Saturday, April 5, 2008

Pulp and Paper Development

Paper is a sheet of interlaced fibers-usually cellulose fibers from plants, but sometimes from cloth rags or other fibrous materials-that is formed by pulping the fibers and causing them to felt, or mat, to form a solid surface.


The evolution of writing materials culminated in the development of paper. The oldest written records still surveying are Sumerian clay tablets dating from the 4th millennium BC. Papyrus came into use about 3500 BC. Parchment, made from the skins of animals, was another important material used in Europe from about the 2d century BC. Almost any portable surface that would retain the marks of brush or pen was also used as a writing surface.


The Development of Paper Manufacture

The invention of paper is generally attributed to a Chinese court official, Cai Lun, in about AD 105, he was the first to succeed in making a paper from vegetable fibers-tree bark, rags, old fish netting. The art of making paper was kept secret for 500 years, the Japanese acquired it only in the 7th century.


In AD 751 the Arab city of Samarkand was attacked by marauding Chinese. Among the Chinese prisoners taken were several skilled in papermaking. They were forced by the city's governor soon became the papermaking center of the Arab world.


The Spread of Papermaking in Europe

Knowledge of papermaking traveled westward, spreading throughout the Middle East. The Moorish invasion of Spain led to the erection (c. 1150) of the first European paper mill, at Jativa in the province of Valentica. Knowledge of the technology spread quickly, and by the 16th century paper was being manufactured throughout most of Europe.


Vegetable fibers were shredded and reduced to a pulp in water; a screen was dipped and removed with a thin layer of pulp. As the water drained off, the pulped fibers meshed and metted into a sheet, which was then dried and pressed.


19th Century Improvement

Papermaking technology improved rapidly throughout the 19th century. The introduction of chlorine for bleaching meant that white paper could now be manufactured from colored linen and cotton rags, thus increasing the range of available raw materials. Esparto grass from Spain and North Africa became a valued commodity for papermaking. Only when it was realized that wood pulp be used as a source, however, did large scale paper manufacture that could pulp logs using grindstones revolving in water, but because the pulp contained large amounts of impurities, it was found that these impurities could be removed by boiling the wood pulp with various chemical reagents; soda and sulfite in the 1850s, sulfate in the 1880s.

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