We all know that paper is made from trees. Some of you might even be aware that before the wood becomes paper it forms a material known as pulp. But, given how ubiquitous paper is in our lives, it seems strange that so few of us really understand the process of its manufacture.
The paper industry has changed as time has gone on and it now places a much greater emphasis than before on making the production process as environmentally friendly as possible. Trees to make pulp are increasingly sourced from renewable forests, which are maintained at a constant level so that every time a tree is removed another one matures.
Below we take a quick look at the process of making paper from wood.
The Tree
Looking at a tree, in particular, a strong and majestic one, it is kind of hard to imagine that such a strong and sturdy object could end up becoming something as flimsy as a piece of paper.
To understand how this occurs, we need to understand the composition of wood on a molecular level. Wood is made up of fibers. We call these fibers ‘cellulose’. These cellulose fibers are, in turn, held together by a glue-like substance called ‘lignin’. Before this wood can be turned into paper, the lignin has to be removed so that the cellulose can be separated and made into paper.
Other Materials
Paper can also be made from materials such as cotton, flax, and hemp. Cotton fibers, for example, are used to make the paper that the United States prints its currency on. However, the vast majority of the commercially available paper is printed on paper made from wood.
Pulp
There are a number of different mechanical and chemical processes which can be used to make pulp from wood. Pulp can be thought of as a kind of soup, one that contains the cellulose fibers, alongside lignin and water. Sometimes, other chemicals are added to the pulp, but this depends on exactly which manufacturing technique is going to be used.
These days, the most commonly used process is a chemical-based method which is known as ‘kraft’. To achieve this, certain chemicals are added to the pulp, which allows the lignin and fibers to separate; the extent to which this is done depends on the desired quality of the paper.
For newspapers, phonebooks, and other sources where the quality of the paper isn’t as important, there is no separation of the cellulose and lignin. This leads to a paper that is made of very short fibers, which gives the final product a rough feel.
Pulp to Paper
Once the pulp or kraft has been formulated to the desired standard, then it is time to turn it into paper in the final stage. This is done by spraying the pulp into a mesh screen. It is then dried, heated, and squeezed to remove any residual moisture and compress it into a roll of paper, which can then be cut to size. The final stage is quality control (known as QM management); most paper producers have a dedicated paper and packaging QM management.
The papermaking process is a fascinating one and it is something that you can try on a smaller scale yourself at home!
