Pencil Facts: How Erasers Work
We know pencils work thanks to graphite molecules breaking off and catching onto the fibers of paper. Today, we’re going to figure out how erasers work to remove those bits of graphite when you make a mistake.
As it turns out, erasers work using complicated chemistry. Because this is a pencil blog, we’ll try to avoid too much scientific jargon, but If you would like more detailed information, check out the links at the bottom of this article.
What Makes up an Eraser
Erasers are most commonly made of either rubber or vinyl. These main materials are the substances that give erasers their stickiness, the quality that allows them to pick up graphite from paper.
The sticky base is counteracted with a softener – vegetable oil, factis – and then vulcanized with sulfur. The factis has an uncanny penchant for picking up graphite. To give the eraser color, chemists add various dyes.
How Erasers Erase
Most of us assume that the eraser is ‘rubbing out’ the marks on our paper when we need to correct a mistake. It seems like the eraser might be eliminating the graphite on the page.
The truth is, the way erasers actually work is a bit counterintuitive. As we’ve explained, you make pencil marks when flakes of graphite ‘catch’ onto and in-between the paper fibers, thanks to a phenomenon called the London Force.
When you rub an eraser on a pencil-marked piece of paper, you produce heat through friction. When the rubber molecules get hot, they become sticky. The graphite molecules start mingling once again – this time with the sticky eraser molecules. Rubber molecules ‘pick up’ the graphite molecules, and the molecular mixtures break off from the eraser in tiny particles. That’s why erasers produce “dust!”
For more information on the workings of an eraser, check out the following links:
Wonderopolis: How Does An Eraser Work?
Obviously, erasers contain volatile chemistry and thus are able to dry-out and become stiff and non-usable. What is the best way to store erasers, and can they be rejuvenated in any way?
As a chemist, I really loved to read this post and would like to know even more! Thank you for sharing such a delightful read. I would buy something in appreciation if I weren’t fighting so hard to get my career/reputation restored! Thank you!