eraser

EraserFrom Wikipedia, the free encyclopedia

For other uses, see Eraser (disambiguation).

An eraser, (also called a rubber in the UK, Ireland, India, Australia, New Zealand, and South Africa, fromthe material first used) is an article of stationery that is used for removing writing from paper. Erasers have arubbery consistency and come in a variety of shapes, sizes and colours. Some pencils have an eraser on one end.Less expensive erasers are made from synthetic rubber, but more expensive or specialized erasers are vinyl,plastic, or gum-like materials. Cheaper erasers can be made out of synthetic soy-based gum.

Erasers were initially made for pencil markings, but more abrasive ink erasers were later introduced. The termis also used for things that remove writing from chalkboards and whiteboards.

History

Before rubber erasers, tablets of rubber or wax were used to erase lead or charcoal marks from paper. Bits ofrough stone such as sandstone or pumice were used to remove small errors from parchment or papyrusdocuments written in ink. Crustless bread was used as an eraser in the past; a Meiji -era (1868-1912) Tokyostudent said: "Bread erasers were used in place of rubber erasers, and so they would give them to us with norestriction on amount. So we thought nothing of taking these and eating a firm part to at least slightly satisfy ourhunger."[1]

In 1770 English engineer Edward Nairne is reported to have developed the first widely-marketed rubber eraser,for an inventions competition. Until that time the material was known as gum elastic or by its native Americanname (via French) caoutchouc. Nairne sold natural rubber erasers for the high price of three shillings perhalf-inch cube. According to Nairne, he inadvertently picked up a piece of rubber instead of breadcrumbs,discovered rubbers erasing properties, and began selling rubber erasers. The invention was described by JosephPriestley on April 15, 1770, in a footnote: "I have seen a substance excellently adapted to the purpose of wipingfrom paper the mark of black-lead-pencil. ... It is sold by Mr. Nairne, Mathematical Instrument-Maker, oppositethe Royal-Exchange."[2] In 1770 the word rubber was in general use for any object used for rubbing;[3] theword became attached to the new material sometime between 1770 and 1778.[4]

However, raw rubber was perishable. In 1839 Charles Goodyear discovered the process of vulcanization, amethod that would cure rubber, making it durable. Rubber erasers became common with the advent ofvulcanization.

On March 30, 1858, Hymen Lipman of Philadelphia, USA, received the first patent for attaching an eraser tothe end of a pencil. It was later invalidated because it was determined to be simply a composite of two devicesrather than an entirely new product.[5]

Erasers may be free-standing blocks (block and wedge eraser), or conical caps that can slip onto the end of apencil (cap eraser). A barrel or click eraser is a device shaped like a pencil, but instead of being filled withpencil lead, its barrel contains a retractable cylinder of eraser material (most commonly soft vinyl). Many, butnot all, wooden pencils are made with attached erasers.[6] Novelty erasers made in shapes intended to beamusing are often made of hard vinyl, which tends to smear heavy markings when used as an eraser.

Types

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Pencil or cap erasers

Originally made from natural rubber, but now usually from cheaper SBR, this type contains mineral fillersand an abrasive such as pumice with a plasticizer such as vegetable oil.[6] They are relatively hard (in orderto remain attached to the pencil) and frequently colored red.

Artists gum eraser

The stylized word "Artgum" was first used in 1903 and trademarked in the USA in 1907.[7] That type of eraserwas originally made from oils such as corn oilvulcanized with sulfur dichloride[8] although may now be madefrom natural or synthetic rubber or vinyl compounds. It is very soft yet retains its shape and is not mechanicallyplastic, instead crumbling as it is used. It is especially suited to cleaning large areas without damaging paper.However, they are so soft as to be imprecise in use. The removed graphite is carried away in the crumbles,leaving the eraser clean, but resulting in a lot of eraser residue. This residue must then be brushed away withcare, as the eraser particles are coated with the graphite and can make new marks. Art gum erasers aretraditionally tan or brown, but sometimes are sold in blue.

Vinyl erasers

Quality plasticized vinyl or other "plastic" erasers, originally trademarked Mylar in the mid-20th century, aresofter, non-abrasive, and erase cleaner than standard rubber erasers. This was because the removed graphite didnot remain on the eraser as much as rubber erasers, but was instead absorbed onto the discarded vinyl scraps.Being softer and non-abrasive, they were less likely to damage canvas or paper. Engineers favor this type oferaser for work on technical drawings due to their gentleness on paper with less smearing to surrounding areas.They often come in white and can be found in a variety of shapes. More recently, very low cost erasers aremanufactured from highly plasticized vinyl compounds and made in decorative shapes.

Kneaded erasers

Main article: Kneaded eraser

Kneaded erasers having a plastic consistency are common to most artists standard toolkit. They can be pulledinto a point for erasing small areas and tight detail erasing, molded into a textured surface and used like areverse stamp to give texture, or used in a "blotting" manner to lighten lines or shading without completelyerasing them. They gradually lose their efficacy and resilience as they become infused with particles picked upfrom erasing and from their environment. They are not suited to erasing large areas, as they deform undervigorous erasing.

Poster putty

Commonly sold in retail outlets with school supplies and home improvement products, this soft, malleable puttyappears in many colours and under numerous brand names. Intended to adhere posters and prints to wallswithout damaging the underlying paint, poster putty works much the same as traditional kneaded erasers, butwith a greater tack or lifting strength. Poster putty does not erase so much as lighten by lifting graphite, charcoalor pastel off a drawing. In this regard, it does not smudge or damage work in progress. Repeatedly touching theputty to a drawing pulls ever more medium free, gradually lightening the work in a controlled fashion. Posterputty can be shaped into fine points or knife edges, making it ideal for detailed or painstaking work. It can berolled across a surface to create visual textures. Poster putty loses its efficacy with use, becoming less tacky as


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the material grows polluted with debris and oils from the users skin.

Electric erasers

The electric eraser was invented in 1932 by Arthur Dremel of Racine, Wisconsin, USA.[9] It used a replaceablecylinder of eraser material held by a chuck driven on the axis of a motor. The speed of rotation allowed lesspressure to be used, which minimized paper damage. Originally standard pencil-eraser rubber was used, laterreplaced by higher-performance vinyl. Dremel went on to develop an entire line of hand-held rotary powertools.

Fibreglass erasers

A fibreglass eraser, a bundle of very fine glass fibres, can be used for erasing[10] and other tasks requiringabrasion. Typically the eraser is a pen-shaped device with a replaceable insert with glass fibres, which weardown in use. The fibres are very hard; in addition to removing pencil and pen markings, such erasers are usedfor cleaning traces on electronic circuit boards to facilitate soldering, removing rust, and many otherapplications. As an example of an unusual use, a fibreglass eraser was used for preparing an archaeologicalfossil embedded in a very hard and massive limestone.[11]

Other

Felt chalkboard erasers or blackboard dusters are used to erase chalk markings on a chalkboard. Chalk writingleaves light-coloured particles weakly adhering to a dark surface (e.g., white on black, or yellow on green); itcan be rubbed off with a soft material, such as a rag. Erasers for chalkboards are made, with a block of plastic orwood, much larger than an eraser for pen or pencil, with a layer of felt on one side. The block is held in the handand the felt rubbed against the writing, which it easily wipes off. Chalk dust is released, some of which sticks tothe eraser until it is cleaned, usually by hitting it against a surface.

Various types of eraser, depending upon the board and the type of ink used, are used to erase a whiteboard.

Dedicated erasers that are supplied with some ballpens and permanent markers are intended only to erase theink of the writing instrument they are made for; sometimes this is done by making the ink bond more stronglyto the material of an eraser than the surface it was applied to.[12]

See also

Ink eraserChalkboard eraserKneaded eraser

References

^ Teiykai (1926). Kbu daigakk mukashibanashi (in Japanese). Tokyo: Teiykai. pp. 2526.1. ^ See the footnote on page xv at the end of the preface to the following: Priestley, Joseph (1770). A FamiliarIntroduction to the Theory and Practice of Perspective. London: J. John and J. Payne.

2.

^ Joseph Priestley (1769). A Familiar Introduction to the Study of Electricity. J. Dodsley; T. Cadell, successor to Mr.Millar; and Johnson and Payne. p. 84.

3.

^ R.B. Simpson (ed.), Rubber Basics, iSmithers Rapra Publishing, 2002, ISBN 185957307X, p.46 "Rubber"4.


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