Since 1970, when I first started working in an office in Houston, I have been fascinated with the dry coping process called Xerox, how it works and how it was invented. It is a long and fascinating story, but I am going to give the highlights here, and for more information copy and paste  the following link in a browser

The picture to the left is Chester Carlson, inventor of the Xerox Process

The inventor of the Xerox process, Chester Carlson, is not a name recognized by most people like Thomas Edison, or Alexander Graham Bell, but he started out as a lone inventor, similar to how they started out.

I won’t go into Carlson’s early life except to say that he came from a very poor family, and his father contracted tuberculosis and his mother contracted malaria, so Carlson had to work to support his family from an early age.

His mother died when he was 17, and his father, a short time later.

He had been fascinated with printing and graphic arts from childhood, and had experience using an old printing press to publish a few issues of a little newspaper that he started.

That experience impressed him with the difficulty of getting words into hard copy, and started him thinking about a duplicating process. He started an inventor’s notebook and jotted down ideas from time to time.

After graduating from high school, Chester was determined to get a college degree. He sometime worked as many as three jobs, to pay for his living expenses and school expenses.

He graduated from Caltech in 1930 with a B.S. in Physics at the beginning of the great depression, and had a difficult time finding a job.

As a last resort, he began working for Bell Telephone Laboratories in New York City as a research engineer. He found the work dull and routine, and after a year, Carlson transferred to the company’s patent department as a patent attorney’s assistant.

Carlson wrote over 400 ideas for new inventions in his personal notebooks while working at Bell Labs. He kept coming back to his love of printing, especially since his job in the patent department gave him new determination to find a better way to copy documents.

“In the course of my patent work,” wrote Carlson, “I frequently had need for copies of patent specifications and drawings, and there was no really convenient way of getting them at that time.”

At the time, the department primarily made copies by having typists retype the patent application in its entirety, using carbon paper to make multiple copies at once. There were other methods available, such as mimeographs and Photostats, but they were more expensive than carbon paper, and they had other limitations that made them impractical.

Carlson wanted to invent a ‘copying’ machine, that could take an existing document and copy it onto a new piece of paper without any intermediate steps.

After a series of job changes he began working at the electronics firm P. R. Mallory Company, founded by Philip Mallory (now known as the Duracell division of Procter & Gamble), where Carlson was promoted to head of the patent department.

“By 1935, Carlson wrote about this time, “I was more or less settled. I had my job, but I didn’t think I was getting ahead very fast. I was just living from hand to mouth, you might say, and I had just got married. It was kind of a hard struggle. So, I thought the possibility of making an invention might kill two birds with one stone; it would be a chance to do the world some good and also a chance to do myself some good.”

In 1936, Carlson began to study law at night at New York Law School, receiving his LL.B. degree in 1939.

He began supplementing his law studies with trips to the Public Library’s science and technology department. It was there that he was inspired by a brief article, written by Hungarian physicist Pál Selényi in an obscure German scientific journal, that showed him a way to obtain his dream machine.

Carlson’s early experiments, conducted in his apartment kitchen, were smoky, smelly, and occasionally explosive. In one set of experiments, he was melting pure crystalline sulfur (a photoconductor) onto a plate of zinc by moving it just so over the flame of his kitchen stove. This often resulted in a sulfur fire, filling the building with the smell of rotten eggs. In another experiment, the chemicals he was working with caught fire, and he and his wife were hard-pressed to extinguish the flames.

Having learned about the value of patents in his early career as a patent clerk and attorney, Carlson patented his developments every step along the way. He filed his first preliminary patent application on October 18, 1937.

By the fall of 1938, Carlson’s wife had convinced him that his experiments needed to be conducted elsewhere. He rented a room on the second floor of a house owned by his mother-in-law at 32-05 37th Street in Astoria, Queens. He hired an assistant, Otto Kornei, an out-of-work Austrian physicist.

Carlson knew that several major corporations were researching ways of copying paper. The Haloid Company had the Photostat, which it licensed to Eastman Kodak, the photography giant. However, these companies were researching along photographic lines, and their solutions required special chemicals and papers. The Photostat, for instance, was essentially a photograph of the document being copied.


Selényi’s article described a way of transmitting and printing facsimiles of printed images using a beam of directed ions directed onto a rotating drum of insulating material. The ions would create an electrostatic charge on the drum. A fine powder could then be dusted upon the drum; the powder would stick to the parts of the drum that had been charged, much as a balloon will stick to a static-charged stocking.

To this point, Carlson’s apartment-kitchen experiments in constructing a copying machine had involved trying to generate an electric current in the original piece of paper using light. Selényi’s article convinced Carlson to instead use light to ‘remove’ the static charge from a uniformly-ionized photoconductor. As no light would reflect from the black marks on the paper, those areas would remain charged on the photoconductor, and would therefore retain the fine powder. He could then transfer the powder to a fresh sheet of paper, resulting in a duplicate of the original. This approach would give his invention an advantage over the Photostat, which could create only a photographic negative of the original.

The world’s first xerographic image

On October 22, 1938, they had their historic breakthrough. Kornei wrote the words “10.-22.-38 ASTORIA.” in India ink on a glass microscope slide.  The Austrian prepared a zinc plate with a sulfur coating, darkened the room, rubbed the sulfur surface with a cotton handkerchief to apply an electrostatic charge, then laid the slide on the plate, exposing it to a bright, incandescent light. They removed the slide, sprinkled lycopodium powder to the sulfur surface, softly blew the excess away, and transferred the image to a sheet of wax paper. They heated the paper, softening the wax so the lycopodium would adhere to it, and had the world’s first xerographic copy.

To the Left is a picture of the World’s First Xerographic Copy


After repeating the experiment to be sure it worked, Carlson celebrated by taking Kornei out for a modest lunch.

Kornei was not as excited about the results of the experiment as Carlson. Within a year, he left Carlson on cordial terms. His pessimism about electrophotography was so strong that he decided to dissolve his agreement with Carlson that would have given Kornei ten percent of Carlson’s future proceeds from the invention and partial rights to the inventions they had worked on together. Years later, when Xerox stock was soaring, Carlson sent Kornei a gift of one hundred shares in the company.   Had Kornei held onto that gift, it would have been worth more than $1 million by 1972.

The road to Carlson’s success—or that for xerography’s success—had been long and filled with failure. He was turned down for funding by more than twenty companies between 1939 and 1944. He tried for some time to sell the invention to International Business Machines (IBM), the great vendor of office equipment, but no one at the company saw merit in the concept—it is not clear that anyone at IBM even ‘understood’ the concept

On October 6, 1942, the Patent Office issued Carlson’s patent on electrophotography.

Battelle Memorial Institute

When Carlson was close to giving up on getting his invention from a proof-of-concept to a usable product, happenstance provided a solution. In 1944, Russell W. Dayton, a young engineer from the Battelle Memorial Institute in Columbus, Ohio, visited the patent department at Mallory where Carlson worked. Dayton, brought in as an expert witness in a patent appeal case by Mallory, seemed to Carlson to be “the kind of fellow who looked like he was interested in new ideas.”   Although Battelle had not previously developed ideas generated by others, Dayton was fascinated by Carlson’s invention. When Carlson was invited to Columbus to demonstrate his invention, Dayton’s statement to the Battelle scientists and engineers present showed that he understood the importance of Carlson’s invention: “However crude this may seem, this is the first time any of you have seen a reproduction made without any chemical reaction and a dry process.”

By the fall of 1945, Battelle agreed to act as Carlson’s agent for his patents, pay for further research, and develop the idea. Battelle tried to interest major printing and photography companies, like Eastman Kodak and Harris-Seybold, to license the idea, but to no avail.

Haloid Company

The commercial breakthrough came when John Dessauer, chief of research at the Haloid Company, read an article about Carlson’s invention. Haloid, a manufacturer of photographic paper, was looking for a way out of the shadow of its Rochester, New York, neighbor, Eastman Kodak. Through previous acquisitions, Haloid was already in the duplicating-machine business; Dessauer thought that electrophotography might allow Haloid to expand into a new field that Kodak did not dominate.

In December 1946, Battelle, Carlson, and Haloid signed the first agreement to license electrophotography for a commercial product. The $10,000 contract—representing ten percent of Haloid’s total earnings from 1945—granted a nonexclusive right to make electophotography-based copying machines intended to make no more than twenty copies of an original. Both sides were tentative; Battelle was concerned by Haloid’s relatively small size, and Haloid had concerns about electrophotography’s viability.

In 1947, Carlson was becoming worried that Battelle was not developing electrophotography quickly enough; his patent would expire in ten years. After meeting with Joe Wilson, Carlson accepted an offer to become a consultant to Haloid. He and his wife Doris moved to the Rochester area, to be near the company’s base of operations.

By 1948, Haloid realized that it would have to make a public announcement about electrophotography in order to retain its claims to the technology. However, the term electrophotography troubled Haloid; for one thing, its use of the term “photography” invited unwelcome comparisons with traditional duplicating technologies. After considering several options, Haloid chose a term invented by a public-relations employee at Battelle, who had asked a classics professor at Ohio State University for ideas. The professor suggested the term xerography—formed by combining the Greek words xeros (“dry”) and graphein (“writing”).

Xerox Model A

On October 22, 1948, ten years to the day after that first microscope slide was copied, the Haloid Company made the first public announcement of xerography.

In 1949, it shipped the first commercial photocopier: the Xerox Model A Copier, known inside the company as the “Ox Box.” The Model A was difficult to use, requiring thirty-nine steps to make a copy, as the process was mostly manual. The product would likely have been a failure, except that it turned out to be a good way to make paper masters for offset printing presses, even with the difficulty of use. Sales of the Model A to the printing departments of companies like Ford Motor Company kept the product alive.

Haloid Xerox

In 1955, Haloid signed a new agreement with Battelle granting it full title to Carlson’s xerography patents, in exchange for fifty thousand shares of Haloid stock. Carlson received forty percent of the cash and stock from that deal, due to his agreement with Battelle.   That same year, the British motion picture company Rank Organisation was looking for a product to sit alongside a small business it had making camera lenses. Thomas A Law, who was the head of that business, found his answer in a scientific magazine he picked up by chance. He read about an invention that could produce copies of documents as good as the original. Mr Law tracked down the backers – Haloid. In order to exploit those patents in Europe, Haloid partnered with the Rank Organisation in a joint venture called Rank Xerox.

As photocopying took the world by storm, so did Rank’s profits. According to Graham Dowson, later Rank’s chief executive, it was “a stroke of luck that turned out to be a touch of genius … If Tom Law had not seen that magazine, we would not have known about xerography – or at least not before it was too late”.

The Xerox 914

The first device recognizable as a modern photocopier was the Xerox 914. Although large and crude by modern standards, it allowed an operator to place an original on a sheet of glass, press a button, and receive a copy on plain paper. Manufactured in a leased building off Orchard Street in Rochester, the 914 was introduced to the market at the Sherry Netherland Hotel in New York City on September 16, 1959. Even plagued with early problems—of the two demonstration units at the hotel, one caught fire, and one worked fine—the Xerox 914 became massively successful. Between 1959, when the Model 914 first shipped, and 1961, Haloid Xerox’s revenues nearly doubled.

In 1961, because of the success of the Xerox 914, the company changed its name again, to Xerox Corporation.

For Carlson, the commercial success of the Xerox 914 was the culmination of his life’s work: a device that could quickly and cheaply make an exact copy of an existing document. After the 914 went into production, Carlson’s involvement with Xerox declined as he began devoting his wealth to philanthropic purposes. He donated over $150 million to charitable causes during his lifetime.

On September 19, 1968, Carlson died of a heart attack in the Festival Theatre, on West 57th Street in New York.


The New York Civil Liberties Union was among the beneficiaries of his bequests. The Center for the Study of Democratic Institutions received a bequest of over $4.2 million from Carlson, in addition to the more than $4 million he had contributed while alive.

In 1981 Carlson was inducted into the National Inventors Hall of Fame.

United States Public Law 100-548, signed into law by Ronald Reagan, designated October 22, 1988, as “National Chester F. Carlson Recognition Day”. He was honored by the United States Postal Service with a 21¢ Great Americans series postage stamp.

On October 25, 2019 the New York City honored Carlson’s legacy by officially co-naming the 37th Street in Queens, NY — where his first makeshift lab was — after him.