How Does Eraser Erase Pencil Traces?

How Does Eraser Erase Pencil Traces?

Maybe there are two indispensable tools that we all use every day: pencil and eraser. So how does an eraser erase pencil marks on our paper? In this article, we will examine this situation.

Before moving on to the working principle of the eraser, let’s take a closer look at the tool that makes the writing permanent: Pencil.

Let’s start by explaining this misnomer. Although the lead element is thought to be in pencils, it is not used in them. The lead pencils we use every day consist of a form of the element carbon, called graphite .

The world of chemistry is interesting. The bonds that the elements form with each other affect both the interior and exterior appearance. In other words, it changes both chemical and physical properties. For example, graphite conducts electricity, while diamond is an insulator. The differences resulting from these different geometric shapes are called allotropes. Allotrope means “other form” in Greek. A dazzling diamond and a lump of black coal are just different forms of the element carbon. In fact, coal is called a “black diamond” because of this similarity.

Graphite, which is one of the allotropes of the element carbon, has weak carbon bonds, while those of diamond is very strong.

Graphite, which is made up of these weak carbon bonds, is found in pencils we use every day. The reason why graphite is weak is that the carbons are bonded to each other in flat layers stacked on top of each other.

(You can think of the graphite structure as Jenga towers built on top of each other.)

Thanks to the heat created by the friction force, the carbon atoms at the graphite tip are separated from each other when they come into contact with the paper and bond to the fibers of the paper. We complete the writing process as a result of the carbon atoms at the tip of our pen being transferred to the paper with the help of friction.

Let’s think about the moment when we rub the pen against the paper to write and the Jenga analogy just before. With each friction, a layer of our tower sticks to the paper and stays there.

How does the eraser work?

The working principle of the erasers is based on the removal of the adhered carbon atoms from the paper with the help of friction. Synthetic plastics called PVC are used in almost all of the erasers we use in our daily life. Rubber-like materials such as PVC become more sticky when the temperature rises. When the eraser comes into contact with the paper, it creates a high friction force and therefore high heat is produced. In this way, the carbon atoms on the paper are combined with the eraser, which becomes more sticky, and the paper surface is cleaned.

NOTE: The invention of the pencil is much older than the invention of the eraser. The eraser was invented in 1770 by an English engineer named Edward Nairne. Before the invention of the eraser, various methods were used to clean paper. Perhaps the most interesting of these was the white bread crumb. (You can try this interesting method yourself at home.) When the bread crumb is exposed to heat, it turns into a doughy structure and becomes more sticky. For this reason, it has been used instead of an eraser for a long time by moving it on the paper quickly.

In fact, legend has it that Nairne accidentally took a piece of rubber instead of bread one day and discovered that it was cleaning up pencil marks. The word “rub”, which is the root of the English word “rubber”, which means both eraser and rubber.

References and Further Readings

Allotropes of carbon. (2021, February 14). Retrieved February 21, 2021, from https://en.wikipedia.org/wiki/Allotropes_of_carbon

How does an eraser work? (n.d.). Retrieved February 21, 2021, from https://www.wonderopolis.org/wonder/how-does-an-eraser-work#:~:text=When%20you%20rub%20an%20eraser,to%20loosen%20the%20graphite%20particles.&text=The%20sticky%20rubber%20in%20the,Erasers%20work%20because%20of%20friction.

Rıtter, S. (2001, October 15). C&EN: What’s that STUFF? – PENCILS & pencil lead. Retrieved February 21, 2021, from http://pubsapp.acs.org/cen/whatstuff/stuff/7942sci4.html

Trimarchi, M. (2020, June 22). How do erasers erase? Retrieved February 21, 2021, from https://science.howstuffworks.com/innovation/everyday-innovations/erasers-erase.htm

You can access the sources of the images used by clicking on the images.

The proofreading has been done by Asu Pelin Akköse and Mete Esencan.