Copies in Seconds           Copies in Seconds

                Copies in Seconds                  Copies in Seconds

Chester Carlson and the

Birth of the Zerox machine.

THE FIRST PLAIN-PAPER OFFICE COPIER —which was introduced in 1960 and has been called the most successful product ever marketed in America —is unusual among major high-technology inventions in that its central process was conceived by a single person. David Owen’s fascinating narrative tells the story of the machine nobody thought we needed but now we can’t seem to live without.


People often assume that xerography must be related to conventional photography, but it’s not. It is unlike any technology that preceded it, and it was not a refinement of a previously existing process. Its central component is a surface known as a photoreceptor. In the 914, the photoreceptor was a thin layer of selenium applied to the outside of an aluminum cylinder. Selenium is an unusual element in that it acts as an electrical insulator in the dark and as an electrical conductor in the light. If you place a selenium photoreceptor in a dark room and spray a uniform electrostatic charge onto its surface, the charge will remain until you turn the lights back on, at which point the selenium will become conductive and carry the charge away into the (grounded) aluminum cylinder underneath.

If you shine a light on a document in such a way that an image of the document is projected onto a charged selenium photore-ceptor, the selenium coating will retain its charge in those areas t here no light falls—that is, in those areas that correspond to the dark ink on the document—and lose it everywhere else. If you then sprinkle an oppositely charged powdered resin onto the selecopiium coating, the resin will stick to the areas where the charge remains, in the same way that house dust sticks to a staticly balloon. Doing so will produce on the surface of the selenium a visible mirror image of the original document.

Chester Carlson grew up in unspeakable poverty, worked his way through junior college and the California Institute of Technology, and made his discovery in solitude in the depths of the Great Depression.


ALL FOUR OF CHESTER CARLSON’ S GRANDPARENTS emigrated from Sweden to the United States in the mid-nineteenth century. For the most part, they came seeking religious freedom. (Carlson‘s grandfather on his father’s side, for example, had been disinherited by his own father after becoming interested in baptism by immersion and other practices proscribed by the Swedish National Church.) They settled, at different times, on what turned out to be neighboring homesteads in Grove City, Minnesota, a tiny Swedish farming community about seventy-five miles west of Minneapolis.

Chester’s father, Olof Adolph Carlson, was born in Grove City in 1870. He hated farming and hated working for his father, and he fled as soon as he was wenty-one. He learned to cut hair in a barbershop in Elgin, Illinois—where he also briefly attended a “business college”—then drifted west, traveling partly by bicycle, giving haircuts along the way. He ran a barbershop in Ogden, Utah, which in the 1 890s was a booming frontier railway junction. Then he took to the road again, probably spurred by reports of gold discoveries in Alaska. He covered his expenses by cutting the matted hair and beards of miners in camps in southeastern Washington, and eventually found steady work in a barbershop in Seattle. Sometime afterward, his old Grove City neighbor Ellen Josephine Hawkins—who was three months younger and had been a friend throughout his childhood—traveled to Seattle to attend a convention of Swedish Baptists. They renewed their acquaint- ance and married shortly afterward.

A relative later described Olof as “brilliant”—a reader and a deep thinker, although his formal education was sketchy. Ellen was bright, cheerful, and reasonably attractive, and she had an indomitably optimistic outlook. She was the third eldest in a family of ten children (four boys and six girls) “and was looked up to by her sisters as one of the wisest and as a sort of leader,” Chester Carlson wrote later. She also had a “great capacity for personal sacrifice of her own self-interest for others, and for endurance of hardship.”


Ellen had many opportunities to demonstrate these noble qualities, because the Carlsons’ life together was unlucky from the start. Chester’s birth—in Seattle, on February 8, l906—was preceded by that of a stillborn boy and followed by a stillborn girl. When Chester was an infant, Olof came home from work one day with what at first seemed to l)e a cold and then seemed to he pneumonia hut turned out to be tuberculosis. Olof also suffered increasingly from arthritis in his spine, and the two illnesses combined to incapacitate him—especially in later years, when they were accompanied by what was almost certainly a severe, unremitting depression. Chester knew his father only as an invalid, never as a provider, and remembered him later as “a bent walking skeleton, who had to spend the greater part of his time lying flat on his back.” Olof was strikingly handsome when he was young but looked eighty by the time he was forty-five. In a family photograph taken when Chester was nine, Olof lurks in the back-ground, a wraith suspended from a pair of crutches, his sunken cheeks gnawed by shadows. His forehead is lowered and his chin is drawn back: he is straining for breath. He looks old enough to be his son’s grandfather.

Olof’s ill health dominated Chester’s childhood. When Chester was three and a half, in 1909, Olof moved the family to Kingsburg, California, where one of his brothers owned a vineyard and where he hoped the mild climate would help him. It did mt. Four months later, thinking dry air might bring relief, he moved the family again, to what must have been a religious camp or a sanitarium, called Camp Freedom, in the desert near Yurna, Arizona. The Carlsons lived there in a two-story wood-framed tent erected among sand dunes, and Olof spent much of every day lying on a cot in the tent’s oven like interior, hoping to bake the disease from his lungs. He had a deep, excruciating cough, and each cough wrenched his spine. One day, in agony, he suddenly cried out that he wished he could die, and Chester, who was now bur years old, heard him and was deeply frightened.

In 1910, after eight months in Arizona, Olof moved the family gain. “My father had been roped in on a crazy American land colinization scheme in Mexico,” Chester wrote later. “I suspect he sunk the bulk of his remaining savings into it, sight unseen. We raveled to the site, which was several hundred miles down the west coast of Mexico, with all our personal belongings. On arrival he found that the ‘ farm’ my father had presumably bought was nothing but dry adobe clay and cactus, totally unproductive.”

The property was near the town of Abuya, in the state of Sinaloa. Olof, who was no longer physically able to cut hair, had been attracted to the scheme in part by promises of plentiful ine.ensive Mexican labor. The promises turned out to be false but irelevant, since the land was too poor to have occupied even a single worker. The Carlsons bought a cow and some chickens but had no hope of planting crops, and they were barely able to feed themselves. Then the rainy season arrived, and the parched ground was transformed into thick, gluelike mud. Water stood a foot deep on the floor of the two-room adobe hut in which they lived, and they were forced to take refuge in bed—the only dry surface in their home. Periodically, the cow and chickens became stuck in the mire, and Ellen had to wade outdoors to free them. And that wasn’t the worst of it. “My father’s health deteriorated further,” Chester wrote later, “my mother contracted malaria, and we were beset by scorpions, tarantulas and snakes, chicken thieves, and eventually the threat of danger from the Mexican revolution.”

The Carlsons lived in Mexico for seven months, a period that Chester described later as “probably the most grueling and depressing time in my young life, although much more so for my partents, who protected me from the worst.” Ellen, in particular, strove to shield her son from their destitution. She remained cheerful during her own serious illness, and Chester said later that throughout his childhood she had always somehow managed to make the family’s poverty seem like a game—a challenging puzzle that could he solved with good spirits and ingenuity. In Mexico, furthermore, Chester, for just the second time in his life, had other children to play with. (The first time had been during the family’s four months in Kingsburg, where he had enjoyed what he would later describe, in the heartbreakingly flat tone that characterizes nearly all his written childhood reminiscences, as “the first experience I had had with playfellows.”) The Carlsons’ Mexican farm was situated near the farms of four or five other American families, all of whom had been duped by the same land fraud, and one of the other fathers started a small school, in which Chester constituted half the kindergarten. It was at this school that he made his first real friend, a little girl named Pauline Nickerson, who was so fond of him that five years later she was still sending him letters.

The turmoil that became the Mexican Revolution commenced in November 1910, and American officials advised all U.S. citizens to leave the country. Olof, who was now nearly penniless, abandoned his adobe hut and booked passage on the only form of transportation he could afford, a rusting freighter bound for Los Angeles. Baggage wasn’t a problem, because the Carlsons’ remaining possessions fit easily into a single trunk. At sea on Christmas morning, the freighter~s captain, feeling sorry for his youngest passenger, gave Chester the only present he would receive that day: a chocolate bar.

He offered his big idea to two dozen major corporations —among them IBM, RCA, and General Electric—all of which turned him down. So persistent was this failure of capitalist vision that by the time the Xerox 914 was manufactured by an obscure photographic-supply company in Rochester, New York, Carlson’s original patent had expired. Xerography was so unusual and nonintuitive that it conceivably could have been overlooked entirely. Scientists who visited the drafty warehouses where the first machines were built sometimes doubted that Carlson’s invention as even theoretically feasible.


WHEN GUTENBERG MADE BOOKS, he reproduced illustrations the way the Chinese did: with carved wood blocks, which he incorporated into his page forms. Printing from wood blocks and printing from metal type are both subsets of a single general printing technique, called relief printing: the ink is applied to surfaces that stand out in relief, or protrude, from a nonprinting background, and when paper is pressed onto those surfaces and then pulled away, much of the ink comes with it.

Around the time of Gutenberg’s birth, an Italian invented a method of reproducing images which solved the same problem from the opposite direction. The method is called intaglio. An intaglio engraver creates a printable surface not by removing the nonprinting background areas, the way a woodcarver or a type founder does, but by carving away the lines of the image itself, usually on a plate made of polished copper or some other soft metal. After the desired text or image has been engraved (in reverse), the plate is inked and then wiped clean, so that the ink remains only inside the carved indentations, below the surface of the plate. A piece of paper is then pressed firmly against the plate, causing the ink in the indentations to transfer to the sheet. The finely detailed enravings in old books are often examples of intaglio printing; so are engraved wedding invitations and all U.S. currency. (On an engraved wedding invitation or a reasonably recent dollar bill, the areas directly behind any printed characters or images appear slightly depressed, you’ll notice if you look closely, because those areas were squeezed into the indentations in the plate.)

THE NEXT GREAT STEP FORWARD in duplication was the invention of lithography, or “stone writing.” Because lithography was invented after printing and copying had become comparatively common, we know much more about its creator and the circumstances of his discovery than we do about Gutenberg. In 1795, a twenty-four-year-old German playwright and former law student named d Alois Senefelder—who looked like a slightly scruffy version of Beethoven—was experimenting with printing methods. His father, a noted actor, had died a few years before, leaving Senefelder largely responsible for the support of his mother and eight siblings. His inaugural effort as a professional writer—a play aIled The Connoisseur of Girls, which was first performed in 1789, shortly before his father’s death—had been a financial success, but since that time he had had difficulties with publishers, and he set ut to devise an economical means of printing his works himself.

Senefelder was an engagingly open-minded researcher; at one point, he explored the possibility of fashioning printing plates from /hat was almost baked pastry. He also reasoned that stone might rmake an inexpensive and easy-to-use engraving medium for inaglio printing, and he tried his idea several times, with mixed success. Then, one day, his mother asked him to quickly make a list of the items in a load of clothing she was about to send out for laundering. “1 happened not to have even the smallest slip of paper at hand,” he wrote, “as my little stock of paper had been entirely exhausted by taking impressions from the stones; nor was there even a drop of ink in the inkstand.” His mother was in a hurry, though, so he flipped a pen in a waxy, experimental ink (which he had recently created for use in his intaglio experiments) and wrote the list on the polished surface of a large piece of Kelheim limestone, Intending to copy it later with a pen and paper.

As soon as the laundry was out the door, though, Senefelder looked at the waxy marks on the stone and was inspired: perhaps the stone could be used to make relief prints instead of intaglio ones. 1-fe bathed the limestone surface in a solution of nitric acid, figuring the acid would etch away stone everywhere except in the places where the waxy ink protected it. After five minutes, he removed the acid and rinsed the surface—but was disappointed to find that the stone appeared to have been affected very little, rather than being deeply etched, as he had hoped. He applied printer’s ink to the written image anyway, and the ink, which was oil based, stuck readily to the wax. After the stone had dried, Senefelder pressed a piece of paper onto its surface, then peeled away a print—a lithograph. Although the difference in relief between the etched and unetched parts of the stone was less than a hundredth of an inch, Senefelder estimated, the stone plate printed as effectivelv as a carved block of wood.

Drawing on interviews, Xerox company.archives, and the private papers of the Carlson family, David Owen has woven together a fascinating and instructive story about persistence, courage, and technological innovation—a story that has never before been fully told.


IT TOOK TWO NEW INVENTIONS working together to begin to displace the copying press as the world’s foremost device for re-producing routine office correspondence. The first was carbon paper, which was invented in 1806 by an Englishman named Ralph Wedgewood; the second was the typewriter, which was introduced in the I 870s. Neither carbon paper nor the typewriter alone would have been sufficient, hut the two inventions together eventually put copying press manufacturers out of business.

Ralph Wedgewood was a black sheep member of the famous pottery family and therefore also a relative of Charles Darwin’s. (Darwin’s maternal grandfather was Josiah Wedgwood.) He called his invention Wedgewood’s Patent Stylographic Manifold Writer, and originally intended it as a writing aid for the blind. The system’s central element was a sheet of ink-soaked paper, which Wedgewood called “carbonic” or “carbonated” paper. Thomas Jefferson, America ‘s original copying evangelist, tried it and didn’t like it very much, although he acknowledged that a traveler might find it useful. “The fetid smell of the copying paper would render a room pestiferous if filled with presses of such paper,” he wrote in a letter to Charles Willson Peale, who had been worried about the competition. Wedgewood’s system, in addition to smelling bad, was harder to use than later carbon papers would be. The main difference was that Wedgewood’s paper, having been fully saturated with a pigmented oil, was inky on both sides. A user placed a sheet of it between a sheet of translucent paper and a sheet of regular paper, and wrote on the translucent sheet with a stylus made of metal, glass, or agate. Pressure from the stylus, which wasn’t inked, pro(luced a reversed image on the hack of the translucent sheet and a properly oriented image on the front of the regular sheet. The regular sheet was treated as the “original”—it was the page that went into the mail—while the translucent sheet, which had to be flipped over in order to be read in the correct orientation, was tiled. This awkward-seeming system was made necessary by quill pens, which couldn’t be pressed hard enough to cause Wedgewood’s carbon paper to leave a legible image.

By mid-century, pens and carbon paper had both been improved to the point where carbon copies could be made in the manner familiar to twentieth-century users. The 1881 edition of a popular reference book, The Household Gyclopedia of General Information, contained a recipe for making your own: “A mixture of equal parts of Frankfort black, and fresh butter is now to be smeared over sheets of paper, and rubbed off after a certain time. The paper, thus smeared, is to be pressed for some hours, taking care to have sheets of blotting paper between each of the sheets of black paper.” Frankfort black was a popu]ar nineteenth-century pigment, originally imported from Germany. According to a 1913 dictionary, it was prepared by “burning vine twigs, the lees of wine, etc.”

Wedgewood made some money from his invention, but carbon paper didn’t really flourish until it was paired with the typewriter, which struck paper with enough force to create an attractive original and several acceptable facsimiles. The first truly practical type-writer was the Sholes & Gliddon, introduced in 1874 by E. Remington & Sons, a manufacturer of sewing machines and guns. (The earliest model looked like a sewing machine—it had a treadle-powered carriage return —and sounded like a gun.) Among the first customers was Mark Twain, who was almost as much of a gadget-loving early adopter as Thomas Jefferson. Twain paid $125 for his machine, which typed only in capital letters. Late in his life, he claimed (in an unpublished autobiography) to have been “the first person in the world to apply the type-machine to literature”—since in 1874 he had hired a typist

to make a copy of part of the manuscript for one of his books, most likely The Adventures of Tom Sawyer (Twain is also often said to have been the first person in the world to have had a telephone installed in his home.)

Twain actually despised his typewriter, which he found complicated and frustrating, and soon got rid of it. When Remington, in 1875, asked him for an endorsement, he wrote, “GENTLEMEN: Please do not use my name in any way. Please do not even divulge the fact that I own a machine. I have entirely stopped using the Type-Writer, for the reason that I never could write a letter with it to anybody without receiving a request by return mail that I would not only describe the machine, but state what progress I had made in the use of it, etc., etc. I don’t like to write letters, and so I don’t want people to know I own this curiosity -breeding little joker. Yours truly, SAML. L. CLEMENS.” Remington happily, and quite understandably, reproduced this note (under the heading WHAT “MARK TWAIN” SAYS ABOUT IT) in all its advertising.

The function performed by the carbon-paper-and-typewriter combination fell somewhere between copying and duplicating. Carbon paper isn’t really a copying device, since you couldn’t use it to (for example) make a copy of the crossword puzzle in today’s newspaper. But it produced as many as ten duplicates without an intermediate step, and it economically performed almost all the same functions that a copying press did. As a result, the copying press gradually disappeared, not only from offices but also from the collective memory of the world.

ONE OF THE MOST IMPORTANT nineteenth-century advances in copying technology didn’t involve the creation of a new device—although it did enhance all existing copying devices (and several still-to-be-developed ones). This was the invention of aniline dyes, the world’s first synthetic coloring agents. In 1856, an

eighteen-year-old English college student named William Henry Perkin was experimenting with coal-tar derivatives in an effort to create a substitute for quinine, which was made from the bark of a Peruvian tree and was then the only treatment for that great scourge of the far-flung British Empire, malaria. At the conclusion of one unsuccessful experiment, Perkin noticed a dark residue in the bottom of a test tube. Later, by accident, he discovered that the residue stained cloth bright purple. This substance came to be called mauveine, or aniline purple, and it was soon followed by numerous similar substances in various shades.

Aniline dyes—which were far more vivid and uniform than natural colorants, such as Frankfort black—transformed fashion (Queen Victoria wore mauve to her daughter’s wedding, in 1858), interior decoration (the colors that defined Victorian homes were the colors of aniline dyes), chemistry (Perkin had shown that a test tube could make a man rich), and industry (the mass production of fabrics and other colorful consumer products became increasingly practical and profitable).*

(*An interesting book on this very topic not only could be written hut has been:

Mauve: “How One Man Invented a Color That Changed the World”, by Simon Garfield.)

Copying also changed. “Aniline dyes were swiftly adopted for copying inks”—the kind used with copying presses-—”because they possess great tinctorial power, a property required in order to create multiple copies,” Barbara Rhodes and William Wells Streeter write in a wonderfully comprehensive book called Before

Photocopying: The Art & History of Mechanical Copying, 1780—1938. (“Tinctorial power” could also be called “stainability.”) The new dyes “were also thought to increase the ‘delicacy’ of the copied image, retaining more of the original character of the handwriting than was possible with the diffuse lines of iron-gall copying inks.” Copying presses, carbon paper, and typewriters all produced sharper images when vivid aniline dyes were used in place of old-fashioned natural pigments. The existence of the dyes also made possible the invention of the copying pencil—a very hard pencil whose graphite-and-clay -based lead was suffused with synthetic colorant. A letter written with a copying pencil could be copied Ofl a copying press, just as one written with copying ink could be. A copying pencil could also l)e pressed hard enough to make a legible impression with carbon paper.

Early synthetic dyes, like many newly discovered and widely embraced nineteenth-century chemical innovations, also posed serious unanticipated health risks, of which most users remained unaware for decades. Aniline (lyes were deadly poisons and could cause serious injury if, say, a user of a copying pencil accidentally stuck himself with its point. An 1899 issue of Scientific American, as quoted by Rhodes and Streeter, (described a particularly gruesome poisoning case, involving a typewriter and a woman in Cincinnati: “Hcr fingers were stained by the blue ink used on the typewriter ribbon and in trying to break a small blister on her lip she placed the stained finger on it, and very soon she felt a slight pain in her face. This was followed in a short time iw a slight swelling. The pain then became almost unendurable and her lip began to swell badly and turn black. Everything that medical skill could do was done, hut she got rapidly worse and died in great agony. The poisoned lip had swollen to gigantic proportions and nothing could reduce it.”

A MAJOR BENEFICIARY of the invention of synthetic dyes was a document reproduction technique known as stencil duplicating. Its earliest form was invented in 1874 by Eugenio de Zuccato, a young Italian studying law in London, who called his device the Papyrograph. Zuccato’s system involved writing on a sheet of varnished paper with a caustic ink, which ate through the varnish and the paper fibers, leaving holes where the writing had been. This sheet—which had now become a stencil—was placed on a blank sheet of paper, and ink was rolled over it so that the ink oozed through the holes, creating a duplicate on the second sheet. One year later, the man who invented everything, Thomas Edison, introduced a stencil duplicating device of his own: Edison’s Automatic Press and Electric Pen. This was a stylus with a sharp tip that moved rapidly up and down, like the needle on a sewing machine. The tip was powered by an electric motor the size of a fishing reel which was mounted at the other end of the pen. By carefully maneuvering the pen around an impervious sheet, a user could create a perforated stencil through which ink could depressed. (In his patents, Edison cited the “cartoons” used by artists beginning in the sixteenth century to transfer large designs to canvas: full-size paper sketches, which the artists pricked with pins and dusted with powdered charcoal or graphite, creating a dotted outline). Duplicates made with Edison’s Electric Pen had a distracting pointillist quality but were otherwise legible. The battery,.which was connected to the motor by wires, was a machine in itself: two humidor-size jars containing water and sulfuric acid mounted on an iron stand. This ungainly contraption was “the first electric motor and associated battery ever to be manufactured and sold as a working unit,” according to W B. Proudfoot, the author of The Origin of Stencil Duplicating.

In the 1880s, Albert Blake Dick—the famous A. B. Dick, whose name brought joy to any schoolboy who suddenly discovered it (as I did) on the side of a machine in the office of his school’s secretary—thought of placing a sheet of impervious paper (usually waxed) on top of a file like metal plate and then “writing” on the paper with a metal stylus in such a way that the sharp points on the plate perforated the sheet, which could then be used as a duplicating stencil. Dick was a lumberman. Like James Watt a century before him, he originally intended merely to address his own company’s copying needs. When he applied for a patent, he discovered that Edison had invented but never developed a similar idea. The two men met to discuss a licensing agreement, and Edison said, “Dick, I would give everything I own to be a young man like you again because there is so much I want to accomplish before I die.” (Dick was thirty-three at the time, and Edison was forty-two.) Dick called the new device a Mimeograph and had the marketing wisdom to give all the credit to his famous partner. Edison Mimeographs in a variety of shapes and sizes sold well for decades—by 1940, roughly half a million were in use in the United States—and A. B. Dick and his descendants eventually forgot all about two-by-fours.

Among Dick’s competitors during the late nineteenth century and early twentieth century was the Gestetner Co., which was based in England. In 1881, David Gestetner patented a device he called the Cyclostyle: a stylus with a small toothed wheel at the tip. “The waxed paper or stencil was placed not on a file plate; but on a smooth surface such as a sheet of tinned metal or zinc (a soft metal),” Proudfoot writes, “and the Cyclostyle was held in the hand like a pen. Indeed it was a pen—a wheel pen—and the teeth of the wheel, cut in the rim, effectively punctured both wax and paper, forming good perforations through which the ink could freely pass.”

Another competitor was the gelatin duplicator—more commonly known as the hectograph. It was invented in 1878 and was used for so long in so many versions that you don’t have to be a grandparent to remember taking a school exam that had been printed on one, or using one to publish a neighborhood newspaper, or making signs and posters on a REMCO Hectographic Copier (a children’s toy sold in the late 1960s).* The hectograph’s name was derived from the Greek word hekaton, meaning “hundred”—the number of legible copies that could supposedly made from a single original. In Germany, bectographs were known for a time as Schapirographs.

The idea behind the hectograph was so simple that a determined kid with sympathetic parents might hope to make one for himself. The key. component was a shallow, pagc-size tin or tray containing a mixture of gelatin and glycerin and (sometimes) a few other ingredients; it looked like a mean, unappetizing grayish Jell—O. A user created a duplicating master by writing or drawing on a sheet of paper using hectographic ink, which was similar to the copying ink used with Copying presses and contained an aniline dye. Once the ink had dried, the gelatin pad was moistened with water, and the paper was pressed, ink side down, against it. Some of the ink transferred to the gelatin, which kept it damp. Copies were made by pressing blank sheets of paper against the pad, a process that could be repeated until the last of the ink was gone. The hectograph soon evolved into more convenient versions, in which the gelatin pad was replaced by a waxed-paper master sheet, and the liquid ink was replaced by a form of carbon paper, which made distinctively purple impressions on the master. Rotary spirit duplicators, the best known of which were produced by the Ditto Co., employed versions of both innovations and were therefore direct descendants of the hectograph. The “spirit” in that name refers to methyl alcohol, a small amount of which was applied to each sheet of copy paper as it entered the machine, dampening it just enough to dissolve a bit of the waxy purple ink from the master, which was attached to a rotating drum. The alcohol gave the copies a characteristically terrible smell, adored by schoolchildren of my generation.

In all of the nineteenth century, only two true copying technologies (as opposed to duplicating technologies) were devised, and both of them had severe limitations insofar as documentary reproduction was concerned. One was photography and the other was blueprinting, which was invented in 1842 by an Englishman named Sir John Frederick WIlliam Herschel and was used mainly to reproduce engineering and architectural drawings. (A related process, called diazo, actually was used for ordinary office copying, but not until well into the twentieth century.) Blueprinting was fairly common in Europe after 1842 but was not introduced in the United States until 1876, when a Swiss exhibitor demonstrated it at the Philadelphia Centennial Exposition. To create a blueprint, a draftsman made a drawing on translucent paper; the paper was pressed, in a frame, against a sheet that had been treated with potassium ferrocyanide and ferric citrate or similar photosensitive chemicals; the paired sheets were exposed to sunlight or (after the introduction of electrical service) to a bright arc light. This exposure eventually caused the treated paper to turn dark blue except where the dark lines of the original blocked the light. Blueprinting had inherent limitations that made it all but useless for ordinary office copying: it took forever; the original was often ruined, since it was usually oiled to make it more translucent; and the chemicals smelled so horrendous that many architects and engineers preferred to use gigantic copying presses instead.

And that, more or less, is where copying technology stood in 1906, the year Chester Floyd Carlson, the inventor of xerography, was born.



CHESTER CARLSON and the Birth of the Xerox Machine.

          Copyright@2004 by David Owen


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