and Jan Lebenstein, among others. Focused almost exclusively on non-representational art and organized by a major U.S. institution, the show championed abstraction as a symbolic manifestation of Poland's cultural and political freedom during the Cold War era. Also in 1961, art dealers Madeleine Chalette-Lejwa and Arthur Lejwa, the founders of Galerie Chalette in New York, featured Stażewski's work in a small group exhibition, offering him an early exposure to the American market. By the mid-1960s, Stażewski had begun using aluminum and copper for his relief work, shunning painted material in favor of the intrinsic color properties of metal. According to art historians Maja and Reuben Fawkes, the reliefs made of metal simulate "the effect of depth by rhythmically layering shapes and optical effects on the surface, exchanging visual determinism for the randomness of reflected light." In 1964, Kazimir Karpuszko, a Polish ex-pat art dealer, organized a show of Stażewski's work at Chicago's Contemporary Art Gallery, the artist's first solo exhibition in the United States and an opportunity to introduce his reliefs to the wider American public. In subsequent years, Stażewski's work was also shown at Marlborough-Gerson Gallery and Sidney Janis Gallery in New York. In Poland, several of Stażewski's works, including a large-scale geometrical metal sculpture modeled after one his abstract reliefs, were included in the First Biennial of Spatial Forms in Elbląg in 1965. By 1968, Stażewski had returned to polychromatic relief compositions, often made with wood on Masonite board and painted over with acrylic, frequently juxtaposing simple geometrical figures in contrasting colors to achieve a sense of visually dynamic arrangement. Referring to his sustained engagement with color during a 1968 interview, the artist said: "I gradually move from cold to warm colors according to their wavelengths, from pure to grey, from light to dark, using vertical and horizontal combinations. This gives me an infinite number of variants." Later career (1966–1988) In 1966, Stażewski was one of the artists representing Poland at the XXXIII Venice Biennale, where his relief works received an honorable mention. Throughout the 1960s, Stażewski collaborated regularly with contemporary galleries in and outside of Poland. Key among them was his long-standing collaboration with Foksal Gallery, which he co-founded in 1966, a non-commercial art space in Warsaw that would play a key role in the development of Polish post-war avant-garde. Unlike traditional exhibition venues, Foksal revolved around robust collaboration between participating artists and was supposed to present