How to make Paper :: essays research papers

Paper is a thin, flat material produced by the compression of fibres. The fibers used are usually natural and based upon cellulose. The most common material is wood pulp from pulpwood (largely softwood) trees such as spruces, but other vegetable fiber materials including cotton, linen, and hemp may be used. A stack of 500 sheets of paper is called a ream. The edges of paper sheets can act as very sharp razors, leading to paper cuts. Manufacture Whether done by hand or with a Fourdrinier Machine, the paper making process has four simple steps: Preparation of the fibres The material to be used for making paper is first converted into pulp, a concentrated mixture of fibers suspended in liquid. As many of these fibres are derived from natural sources, this process often requires many stages of separation and washing. Once the fibers have been extracted, they may also be bleached or dyed to alter the appearance of the final product. Forming into sheets The pulp mixture is then further diluted with water resulting in a very thin slurry. This dilute slurry is drained through a fine-mesh moving screen to form a fibrous web. A watermark may be impressed into the paper at this stage of the process. This moving web is pressed and dried into a continuous sheet of paper. In the case of the mould process, a quantity of the pulp is placed into a form, with a wire-mesh base (or other draining device), so that the fibres are left coated on the mesh and excess water can drain away. At this time, pressure may be applied to remove more water through a squeezing action. The paper may then be removed from the mould, wet or dry, and go on to further processing. Most mass-produced paper is made using a continuous (Fourdrinier) process to form a reel or web. When dried, this continuous web may be cut into rectangular sheets by slitting the web vertically and then cutting it horizontally to the desired length. Standard sheet sizes are prescribed by governing bodies such as the International Organization for Standardization (ISO). Further additives Raw paper that contains only pressed and dried pulp is very absorbent (for example, blotting paper), and does not provide a good surface upon which to write or print. Thus, a huge variety of additives are employed to add desired properties to the paper. These are applied in a coating called the size. Sizing agents are often polymers designed to provide a better printing surface.