Paper—That Versatile Product!
IMAGINE something so versatile that you can drink out of it, wrap things in it, blow your nose on it, write on it, wear it, make furniture out of it, and even eat off it! Impossible? Well, such a product already exists and has been around for a very long time.
This versatile product is paper. Perhaps ordinary paper somehow lacks the glamor of computerized gadgetry. Nevertheless, paper has had quite a profound impact on your life. Before the advent of paper, writing was a cumbersome process of chiseling letters on stone and engraving words on clay tablets. Knowledge was thus reserved for a privileged few. Paper helped change all of that.
It all began when the Egyptians found a clever way to use a water reed named papyrus. They would cut the stalk into thin strips and line them up slightly overlapping. Another layer of strips was then placed at right angles to the first and glued on top. Then the whole thing was hammered flat and left in the sun to dry. As a finishing touch, it was polished to give it a relatively smooth surface for writing.
Apparently, papyrus was used as far back as the days of the Biblical patriarch Abraham. And though manufacturing it back then was not easy, it was still superior to chiseling away on stone. So it became an important medium of communication in ancient times. In fact, early copies of the Bible were made on papyrus. True, other writing materials, such as vellum, usually made from calfskin, also came into use. But papyrus had made its mark. From it would come the English word “paper.”
From Rags to Tree Trunks
Paper from old rags? It might sound strange, but that was the next step forward for paper. Old rags, you see, contained cellulose—the main ingredient of paper. And the Chinese, about 105 C.E., figured out how to manufacture paper from a pulpy mixture of old rags, tree bark, hemp, and even fishing nets!
The Chinese art of papermaking took time to spread abroad, but by the 12th century it reached Europe. So when in the 15th century Gutenberg began to print his famous Bible, paper was already on the scene, a willing servant ready for the job. Paper thus gave impetus to the rapid spread of knowledge during the Renaissance. But dramatic discoveries in the manufacture of paper were still to come.
As the demand for paper grew, the supply of rags ran short. Men then began toying with the idea of using tree trunks as the prime ingredient. The problem, though, was finding an easy way to reduce wood to pulp. In the 19th century, a chemical process was discovered that could do the job. Inventors came up with a machine that could make paper in continuous rolls. The scene was set for the modern paper revolution—mass production!
Papermaking Today
Though refined by modern technology, paper manufacturing has changed little. It begins either in natural forests or in groves of trees grown specifically for papermaking. (One South African paper manufacturer plants over 12 million saplings a year.) The trees are felled and ground into chips that are then cooked into a pulpy mass. This pulp is refined and bleached and sent to a papermaking machine called a fourdrinier.
How does it work? First the pulp enters the forming section of the machine, via a moving belt of fine wire-mesh. The wood fibers tend to align themselves in the direction of travel, which accounts for the grain of the paper. Too, the belt is shaken sideways to mesh the fibers. This gives the paper strength. Water drains through this mesh belt by gravity and with the help of vacuum boxes below.
Now the pulp enters the press section of the machine. At this point the pulp is still 80-85 percent water by weight, and a series of rollers, along with suction, removes more water and compacts the paper web. On to the drying section. Here the web passes over steam-heated cylinders, which remove yet more water by evaporation. Finished? Not necessarily. For some paper the dried web passes through another set of rollers that iron out any unevenness and give the paper a smoother surface. The finished product is now ready to be wound onto a reel and trimmed to its desired size.
You may wonder, though, how process-control checks are made in such a high-speed operation. Well, modern technology has developed quite a system of on-line process-control systems. Sensing devices continuously scan the moving web. Beta rays may be used to check basis weight, and the paper may pass through a magnetic field to check its thickness. Infrared reflection may be used to gauge moisture content. And, yes, computers are used to monitor the paper as it passes through its various stages of production.
Making Paper Versatile
How is it, though, that paper is so versatile? While most paper is made of wood pulp, other materials are also used, such as esparto grass, bagasse (the residue from sugarcane), and bamboo. Linen, cotton, and hemp are also still used, especially for high quality writing and specialty papers, such as Bible paper. What results when these different fibers are used in different combinations? Papers that have vastly different qualities.
Consider greaseproof paper and blotting paper. Though opposites, they are made from the very same fiber! How so? Different refining and manufacturing procedures are used. In fact, simply using different additives can impart different qualities to paper. China clay gives paper a smoother finish by filling the gaps between the fibers. Bleaches and dyes improve the color. Titanium dioxide improves opacity, so that the printing on the other side of the paper does not show through. Formaldehyde resins help paper stay strong when wet—a necessary quality for tea bags! Why, even melted paraffin may be a key ingredient. It coats waxed paper.
The possible uses for paper seem endless. Paperboard coated with plastic is used in bookcases and chairs. Synthetic fibers, such as nylon and orlon, have also been used on their own or blended with wood pulp to make papers with fabriclike qualities for clothing and electrical insulation.
Meeting the Growing Demand
It has been said that the progress of a modern society can be measured by its paper consumption. Interestingly, in 1982 paper and paperboard production totaled 67 million tons in the United States alone. This astonishing demand creates new challenges for manufacturers.
For one thing, paper mills consume vast quantities of water—250 tons per ton of wood pulp! As the Britannica 1983 Yearbook of Science and the Future puts it, ‘A large paper mill uses as much water per day as a city of 50,000 inhabitants’! Then there is the problem of what to do with wastepaper.
Manufacturers have met these problems with ingenuity. A major plant in South Africa treats domestic sewage and uses the reclaimed water to wash logs. This greatly cuts down on water use. Another popular strategy is the recycling and repulping of wastepaper. In the United States over 25 percent of the fibrous material used in papermaking is obtained from wastepaper.
Whether manufacturers will be able to keep pace with both the needs of a wasteful population and the realities of a depleted planet, only time will tell. For sure, the demand for paper will continue to be great. The publishers of this magazine put to use huge quantities of it in the printing of Bibles and Bible literature. And they plan no letup in that grand work. (Matthew 24:14) Educators, industrialists, scientists, businessmen, and housewives will likewise continue using paper.
So the next time you pick up a book, write a letter, or eat off a paper plate, take a brief moment to contemplate the importance, usefulness, and indispensability of this simple yet versatile product—paper!
[Picture on page 23]
Johannes Gutenberg and his press. Without paper he could not have printed the Bible
[Picture on page 24, 25]
The fourdrinier, with the starting (wet) end at the left
[Picture on page 24]
Wet end of a large high-speed fourdrinier