interest in the artistic possibilities of welding, after learning the technique whilst working in the Renault factory at Boulogne-Billancourt. This technique would subsequently become his principal contribution to sculpture, though during this period he also painted and —especially— created jewellery pieces. In 1920 he renewed his acquaintance with Picasso, for whom he later provided technical assistance in executing sculptures in iron, participating to Picasso's researches on analytic cubism. He also forged the infrastructures of Constantin Brâncuși's plasters. In the winter of 1927–28, he showed Picasso how to use oxy-fuel welding and cutting. When their friendship re-established itself, Picasso and González collaborated on a piece called Woman in the Garden between 1928–1930. From October 1928 till 1932, both men worked together—and in 1932, González was the only artist with whom Picasso shared his own personal art notebook. Influenced by Picasso, the fifty-year-old González deeply changed his style, exchanging bronze for iron, and volumes for lines. González began to formalize a new visual language in sculpture that would change the course of his career. Ironwork 1932–1937 González created ironwork at this time that would establish him as "the father of all iron sculpture of this century". During the early 1930s, few artists utilized forged or welded metal as a potential medium for their art. This is because, at the time, many artists did not directly work with the medium. Rather, artists worked with a foundry and expert technicians to execute the works of art. González was unique in this instance because his work demanded an active interaction- something that required the skills shaped by a long and specialized apprenticeship. In 1937 he contributed to the Spanish Pavilion at the World Fair in Paris (La Montserrat, standing near Guernica), and to Cubism and Abstract Art at the Museum of Modern Art in New York. 1938–1942: later years As González aged between 1938 and 1940, he drew more. These later works, as scholar Joseph Withers states, “touch on larger problems and personal concerns which necessitated our discussion of these works in the context of González's evidently pessimistic reaction to the Spanish Civil War and the Second World War. Julio González was directly affected by the Second World War; his daughter Roberta González married German painter—and Julio's assistant—Hans Hartung in 1938. When the German invasion occurred in France, the couple had to separate from the rest of the family since Hans Hartung was an anti-Nazi