How Paper is Made
How Paper Is Made
The first historical evidence of a paper dates back nearly 6000 years to the Egyptians and their making of Papyrus, which, by the way, is the root of our modern word “paper”. The Egyptians wove strands of flat reeds and plants together and then pounded it flat to make it smoother for writing and drawing. The Greeks and Romans also used this technique to make paper and were probably the first to use animal skins to make parchment for writing. It wasn’t until 105 AD that the Chinese developed the paper making method we use today, that of combining tree bark with cotton fiber and water. It is interesting to note that up until the mid-19th century, the primary content in paper was cotton rags
Today, paper making starts with a visit to the forest and understanding a few things about trees and wood.
First, there are two basic types of trees for paper making: hard wood and soft wood. Hard woods, such as oak and maple, have shorter wood fibers and are used for paper that require a harder and smoother surface. These papers are better for writing and printing.
Pine and spruce trees are the primary softwood for paper making. Their fibers are longer and add strength to paper for such products as grocery bags, corrugated boxes and the like. However, where the product is stronger, the surface is rougher and less desirable for writing. In most paper making today there is a blending of the two types of fiber to yield a combination of strength and smoothness.
Another source of paper making material today is recycled paper. Every year more and more paper is recycled and in many cases the paper you use or read from contains wood fibers that have been recycled several times. It’s estimated that about 50% of the paper used in America is recovered and used again for paper making and other uses.
Note – I see a lot of emphasis today put on the reduction of printed materials for the sake of saving trees and the world’s forests. A noble gesture and one to be applauded. One of the great things about paper is that its primary raw material –wood – is renewable. The paper and forest products industry replenishes more that it takes and ensures the sustainability of our forests by planting 1.7 million trees every single day, more than three times what is harvested.
After the trees are selected for harvesting they are cut and transported to the paper factory where they are washed, debarked and chipped. The wood chips are sorted by size and then processed into pulp. Pulp is the wet “oatmeal” like material that is the fist big step in becoming paper. Pulping is done in several steps. The wood chips are ground then treated chemically to remove the undesirable material. Water is a main component of pulping and heat is often used, as well.
It’s at this point that cleaning and bleaching agents are used to brighten the pulp for when it is ultimately paper. Dyes and other materials are added at this phase to make a wide variety of colors and shades of paper
Once the pulping is complete it’s time to make paper.
The wet pulp is sprayed onto a wide long vibrating screen called “the wire.” This can be as much as 30 feet wide. The water begins to drain from the pulp and slowly the fibers in the pulp begin to compress together. It’s at this point too that fibers align with each other and form the grain direction of the paper. From here the wire passes through a vacuum stage where suction gently removes more of the water.
Next, the drying pulp is fed between large, felt-covered rollers that absorb still more moisture. The process continues from here with the soon-to-be paper pressed between large steam-heated cylinders that extract the last of the moisture from the pulp and, as the pulp dries, the fibers slowly press closer together, creating paper!
From the dryers the paper moves on to be “calendared”. Calendars are large, smooth, steel rollers grouped in different numbers. As the paper moves across these rollers, the paper begins to be polished making it smoother and smoother with each pass. The degree of calendaring determines how polished the sheet is to be, ranging from uncoated to matte, dull, velvet, satin or gloss. The finished paper can be given more variety by putting it through patterned rollers to create specialty paper of embossed, ribbed, or linen finishes.
This article is a simple overview of a very complex process. I recommend that if you ever get the opportunity to tour a paper making plant that you take the time to do so. You will find it informative, very educational and fascinating.
