Paper
Derived from cellulose (plant) fibers that are made into pulp and felted (pressed) together, paper is one of the most common of man-made materials. There are approximately 7,000 types of paper, used not for writing or printing, but for products like paper bags and cardboard boxes.
The oldest extant writing surfaces include Babylonian clay tablets and Indian palm leaves. Around 3000 b.c., the Egyptians developed a writing material using papyrus, the plant for which paper is named. This substance was composed of strips cut from stalks of the papyrus reed, which were dried, laid across each other crosswise, and glued together to form a somewhat nubby writing surface. Other early materials were parchment, made from the untanned skins of sheep or goats and vellum, or fine parchment, made from calf-, kid-, and lambskin. Used in Europe from the second century b.c., they were expensive and impractical--the equivalent of a 200-page book, for example, would require twelve animal skins.
The invention of paper similar to the kind used today is credited to Cai Lun, a Minister of Public Works under Emperor He Di during China's Han Dynasty (202 b.c. to a.d. 202). The Chinese had earlier written on bamboo, bone, and silk, but these surfaces were either too heavy and cumbersome or too expensive. In the year a.d. 105, Cai Lun devised a way to make the bark of the mulberry tree into paper. The process he used contained the basic elements still found in paper mills today: the raw material was chopped and mixed with water to form a pulp, which was spread thin on porous screens, drained, and dried in sheets. The Chinese also used hemp, rag, and fish nets to make paper. At first, paper was used for clothing, household articles, decorative arts, and for wrapping. By the fourth century, papermaking was firmly established in China, although the technology would not reach Europe for another 1000 years.
The Chinese managed to keep papermaking a secret for 500 years, and it was not until the seventh century that is spread to Korea and Japan. Chinese prisoners (from eighth-century battles fought in what is now Turkistan) taught their Arab captors to make paper, which led to the establishment of papermaking workshops at Baghdad, Damascus, and Samarkind. The Spanish Moors finally brought paper to Europe in the twelfth century; they used essentially the same process as the Chinese, producing a very absorbent product similar to modern plotting paper. Europeans initially referred to paper as cloth parchment, and used linen rags (sometimes with cotton or straw added) to produce it. By the year 1276, a paper mill had been established in Italy's Appenine region. The invention of the printing press in 1450 created an increased demand for paper. During the sixteenth century, sizing (treating paper with starch to stiffen it and prevent smudging) was introduced, and papers began to be coated with opaque mineral powders (such as lime) to improve quality.
The first American paper mill was established near Philadelphia in 1690; by 1810 there were 185 paper mills in the United States. The papermaking process remained quite slow and tedious until 1750, when a Dutch inventor designed a machine that reduced the time it took to break rags down to fiber. In 1798, Nicholas Louis Robert, a Frenchman, invented a machine that made paper in continuous rolls. The English Foudrinier brothers, Henry and Sealy financed his idea and produced a successful model in 1805. The device, which bears their name, is still used in modern papermaking. The Foudrinier machine was first used in the United States in 1816, when Thomas Gilpin and his brother Joshua built America's first mechanized paper mill. They "borrowed" a state-of-the-art design from English inventor John Dickinson and even persuaded Dickinson's foreman to defect to their operation. The Gilpins' monopoly on American papermaking was broken only when improved technology became widely available.
By the early nineteenth century, wood and other plant pulps began to replace the rags that had been used earlier, particularly in Europe. In 1840, a method for reducing logs to chips was invented, thus facilitating pulp production. In 1867 an American inventor named Tilghman discovered that wood fibers could be easily separated if the chips were soaked in a sulfurous acid solution. In 1883, German inventor Carl Dahl incorporated sodium sulfate into his papermaking process, producing a very strong pulp that became known as kraft (which means "strength" in German). Kraft pulp is still used, in bleached and unbleached forms, for such products as paper bags, milk cartons, and paper cups. Most paper now produced is made from wood, either harvested particularly for that purpose or from lumber or woodworking waste. Wood pulp is created by both mechanical and chemical processes designed to break down the wood fibers. Once the pulp has been produced, it is washed to remove any chemicals; foreign matter is filtered out, and the pulp is drained, bleached, washed, and formed into sheets that are pressed by heavy rollers and dried by air suction. Cylindrical colander presses put a smooth finish on the paper, which is finally wound into large rolls. Some paper, however, is made from such plants as cotton, rice, wheat, cornstalks, hemp, and jute; very high quality "rag" paper is still derived from cotton rags.
By 1991, Americans were producing nearly 70 million tons (64 million metric tons) of paper per year and consuming 660 pounds (300 kilograms) per person each year. With increasing concern about the environmental implications of forest depletion and waste disposal, many communities have begun paper recycling programs, chopping newspaper, magazines, and other waste papers into a pulp that is then treated to remove ink. The end product, called secondary fiber, is made into paperboard, some forms of printed paper, napkins, and towels. Despite the continued promise of a "paperless office" because of computer technology, paper consumption continues to grow. The future of paper might be affected by such technology, however. In 1994, Xerox corporation announced its development of "smart paper." Such paper will have dataglyphs, which can microencode digital information, embedded within it. Smart paper can count copies made from it, assure authenticity, and become part of the inter-office routing system.
This is the complete article, containing 1,023 words
(approx. 3 pages at 300 words per page).
