Xerography
Xerography is a dry photocopying technique.[1] Originally called electrophotography, it was renamed xerography—from the Greek roots ξηρός xeros, meaning "dry" and -γραφία -graphia, meaning "writing"—to emphasize that unlike reproduction techniques then in use such as cyanotype, the process of xerography used no liquid chemicals.[2]
"Electrophotography" redirects here. For the photographic technique, see Kirlian photography.History[edit]
Xerography was invented by American physicist Chester Carlson, based significantly on contributions by Hungarian physicist Pál Selényi. Carlson applied for and was awarded U.S. patent 2,297,691 on October 6, 1942.
Carlson's innovation combined electrostatic printing with photography, unlike the dry electrostatic printing process invented by Georg Christoph Lichtenberg in 1778.[3] Carlson's original process was cumbersome, requiring several manual processing steps with flat plates.
In 1946, Carlson signed an agreement with Haloid Photographic Company to develop it as a commercial product. Before that year, Carlson had proposed his idea to more than a dozen companies, but none was interested. Haloid's president, Joseph C. Wilson, saw the promise of Carlson's invention, and saw to it that Haloid diligently worked to produce a working commercial product.
It was almost 18 years before a fully automated process was developed, the key breakthrough being the use of a cylindrical drum coated with selenium instead of a flat plate. This resulted in the first commercial automatic copier, the Xerox 914, being released by Haloid/Xerox in 1960.
Xerography is now used in most photocopying machines and in laser and LED printers.
Durability[edit]
Xerographic documents (and the closely related laser printer printouts) can have excellent archival durability, depending on the quality of the paper used. If low-quality paper is used, it can yellow and degrade due to residual acid in the untreated pulp; in the worst case, old copies can literally crumble into small particles when handled. High-quality xerographic copies on acid-free paper can last as long as typewritten or handwritten documents on the same paper. However, xerographic copies are vulnerable to undesirable toner transfer if they are stored in direct contact or close proximity to plasticizers, which are present in looseleaf binders made with PVC. In extreme cases, the ink toner will stick directly to the binder cover, pulling away from the paper copy and rendering it illegible.
Uses in animation[edit]
Ub Iwerks adapted xerography to eliminate the hand-inking stage in the animation process by printing the animator's drawings directly to the cels. The first animated feature film to use this process was One Hundred and One Dalmatians (1961), although the technique was already tested in Sleeping Beauty, released two years earlier. At first, only black lines were possible, but in 1977, gray lines were introduced and used in The Rescuers and in the 1980s, colored lines were introduced and used in animated features like The Secret of NIMH.[7]
Uses in art[edit]
Xerography has been used by photographers internationally as a direct imaging photographic process, by book artists for publishing one-of-a-kind books or multiples, and by collaborating artists in portfolios such as those produced by the International Society of Copier Artists founded by American printmaker and book artist, Louise Odes Neaderland.[8] Art critic Roy Proctor said of artist/curator Louise Neaderland during her residency for the exhibition Art ex Machina at 1708 Gallery in Richmond, Virginia, "She's living proof that, when a new technology begins to be mass-produced, artists will be curious enough—and imaginative enough—to explore its creative uses.[9]