Paper (Forensic Science)
A piece of paper, independent of any writing or printing that may appear on it, conveys a wealth of information. By examining it closely, an expert can often tell where and when it was manufactured. Telltale signs of its subsequent history—how it was stored and whether it was treated in any way—may be discernible as well. forensic scientists may also be able to match paper fragments that have been torn or cut from larger original pieces to those original pieces in a process known as fracture matching.
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Differing Characteristics (Forensic Science)
Paper manufacture originated in the Orient and was imported into Europe in the late Middle Ages. Paper is basically a felt made of plant fibers, compressed to form a thin, tough sheet. Certain characteristics imparted by the papermaking process are visible in the finished product. These include the species of plant from which the fibers were derived, the chemical and mechanical means used to extract and treat the fibers to make them suitable for papermaking, bleaching agents and dyes, density, surface texture imparted by rollers, watermarks, fillers, and substances used for coating.
The older the paper, the more likely the species of plant used in its manufacture is to be diagnostic. In the twenty-first century, wood chips used in pulping are shipped all over the world. In contrast to new paper from large international conglomerates, which varies little in its species composition, recycled paper can be highly diagnostic, because the species mix changes so much from batch to batch.
Because visible surface features of documents can be photocopied, many firms and government agencies print their most sensitive documents on security paper that is manufactured for specific purposes. Such paper incorporates fibers, watermarks, invisible reactive inks, and other features that forgers and counterfeiters cannot reproduce without access to the original, tightly controlled paper stock.
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Analysis Techniques (Forensic Science)
Document analysts use radiocarbon dating as well as the analysis of paper manufacturing techniques to determine the ages of old documents and drawings. Serious forgers of purportedly old documents attempt to avoid discovery by using antique paper. In initial authentication of the Vinland map, which was claimed to be a fifteenth century copy of a thirteenth century map proving Viking settlement in the New World, investigators concluded that the map was genuine because it was drawn on fifteenth century parchment. A supposed center fold, however, turned out to be a seam where two leaves were joined before the map itself was drawn. Through microscopic examination, forensic document examiners can readily determine whether folds or mechanical damage on a piece of paper occurred before or after the paper was written on. Something written after the paper was damaged raises suspicion of forgery.
The origins of the fibers used in paper can be determined through examination of the morphology of individual fibers with either transmitted light or scanning electron microscopy (SEM). Forensic scientists use the same spectrographic methods they apply to analyzing ink in analyzing paper. SEM produces a high-resolution image of surface features, and a laser scanning confocal microscope produces a three-dimensional image. As an adjunct to SEM, energy-dispersive spectroscopy (EDS; also known as energy-dispersive X-ray spectroscopy, or EDX)...
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Further Reading (Forensic Science)
Conners, Terrance E., and Sujit Banerjee, eds. Surface Analysis of Paper. Boca Raton, Fla.: CRC Press, 1995. Technically oriented volume provides detailed information on paper surfaces. Intended mainly for use in quality-control applications in the paper industry.
Dines, Jess E. Document Examiner Textbook. Irvine, Calif.: Pantex International, 1998. Practical manual for forensic document examiners includes good coverage on watermarks.
Eckert, William G., ed. Introduction to Forensic Sciences. 2d ed. Boca Raton, Fla.: CRC Press, 1997. Text aimed at students considering careers in forensic sciences offers useful tips on identifying types of paper.
Houck, Max M. Forensic Science: Modern Methods of Solving Crime. Westport, Conn.: Praeger, 2007. Highly readable volume provides a rigorous overview of many aspects of forensic science, with numerous examples. Includes brief coverage of document analysis.
Kaye, Brian H. Science and the Detective. Selected Reading in Forensic Science. New York: VCH, 1995. Presents clear descriptions of the manufacturing processes used in the paper industry and discusses how to detect the differences among types of paper.
Spencer, Ronald D. The Expert Versus the Object: Judging Fakes and False Attributions in the Visual Arts. New York: Oxford University Press, 2004. Describes scientific methods for the authentication of...
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Background (Encyclopedia of Global Resources)
Before the invention of paper, written words were preserved on fabric in the form of scrolls. The Chinese are credited with inventing paper around 105 c.e. Historians note that this date was chosen somewhat subjectively, as early experiments in the process of papermaking probably stretched over a long period of time before the process was perfected. No records exist that indicate how the Chinese first made paper, but it is believed that this early paper was made by pouring fibrous pulp onto flat cloth-covered molds, then drying it—essentially the same way paper is produced today. Once the pulp had dried, an interlocking matrix of fibers created the paper. Early forms of paper were not as well processed as modern paper products. In fact, early forms of paper had more in common with the fabrics they replaced than with modern paper. They were coarse in nature, but they did lie flat. This quality made it possible for the first real books to be produced.
Over the following five hundred years, the Chinese papermaking process slowly spread throughout Asia, from Vietnam and Tibet to Korea and eventually to Japan in the sixth century. The Japanese refined the process and continued to produce high-quality paper varieties for centuries. The process moved west through Nepal and India. Several papermaking devices were captured by Islamic warriors, thus moving the technology further west through the Muslim world. It went to Baghdad into...
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The Fourdrinier Machine (Encyclopedia of Global Resources)
The first major improvement in papermaking was dipping the molds directly into the fibrous pulp (the exact date of this improvement is unknown). Dipping the molds allowed artisans to produce a greater quantity of high-quality paper.
Paper was made by hand until the early nineteenth century, when the Fourdrinier brothers, Henry and Sealy, introduced the first machine designed specifically for the manufacture of paper. The Fourdrinier brothers were the financiers of the first modern papermaking machine, which was designed by Nicholas Louis Robert in Essonnes, France. Robert received a patent for the continuous papermaking machine in 1799. Unable to afford the cost of development and implementation of his machine, Robert and his partner, Saint-Léger Didot (who often claimed the continuous papermaking machine was of his own invention), sent Didot’s brother-in-law, John Gamble, to England to find financial backing. A British patent was awarded in October, 1801. The first continuous paper machine was installed and made operational in Hertfordshire, England, in 1803. The next year, another machine followed. Robert sold the rights to his invention to the Fourdrinier brothers in England. The principle of Robert’s machine was to construct the paper on an extensive woven-wire cloth that retained the matted fibers while allowing the excess water to drain through—this same principle holds with all modern papermaking...
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Production of Pulp and Paper (Encyclopedia of Global Resources)
Paper production has changed significantly since the early industrial days and even the boom manufacturing years of the 1960’s and 1970’s. The recycling of paper products has become commonplace, as have government-mandated levels of postconsumer fiber content. A single sheet of paper could contain fibers from hundreds of different trees around the world. These fibers travel thousands of kilometers from the forest to the office printer. While recycling technologies have greatly improved in the twenty-first century, there is still only a 10 percent chance that the common paper used in personal printers contains postconsumer recycled fibers. On average, office employees in the United States use almost ten thousand sheets of paper, roughly 12 kilograms of paper per person per year. In 2005, the average North American created 302 kilograms of paper waste per year compared to 231 kilograms for citizens of high-income countries other than the United States and Canada, or 39 kilograms for citizens of middle-income countries, or 4 kilograms for citizens of low-income countries.
The manufacturing of paper and paperboard involves the production and conversion of pulp from some fibrous furnish. “Furnish” is any blend of fibrous materials (such as timber, wood chips, or recycled paper) used to produce pulp. Wood is the most commonly used furnish—roughly 95 percent of all pulp and paper manufacturers use wood in some...
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Pulp Production (Encyclopedia of Global Resources)
The production of pulp once involved the breaking down of homogeneous furnish feedstock into its fibers, often bleaching to increase the whiteness of the paper fibers, and mixing with water to produce a slurry. In August, 1998, the Environmental Protection Agency (EPA) passed a regulation called the cluster rule. This rule requires the pulp industry to stop the use of bleaches in paper production and imposes the use of chlorine-free colorants instead. These chlorine dioxide derivatives are created from sodium chlorate instead of chlorine. A totally chlorine-free future is being sought by the EPA for paper production in the United States and other countries.
There are four types of pulping processes: chemical, semichemical, mechanical, and secondary fiber pulping. Chemical pulping includes the kraft (sulfate) process, soda pulping, sulfite pulping, and neutral sulfite chemical pulping. Mechanical pulping includes chemi-mechanical, thermo-mechanical, chemi-thermo-mechanical, refiner mechanical pulping, and stone groundwood pulping. The type of pulping process affects the durability, appearance, and intended use of the resulting paper product. Regardless of the pulping method employed, pulping is “dirty.” During the pulping stage of production, nuisance odors may be released into the air, and dioxins from kraft chemical bleaching may be released into wastewater. Thus the pulping process is a major concern to the EPA in the...
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Manufacturing Paper (Encyclopedia of Global Resources)
There are two general steps in the process of making paper and paperboard: wet-end operations and dry-end operations. During the wet-end operations, processed pulp is transformed into a paper product via a paper machine, the most common of which is the Fourdrinier paper machine.
Pulp slurry (more than 90 percent water at the start) is deposited on a rapidly moving wire mesh for removal of the water by gravity, vacuum chambers, and vacuum rolls. After vacuum rolling, a continuous sheet is left, which is then pressed between a progression of rollers to extract any additional water and to compress the fibers. The sheet is then ready for dry-end operations. During this stage, the sheet enters a drying area, where the paper fibers start to bond as they are compressed by steam-heated rollers. The sheets are then pressed between massive rollers to reduce paper thickness and to produce a smooth surface. After a smooth thin sheet of paper is produced, coatings may be applied to improve the color, luster, printing detail, and brilliance. Finally, the paper product is spooled for storage.
From there, the process of bringing the consumer a standard 8.5-inch-by-11-inch sheet of paper involves nothing more than loading the spool of oversized paper onto a machine and slitting it down to size. Large mechanical guillotine cutters that operate at incredibly high speeds cut the mother sheet into smaller segments and the finished...
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Further Reading (Encyclopedia of Global Resources)
Biermann, Christopher J. Handbook of Pulping and Papermaking. 2d ed. San Diego, Calif.: Academic Press, 1996.
Gray, Wayne B. Productivity Versus OSHA and EPA Regulations. Ann Arbor, Mich.: UMI Research Press, 1986.
Holik, Herbert, ed. Handbook of Paper and Board. Weinheim, Germany: Wiley, 2006.
Hunter, Dard. Papermaking: The History and Technique of an Ancient Craft. 2d ed., rev. and enlarged. New York: A. A. Knopf, 1947. Reprint. New York: Dover Publications, 1978.
Joint Textbook Committee of the Paper Industry. Pulp and Paper Manufacture. 2d ed. Edited by Ronald G. Macdonald and John N. Franklin. New York: McGraw-Hill, 1969.
Smith, David C. History of Papermaking in the United States, 1691-1969. New York: Lockwood, 1971.
Smith, Maureen. The U.S. Paper Industry and Sustainable Production: An Argument for Restructuring. Cambridge: Massachusetts Institute of Technology Press, 1997.
Thorp, Benjamin A., and M. J. Kocurek, eds. Paper Machine Operations. Pulp and Paper Manufacture, Series Seven. 3d ed. Atlanta, Ga.: Joint Textbook Committee of the Paper Industry, 1991.
Tillman, David A. Forest Products: Advanced Technologies and Economic Analyses. Orlando, Fla.: Academic Press, 1985.
U.S. Environmental Protection Agency Office of Enforcement and Compliance Assurance. EPA Office of...
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Paper (Encyclopedia of Science)
Paper is an indispensable part of everyday life. Beyond its use as the basic material for written and printed communication, paper in its various forms are used for hundreds of other purposes, including packaging, wrapping, insulating, and toweling. Each year, Americans use an average of 750 pounds (340 kilograms) of paper products per person. That equates to 210 billion pounds (95 billion kilograms) of paper products used in the United States per year.
The word paper comes from papyrus, a reedy plant that used to grow abundantly along the Nile River in Egypt. Centuries ago, ancient Egyptians removed the fibrous layers from the stem of this plant and cemented them together to create a durable woven writing material also known as papyrus. Examples of papyrus manuscripts have survived to the present.
Many sources claim that paper (as we know it) was first invented in A.D. 105 by Ts'ai Lun, a Chinese court official. Historians believe he mixed mulberry bark, hemp, and rags with water, mashed it into a pulp, pressed out the liquid, then hung the thin mat on a mold of bamboo strips to dry in the Sun. Paper made from rags in about A.D. 150 still exists today.
By the early seventh century, paper and its production had been introduced into Japan. From here, it spread to Central Asia by 750. Paper did not make its way into Europe until about 1150, but it...
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Paper (West's Encyclopedia of American Law)
A document that is filed or introduced in evidence in a lawsuit, as in the phrases papers in the case and papers on appeal.
Any written or printed statement, including letters, memoranda, legal or business documents, and books of account, in the context of the FOURTH AMENDMENT to the U.S. Constitution, which protects the people from unreasonable SEARCHES AND SEIZURES with respect to their "papers" as well as their persons and houses.
In the context of accommodation paper and COMMERCIAL PAPER, a written or printed evidence of debt.
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Paper (How Products are Made)
Formed from wood pulp or plant fiber, paper is chiefly used for written communication. The earliest paper was papyrus, made from reeds by the ancient Egyptians. Paper was made by the Chinese in the second century, probably by a Chinese court official named Cai Lun. His paper was made from such things as tree bark and old fish netting. Recognized almost immediately as a valuable secret, it was 500 years before the Japanese acquired knowledge of the method. Papermaking was known in the Islamic world from the end of the eighth century A.D.
Knowledge of papermaking eventually moved westward, and the first European paper mill was built at Jativa, in the province of Valencia, Spain, in about 1150. By the end of the 15th century, paper mills existed in Italy, France, Germany, and England, and by the end of the 16th century, paper was being made throughout Europe.
Paper, whether produced in the modern factory or by the most careful, delicate hand methods, is made up of connected fibers. The fibers can come from a number of sources including cloth rags, cellulose fibers from plants, and, most notably, trees. The use of cloth in the process has always produced high-quality paper. Today, a large proportion of cotton and linen fibers in the mix create many excellent papers for special uses, from wedding invitation paper stock to special paper for pen and ink drawings.
The method of making paper is essentially a simple oneix up vegetable fibers, and cook them in hot water until the fibers are soft but not dissolved. The hot water also contains a base chemical such as lye, which softens the fibers as they are cooking. Then, pass a screen-like material through the mixture, let the water drip off and/or evaporate, and then squeeze or blot out additional water. A layer of paper is left behind. Essential to the process are the fibers, which are never totally destroyed, and, when mixed and softened, form an interlaced pattern within the paper itself. Modern papermaking methods, although significantly more complicated than the older ways, are developmental improvements rather than entirely new methods of making paper.
Probably half of the fiber used for paper today comes from wood that has been purposely harvested. The remaining material comes from wood fiber from sawmills, recycled newspaper, some vegetable matter, and recycled cloth. Coniferous trees, such as spruce and fir, used to be preferred for papermaking because the cellulose fibers in the pulp of these species are longer, therefore making for stronger paper. These trees are called "softwood" by the paper industry. Deciduous trees (leafy trees such as poplar and elm) are called "hardwood." Because of increasing demand for paper, and improvements in pulp processing technology, almost any species of tree can now be harvested for paper.
Some plants other than trees are suitable for paper-making. In areas without significant forests, bamboo has been used for paper pulp, as has straw and sugarcane. Flax,
Cotton and linen rags are used in fine-grade papers such as letterhead and resume paper, and for bank notes and security certificates. The rags are usually cuttings and waste from textile and garment mills. The rags must be cut and cleaned, boiled, and beaten before they can be used by the paper mill.
Other materials used in paper manufacture include bleaches and dyes, fillers such as chalk, clay, or titanium oxide, and sizings such as rosin, gum, and starch.
The Manufacturing Process
- 1 Several processes are commonly used to convert logs to wood pulp. In the mechanical process, logs are first tumbled in drums to remove the bark. The logs are then sent to grinders, which break the wood down into pulp by pressing it between huge revolving slabs. The pulp is filtered to remove foreign objects. In the chemical process, wood chips from de-barked logs are cooked in a chemical solution. This is done in huge vats called digesters. The chips are fed into the digester, and then boiled at high pressure in a solution of
- 2 The pulp is next put through a pounding and squeezing process called, appropriately enough, beating. Inside a large tub, the pulp is subjected to the effect of machine beaters. At this point, various filler materials can be added such as chalks, clays, or chemicals such as titanium oxide. These additives will influence the opacity and other qualities of the final product. Sizings are also added at this point. Sizing affects the way the paper will react with various inks. Without any sizing at all, a paper will be too absorbent for most uses except as a desk blotter. A sizing such as starch makes the paper resistant to water-based ink (inks actually sit on top of a sheet of paper, rather than sinking in). A variety of sizings, generally rosins and gums, is available depending on the eventual use of the paper. Paper that will receive a printed design, such as gift wrapping, requires a particular formula of sizing that will make the paper accept the printing properly.
Pulp to paper
- 3 In order to finally turn the pulp into paper, the pulp is fed or pumped into giant, automated machines. One common type is called the Fourdrinier machine, which was invented in England in 1807. Pulp is fed into the Fourdrinier machine on a moving belt of fine mesh screening. The pulp is squeezed through a series of rollers, while suction devices below the belt drain off water. If the paper is to receive a water-mark, a device called a dandy moves across the sheet of pulp and presses a design into it.
The paper then moves onto the press section of the machine, where it is pressed between rollers of wool felt. The paper then passes over a series of steam-heated cylinders to remove the remaining water. A large machine may have from 40 to 70 drying cylinders.
- 4 Finally, the dried paper is wound onto large reels, where it will be further processed depending on its ultimate use. Paper is smoothed and compacted further by passing through metal rollers called calendars. A particular finish, whether soft and dull or hard and shiny, can be imparted by the calendars.
The paper may be further finished by passing through a vat of sizing material. It may also receive a coating, which is either brushed on or rolled on. Coating adds chemicals or pigments to the paper's surface, supplementing the sizings and fillers from earlier in the process. Fine clay is often used as a coating. The paper may next be supercalendered, that is, run through extremely smooth calendar rollers, for a final time. Then the paper is cut to the desired size.
The number of trees and other vegetation cut down in order to make paper is enormous. Paper companies insist that they plant as many new trees as they cut down. Environmentalists contend that the new growth trees, so much younger and smaller than what was removed, cannot replace the value of older trees. Efforts to recycle used paper (especially newspapers) have been effective in at least partially mitigating the need for destruction of woodlands, and recycled paper is now an important ingredient in many types of paper production.
The chemicals used in paper manufacture, including dyes, inks, bleach, and sizing, can also be harmful to the environment when they are released into water supplies and nearby land after use. The industry has, sometimes with government prompting, cleared up a large amount of pollution, and federal requirements now demand pollutionfree paper production. The cost of such clean-up efforts is passed on to the consumer.
Where To Learn More
Biermann, Christopher J. Essentials of Pulping & Papermaking. Academic Press, 1993.
Bell, Lilian A. Plant Fibers for Papermaking. Liliaceae Press, 1992.
Ferguson, Kelly, ed. New Trends and Developments in Papermaking. Miller Freeman, Inc., 1994.
Munsell, Joel. Chronology and Process of Papermaking, 1876-1990. Albert Saifer Publisher, 1992.
deGrassi, Jennifer. "Primitive Papermaking." Schools Arts, February 1981, pp. 32-33.
Kleiner, Art. "Making Paper." Co-Evolution Quarterly, Winter 1980, p. 138.
Lamb, Lynette. "Tree-Free Paper." Utne Reader, March-April 1994, p. 40.
Saddington, Marrianne. "How to Make Homemade Paper." Mother Earth News, December-January 1993, p. 30+.
Sessions, Larry. "Making Paper." Family Explorer, October 1994.
i>Lawrence H. Berlow