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Paper, how is paper made from trees

Paper in more or less the form we know it today was first made from trees in a.d. 105 by a Chinese, Tsai Lun. He discovered that certain plant materials could be broken down into fibers (of cellulose) and pressed into a sheet which made a good writing material.

Until the mid-1800's most paper was band-made from rags or from grasses such as hemp and esparto. But then it was received the answer to a question: how is paper made from trees (wood-pulp). Wood-pulp is produced mainly from soft-wood trees such as fir, pine, and spruce. The felled trees are cut into logs and transported, often by water, to the pulp-mills. There they are first debarked in a revolving drum. Then they are broken down into a pulp either by grinding or by boiling with chemicals in a pressure cooker called a digester. Chemical digestion is used to produce rag and esparto pulp, too.

 The diagram shows how is paper made from trees

The diagram shows how paper is made from trees.

It may take the timber of 7,000 trees to make enough wood pulp for 400 tons of paper. But this amount may be used in one edition of a newspaper (click to increase)

Ground wood, or mechanical pulp, is used mainly for producing newsprint - the paper on which newspapers are printed. The pulp may be pressed into sheets for transport to the paper-mill. There, the sheets are converted back into a wet pulp in a big tub (the hydropulper). The wet pulp then passes to a beating machine, which frays the fibers.

Newspaper, how is paper made from trees

Constant inspection of the complicated machinery in a paper mill is necessary to produce high quality paper

At the 'wet end' of the paper-making machine, the watery pulp is spread over a wire-mesh belt. Most water drains or is sucked away to leave a damp paper web. The web is then pressed into a firm sheet by heavy rollers and dried by being passed over a series of heated cylinders. Finally, calendar presses (heavy, heated rollers) give the paper a smooth finish.

Different grades of paper are made by blending various pulps and by varying the amount of beating in the heating machines - the more beating, the denser the paper. High-quality printing papers are coated with materials such as clay to give them a glossy surface. Some papers are sized (treated with glue) to make them take writing better. Tissue papers are given their texture by being scraped off the drying cylinders.

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