How Does an Eraser Work?

Erasers

When the tip of a pencil is moved across a piece of paper, graphite particles from the pencil stick to the paper fibers. An eraser rubbed against the paper will remove the mark. The most common erasers are the kind you find on the end of pencils or their siblings, the rectangular-shaped rubber erasers. There are also cylindrical erasers, which are enclosed in plastic and are retractable so that they can be held like pencils. Art gum erasers are soft erasers used for erasing large areas. Kneaded erasers are soft, pliable erasers that pick up pencil marks by being pressed on to the paper instead of being rubbed.

What Erasers Are Made of

Erasers are composed mostly of either natural or synthetic rubber, although plastic and vinyl are also commonly used. The rubber is combined with sulfur in order to vulcanize it, which makes it longer lasting and heat-resistant. A softener, usually vegetable oil, is added to control the flexibility of the eraser. Kneaded erasers, for instance, have more softeners than the eraser on the end of a pencil. Abrasives, such as powdered pumice or quartzite, are then added. A dye is also added to give the eraser its characteristic pink, white, green or brown color.

How Erasers Remove Pencil Marks

The abrasives in the eraser work by gently scratching the surface of the paper to release the graphite particles, while the softeners keep the paper from being too damaged during the rubbing. The graphite particles stick to the rubber pieces of the eraser. The more abrasive an eraser is, the more a thin layer of paper comes off with the graphite. Kneaded erasers work by absorbing the graphite without damaging the paper, but they can only absorb so much graphite before they begin to leave marks on the paper.

Resources

• Erasers World