The distinction between paper and board, however, is not sharp, but, in the usual case, paper is lighter in BASIS WEIGHT , thinner, and more flexible than board. Usually, all sheets 12 points (0.012 inch) or more in thickness are classed as boards, while those less than 12 points are classed as paper. The exceptions to this include blotting paper, which is greater than 12 points in thickness, and chipboard, which is less than 12.
Paper may be produced from animal fibers, e.g., wool, fur, hair, silk; mineral fibers, e.g., asbestos; synthetic fibers, e.g., rayon or nylon; and even ceramics, metals, glass, and other materials. Most paper, however, is produced from cellulosic plant fibers, principally those obtained from wood pulp (trees), cotton and linen (rags),ESPARTO (GRASS) , and cereal (straw). Other materials used at times and in specialized places include: Abaca, Addar grass, Arundo donax (Spanish grass), bagasse, bamboo, baobab, carob, cotton linters, hemp, henequen, Johnson grass, jute, manila hemp, sisal, and sunflower stalks.
The earliest known paper was made in China, by Ts'ai Lun, although whether he actually invented the process or simply recorded its importance is debatable, and, while its origin has been tentatively established to be 104 to 105 A.D., there is evidence that it may have been known a hundred or more years earlier. Nearly a thousand years later the invention spread from China, moving eastward to Japan, south to India, and west to the Near East. From there is spread to Egypt, Morocco, and Spain (Toledo) in the 12th century. At about the same time the Italians learned the process in Palestine and returned with it to Italy. From Spain it spread to France, Holland, Germany, and the rest of Europe. In 1490, papermaking was begun in England by John Tate at Stevenage in Hertfordshire. William Rittenhouse established the first paper mill in the United States (Philadelphia) in 1690, some 100 years after paper was first made in Mexico.
The quality of early European paper (all of which was made from linen or cotton rags, or a mixture of the two) was very superior. Most of it seems to be of a relatively heavy substance with considerable character in the texture of the surface. It was also well sized. Subsequent to the invention of the stamping mill, in Valencia, Spain, in the 12th century, which shortened and facilitated the maceration of the pulp, the fibers of paper became shorter and the character of paper gradually changed, becoming smoother and thinner.
Very early in the 19th century, the manufacture of paper became mechanized, an event which was to have a profound effect on the craft of bookbinding. Whereas in paper made by hand the stretch caused by pasting or other moistening is virtually the same in all directions, the stretch in paper made on a machine is far greater in the cross direction than in the MACHINE DIRECTION .
This affects the bookbinder in many important ways; e.g., if the machine direction of the paper making up the leaves of a book runs the wrong way—at right angles to the spine—the leaves will probably not lie flat under their own weight, unless the paper is very thin or the surface area of the leaves is very great.
When the shortage of rags became chronic late in the 18th century, papermakers were forced to turn to other potential sources of vegetable fiber. Experimental papers were produced, but nothing new was adopted on a large scale until early in the 19th century when straw was first used.ESPARTO (GRASS) , the first really successful substitute for linen and cotton fibers, was put into commercial production early in the 1860s, and about 20 years later chemical and mechanical wood pulp papers were being produced in great quantities for use as book papers.
Early in the 19th century papermakers discovered that it was more economical to add rosin to the pulp while it was being beaten instead of dipping the sheet of waterleaf into a solution of gelatin in the manner practiced since the 12th century. Rosin reduced the absorbency of the paper, but, unlike gelatin, did not increase its strength. A great deal of the machine-made paper of this period is of low quality, having little tensile strength. It is also subject at times to severe FOXING .
The weakness, however, is probably due more to the ALUM used to precipitate the rosin than the rosin itself.
Paper coated with one of the clays, e.g., china clay, came into common use at the end of the 19th century. This type of paper is ideal for printing fine halftones, but it lacks strength, is easily damaged by moisture, and unless synthetic resins instead of starch are used as binders, the surface strips off easily. See: HANDMADE PAPER ;PAPERMAKING . See also: ABSORBENT PAPERS ;ACCELERATED AGING TESTS ;ACID-FREE PAPER ;AIR PERMEABILITY ;BASIC SIZE ;BASIS WEIGHT ;BREAKING LENGTH ;BRIGHTNESS ;BRIGHTNESS REVERSION ;BRITTLENESS ;BULK (2 , 3 , 4 );BULK EQUIVALENTS ;BURST FACTOR ;BURSTING STRENGTH ;COMPRESSIBILITY ;CONDITIONING ;COTTON FIBER CONTENT PAPER ;DECKLE EDGE ;DUPLEX (1) ;
FOLDING ENDURANCE ;FORMATION ;FOURDRINIER MACHINE ;FOURDRINIER WIRE ;GROUNDWOOD FREE PAPER ;M.M. SYSTEM ;MOLD-MADE PAPER ;SIZES OF PAPER ;
WATERLEAF ;WATERMARK .
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Timestamp: Saturday, 19-Nov-2011 13:18:43 PST
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