From Bread Crumbs to Erasers: How Fixing Mistakes Got Easier

From Bread Crumbs to Erasers

1Every student makes mistakes on paper, and today most of us fix them with a quick rub of an eraser. Yet for a long time after pencils became common in Europe, there were no erasers at all. To remove pencil marks, people often rubbed the paper with a lump of soft bread. The bread did pick up some of the marks, but it left crumbs behind and soon went stale.

2The answer to the problem came from far away. For thousands of years, people in Central and South America had collected a milky sap, called latex, from certain trees. When the sap dried, it became a stretchy material. They used it to make bouncing balls for games and to keep things dry. Later, European explorers brought samples of this material back to Europe.

3In 1770, the English scientist Joseph Priestley wrote that a small piece of this material was excellent for wiping away pencil marks. Because it could rub marks out, people in England began calling it "rubber." Shops soon sold small cubes of rubber for erasing.

4How does an eraser work? A pencil mark is made of tiny bits of graphite that cling to the rough fibers of the paper. When you rub, the bits of graphite stick to the eraser more strongly than they stick to the paper. The crumbs that roll off the eraser carry the graphite away with them.

5Natural rubber still had problems, though. In hot weather it turned soft, sticky, and smelly. In cold weather it became hard and could crack. An eraser that changed with the weather was not very useful.

6In 1839, an American inventor named Charles Goodyear found that heating rubber with sulfur made it much tougher. The treated rubber stayed firm and springy in both heat and cold. This discovery made rubber useful for many products, such as boots, hoses, and better erasers.

7The last step was to bring the pencil and the eraser together. In 1858, a Philadelphia man named Hymen Lipman received a patent for a pencil with an eraser attached to one end. Now a writer would not have to search for a separate eraser. Many pencils are still made this way. Today, some erasers are made from plastic instead of rubber, but they work in a similar way.