Ms. Sánchez was making abstractions with blocky passages of color and interconnected geometric lines and shapes. An untitled work from 1958 looks like a rendering of a complex system floating in oceanic turquoise space. As in so many other places, this kind of gestural painting had become the new Cuban avant-garde; Los Once (The Eleven), the country’s first abstract artists’ group, debuted the same year as Ms. Sánchez’s inaugural solo show, and her work was often exhibited with theirs. The 1950s were also her most expressly political years, as she participated in protest exhibitions against the dictator Fulgencio Batista.

The situation changed when Fidel Castro seized power on New Year’s Day 1959. Ms. Sánchez hasn’t said that she left because of the revolution, but already by the end of that first year, Communist Party officials were expressing doubts about the expediency of abstract art to further their cause. The homophobia of the party, and of Cuban society in general, also made it difficult for her as a queer woman making work that would go on to address lesbian desire. Ms. Sánchez moved to New York City in 1960. She would remain a citizen of Cuba but never live there again.

New York in the ’60s was a modern art mecca, yet it was an unwelcoming place for Ms. Sánchez, who didn’t speak the language and didn’t identify with the cold, impersonal style of Minimalism, despite its visual connections to her work. She found an expatriate social circle and took printmaking classes, while also holding down a series of day jobs. Most important, though, she was developing her relief paintings, or “structures,” as she then called them, the idea for which came to her when her father died several years before. The sheet from his bed had been hung out to dry, and she had seen it flapping in the wind and hitting a pipe or tube, creating a haunting, indelible image.