Twentieth-century art underwent a profound transformation: in a more materialist, more consumerist society, art was directed to the senses, not to the intellect. The avant-garde movements arose, which sought to integrate art into society through a greater interrelation between artist and spectator, since it is the latter who interprets the work, being able to discover meanings that the artist did not even know. The most commonly used graphic methods were woodcut, lithography, etching and silkscreen printing, and new techniques such as color aquatint were developed. The offset printing also emerged, which revolutionized graphic art. Offset is a process similar to lithography, consisting of applying an ink on a metal plate, usually aluminum. It was the parallel product of two inventors: in 1875, the British Robert Barclay developed a version for printing on metals (tin) and, in 1903, the American Ira Washington Rubel adapted it for printing on paper. Ambroise Vollard At the turn of the century, the art dealer and gallery owner Ambroise Vollard became a significant publisher. In 1890 he opened a gallery in Paris, where he exhibited the work of artists such as Paul Gauguin, Henri Matisse, Paul Cézanne and Pierre-Auguste Renoir. In 1901 he organized the first exhibition of works by Pablo Picasso. Vollard was especially concerned with promoting the work of marginal artists, artists rejected by the official salons. A true lover of prints, his success in the sale of paintings allowed him to subsidize the editions of prints purely out of personal interest, since it rarely brought him profits. He was also concerned about the quality of the productions, always trying to have the best materials and the best technicians. Most of Vollard's production focused on limited editions for collectors, made by the best artists of the day. Another field of publishing for Vollard was the illustrated book for bibliophiles, of which he promoted twenty-two projects between 1900 and 1939. Vollard always selected the artist, whom he sometimes let select the text he would like to illustrate.