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You’re probably staring at a screen right now, whether it is a laptop, cell phone or tablet, but look at the space around you and there is a good chance that you’ll see something that is made of paper. Yes, paper is one of the most ubiquitous and useful inventions ever conceived by man, and it is also one of the simplest substances to create.
However, you’ve probably also noticed that paper has a surprisingly good memory. Whether it is creasing over the corner of your favorite book or getting an unfortunate fold in a resume moments before you hand it over to a potential employer, we all know about the idiosyncrasies of paper. The question is, once a fold is made in paper, why is it nearly impossible to remove?
People and Paper
Humans have been making and using paper for nearly 2,000 years, and while the details of the materials and processes used have changed slightly over time, the basics remain the same. Despite the recent push for more green production of paper, as well as an increased use of recycled paper, most paper that is produced today still comes from woodpulp, which comes from trees.
More specifically, the wood from the trees is ground up and then smashed around or pressed, which releases the plant fibers. It is then mixed with water so the fibers separate into what is known as pulp. When that pulp is laid down on a rack or mesh screen, the fibers re-bond and can be pressed flat and dried, resulting in a sheet of paper. Now, that is a very rudimentary explanation of what is now a major industrial process (paper is rarely made by hand anymore), but the basic physical manipulation of the material remains the same. This practice has been perfected in countless cultures over the centuries and perfected into the process we know today. Other materials than woodpulp can be used, such as bamboo, hemp or cotton, but the vast majority is derived from trees.
Creases in Paper
When you fold a newspaper or a letter in an envelope, those aren’t temporary decisions, because paper is nearly impossible to un-crease once it has been folded over. Given how flexible and durable (relatively speaking) paper is, it seems odd that it has such a permanent memory, particularly because the paper is then weaker at those folded points.
The reason for this one-way ticket to Creasetown is because of the composition of paper. As described above, paper is essentially a mat of smashed together plant fibers that is smoothed down into a flat sheet. When you bend the paper, you snap or fracture those plant fibers alone the line of force applied. Even if the paper is unfolded and smoothed down, that line of snapped fibers remains, as will the obvious crease in the paper. A crease is nothing more than the memory of destruction!
For those who simply can’t abide a crease in their letters, there are other forms of paper—albeit archaic—that don’t experience the same permanent folding problem. Animal vellum, for example, which was used in the preparation of parchment for centuries, is similarly composed of fibers, but they are of animal origin. Animal tissues tend to be more elastic and malleable than plant tissues, so the temporary distortion or bending of animal fibers can be undone, whereas folds in plant fiber cannot. This might take some time, as the animal tissues don’t immediately snap back into place, but with a crease in plant-based paper, you’ll be waiting a LOT longer.
A Final Word
Given how universally used and desired paper is, it is more important than ever to be aware of how you use this precious material. There are as many as 7 billion trees cut down each year, which is a staggering number, considering how rapid deforestation has been escalating in recent decades. Recycling paper and being more careful with your waste of this critical resource is one important way that you can make a difference in this modern-day green revolution!
- Explain That Stuff
- British Origami Society
- Environmentally Friendly Technologies for the Pulp and Paper Industry edited by Raymond A. Young
- CAB Direct