Pollock interacted dynamically with the work, using unstretched canvases laid out on the floor of his studio, covering the whole surface of the canvas and using liquid paint which he dripped and spattered in thick, carefully built-up layers.
Pollock was one of the chief exponents of abstract impressionism and acknowledged numerous influences both contemporary and traditional. He is said to have observed American Indian sand-painting, and to have studied the work of Mexican muralists.
The picture is wholly abstract, and does not portray any individual, though the "H.M." of the title may refer to his friends Helen Marot or Herbert Matter. It has also been suggested that the initials may be those of the 19th century American novelist Herman Melville, author of Moby Dick.
The painting is oil on canvas and measures 36 1/8 x 43 1/8 inches. It is now in the collection of the University of Iowa Museum of Art, having been donated by Peggy Guggenheim.
A picture in the same collection, 'Mural', has been insured for $140 million. 'Portrait of HM' has appeared in several major retrospectives of Pollock's work.
Jackson Pollock (1912-1956) is one of the most significant and influential modern artists of the 20th Century.
Though he worked for a relatively short time before his premature death in 1956, his ground-breaking technique and style has continued to make him popular with museums, art galleries and collectors.
He was most famous for producing action paintings, a series of abstract works in which he abandoned the traditional format of art painted on a stretched canvas set on an easel.