In 1770, the noted scientist Sir Joseph Priestley (discoverer of oxygen) recorded the following, "I have seen a substance excellently adapted to the purpose of wiping from paper the mark of black lead pencil." Europeans were rubbing out pencil marks with the small cubes of rubber, the substance that Condamine had brought to Europe from South America. They called their erasers "peaux de negres". However, rubber was not an easy substance to work with because it went bad very easily -- just like food, rubber would rot.

In 1839, Charles Goodyear discovered a way to cure rubber and make it a lasting and useable material. He called his process vulcanization, after Vulcan, the Roman god of fire. In 1844, Goodyear patented his process. With the better rubber available, erasers became quite common.

The first patent for attaching an eraser to a pencil was issued in 1858 to a man from Philadelphia named Hyman Lipman. This patent was later held to be invalid because it was merely the combination of two things, without a new use.

Today's pencil erasers are made from either a synthetic rubber compound or from vinyl. In either case, the raw material is blended to the proper consistency and is put into a machine called an "extruder." The eraser material is forced through a small hole producing a long ribbon of eraser.

Each ribbon is cut into strands about 3 feet in length. If the eraser is made of synthetic rubber, the strands are placed in a "vulcanizer," which cooks them under pressure to cure the rubber. When cool, the strands are put into a rotary cutter and chopped into bits -- called plugs. (Vinyl eraser strands go straight to the rotary cutter -- vinyl does not need to be vulcanized!)

Rubber eraser plugs must be tumbled to round-off the edges. The tumbler is a big drum that rotates slowly -- and it holds 600 pounds of rubber eraser plugs at a time! Vinyl eraser plugs do not need to be tumbled -- they're ready to insert right from the cutter

Factoid #1: A lot of erasers are made by pencils manufacturers! That makes sense, since we think of the eraser as a regular component of the everyday pencil. But pencils didn't always have erasers. The first patent for attaching an eraser to a pencil was issued in 1858 to a man from Philadelphia named Hyman Lipman. And even today in Europe, most pencils are sold without erasers!

Factoid #2: Erasers weren't always called erasers! The item was originally referred to as a "rubber," because the tree resin it was made of "rubbed out" marks made by a pencil. In Great Britain, the eraser is still called a "rubber!"

Factoid #3: To eraser manufacturers, those little erasers on the ends of pencils aren't called "erasers" at all. They call them "plugs!"

Factoid #4: More and more of today's erasers are made from something other than rubber! While some of the "pink" erasers you find on pencils are made from synthetic rubber blended with pumice (a grit that enhances its ability to erase), an increasing number of erasers are made from vinyl. Vinyl is a type of durable, flexible plastic.

Well I hope you had fun learning some fun facts about the eraser.