How Paper Is Made

The steps of the paper-making process.

Paper is a product that dates back hundreds of years. The most general uses for paper are writing and printing. However, it has several other useful forms in today's marketplace. Paper is used to make cardboard boxes, disposable dinnerware, grocery bags, and various craft supplies. Though paper can be made from almost any plant, 95% is made from trees and recycled paper products. Other common plants used for making paper are rice, linen, cotton, or hemp.

The process for turning wood into paper has evolved over the centuries. Though most paper production is mechanical, the basic premise remains the same. For most paper production, small trees and left over scraps from lumberyards are used. Many trees used for paper are grown on tree farms. They are planted exclusively for paper production. Each tree is replaced as it is harvested to keep the supply steady and plentiful.

There are two kinds of wood used in papermaking. Hardwood trees produce a smoother paper surface, but their smaller fibers tend to make the paper weak. Softwood trees produce a stronger paper, but the finished product is not good for writing and printing. Most paper made today is a mix of the two types, resulting in a strong and smooth paper. Paper used for grocery bags and shipping materials is almost always made of softwood tree fibers. This is due to the fact that the paper is strong, but does not need to be smooth for writing purposes.

After the trees are harvested for paper production, they are cleaned with water and stripped of their bark. The wood is then chopped down to wood chips. Sometimes the chips are passed under a large magnet to ensure that no nails or other metal products are mixed in with the wood. If recycled materials are going to be used, they are added to the wood chips at this point in the process.

The next step is turning the wood chips into pulp. Large amounts of water are used in this process. There are a variety of ways to accomplish this task. Some papermakers have machines that grind the wood and some use a pulp digester. The digester uses steam and chemicals to break down the wood. The end result is wood fibers that are separated from each other. Other than the wood fibers and the water, the pulp also contains wood resins and lignin. These can act as natural bonding agents and are chemically removed so that only the water and wood fibers remain.

After this step, the pulp is 99% water and 1% wood fiber. The pulp is bleached at this point in the process if needed. Chemicals may be added to produce a resistance to ink breakthrough. Lime and clay are often added to promote a smoother, glossier finished product.

The mixture is sprayed onto a wire screen. The water begins to seep through the screen, leaving a matt of pulp. As the water begins to leave the pulp, the remaining fibers begin to bond to one another. This matt of pulp is then fed through enormous felt-lined rollers that press the pulp down and extract more of the water.

The pulp is then run through large steam-filled rollers. These cylinders use heat and pressure to dry the remaining water from the pulp, turning it into paper. The pulp may be run through any number of these cylinders until the desired result is achieved. Sometimes as many as a dozen or more trips through these rollers are needed to complete this process.

The paper is then spooled onto very large rollers to be shipped out, usually by truck. This paper is delivered to companies who use it to make the paper products you find in your local stores. Paper is also sent out for use in newspaper, magazine, or book printing.

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