Erasers
A must-have for first day of school, these small bits of molded rubber are handy to have when you need to fix something written in pencil or pen.
Credit: iStock
Although there are felt-pad chalkboard and white board erasers, the essence of an eraser is a plain piece of rubber–”graphite grabbers,” some people in the industry like to call them. Even so, there are many types of these erasers, including handheld flat rectangles, cylindrical plugs attached to a pencil, or caps that fit over the end of a pencil. There are also all sorts of colorful novelty erasers in various geometric shapes with holiday, animal, sports, and other motifs.
The story of the chemistry behind erasers is really a historical tale about rubber. It begins with the development of the pencil. Graphite began to be used as a writing device by the 1560s, and the first crude pencils were fashioned shortly thereafter (C&EN, Oct. 15, 2001, page 35). At first, unwanted pencil marks were rubbed off with a ball of moist bread and probably other similar materials.
In 1752, the proceedings of the French Academy of Sciences noted that caoutchouc (condensed latex) obtained from the Hevea brasiliensis rubber tree could be used to erase pencil marks. The first scientific description of caoutchouc had come during a French geographic expedition to South America in 1735. The name rubber was given to caoutchouc in 1770, and is attributed to none other than British-American chemist Joseph Priestley. He noted that caoutchouc was useful to “rub out” pencil marks; hence the name rubber was born. In most parts of the world, erasers are still called rubbers.
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Excerpted with permission, Chemical & Engineering News
Copyright © 2002 American Chemical Society