Eraser

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Common erasers

An eraser or rubber is an article of stationery that is used for removing pencil and sometimes pen writings. Erasers have a rubbery consistency, and they are often white, brown or pink although with modern materials they can be of any color. Many pencils are equipped with an eraser on one end. Typical erasers are made of synthetic rubber, but more expensive or specialized erasers can also contain vinyl, plastic, or gum-like materials. Other more inexpensive erasers can be made out of synthetic soy-based gum.

1 History
2 Types
3 References
- 3.1 Notes
- 3.2 Bibliography
4 See also
5 External links

[edit] History

A pencil eraser.

Prior to the invention of the rubber eraser, tablets of wax would be used to erase lead/charcoal marks from paper. Some people claim that white bread (without crust) would be used as an eraser along with wax tablets, this would work effectively, but the bread would disintegrate, and would be too costly to replenish.^[1]

In 1770, Edward Nairne, an English engineer, is credited with creating the first rubber eraser because he heard that there was a competition for the entire world, to see who could have the best innovation. He reportedly sold natural rubber erasers for the high price of 3 shillings per half-inch cube. According to Nairne, he inadvertently picked up a piece of rubber instead of breadcrumbs, discovered rubber's erasing properties, and began selling rubber erasers. Incidentally, this was the first practical application of the substance in Europe, and rubbing out the pencil marks gave it its English name.

However, rubber in its raw form shared the same inconveniences as bread, since it was perishable and would go bad over time. In 1839, inventor Charles Goodyear discovered the process of vulcanization, a method that would cure rubber and make it a durable material. Rubber erasers became common with this advent of vulcanization.

On March 30, 1858, Hymen Lipman of Philadelphia, USA, received the first patent for attaching an eraser to the end of a pencil. It was later invalidated because it was determined to be simply a composite of two devices rather than an entirely new product ^[2].

[edit] Types

Cap erasers.

Two kneaded erasers. A new eraser is on the left, and an older eraser on the right. The older eraser is darker due to the graphite and charcoal dust that has become incorporated into the eraser.

Erasers are often found on the end of a pencil opposite the graphite point. The type of eraser often attached to pencils is usually pink, red or green, and has a smooth, rubbery texture. Erasers also come in many different colors to match the pencil to which they are attached, especially for novelty purposes. Pulverized pumice is blended into this type of eraser to make it abrasive. It is good for most erasing purposes, though it tends to smear and can damage the paper if used too heavily. It leaves eraser residue that must be brushed away; care must be taken in brushing away residue, as the eraser particles can leave marks on the paper. Some erasers do not erase well because they lack the flexibility to clear the paper of the pencil markings.

Another eraser type that is popular with artists is the art gum eraser, made of soft, coarse rubber. It is especially suited to removing large areas, and does not damage the paper. As gum erasers tend to crumble as they are used, this type leaves a lot of eraser residue, however, and is not very precise. Many artists use a broad brush to sweep away the loose eraser residue. Art gum erasers are commonly tan or brown.

The kneaded eraser (or kneaded rubber eraser) is also well-known among artists. It is usually made of a grey or white pliable material that resembles putty or chewing gum. It functions by "absorbing" and "picking up" graphite and charcoal particles. It does not wear away and leave behind eraser residue, thus it lasts much longer than other erasers. Kneaded erasers can be shaped with the fingers and used for precision erasing, to create highlights, or for detailing work. It is commonly used to remove light charcoal and light graphite marks in subtractive drawing techniques. However, it is not well-suited to completely erasing large areas, and may smear or stick if it becomes too warm. Though it does not wear away like other erasers, it can become exhausted, unable to absorb any more graphite or charcoal in which case it will start to smear and actually make marks instead of erasing them.

Soft vinyl erasers have a plastic-like texture and erase cleaner than standard pink erasers. They are somewhat softer and non-abrasive, making them less likely to damage canvas or paper. They are prone to cause smearing when erasing large areas or dark marks, so are more frequently used for erasing light marks and precision erasing. Engineers favor this type of eraser for work on technical drawings due to their gentleness on paper. Vinyl erasers are commonly white.

Another type of eraser is used specifically for marks on a chalkboard or whiteboard. Rather than being rubbery or gummy like pencil erasers, it is a hand-held wooden or plastic block with a dark felt pad on one side.

Erasers come in several shapes and sizes. In addition to those that come attached to pencils, they may also be rectangular blocks (block and wedge eraser), or conical caps that can slip onto the end of a pencil (cap eraser). A barrel or click eraser is a device shaped like a pencil, but instead of being filled with pencil lead, its barrel contains a retractable cylinder of eraser material (most commonly vinyl). Novelty erasers are made in a wide variety of shapes, colors, and designs to suit their themes (such as musical notes, animals, confectionery), and they are typically acquired more for their decorative nature than for any practical use.