Commercial Papermaking :: essays papers

Commercial Papermaking Paper in 20th-century civilization, is one of our most important industrial products. Books, magazines, and newspapers are printed on paper. Data from computers are usually printed on paper. Education, government and industry could not operate without printing and writing on paper. Paperboard (used in packaging), and absorbent papers (tissue and towelling) are other widely used paper products. Paper is made from cellulose fibbers, which are found in all plant cell walls. When a mixture of water and fibbers is filtered through a fine screen, the fibbers tangle together to form a sheet of paper. As the wet sheet is dried chemical bonds form between the molecules in cellulose fibbers next to one and other. This gives the sheet of paper its strength. The grade and type of any paper depends on the fibbers and processes used in making it. The basic process of making paper has not changed in more than 2000 years. It involves two stages: the breaking up of raw materials in water to make a suspension of individual fibbers and the formation of felted sheets by spreading this suspension on a porous surface, to drain excess water. The essential steps of papermaking by machine are identical with those of hand papermaking just much more complex. The first step in machine papermaking is the preparation of the raw material. For centuries, the main raw materials used in papermaking were cotton and linen fibbers obtained from rags. Today more than 95 percent of paper is made from wood cellulose. Wood is used mainly for the cheapest grades of paper, such as newsprint. Cotton and linen fibbers are still used for high quality writing and artist’s papers. Many kinds of wood can be used such as aspen, beach, birch fir, gum, hemlock, oak, pine, and spruce. The preparation of making wood into a pulp for papermaking is accomplished in two different ways. In the groundwood process, blocks of wood are held against a fast revolving grindstone that shreds off short wood fibbers from the block. The fibbers produced by this process are short and are used only in the production of cheap newsprint and used to be added with other types of wood fibber in the making of high-quality paper. Another technique uses a chemical-solvent processes where wood chips are treated with solvents that remove â€Å"resinous material and lignin† from the wood, leaving pure fibbers of cellulose.