraries are stocked with material printed on paper, although archival material is also stored on microfilm and electronic media. To some extent, education is conducted orally and through the use of audiovisual and computer technologies, but paper continues to be used in large quantities.

Businesses, too, utilize a great deal of paper. Besides using standard office paper, businesses use large quantities of paper for business cards, advertising media, brochures, reports, bookkeeping and other accounting tasks, packaging and shipping, displays and display mounting, and so forth. The collapse of New York City's Twin Towers on September 11, 2001, after they were hit by two hijacked airliners, has been attributed largely to heat generated by the burning of huge amounts of office paper ignited by the crashes and the fuel they spilled.

Paper is important for scientific activity as well. It is used for recording, publishing, and preserving experimental data and analyses. The date or publication in a scientific journal or elsewhere—usually on paper—is generally used for establishing priority of discovery.

Life's momentous events—such as births, weddings, graduations, and deaths—are recorded, commemorated, and celebrated with the use of paper. It is considered appropriate to acknowledge and mark such events by sending and receiving paper-based cards, leading to growth of the greeting card industry. A heroic deed or achievement of a major goal is often commended on a paper document.

When trying to uncover and piece together past events, historians and others rely heavily on paper records and documents. Likewise, paper plays a crucial role in museums, archives, and other places that preserve historical records. Conversely, people shred or burn letters, documents, and other records when they want to preserve privacy, keep secrets, forestall spying, or blot out parts of history.

Paper is a medium for preserving images as well as text. Usually, photographs are printed first on photographic paper, then reproduced in magazines, newspapers, and books. The images stored on paper are frequently of equal or greater importance than words, particularly when informing future generations about past events. Examples of memorable images include the raising of the U.S. flag on Iwo Jima in World War II, and the celebrations in Paris after liberation from Nazi rule.

An especially important technological development linked to the use of paper is photocopying. Before the advent of this technology, people duplicated their documents by making "carbon copies" or by a process known as mimeographing. Today, those processes are obsolete, as photocopiers can be used to generate many copies of a document quickly, for use by students, businesses, government agencies, and so forth. This has resulted in a large increase in the consumption of paper.

• Computers and electronic storage have not replaced the use of paper.

A paper trimmer

Some other important uses of paper are summarized below.

• Certain types of printed paper represent monetary value. Examples include paper currency, checks, vouchers, tickets, and postage stamps.
• Maps and routes or representations of terrain, waterways, and skyways are printed and preserved on paper.
• Military documents and strategies are usually presented and/or stored on paper.
• Architects use paper and cardboard to depict architectural drawings and construct models of proposed structures.
• Engineers sometimes make paper models of proposed products, such as cars or airplanes.
• When someone makes an audiovisual presentation, the person may also distribute paper copies of the images and text, to make a greater or longer-lasting impression on the audience.
• Combining decorative and protective functions, paper may be used in the form of wallpaper.
• Paper and cardboard are often used as building materials and in the construction of furniture.
• Sandpaper is used for smoothening rough surfaces or removing coatings.
• Blotting paper is used to absorb ink and other liquids.
• Litmus paper is used to test the acidity or alkalinity of a solution.
• In chemical and biological work, special paper is used to separate solids from liquids by the process of filtration, and to separate substances in solution by a process called paper chromatography.

<<MOVE:>>manufacturing and printing costs are relatively low, and the average user can readily afford paper and paper products.

History of paper and papermaking

The history of paper begins with the ancient Egyptians and continues until today. The term "paper" comes from papyrus, the plant material used by the early Egyptians, Greeks, and Romans. In more northern regions, parchment or vellum, made of processed sheepskin or calfskin, was used instead of papyrus because the papyrus plant needs subtropical conditions for growth. In China, bamboo was used for documents, but this made them heavy and awkward to transport. Silk was also used sometimes, but it was rare and expensive.

Besides papyrus, other early papermaking materials came from the inner bark of certain trees and shrubs, especially mulberry, fig, and daphne. The term "tapa" includes papyrus and those other materials. Tapa was used in most cultures along the equator and is still being used in some parts of Asia. Some of the oldest tapa has been found in China, indicating that China was using paper before the beginning of Western records. [1]

According to a Chinese court chronicle, in CE 105, the court official Ts'ai Lun invented a process of producing paper from rags. Somewhat later, papermakers in China developed ways to make sized, coated, and dyed paper, and paper that was resistant to insect attacks. They also used bamboo, which they heated in lye to remove its fibers. [2]

In the year 600, Chinese papermaking technology was transferred to Korea. Around 610, a Buddhist priest, Dam Jing (曇徴) from Goguryeo, brought the process to Japan, where fibers (called bast) from the mulberry tree were used. Since then, the technology spread to Central Asia and India. These papermakers used hemp and linen rags as sources of fiber. The Missel of Silos (eleventh century) is the oldest known Western paper document.

As the Arabs expanded eastward, they became acquainted with the technology of large-scale paper manufacture. They went on to establish paper mills in various parts of the Middle East, Morocco, Spain, and Sicily. In the absence of fresh fibers, they relied mostly on rags to produce the paper. Their defective processing equipment generated poor-quality pulp, but by coating their sheets with starch paste they managed to produce paper that was attractive to look at and good to write on.

This Arab-made paper and the techniques to make it spread quickly to Europe. During the thirteenth century and thereafter, paper producers in the Italian towns of Amalfi and Fabriano developed new ways to improve the papermaking process, including the use of water power, a stamping mill, a wire-mesh mold, and a screw press. [3]

In subsequent years, there were continuing improvements in papermaking techniques and equipment in Europe. The Reformation of the sixteenth century, accompanied by the invention of the printing press using movable type, led to a huge rise in paper consumption and production. The subsequent shortage of raw materials, along with regulations governing the trade in rags, led to a search for substitute materials. The problem was not solved until Saxon Keller invented groundwood pulp in 1843 and Mellier Watt patented chemical pulp in 1854. [4]

Papermaking grew into a huge industry during the nineteenth and twentieth centuries. The main developments can be summarized in the following five overlapping periods.

1. 1800–1860: Much of the work previously done by hand was mechanized. It included the development of machines for making, finishing, and packaging the paper product.
2. 1840– 1880: Groundwood pulp and chemical pulp were used as substitutes for rags, and mills were set up to process these new materials.
3. 1860–1950: The papermaking apparatus was adjusted to make wider rolls of paper at higher speeds. New machines were developed to operate on electricity and produce various kinds and grades of paper.
4. 1950–1980: The operational speeds of the machines and the width of the paper web were increased further, and new sheet-forming processes were introduced. New materials—including thermo-mechanical pulp and deinked, recycled paper—began to be used. Steps were taken to protect the ecology by changing the ways of handling and disposing of chemicals. Most significantly, new, automated processes were introduced. These changes led to specialization in the production of specific types and grades of paper. They also led to corporate mergers and the closing of unprofitable companies.
5. 1980 onward: New chemical pulp processes and sheet-forming approaches were developed. The biggest changes in this era, however, have been related to increased demand for paper products, especially in developing countries, leading to a rise in prices of chemical pulp and problems with the location of mills. Given the need for large amounts of capital to finance these operations, big international companies have been formed, but there remain opportunities for smaller firms that meet local needs. [5]

The current process of making paper

Currently, the papermaking process involves the following stages.

Preparation of the fibers

The material to be used for making paper is first converted into pulp, which is a concentrated mixture of fibers suspended in liquid. The fibers are often derived from natural sources, such as softwood or hardwood trees or other plants.

To manufacture high-quality sheets of paper from plant material, it is usually necessary to break down lignin, a polymeric material that gives rigidity to the plant's cells walls. The breakdown of lignin is usually a chemical process, such as the Kraft process. This step is not needed when breaking down recycled fibers, as the lignin has already been removed from the source material. If lignin is retained in the pulp, the paper will yellow when exposed to air and light.

Alternatively, wood chips may be broken down mechanically, without using chemicals, to produce what is called "groundwood pulp." Because lignin is not removed from this pulp, yields are as high as 90–98%. The presence of lignin, however, causes paper to yellow, as noted above. For this reason, groundwood pulp is most often used for non-permanent goods such as newspapers.

Pulp that is broken down chemically is known as "chemical pulp." The chemical pulping process breaks down the lignin and renders it soluble in a liquid (usually water), so it may be washed from the remaining fibers. Removing the lignin from wood chips also breaks them apart into the fibers that compose pulp.

It is also possible to obtain the fibers from recycled material, such as old corrugated boxes, newsprint, or mixed paper. Recycled fibers do not need to be pulped in the conventional sense. As they were treated earlier, they need a more gentle process to break the fibers apart while preserving their integrity. The manufacture of paper from recycled paper products is increasing in the industrialized world today. It is now possible to buy office paper, for example, that is made from 100% recycled paper.

Once the fibers have been extracted, they may be bleached or dyed, and special ingredients may be added to alter the appearance of the final product. For example, kaolin (a clay rich in aluminum silicate hydroxide) or calcium carbonate is added to produce the glossy papers typically used for magazines.

Sheet formation

The pulp mixture is diluted with water to produce a thin slurry. The slurry is drained through a fine-mesh moving screen, leaving a fibrous web on the screen. A watermark, such as the mark used in paper currency, may be impressed into the paper at this stage. The moving web is pressed and dried into a continuous sheet of paper.

In the mold process, a quantity of pulp is placed into a form, with a wire-mesh base, so that the fibers form a sheet and excess water drains away. Pressure may be applied to help remove additional water. The paper may then be removed from the mold, wet or dry, and processed further.

Mass-produced paper is most often made using the continuous Fourdrinier process, to form a reel or web of fibers in a thin sheet. When dried, this continuous web may be cut into rectangular sheets by slicing the web vertically and horizontally to the desired size. Standard sheet sizes are prescribed by governing bodies such as the International Organization for Standardization (ISO). In the United States, the standard size for office paper is 8 1/2 by 11 inches, and paper is usually packaged in reams (with 500 sheets per ream).

Drying

After the paper web is produced, water must be removed from it to create a usable product. This is accomplished by pressing and drying, using different methods but based on the same principles. Pressing the sheet removes the water by force. Another absorbent material must be used to collect this water. On a paper machine, this is called a "felt" (not to be confused with the traditional meaning of felt). When making paper by hand, a blotter sheet is used.

Drying involves using air or heat to remove water from the paper sheet. In the earliest days of papermaking, paper sheets were hung up to dry like laundry. In recent years, various forms of heated drying mechanisms are used. With paper machines, the most common drying method involves use of the steam-heated can dryer. Dryer cans heat to temperatures above 200ºF and are used in long sequences of more than 40 cans. The heat produced by this process can easily dry the paper to less than 6% moisture.

Preservation of paper

A major issue with the use of paper is related to the need to preserve valuable documents, books, and photographs. Important documents that are regularly printed on paper include records of births, deaths, marriages, titles, deeds and real estate transactions, court proceedings, legislative actions, and actions of other governmental agencies.

Most paper is processed with acid during its manufacture, and the acid content causes paper to disintegrate over time. If one examines books published 50–100 years ago, especially those printed during the world wars (when inferior-quality paper was being manufactured), there is much evidence of yellowing and crumbling of the paper. In the case of newspapers, they tend to yellow and fall apart within a few years because newsprint is made with pulp that contains lignin. This problem with the deterioration of paper is a major concern for libraries and archives, both public and private.

The American Library Association has attempted to forestall the deterioration of books by advocating that they be printed on acid-free paper. This effort has had considerable success, as one can frequently see notices in books, especially expensive hardbacks and other books intended to last long, saying that the book has been printed on acid-free paper that conforms to the standards of the American Library Association.

One method of preserving newspaper pages and other materials is to copy them photographically on microfiche or microfilm. By these techniques, information can be preserved for as long as the processed photographic film can be made to last, which can be hundreds of years if the film is processed and stored properly.

In the case of photographs, there has been a concerted effort to get black and white photographs processed and preserved using archival standards. It involves washing the chemicals thoroughly out of the paper during the final washing stage and preserving the photographs by mounting them on acid-free mounting boards or storing them in acid-free boxes. (Because of the relative impermanence of the dyes involved in creating colors, color photographs cannot be made as permanent as black and white ones. The latter are based not on dyes but on highly stable silver and silver-halide particles.)

Preservation of paper-based documents has always been a big problem. Nowadays almost all kinds of documents, especially in the developed world, are increasingly being created and stored electronically as computer files, thus bypassing (at least potentially) the use of paper and the problems of paper preservation. In cases where such documents are still produced on paper, the use of acid-free paper with a high fiber content helps create a document that will resist deterioration. In theory such records stored electronically on computer-created files should be more-or-less permanent. In practice, however, these files often become obsolete or unusable even more quickly than paper ones deteriorate because computer technology and software change rapidly, and something preserved electronically today may become inaccessible in a few years because the computer hardware and software for it no longer exists.

Another problem that has arisen with computer files is the increasing use of computer voting in elections. Many people are afraid that, unless a paper record is also made and kept of each vote, computer error or outright election fraud could occur and it would be impossible to determine that this had happened if only the computer files, and no paper record, were available.

Beyond the facts about rapid changes in computer hardware and software there is the problem that gaining access to records stored in computer files requires that the one desiring access must first have access to the right kind of computer with the right software. Without such computer access, the one desiring access to the documents in question may be unable to do so. If, however, those documents were printed and stored on paper, then anyone who is able to read and understand could get access to them. There is the further problem that when a person is traveling, even though small and lightweight laptop computers have become nearly ubiquitous today, many people still find it more convenient to print out documents on paper and carry the papers with them and read them in a car, bus, train, or airplane than it is to carry a computer and attempt to use it while traveling. So there is a double edge to the question of computer versus paper storage of documents and information – there are both good and bad aspects of each.

Paper production figures

Worldwide paper production figures may not be available. The following data is for just the United States and is taken and adapted from the website: http://www.findarticles.com/p/articles/mi_qa3636/is_200504/ai_n13634551.

In 2004, total paper and paperboard was about 91.471 million tons, an increase of 3.5% from 2003. Paperboard production increased 4.0% and paper 2.9%, according to data by the American Forest & Paper Assn. (All data given here comes from the AF&PA.)

The total estimated U.S. paperboard output for 2004 was 49.942 million tons. This can be compared with 48.018 million tons in 2003 and 48.126 million tons in 2002. Paper output of 41.529 million tons in 2004 increased slightly over the 40.368 million tons produced in 2003 and 41.561 million tons produced in 2002.

Paper and board output in 2004 was the highest level in four years. But 2004 output was 5.0% lower than the 96.309 million tons produced in 2000 and 7.4% below the recent peak in 1999 of 98.837 million tons.

Kraft linerboard at 22.654 million tons in 2004 was up 4.3% over 2003; corrugating medium at 6.560 million tons was 7.6% higher; boxboard at 14.900 million tons was up 2.7%; uncoated free-sheet at 12.387 million tons was 1.0% higher; coated papers at 9.254 million tons was up 6.3%; packaging papers at 4.068 million tons was higher by 4.6%; and newsprint at 5.637 million tons was down 0.7%, AF&PA reported. (The lower production of newsprint may be correlated with the declining circulation figures of most newspapers in the U.S.)

Consumption of recovered paper in 2004 at 35.079 million tons was 3.4% above 2003. (This figure shows that recycling of previously-made paper to make new paper is increasing in the U.S.)

U.S. industry employment in paper and paper products at about 499,000 was down 3.3% from 2003 and in pulp, paper, and board mills at 146,800 was off 2.8%. But annualized average hourly earnings for paper and paper products employees in 2004 at $17.90 were up 3.3% from 2003.

2004 trade data show total U.S. pulp, paper, and board exports up 4.0% from 2003 in volume to 30.033 million tons and up 8.4% in value to $15.558 billion. Yet with total imports up 4.7% in volume to 25.839 million tons and up 11.0% in value to $19.767 billion, the U.S. pulp and paper trade deficit nevertheless stood at $4.209 billion at the end of 2004.

Some recent developments in paper making

Paper made in the west since the industrial revolution has usually been wood based, sometimes with a fabric content, except for a few specialized papers such as those used in banknotes. However, at least one company (Cloudy Bay Cotton) has recently tried to introduce cotton-based tissue papers to Westernized countries, as an alternative to wood-based ones. Cotton-based tissue papers are less abrasive, less likely to cause allergic reactions, and far more environmentally friendly than wood-based papers, as they are made from renewable materials. The cotton fibers used for making paper are the type that are discarded as "unusable waste" by the textile industry, and they can be manufactured using fewer chemicals and less energy.

Some manufacturers, notably AMD, have started using a new, slightly more environmentally friendly alternative to expanded plastic packaging made out of paper, known commercially as "paperfoam." The packaging has very similar mechanical properties to some expanded plastic packaging but is biodegradable and can also be recycled with ordinary paper. [6]

With increasing environmental concerns about synthetic coatings (such as PFOA) and the currently higher prices of hydrocarbon based petrochemicals, there is a recent focus on zein (corn protein) as a coating for paper in high grease applications such as popcorn bags. [7]

See also

• book
• Electronic paper
• Kaolin
• newspaper
• cardboard
• newsprint
• paper recycling
• pulp and paper industry
• stationery
• Tracing paper

External links

Wikimedia Commons has media related to:

Paper

• How is paper made?
• No End to Paperwork
• Paper Online
• How Paper Is Made
• United States Government Printing Office: Government Paper Specification Standards
• History of Paper Making
• Definition of paper

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