Paper is an important part of print production, and it is usually the most expensive material used in the job. It is surprising then that the process of how paper is made is not something that is commonly known.
Commercial paper used in print production is made through several steps. The first step in paper manufacturing is known as pulping. Pulping can be accomplished through mechanical or chemical processes. The mechanical process requires that the wood bark be stripped and the stripped trees are treated by a constant grinding action while water is simultaneously sprayed onto the trees and a grindstone. The debarked trees are pressed against the grind stone, which causes the individual fibres to be crushed, scored, pressed, torn off and sheared.
Chemically pulped paper is taken from woodchips that are similarly treated, but are instead subjected to a chemical form of digestion. Today the sulfate process is being used, which results in paper that is slightly alkaline. Pulp additives are then added to brighten and whiten the paper throughout washing and bleaching. Once the pulp, which is mostly water, has been prepared, the actual paper making machines are used for the remainder of the process. The most common used paper making machine is the Fourdrinier machine.
There are seven sections to paper machines: the first is the headbox, which will distribute the fibres onto a mesh-wire. Second is the wire section that will drain the water from the pulp through gravity and by applying suction. This is followed by a press section, which will further remove water from the newly formed paper web. After the newly formed paper has been drained and mostly dewatered, it moves onto the drying section. Here, the paper web passes around heated cylinders, which will further reduce the water content of the paper.
Sizing and paper coating are applied next to give the paper its properties. After the sizing and coating has been applied, the paper web goes through a calendaring section. In this section of the paper machine, the paper is mechanically evened out to reduce irregularities. After all these processes the paper with its final properties like gloss, absorptivity, brightness and whiteness among many other properties is wound into rolls of finished paper.
Impact of Understanding Paper Making
Understanding how paper is made is important for management because it will help you make informed choices on what kind of paper should be ordered for a particular job. Always keep in mind that the paper properties that influence the runability and cost of a job are determined during the paper making process. In offset and digital printing, for example, the absorption time of the ink can cause paper coating to pick. This can degrade print quality and significantly increase the costs incurred due to waste. Considerations of paper also influence bindery considerations. In particular, the properties of the paper may prevent a sheet from being folded without some form of unsightly cracking. The paper for a particular job should stand at the beginning of the actual job planning, since it will determine the look of the final printed product, as well as meeting all the other end-use requirements.
RYETAGA is Ryerson University’s official Student Chapter of TAGA. We will be submitting our student journal publication to the competition at the 2011 TAGA Annual Technical Conference in March. Our work will be competing against international student chapters from other universities in an attempt to keep the grand prize for best overall student technical journal, the Helmut Kipphan Cup, and Harvey Levenson prize for the undergraduate research paper at Ryerson University.