Question: What proves the authenticity of a Pollock painting?
About the article "Jackson Pollock", section "Authenticity issues".

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In 2003, twenty-four Pollock-esque paintings and drawings were found in a locker in Wainscott, New York.
An inconclusive debate continues about whether or not these works are Pollock originals.
Physicists have argued over whether fractals can be used to authenticate the paintings.
This would require an analysis of geometric consistency of the paint splatters in Pollock's work at a microscopic level, and would be measured against the finding that patterns in Pollock's paintings increased in complexity with time.
Analysis of the synthetic pigments shows that some were not patented until the 1980s, and therefore that it is highly improbable that Pollock could have used such paints.
In 2006 a documentary, "Who the *$&% Is Jackson Pollock?"
was made concerning Teri Horton, a truck driver who in 1992 bought an abstract painting for five dollars at a thrift store in California.
This work may be a lost Pollock painting but its authenticity is debated.
Authenticity issues.
The Pollock-Krasner Authentication Board was created by the Pollock-Krasner Foundation in 1990 to evaluate newly found works for an upcoming supplement to the 1978 catalogue.
In the past, however, the Pollock-Krasner Foundation has declined to be involved in authentication cases.
"Untitled 1950", which the New York-based Knoedler Gallery had sold in 2007 for $17 million to Pierre Lagrange, a London hedge-fund multi-millionaire, was subject to an authenticity suit before the United States District Court for the Southern District of New York.
Done in the painter’s classic drip-and-splash style and signed “J.
Pollock,” the modest-size painting (15 inches by 281 1/2 inches) was found to contain yellow paint pigments not commercially available until about 1970.
The suit was settled in a confidential agreement in 2012. 
Pollock was introduced to the use of liquid paint in 1936 at an experimental workshop in New York City by the Mexican muralist David Alfaro Siqueiros.
He later used paint pouring as one of several techniques on canvases of the early 1940s, such as "Male and Female" and "Composition with Pouring I."
After his move to Springs, he began painting with his canvases laid out on the studio floor, and he developed what was later called his "drip" technique.
He started using synthetic resin-based paints called alkyd enamels, which, at that time, was a novel medium.
Pollock described this use of household paints, instead of artist’s paints, as "a natural growth out of a need".
He used hardened brushes, sticks, and even basting syringes as paint applicators.
Pollock's technique of pouring and dripping paint is thought to be one of the origins of the term action painting.
With this technique, Pollock was able to achieve a more immediate means of creating art, the paint now literally flowing from his chosen tool onto the canvas.
By defying the convention of painting on an upright surface, he added a new dimension by being able to view and apply paint to his canvases from all directions.
A possible influence on Pollock was the work of the Ukrainian American artist Janet Sobel (1894–1968) (born Jennie Lechovsky).
Peggy Guggenheim included Sobel's work in her "The Art of This Century Gallery" in 1945.
With Jackson Pollock, the critic Clement Greenberg saw Sobel's work there in 1946.
In his essay "American-Type Painting," Greenberg noted those works were the first of all-over painting he had seen, and said that "Pollock admitted that these pictures had made an impression on him".
While painting this way, Pollock moved away from figurative representation, and challenged the Western tradition of using easel and brush.
He used the force of his whole body to paint, which was expressed on the large canvases.
In 1956, "Time" magazine dubbed Pollock "Jack the Dripper," due to his painting style.
:My painting does not come from the easel.
I prefer to tack the unstretched canvas to the hard wall or the floor.
I need the resistance of a hard surface.
On the floor I am more at ease.
I feel nearer, more part of the painting, since this way I can walk around it, work from the four sides and literally be "in" the painting.
:I continue to get further away from the usual painter's tools such as easel, palette, brushes, etc.
I prefer sticks, trowels, knives and dripping fluid paint or a heavy impasto with sand, broken glass or other foreign matter added.
:When I am "in" my painting, I'm not aware of what I'm doing.
It is only after a sort of 'get acquainted' period that I see what I have been about.
I have no fear of making changes, destroying the image, etc., because the painting has a life of its own.
I try to let it come through.
It is only when I lose contact with the painting that the result is a mess.
Otherwise there is pure harmony, an easy give and take, and the painting comes out well.
::—Jackson Pollock, "My Painting", 1956 Pollock observed Indian sandpainting demonstrations in the 1940s.
Referring to his style of painting on the floor, Pollock stated, “I feel nearer, more a part of the painting, since this way I can walk round it, work from the four sides and literally be in the painting.
This is akin to the methods of the Indian sand painters of the West.” Other influences on his drip technique include the Mexican muralists and Surrealist automatism.
Pollock denied reliance on "the accident"; he usually had an idea of how he wanted a particular piece to appear.
His technique combined the movement of his body, over which he had control, the viscous flow of paint, the force of gravity, and the absorption of paint into the canvas.
It was a mixture of controllable and uncontrollable factors.
Flinging, dripping, pouring, and spattering, he would move energetically around the canvas, almost as if in a dance, and would not stop until he saw what he wanted to see.
In 1950, Hans Namuth, a young photographer, wanted to take pictures (both stills and moving) of Pollock at work.
Pollock promised to start a new painting especially for the photographic session, but when Namuth arrived, Pollock apologized and told him the painting was finished.
Namuth's said that when he entered the studio:In the 21st century, the physicists Richard Taylor, Micolich and Jonas studied Pollock's works and technique.
They determined that some works display the properties of mathematical fractals.
They assert that the works expressed more fractal qualities as Pollock progressed in his career.
The authors speculate that Pollock may have had an intuition of the nature of chaotic motion, and tried to express mathematical chaos, more than ten years before "Chaos Theory" was proposed.
Their work was used in trying to evaluate the authenticity of some works that were represented as Pollock's.
Other contemporary experts have suggested that Pollock may have imitated popular theories of the time in order to give his paintings a depth not previously seen. 
Pollock is an Atlantic fish of the genus "Pollachius".
Pollock may also refer to:In places:  Pollok, Glasgow, Scotland, UK  Pollock, Louisiana, U.S.  Pollock, Missouri, U.S.  Pollock, South Dakota, U.S.  Pollock, Texas, U.S.
In other uses:  Pollock (surname)  Jackson Pollock, an American abstract expressionist painter  "Pollock" (film), about the painter  Clan Pollock, an armigerous Scottish clan  Alaska Pollock, a Pacific fish of the genus "Theragra"  
Hans Namuth was not initially interested in the work of Jackson Pollock, but was convinced by his teacher Alexey Brodovitch that Pollock was an important painter.
In July 1950, Namuth approached Pollock and asked to photograph the artist working in his studio.
Pollock agreed, encouraged by his wife, Lee Krasner, who was aware of the importance of media coverage.
The resulting images helped to demystify Pollock's famous "drip" technique of painting, revealing it to be a deliberative process rather than a random splashing of paint.
They "helped transform Pollock from a talented, cranky loner into the first media-driven superstar of American contemporary art, the jeans-clad, chain-smoking poster boy of abstract expressionism," according to acclaimed culture critic Ferdinand Protzman.
Not satisfied with black and white stills, Namuth wanted to create a color film that managed to focus on Pollock and his painting at the same time, partially because he found more interest in Pollock's image than in his art.
His solution was to have Pollock paint on a large sheet of glass as Namuth filmed from underneath the work.
As Namuth could not afford professional lighting, the film was shot outside Pollock's Long Island home.
This documentary (co-produced with Paul Falkenberg) is considered one of the most influential for artists.
In November 1950, Namuth and Pollock's relationship came to an abrupt conclusion.
After coming in from the cold-weather shoot of the glass painting, Pollock, who had been treated in the 1930s for alcoholism, poured himself a tumbler of bourbon whiskey after supposedly having been sober for two years.
An argument between Namuth and Pollock ensued with each calling the other a "phony", culminating in Pollock overturning a table of food and dinnerware in front of several guests.
From then on, Pollock reverted to a more figure-oriented style of painting, leading some to say that Namuth's sessions robbed Pollock of his rawness and made Pollock come to feel disingenuous about doing things for the camera that he had originally done spontaneously.
Art critic Jonathan Jones suggests that by filming Pollock, Namuth "broke the myth of trance" and by framing Pollock's work in the larger surrounding landscape, destroyed Pollock's view that his paintings were boundless.
Jeffrey Potter, a close friend of Pollock's, described Namuth as commanding, frequently telling Pollock when to start and stop painting.
According to Potter, Pollock "felt what was happening was phony."
Namuth himself describes Pollock as being "very nervous and very self-conscious" of the filming at the time, but less so when Pollock discussed it in a later interview.
During his time with Pollock, Hans Namuth had created two films and captured more than 500 photographs of the artist.
These photos were first published in 1951 in "Portfolio", a journal edited by Alexey Brodovitch and Franz Zachary.
After the death of Pollock in 1956, Namuth's photos grew in popularity and were often used in articles about the painter in place of Pollock's artwork itself.
Art historian Barbara Rose states that the photographs changed art by focusing on the creation of art rather than the final product alone.
Younger artists such as Bruce Nauman, Richard Serra, and Robert Morris were able not only to view Pollock's paintings, but, with Namuth's images, to see Pollock in the act of painting, giving rise to the popularity of Process Art.
These photos have also allowed art historians to dissect the details of Pollock's method.
For example, art historian Pepe Karmel found that Pollock's painting in Namuth's first black-and-white film began with several careful drippings forming two humanoid figures and a wolf before being covered beneath several layers of paint.